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we discuss the phenomenon of energization of relativistic charged particles in three-dimensional incompressible mhd turbulence and the diffusive properties of the motion of the same particles. we show that the random electric field induced by turbulent plasma motion leads test particles moving in a simulated box to be accelerated in a stochastic way, a second-order fermi process. a small fraction of these particles happen to be trapped in large-scale structures, most likely formed due to the interaction of islands in the turbulence. such particles get accelerated exponentially, provided their pitch angle satisfies some conditions. we discuss at length the characterization of the accelerating structure and the physical processes responsible for rapid acceleration. we also comment on the applicability of the results to realistic astrophysical turbulence. | relativistic particle transport and acceleration in structured plasma turbulence |
energetic particles represent an important component of the plasma in the heliosphere. they range from particles accelerated at impulsive events in the solar corona and at large scale structures in the interplanetary medium, to anomalous cosmic rays accelerated at the boundaries of the heliosphere. in-situ satellite observations, numerical simulations and theoretical models have advanced, often in a cooperative way, our knowledge on the acceleration processes involved. in this paper we review recent developments on particle acceleration, with major emphasis on shock acceleration, giving an overview of recent observations at interplanetary shocks and at the termination shock of the solar wind. we discuss their interpretation in terms of analytical models and numerical simulations. the influence of the particle transport properties on the acceleration mechanism will also be addressed. | recent developments in particle acceleration at shocks: theory and observations |
we provide the first combined cosmological analysis of the south pole telescope (spt) and planck cluster catalogs. the aim is to provide an independent calibration for planck scaling relations, exploiting the cosmological constraining power of the spt-sz cluster catalog and its dedicated weak lensing (wl) and x-ray follow-up observations. we build a new version of the planck cluster likelihood. in the νλ cdm scenario, focusing on the mass slope and mass bias of planck scaling relations, we find ${\alpha }_{\mathrm{sz}}={1.49}_{-0.10}^{+0.07}$ and ${\left(1-b\right)}_{\mathrm{sz}}={0.69}_{-0.14}^{+0.07}$ , respectively. the results for the mass slope show a ~4 σ departure from the self-similar evolution, α sz ~ 1.8. this shift is mainly driven by the matter density value preferred by spt data, ω m= 0.30 ± 0.03, lower than the one obtained by planck data alone, ${{\rm{\omega }}}_{m}={0.37}_{-0.06}^{+0.02}$ . the mass bias constraints are consistent both with outcomes of hydrodynamical simulations and external wl calibrations, (1 - b) ~ 0.8, and with results required by the planck cosmic microwave background cosmology, (1 - b) ~ 0.6. from this analysis, we obtain a new catalog of planck cluster masses m 500. we estimate the ratio between the published planck m sz masses and our derived masses m 500, as a "measured mass bias," ${\left(1-b\right)}_{m}$ . we analyze the mass, redshift, and detection noise dependence of ${\left(1-b\right)}_{m}$ , finding an increasing trend toward high redshift and low mass. these results mimic the effect of departure from self-similarity in cluster evolution, showing different dependencies for the low-mass, high-mass, low-z, and high-z regimes. | combining planck and spt cluster catalogs: cosmological analysis and impact on the planck scaling relation calibration |
a full-halo coronal mass ejection (cme) left the sun on 21 june 2015 from active region (ar) noaa 12371. it encountered earth on 22 june 2015 and generated a strong geomagnetic storm whose minimum dst value was −204 nt. the cme was associated with an m2-class flare observed at 01:42 ut, located near disk center (n12 e16). using satellite data from solar, heliospheric, and magnetospheric missions and ground-based instruments, we performed a comprehensive sun-to-earth analysis. in particular, we analyzed the active region evolution using ground-based and satellite instruments (big bear solar observatory (bbso), interface region imaging spectrograph (iris), hinode, atmospheric imaging assembly (aia) onboard the solar dynamics observatory (sdo), reuven ramaty high energy solar spectroscopic imager (rhessi), covering hα , euv, uv, and x-ray data); the ar magnetograms, using data from sdo/helioseismic and magnetic imager (hmi); the high-energy particle data, using the payload for antimatter matter exploration and light-nuclei astrophysics (pamela) instrument; and the rome neutron monitor measurements to assess the effects of the interplanetary perturbation on cosmic-ray intensity. we also evaluated the 1 - 8 å soft x-ray data and the ∼1 mhz type iii radio burst time-integrated intensity (or fluence) of the flare in order to predict the associated solar energetic particle (sep) event using the model developed by laurenza et al. (space weather7(4), 2009). in addition, using ground-based observations from lower to higher latitudes (international real-time magnetic observatory network (intermagnet) and european quasi-meridional magnetometer array (emma)), we reconstructed the ionospheric current system associated with the geomagnetic sudden impulse (si). furthermore, super dual auroral radar network (superdarn) measurements were used to image the global ionospheric polar convection during the si and during the principal phases of the geomagnetic storm. in addition, to investigate the influence of the disturbed electric field on the low-latitude ionosphere induced by geomagnetic storms, we focused on the morphology of the crests of the equatorial ionospheric anomaly by the simultaneous use of the global navigation satellite system (gnss) receivers, ionosondes, and langmuir probes onboard the swarm constellation satellites. moreover, we investigated the dynamics of the plasmasphere during the different phases of the geomagnetic storm by examining the time evolution of the radial profiles of the equatorial plasma mass density derived from field line resonances detected at the emma network (1.5 <l <6.5 ). finally, we present the general features of the geomagnetic response to the cme by applying innovative data analysis tools that allow us to investigate the time variation of ground-based observations of the earth's magnetic field during the associated geomagnetic storm. | comprehensive analysis of the geoeffective solar event of 21 june 2015: effects on the magnetosphere, plasmasphere, and ionosphere systems |
earth and its magnetosphere are immersed in the supersonic flow of the solar-wind plasma that fills interplanetary space. as the solar wind slows and deflects to flow around earth, or any other obstacle, a `bow shock' forms within the flow. under almost all solar-wind conditions, planetary bow shocks such as earth's are collisionless, supercritical shocks, meaning that they reflect and accelerate a fraction of the incident solar-wind ions as an energy dissipation mechanism1,2, which results in the formation of a region called the ion foreshock3. in the foreshock, large-scale, transient phenomena can develop, such as `hot flow anomalies'4-9, which are concentrations of shock-reflected, suprathermal ions that are channelled and accumulated along certain structures in the upstream magnetic field. hot flow anomalies evolve explosively, often resulting in the formation of new shocks along their upstream edges5,10, and potentially contribute to particle acceleration11-13, but there have hitherto been no observations to constrain this acceleration or to confirm the underlying mechanism. here we report observations of a hot flow anomaly accelerating solar-wind ions from roughly 1-10 kiloelectronvolts up to almost 1,000 kiloelectronvolts. the acceleration mechanism depends on the mass and charge state of the ions and is consistent with first-order fermi acceleration14,15. the acceleration that we observe results from only the interaction of earth's bow shock with the solar wind, but produces a much, much larger number of energetic particles compared to what would typically be produced in the foreshock from acceleration at the bow shock. such autogenous and efficient acceleration at quasi-parallel bow shocks (the normal direction of which are within about 45 degrees of the interplanetary magnetic field direction) provides a potential solution to fermi's `injection problem', which requires an as-yet-unexplained seed population of energetic particles, and implies that foreshock transients may be important in the generation of cosmic rays at astrophysical shocks throughout the cosmos. | autogenous and efficient acceleration of energetic ions upstream of earth's bow shock |
high-energy gamma-ray emission from supernova remnants (snrs) has provided a unique perspective for studies of galactic cosmic-ray acceleration. tycho’s snr is a particularly good target because it is a young, type ia snr that has been well-studied over a wide range of energies and located in a relatively clean environment. since the detection of gamma-ray emission from tycho’s snr by veritas and fermi-lat, there have been several theoretical models proposed to explain its broadband emission and high-energy morphology. we report on an update to the gamma-ray measurements of tycho’s snr with 147 hr of veritas and 84 months of fermi-lat observations, which represent about a factor of two increase in exposure over previously published data. about half of the veritas data benefited from a camera upgrade, which has made it possible to extend the tev measurements toward lower energies. the tev spectral index measured by veritas is consistent with previous results, but the expanded energy range softens a straight power-law fit. at energies higher than 400 gev, the power-law index is 2.92 ± 0.42stat ± 0.20sys. it is also softer than the spectral index in the gev energy range, 2.14 ± 0.09stat ± 0.02sys, measured in this study using fermi-lat data. the centroid position of the gamma-ray emission is coincident with the center of the remnant, as well as with the centroid measurement of fermi-lat above 1 gev. the results are consistent with an snr shell origin of the emission, as many models assume. the updated spectrum points to a lower maximum particle energy than has been suggested previously. | gamma-ray observations of tycho’s supernova remnant with veritas and fermi |
we present sensitive 870 μm continuum measurements from our alma programmes of 114 x-ray selected active galactic nuclei (agn) in the chandra deep field-south and cosmic evolution survey fields. we use these observations in combination with data from spitzer and herschel to construct a sample of 86 x-ray selected agn, 63 with alma constraints at z = 1.5-3.2 with stellar mass >2 × 1010 m⊙. we constructed broad-band spectral energy distributions in the infrared band (8-1000 μm) and constrain star-formation rates (sfrs) uncontaminated by the agn. using a hierarchical bayesian method that takes into account the information from upper limits, we fit sfr and specific sfr (ssfr) distributions. we explore these distributions as a function of both x-ray luminosity and stellar mass. we compare our measurements to two versions of the evolution and assembly of galaxies and their environments (eagle) hydrodynamical simulations: the reference model with agn feedback and the model without agn. we find good agreement between the observations and that predicted by the eagle reference model for the modes and widths of the ssfr distributions as a function of both x-ray luminosity and stellar mass; however, we found that the eagle model without agn feedback predicts a significantly narrower width when compared to the data. overall, from the combination of the observations with the model predictions, we conclude that (1) even with agn feedback, we expect no strong relationship between the ssfr distribution parameters and instantaneous agn luminosity and (2) a signature of agn feedback is a broad distribution of ssfrs for all galaxies (not just those hosting an agn) with stellar masses above ≈1010 m⊙. | identifying the subtle signatures of feedback from distant agn using alma observations and the eagle hydrodynamical simulations |
active galactic nuclei (agn) are believed to be promising candidates of extragalactic cosmic-ray accelerators and sources, and associated high-energy neutrino and hadronic gamma-ray emission has been studied for many years. we review models of high-energy neutrino production in agn and discuss their implications for the latest icecube observation of the diffuse neutrino intensity. | active galactic nuclei as high-energy neutrino sources |
we study the heat engine by a $d$-dimensional charged anti-de sitter black hole by making a comparison between the small-large black hole phase transition and the liquid-vapour phase transition of water. with the help of the first law and equal-area law, we obtain an exact formula for the efficiency of a black hole engine modeled with a rankine cycle with or without a back pressure mechanism. when the low temperature is fixed, both the heat and work decreases with the high temperature $t_{1}$. and the efficiency increases with $t_{1}$, while decreases with the charge $q$. for a rankine cycle with a back pressure mechanism, we find that both the maximum work and efficiency can be approached at the high temperature $t_{1}$. in the reduced parameter space, it also confirms the similar result. moreover, we observe that the work and efficiency of the black hole heat engine rapidly increase with the number of spacetime dimensions. thus higher-dimensional charged anti-de sitter black hole can act as a more efficient power plant producing the mechanical work, and might be a possible source of the power gamma rays and ultrahigh-energy cosmic rays. | charged ads black hole heat engines |
an accurate modelling of baryonic feedback effects is required to exploit the full potential of future weak-lensing surveys such as euclid or lsst . in this second paper in a series of two, we combine euclid-like mock data of the cosmic shear power spectrum with an erosita x-ray mock of the cluster gas fraction to run a combined likelihood analysis including both cosmological and baryonic parameters. following the first paper of this series, the baryonic effects (based on the baryonic correction model of ref. [1]) are included in both the tomographic power spectrum and the covariance matrix. however, this time we assume the more realistic case of a λcdm cosmology with massive neutrinos and we consider several extensions of the currently favoured cosmological model. for the standard λcdm case, we show that including x-ray data reduces the uncertainties on the sum of the neutrino mass by ~30 percent, while there is only a mild improvement on other parameters such as ωm and σ8. as extensions of λcdm, we consider the cases of a dynamical dark energy model (wcdm), a f(r) gravity model (frcdm), and a mixed dark matter model (λmdm) with both a cold and a warm/hot dark matter component. we find that combining weak-lensing with x-ray data only leads to a mild improvement of the constraints on the additional parameters of wcdm, while the improvement is more substantial for both frcdm and λmdm . ignoring baryonic effects in the analysis pipeline leads to significant false-detections of either phantom dark energy or a light subdominant dark matter component. overall we conclude that for all cosmologies considered, a general parametrisation of baryonic effects is both necessary and sufficient to obtain tight constraints on cosmological parameters. | baryonic effects for weak lensing. part ii. combination with x-ray data and extended cosmologies |
supernovae (sne) with strong interactions with circumstellar material (csm) are promising candidate sources of high-energy neutrinos and gamma-rays and have been suggested as an important contributor to galactic cosmic rays (crs) beyond 1015 ev. taking into account the shock dissipation by a fast velocity component of sn ejecta, we present comprehensive calculations of the nonthermal emission from sne powered by shock interactions with a dense wind or csm. remarkably, we consider electromagnetic cascades in the radiation zone and subsequent attenuation in the pre-shock csm. a new time-dependent phenomenological prescription provided by this work enables us to calculate gamma-ray, hard x-ray, radio, and neutrino signals, which originate from crs accelerated by the diffusive shock acceleration (dsa) mechanism. we apply our results to type iin sn 2010jl and type ib/iin sn 2014c, for which the model parameters can be determined from the multiwavelength data. for sn 2010jl, the more promising case, by using the the latest fermi large area telescope pass 8 data release, we derive new constraints on the cr energy fraction, ɛp≲ 0.05-0.1. we also find that the late-time radio data of these interacting sne are consistent with our model. further multimessenger and multiwavelength observations of nearby interacting sne should give us new insights into the dsa in dense environments, as well as pre-sn mass-loss mechanisms. | high-energy emission from interacting supernovae: new constraints on cosmic-ray acceleration in dense circumstellar environments |
the nearby chamaeleon clouds have been observed in γ rays by the fermi large area telescope (lat) and in thermal dust emission by planck and iras. cosmic rays and large dust grains, if smoothly mixed with gas, can jointly serve with the h i and 12co radio data to (i) map the hydrogen column densities, nh, in the different gas phases, in particular at the dark neutral medium (dnm) transition between the h i-bright and co-bright media; (ii) constrain the co-to-h2 conversion factor, xco; and (iii) probe the dust properties per gas nucleon in each phase and map their spatial variations across the clouds. we have separated clouds at local, intermediate, and galactic velocities in h i and 12co line emission to model in parallel the γ-ray intensity recorded between 0.4 and 100 gev; the dust optical depth at 353 ghz, τ353; the thermal radiance of the large grains; and an estimate of the dust extinction, avq, empirically corrected for the starlight intensity. the dust and γ-ray models have been coupled to account for the dnm gas. the consistent γ-ray emissivity spectra recorded in the different phases confirm that the gev-tev cosmic rays probed by the lat uniformly permeate all gas phases up to the 12co cores. the dust and cosmic rays both reveal large amounts of dnm gas, with comparable spatial distributions and twice as much mass as in the co-bright clouds. we give constraints on the h i-dnm-co transitions for five separate clouds. co-dark h2 dominates the molecular columns up to av ≃ 0.9 and its mass often exceeds the one-third of the molecular mass expected by theory. the corrected avq extinction largely provides the best fit to the total gas traced by the γ rays. nevertheless, we find evidence for a marked rise in avq/nh with increasing nh and molecular fraction, and with decreasing dust temperature. the rise in τ353/nh is even steeper. we observe variations of lesser amplitude and orderliness for the specific power of the grains, except for a coherent decline by half in the co cores. this combined information suggests grain evolution. we provide average values for the dust properties per gas nucleon in the different phases. the γ rays and dust radiance yield consistent xco estimates near 0.7 × 1020 cm-2 k-1 km-1 s. the avq and τ353 tracers yield biased values because of the large rise in grain opacity in the co clouds. these results clarify a recurrent disparity in the γ-ray versus dust calibration of xco, but they confirm the factor of 2 difference found between the xco estimates in nearby clouds and in the neighbouring spiral arms. appendices are available in electronic form at http://www.aanda.org | planck intermediate results. xxviii. interstellar gas and dust in the chamaeleon clouds as seen by fermi lat and planck |
we present a series of new, publicly available mock catalogs of x-ray selected active galactic nuclei (agns), nonactive galaxies, and clusters of galaxies. these mocks are based on up-to-date observational results on the demographic of extragalactic x-ray sources and their extrapolations. they reach fluxes below 10-20 erg cm-2 s-1 in the 0.5-2 kev band, that is, more than an order of magnitude below the predicted limits of future deep fields, and they therefore represent an important tool for simulating extragalactic x-ray surveys with both current and future telescopes. we used our mocks to perform a set of end-to-end simulations of x-ray surveys with the forthcoming athena mission and with the axis probe, a subarcsecond resolution x-ray mission concept proposed to the astro 2020 decadal survey. we find that these proposed, next generation surveys may transform our knowledge of the deep x-ray universe. as an example, in a total observing time of 15 ms, axis would detect ∼225 000 agns and ∼50 000 nonactive galaxies, reaching a flux limit of f0.5-2 ∼ 5 × 10-19 erg cm-2 s-1 in the 0.5-2 kev band, with an improvement of over an order of magnitude with respect to surveys with current x-ray facilities. consequently, 90% of these sources would be detected for the first time in the x-rays. furthermore, we show that deep and wide x-ray surveys with instruments such as axis and athena are expected to detect ∼20 000 z > 3 agns and ∼250 sources at redshift z > 6, thus opening a new window of knowledge on the evolution of agns over cosmic time and putting strong constraints on the predictions of theoretical models of black hole seed accretion in the early universe. | mock catalogs for the extragalactic x-ray sky: simulating agn surveys with athena and with the axis probe |
very recently, the tibet-as$\gamma$ collaboration reported the detection of $\gamma$ rays from the galactic disk in the energy range of 100 tev -- 1 pev. remarkably, many of these $\gamma$ rays were observed apart from known very high energy (e$>$ 100 gev) $\gamma$-ray sources. these results are best understood if these diffuse $\gamma$ rays: 1) were produced by a conventional rather than an exotic (i.e. dark matter decay or annihilation) process, 2) have a hadronic rather than a leptonic origin, 3) were produced in impulsive rather than stable sources or, alternatively, in optically thick sources. in addition to that, the detection of the sub-pev diffuse $\gamma$ rays implies a limit on the flux of neutrinos from the galactic disk and a lower limit on the rigidity of the cutoff in the galactic cosmic ray spectrum. | implications of the detection of sub-pev diffuse $\\gamma$ rays from the galactic disk apart from discrete sources |
jellyfish galaxies, characterized by long filaments of stripped interstellar medium extending from their disks, are the prime laboratories to study the outcomes of ram pressure stripping. at radio wavelengths, they often show unilateral emission extending beyond the stellar disk, and an excess of radio luminosity with respect to that expected from their current star formation rate. we present new 144 mhz images provided by the lofar two-metre sky survey for a sample of six galaxies from the gasp survey. these galaxies are characterized by a high global luminosity at 144 mhz (6-27 × 1022 w hz-1), in excess compared to their ongoing star formation rate. the comparison of radio and hα images smoothed with a gaussian beam corresponding to ~10 kpc reveals a sublinear spatial correlation between the two emissions with an average slope of k = 0.50. in their stellar disk we measure k = 0.77, which is close to the radio-to-star formation linear relation. we speculate that, as a consequence of the ram pressure, in these jellyfish galaxies cosmic ray transport is more efficient than in normal galaxies. radio tails typically have higher radio-to-hα ratios than the disks, thus we suggest that the radio emission is boosted by electrons stripped from the disks. in all galaxies, the star formation rate has decreased by a factor ≤10 within the last ~108 yr. the observed radio emission is consistent with the past star formation, so we propose that this recent decline may be the cause of their radio luminosity-to-star formation rate excess. | walk on the low side: lofar explores the low-frequency radio emission of gasp jellyfish galaxies |
the direct detection of particle dark matter through its scattering with nucleons is of fundamental importance to understand the nature of dm . in this work, we propose that the high-energy neutrino detectors like icecube can be used to uniquely probe the dm-nucleon cross-section for high-energy dm of ~ pev, up-scattered by the high-energy cosmic rays. we derive for the first time strong constraints on the dm-nucleon cross-section down to ~ 10-32 cm2 at this energy scale for sub-gev dm candidates. such independent probe at energy scale far exceeding other existing direct detection experiments can therefore provide useful insights complementary to other searches. | probing cosmic-ray accelerated light dark matter with icecube |
context. we present the forward cosmological analysis of an xmm-selected sample of galaxy clusters out to a redshift of unity. we derive mass-observable relations in a self-consistent manner using the sample alone. special care is given to the modelling of selection effects.aims: following our previous 2018 study based on the dn/dz quantity alone, we perform an upgraded cosmological analysis of the same xxl c1 cluster catalogue (178 objects), with a detailed account of the systematic errors. the results are combined with external constraints from baryon acoustic oscillations (bao) and the cosmic microwave background (cmb).methods: this study follows the aspix methodology: we analysed the distribution of the observed x-ray properties of the cluster population in a 3d observable space (count rate, hardness ratio, redshift) and modelled as a function of cosmology along with the scaling relations and the selection function. compared to more traditional methods, aspix allows the inclusion of clusters down to a few tens of photons and is much simpler to use. two m − t relations are considered: that from the canada-france-hawaii telescope (hereafter cfht) and another from the more recent subaru lensing analyses.results: we obtain an improvement by a factor of two compared to the previous analysis, which dealt with the cluster redshift distribution for the xxl sample alone, letting the normalisation of the m − t relation and the evolution of the l-t relation free. adding constraints from the xxl cluster two-point correlation function and the bao from various surveys decreases the uncertainties by 23% and 53%, respectively, and 62% when adding both. the central value is in excellent agreement with the planck cmb constraints. switching to the scaling relations from the subaru analysis and leaving more parameters free to vary provides less stringent constraints, but those obtained are still consistent with the planck cmb at the 1-sigma level. our final constraints are σ8 = 0.99+0.14-0.23 , ωm = 0.296 ± 0.034 (s8 = 0.98+0.11-0.21 ) for the xxl sample alone. combining xxl aspix, the xxl cluster two-point correlation function, and the bao, leaving 11 parameters free to vary, and allowing for the cosmological dependence of the scaling relations in the fit induces a shift of the central values, which is reminiscent of that observed for the planck s-z cluster sample. we find σ8 = 0.793+0.063-0.12 and ωm = 0.364 ± 0.015 (s8 = 0.872+0.068-0.12 ), which are still compatible with planck cmb at 2.2σ.conclusions: the results obtained by the aspix method are promising; further improvement is expected from the final xxl cosmological analysis involving a cluster sample that is twice as large. such a study paves the way for the analysis of the erosita and future athena surveys. | the xxl survey. xlvi. forward cosmological analysis of the c1 cluster sample |
in this work, we extend the work on the recently discovered role of cosmic rays (crs) in regulating the average co/h_2 abundance ratio in molecular clouds (and thus their co line visibility) in starburst galaxies, and find that it can lead to a co-poor/c i-rich h_2 gas phase even in environments with galactic or in only modestly enhanced cr backgrounds expected in ordinary star-forming galaxies. furthermore, the same cr-driven astro-chemistry raises the possibility of a widespread phase transition of a molecular gas towards a co-poor/ci-rich phase in: (a) molecular gas outflows found in star-forming galaxies, (b) active galactic nuclei (agns), and (c) near synchrotron-emitting radio jets and the radio-loud cores of powerful radio galaxies. for main sequence galaxies we find that crs can render some of their molecular gas mass co-invisible, compounding the effects of low metallicities. imaging the two fine structure lines of atomic carbon with resolution high enough to search beyond the ci/co-bright line regions associated with central starbursts can reveal such a co-poor/c i-rich molecular gas phase, provided that relative brightness sensitivity levels of tb(c i 1 - 0)/tb(co j = 1 - 0) ∼0.15 are reached. the capability to search for such gas in the galaxy is now at hand with the new high-frequency survey telescope heat deployed in antarctica and future ones to be deployed in dome a. alma can search for such gas in star-forming spiral discs, galactic molecular gas outflows, and the cr-intense galactic and circumgalactic gas-rich environments of radio-loud objects. | new places and phases of co-poor/c i-rich molecular gas in the universe |
this study was conducted to evaluate the performance of a preliminary soil moisture product estimated from the cosmic-ray neutron probe (crnp) installed at a densely vegetated and monsoon climate area, namely the soil moisture - fdr and cosmic-ray (sm-fc) site in south korea. in this study, different calibration approaches, considering soil wetness conditions, were evaluated to select the most appropriate calibration method for deriving the best cosmic-ray soil moisture at the sm-fc site. we tested the potential application of two horizontal-vertical weighting methods, including the linear and non-linear approaches, with regard to the specific characteristics of the sm-fc site. the comparison of the two weighting approaches for in-situ soil moisture measurement suggested that the linear approach provided better performance compared to the non-linear in term of representing field-average soil moisture within the crnp footprint. our calibration results revealed that dry condition-based calibration outperformed wet condition-based calibration. the comparison of the cosmic-ray soil moisture utilizing dry condition-based calibration showed reasonable agreement with the linear weighted average soil moisture estimated from the fdr sensor network, with rmse = 0.035 m3 m-3, and bias = -0.003 m3 m-3; while the worst calibration solution with the wettest conditions had rmse and bias values of 0.077 m3 m-3 and 0.063 m3 m-3, respectively. the application of a biomass correction significantly improved the cosmic-ray soil moisture product at the sm-fc site, resulting in the reduction of rmse from 0.035 to 0.013 m3 m-3. a temporal stability analysis was conducted to demonstrate the feasibility of cosmic-ray soil moisture in representing soil moisture for a large heterogeneous sm-fc site. our temporal stability analysis results indicated the representativeness of cosmic-ray soil moisture over an area with a high degree of heterogeneity, compared to single measurements from fdr stations. | evaluation of the soil water content using cosmic-ray neutron probe in a heterogeneous monsoon climate-dominated region |
drift effects play a significant role in the transport of charged particles in the heliosphere. a turbulent magnetic field is also known to reduce the effects of particle drifts. the exact nature of this reduction, however, is not clear. this study aims to provide some insight into this reduction and proposes a relatively simple, tractable means of modeling it that provides results in reasonable agreement with numerical simulations of the drift coefficient in a turbulent magnetic field. | toward a greater understanding of the reduction of drift coefficients in the presence of turbulence |
cosmogenic nuclide records can in principle allow for the estimation of the behavior of the heliospheric magnetic field (hmf) in the distant past. this requires careful modeling of cosmic-ray transport in a manner that is as realistic as possible, taking into account as many of the factors affecting the transport of cosmic-rays (crs) as possible. the present study presents a 3d time-dependent ab initio cr modulation code that utilizes as inputs simple theoretically and observationally motivated temporal profiles to model large-scale (such as the tilt angle) and small-scale (such as the magnetic variance) parameters relevant to cr transport. galactic cr proton differential intensities computed using this model for the period 1977-2001 are in reasonable to good agreement with spacecraft observations, reproducing the major salient features of the observed cr intensity temporal profile. to investigate pre-space-age cosmic-ray modulation, and to test conclusions previously drawn regarding the relative importance of drift effects on said modulation, historic estimates of the past hmf presented by mccracken & beer were used as inputs for the model. the resulting cr temporal intensity profile displays clear evidence of drift effects, with a sharp peak in intensities during the dalton minimum. | a fully time-dependent ab initio cosmic-ray modulation model applied to historical cosmic-ray modulation |
we perform a complete study of the gravitational lensing effect beyond the born approximation on the cosmic microwave background (cmb) anisotropies using a multiple-lens raytracing technique through cosmological n-body simulations of the demnuni suite. the impact of second-order effects accounting for the non-linear evolution of large-scale structures is evaluated propagating for the first time the full cmb lensing jacobian together with the light rays trajectories. we carefully investigate the robustness of our approach against several numerical effects in the raytracing procedure and in the n-body simulation itself, and find no evidence of large contaminations. we discuss the impact of beyond-born corrections on lensed cmb observables, and compare our results with recent analytical predictions that appeared in the literature, finding a good agreement, and extend these results to smaller angular scales. we measure the gravitationally-induced cmb polarization rotation that appears in the geodesic equation at second order, and compare this result with the latest analytical predictions. we then present the detection prospect of beyond-born effects with the future cmb-s4 experiment. we show that corrections to the temperature power spectrum can be measured only if a good control of the extragalactic foregrounds is achieved. conversely, the beyond-born corrections on e and b-modes power spectra will be much more difficult to detect. | cmb weak-lensing beyond the born approximation: a numerical approach |
we present results from radiation non-ideal magnetohydrodynamics (mhd) calculations that follow the collapse of rotating, magnetized, molecular cloud cores to stellar densities. these are the first such calculations to include all three non-ideal effects: ambipolar diffusion, ohmic resistivity, and the hall effect. we employ an ionization model in which cosmic ray ionization dominates at low temperatures and thermal ionization takes over at high temperatures. we explore the effects of varying the cosmic ray ionization rate from ζcr = 10-10 to 10-16 s-1. models with ionization rates ≳10-12 s-1 produce results that are indistinguishable from ideal mhd. decreasing the cosmic ray ionization rate extends the lifetime of the first hydrostatic core up to a factor of 2, but the lifetimes are still substantially shorter than those obtained without magnetic fields. outflows from the first hydrostatic core phase are launched in all models, but the outflows become broader and slower as the ionization rate is reduced. the outflow morphology following stellar core formation is complex and strongly dependent on the cosmic ray ionization rate. calculations with high ionization rates quickly produce a fast (≈14 km s-1) bipolar outflow that is distinct from the first core outflow, but with the lowest ionization rate, a slower (≈3-4 km s-1) conical outflow develops gradually and seamlessly merges into the first core outflow. | the collapse of a molecular cloud core to stellar densities using radiation non-ideal magnetohydrodynamics |
the supernova remnant (snr) w49b originated from a core-collapse supernova that occurred between one and four thousand years ago, and subsequently evolved into a mixed-morphology remnant, which is interacting with molecular clouds (mc). gamma-ray observations of snr-mc associations are a powerful tool to constrain the origin of galactic cosmic rays, as they can probe the acceleration of hadrons through their interaction with the surrounding medium and subsequent emission of non-thermal photons. we report the detection of a γ-ray source coincident with w49b at very high energies (vhe; e > 100 gev) with the h.e.s.s. cherenkov telescopes together with a study of the source with five years of fermi-lat high-energy γ-ray (0.06-300 gev) data. the smoothly connected, combined source spectrum, measured from 60 mev to multi-tev energies, shows two significant spectral breaks at 304 ± 20 mev and 8.4-2.5+2.2 gev; the latter is constrained by the joint fit from the two instruments. the detected spectral features are similar to those observed in several other snr-mc associations and are found to be indicative of γ-ray emission produced through neutral-pion decay. the h.e.s.s. gamma-ray excess map (see fig. 1, in fits format) of the w49 region is only available at the cds via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?j/a+a/612/a5 | the supernova remnant w49b as seen with h.e.s.s. and fermi-lat |
we have performed a multi-wavelength analysis of two galaxy cluster systems selected with the thermal sunyaev-zel'dovich (tsz) effect and composed of cluster pairs and an inter-cluster filament. we have focused on one pair of particular interest: a399-a401 at redshift z ~ 0.073 seperated by 3 mpc. we have also performed the first analysis of one lower-significance newly associated pair: a21-psz2 g114.09-34.34 at z ~ 0.094, separated by 4.2 mpc. we have characterised the intra-cluster gas using the tsz signal from planck and, when possible, the galaxy optical and infrared (ir) properties based on two photometric redshift catalogues: 2mpz and wisexscos. from the tsz data, we measured the gas pressure in the clusters and in the inter-cluster filaments. in the case of a399-a401, the results are in perfect agreement with previous studies and, using the temperature measured from the x-rays, we further estimate the gas density in the filament and find n0 = (4.3 ± 0.7) × 10-4 cm-3. the optical and ir colour-colour and colour-magnitude analyses of the galaxies selected in the cluster system, together with their star formation rate, show no segregation between galaxy populations, both in the clusters and in the filament of a399-a401. galaxies are all passive, early type, and red and dead. the gas and galaxy properties of this system suggest that the whole system formed at the same time and corresponds to a pre-merger, with a cosmic filament gas heated by the collapse. for the other cluster system, the tsz analysis was performed and the pressure in the clusters and in the inter-cluster filament was constrained. however, the limited or nonexistent optical and ir data prevent us from concluding on the presence of an actual cosmic filament or from proposing a scenario. | gas and galaxies in filaments between clusters of galaxies. the study of a399-a401 |
the telescope array (ta) experiment is designed to detect air showers induced by ultra high energy cosmic rays. the ta ground surface particle detector (tasd) observed several short-time bursts of air shower like events. these bursts are not likely due to chance coincidence between single shower events. the expectation of chance coincidence is less than 10-4 for five-year's observation. we checked the correlation between these bursts of events and lightning data, and found evidence for correlations in timing and position. some features of the burst events are similar to those of a normal cosmic ray air shower, and some are not. on this paper, we report the observed bursts of air shower like events and their correlation with lightning. | the bursts of high energy events observed by the telescope array surface detector |
biological molecules chose one of two structurally chiral systems which are related by reflection in a mirror. it is proposed that this choice was made, causally, by cosmic rays, which are known to play a major role in mutagenesis. it is shown that magnetically polarized cosmic rays that dominate at ground level today can impose a small, but persistent, chiral bias in the rate at which they induce structural changes in simple, chiral monomers that are the building blocks of biopolymers. a much larger effect should be present with helical biopolymers, in particular, those that may have been the progenitors of ribonucleic acid and deoxyribonucleic acid. it is shown that the interaction can be both electrostatic, just involving the molecular electric field, and electromagnetic, also involving a magnetic field. it is argued that this bias can lead to the emergence of a single, chiral life form over an evolutionary timescale. if this mechanism dominates, then the handedness of living systems should be universal. experiments are proposed to assess the efficacy of this process. | the chiral puzzle of life |
the universe goes through several phase transitions during its formative stages. cosmic reionization is the last of them, where ultraviolet and x-ray radiation escape from the first generations of galaxies heating and ionizing their surroundings and subsequently the entire intergalactic medium. there is strong observational evidence that cosmic reionization ended approximately one billion years after the big bang, but there are still uncertainties that will be clarified with upcoming optical, infrared, and radio facilities in the next decade. this article gives an introduction to the theoretical and observational aspects of cosmic reionization and discusses their role in our understanding of early galaxy formation and cosmology. | an introductory review on cosmic reionization |
we present a revised measurement of the optical extragalactic background light (ebl), based on the contribution of resolved galaxies to the integrated galaxy light (igl). the cosmic optical background radiation (cob), encodes the light generated by star formation, and provides a wealth of information about the cosmic star formation history (csfh). we combine wide and deep galaxy number counts from the galaxy and mass assembly survey (gama) and deep extragalactic visible legacy survey (devils), along with the hubble space telescope (hst) archive and other deep survey data sets, in nine multiwavelength filters to measure the cob in the range from 0.35 μm to 2.2 μm. we derive the luminosity density in each band independently and show good agreement with recent and complementary estimates of the optical-ebl from very high-energy (vhe) experiments. our error analysis suggests that the igl and γ-ray measurements are now fully consistent to within $\sim 10{{\ \rm per\ cent}}$, suggesting little need for any additional source of diffuse light beyond the known galaxy population. we use our revised igl measurements to constrain the csfh, and place amplitude constraints on a number of recent estimates. as a consistency check, we can now demonstrate convincingly, that the csfh, stellar mass growth, and the optical-ebl provide a fully consistent picture of galaxy evolution. we conclude that the peak of star formation rate lies in the range 0.066-0.076 m⊙ yr-1 mpc-3 at a lookback time of 9.1 to 10.9 gyr. | gama/devils: constraining the cosmic star formation history from improved measurements of the 0.3-2.2 μm extragalactic background light |
we present new karl g. jansky very large array radio continuum images of the nuclei of arp 220, the nearest ultra-luminous infrared galaxy. these new images have both the angular resolution to study the detailed morphologies of the two nuclei that power the galaxy merger and sensitivity to a wide range of spatial scales. at 33 ghz, we achieve a resolution of 0.''081 × 0.''063 (29.9 × 23.3 pc) and resolve the radio emission surrounding both nuclei. we conclude from the decomposition of the radio spectral energy distribution that a majority of the 33 ghz emission is synchrotron radiation. the spatial distributions of radio emission in both nuclei are well described by exponential profiles. these have deconvolved half-light radii (r 50d ) of 51 and 35 pc for the eastern and western nuclei, respectively, and they match the number density profile of radio supernovae observed with very long baseline interferometry. this similarity might be due to the fast cooling of cosmic rays electrons caused by the presence of a strong (~mg) magnetic field in this system. we estimate extremely high molecular gas surface densities of 2.2+2.1-1.0 × 10^5 (east) and 4.5+4.5-1.9 × 10^5 (west) m ⊙ pc-2, corresponding to total hydrogen column densities of n h = 2.7+2.7-1.2 × 1025 (east) and 5.6+5.5-2.4 × 1025 cm-2 (west). the implied gas volume densities are similarly high, {nh_{_2} ∼ 3.8+3.8-1.6 × 10^4} (east) and {∼ } 11+12-4.5 × 10^4 cm-3 (west). we also estimate very high luminosity surface densities of σ _ir ∼ 4.2+1.6-0.7 × 1013 (east) and σ _ir ∼ 9.7+3.7-2.4 × 1013 (west) l⊙kpc-2, and star formation rate surface densities of σsfr ~ 103.7 ± 0.1 (east) and σsfr ~ 104.1 ± 0.1(west) m ⊙ yr-1kpc-2. these values, especially for the western nucleus are, to our knowledge, the highest luminosity surface densities and star formation rate surface densities measured for any star-forming system. despite these high values, the nuclei appear to lie below the dusty eddington limit in which radiation pressure is balanced only by self-gravity. the small measured sizes also imply that at wavelengths shorter than λ = 1 mm, dust absorption effects must play an important role in the observed light distribution while below 5 ghz free-free absorption contributes substantial opacity. according to these calculations, the nuclei of arp 220 are only transparent in the frequency range ~5-350 ghz. our results offer no clear evidence that an active galactic nucleus dominates the emission from either nucleus at 33 ghz. | high-resolution radio continuum measurements of the nuclear disks of arp 220 |
kinematic distributions from an inclusive sample of 1.41 ×106 charged-current νμ interactions on iron, obtained using the minos near detector exposed to a wide-band beam with peak flux at 3 gev, are compared to a conventional treatment of neutrino scattering within a fermi gas nucleus. results are used to guide the selection of a subsample enriched in quasielastic νμfe interactions, containing an estimated 123,000 quasielastic events of incident energies 1 <eν<8 gev , with ⟨eν⟩=2.79 gev . four additional subsamples representing topological and kinematic sideband regions to quasielastic scattering are also selected for the purpose of evaluating backgrounds. comparisons using subsample distributions in four-momentum transfer q2 show the monte carlo model to be inadequate at low q2. its shortcomings are remedied via inclusion of a q2-dependent suppression function for baryon resonance production, developed from the data. a chi-square fit of the resulting monte carlo simulation to the shape of the q2 distribution for the quasielastic-enriched sample is carried out with the axial-vector mass ma of the dipole axial-vector form factor of the neutron as a free parameter. the effective ma which best describes the data is 1.23-0.09+0.13(fit)-0.15+0.12(syst) gev . | study of quasielastic scattering using charged-current νμ -iron interactions in the minos near detector |
cosmological parameters deduced from the planck measurements of anisotropies in the cosmic microwave background are at some tension with direct astronomical measurements of various parameters at low redshifts. very recently, it has been conjectured that this discrepancy can be reconciled if a certain fraction of dark matter is unstable and decays between recombination and the present epoch. herein we show that if the superheavy relics have a branching into neutrinos bx →ν ν ¯∼5 ×10-8 , then this scenario can also accommodate the recently discovered extraterrestrial flux of neutrinos, relaxing the tension between icecube results and fermi lat data. the model is fully predictive and can be confronted with future icecube data. we demonstrate that in 10 years of observation icecube will be able to distinguish the monoenergetic signal from x decay at the 3 σ level. in a few years of data taking with the upgraded icecube-gen2 enough statistics will be gathered to elucidate the dark matter-neutrino connection at the 5 σ level. | icecube neutrinos, decaying dark matter, and the hubble constant |
aims: high synchrotron peaked blazars (hsps) dominate the γ-ray sky at energies higher than a few gev; however, only a few hundred blazars of this type have been cataloged so far. in this paper we present the 2whsp sample, the largest and most complete list of hsp blazars available to date, which is an expansion of the 1whsp catalogue of γ-ray source candidates off the galactic plane.methods: we cross-matched a number of multi-wavelength surveys (in the radio, infrared and x-ray bands) and applied selection criteria based on the radio to ir and ir to x-ray spectral slopes. to ensure the selection of genuine hsps, we examined the sed of each candidate and estimated the peak frequency of its synchrotron emission (νpeak) using the asdc sed tool, including only sources with νpeak > 1015 hz (equivalent to νpeak > 4 ev).results: we have assembled the largest and most complete catalogue of hsp blazars to date, which includes 1691 sources. a number of population properties, such as infrared colours, synchrotron peak, redshift distributions, and γ-ray spectral properties have been used to characterise the sample and maximize completeness. we also derived the radio log n-log s distribution. this catalogue has already been used to provide seeds to discover new very high energy objects within fermi-lat data and to look for the counterparts of neutrino and ultra high energy cosmic ray sources, showing its potential for the identification of promising high-energy γ-ray sources and multi-messenger targets. table 4 is only available at the cds via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?j/a+a/598/a17 | 2whsp: a multi-frequency selected catalogue of high energy and very high energy γ-ray blazars and blazar candidates |
we present a new parametrization of the cosmic-ray flux and its mass composition over an energy range from 10 gev to $10^{11}$ gev. our approach is data-driven and relies on theoretical assumptions as little as possible. we combine measurements of the flux of individual elements from high-precision satellites and balloon experiments with indirect measurements of mass groups from the leading air shower experiments. to our knowledge, we provide the first fit of this kind that consistently takes both statistical and systematic uncertainties into account. the uncertainty on the energy scales of individual experiments is handled explicitly in our mathematical approach. part of our results is a common energy scale and adjustment factors for the energy scales of the participating experiments. our fit has a reduced $\chi^2$-value of 0.5, showing that experimental data are in good agreement, if systematic uncertainties are considered. our model may serve as a world-average of the measured fluxes for individual elements from proton to iron from 10 gev to $10^{11}$ gev. it is useful as an input for simulations or theoretical computations based on cosmic rays. the experimental uncertainties of the input data are captured in a covariance matrix, which can be propagated into derived quantities. | data-driven model of the cosmic-ray flux and mass composition from 10 gev to 10^{11} gev |
recent cosmic-ray (cr) studies have claimed the possibility of an excess on the antiproton flux over the predicted models at around 10 gev, which can be the signature of dark matter annihilating into hadronic final states that subsequently form antiprotons. however, this excess is subject to many uncertainties related to the evaluation of the antiproton spectrum produced from spallation interactions of crs. in this work, we implement a combined markov-chain monte carlo analysis of the secondary ratios of b, be and li and the antiproton-to-proton ratio (p̅/p), while also including nuisance parameters to consider the uncertainties related to the spallation cross sections. this study allows us to constrain the galactic halo height and the rest of propagation parameters, evaluate the impact of cross sections uncertainties in the determination of the antiproton spectrum and test the origin of the excess of antiprotons. in this way, we provide a set of propagation parameters and scale factors for renormalizing the cross sections parametrizations that allow us to reproduce all the ratios of b, be, li and p̅ simultaneously. we show that the energy dependence of the p̅/p ratio is compatible with a pure secondary origin. in particular, we find that the energy dependence of the evaluated p̅/p spectrum matches that observed from ams-02 data at energies above ~3 gev, although there is still a constant ~10% excess of p̅ over our prediction. we discuss that this discrepancy is more likely explained from a ~10% scaling in the cross sections of antiproton production, rather than a component of dark matter leading to antiprotons. in particular, we find that the best-fit wimp mass (~300 gev) needed to explain the discrepancy lies above the constraints from most indirect searches of dark matter and the resultant fit is poorer than with a cross sections scaling. | combined analyses of the antiproton production from cosmic-ray interactions and its possible dark matter origin |
cosmic rays (crs) are a plausible mechanism for launching winds of cool material from the discs of star-forming galaxies. however, there is no consensus on what types of galaxies likely host cr-driven winds, or what role these winds might play in regulating galaxies' star formation rates. using a detailed treatment of the transport and losses of hadronic crs developed in the previous paper in this series, here we develop a semi-analytical model that allows us to assess the viability of using crs to launch cool winds from galactic discs. in particular, we determine the critical cr fluxes - and corresponding star formation rate surface densities - above which hydrostatic equilibrium within a given galaxy is precluded because crs drive the gas off in a wind or otherwise render it unstable. our model demonstrates that catastrophic, cr-driven wind loss is a possibility at galactic mean surface densities below ${\lesssim}10^2 \ \mathrm{ m}_{\odot }$ pc-2. in this regime - encompassing the galaxy and local dwarfs - the locus of the cr-stability curve patrols the high side of the observed distribution of galaxies in the kennicutt-schmidt parameter space of star formation rate versus gas surface density. however, hadronic losses render crs unable to drive global winds in galaxies with surface densities above the ~102-103 m⊙ pc-2 transition region. our results show that quiescent, low surface density galaxies like the milky way are poised on the cusp of instability, such that small changes to interstellar mass (ism) parameters can lead to the launching of cr-driven outflows, and we suggest that, as a result, cr feedback sets an ultimate limit to the star formation efficiency of most modern galaxies. | cosmic rays across the star-forming galaxy sequence - ii. stability limits and the onset of cosmic ray-driven outflows |
in the espresso scenario, ultra-high-energy (uhe) cosmic rays (crs) are produced via a one-shot reacceleration of galactic-like crs in the relativistic jets of active galactic nuclei, independently of the scattering rate dictated by magnetic fluctuations. in mbarek & caprioli (2019) we traced test-particle crs in high-resolution magnetohyrodynamic (mhd) jet simulations and found that the associated spectral slope, chemical composition, and anisotropy are consistent with uhecr phenomenology. in this work, we extend such an analysis by including subgrid pitch-angle scattering to model small-scale magnetic turbulence that cannot be resolved by mhd simulations. we find that a large scattering rate unlocks stochastic acceleration and fosters the energization of lower-energy crs, which eventually leads to harder uhecr spectra. yet, the particles that achieve the highest energies (up to the hillas limit) are invariably produced by espresso acceleration and their spectrum is independent of the assumed subgrid scattering rate. | espresso and stochastic acceleration of ultra-high-energy cosmic rays in relativistic jets |
we present an updated cosmic-ray mass composition analysis in the energy range 1016.8 to 1018.3 ev from 334 air showers measured with the lofar radio telescope and selected for minimal bias. in this energy range, the origin of cosmic rays is expected to shift from galactic to extragalactic sources. the analysis is based on an improved method to infer the depth of the maximum xmax of extensive air showers from radio measurements and air shower simulations. we show results of the average and standard deviation of xmax versus primary energy and analyze the xmax dataset at the distribution level to estimate the cosmic ray mass composition. our approach uses an unbinned maximum likelihood analysis, making use of existing parametrizations of the xmax distributions per element. the analysis has been repeated for three main models of hadronic interactions. results are consistent with a significant light-mass fraction, at best fit 23% to 39% protons plus helium, depending on the choice of hadronic interaction model. the fraction of the intermediate-mass nuclei dominates. this confirms earlier results from lofar, with systematic uncertainties on xmax now lowered to 7 to 9 g /cm2 . we find agreement in mass composition compared to results from pierre auger observatory, within statistical and systematic uncertainties. however, in line with earlier lofar results, we find a slightly lower average xmax. the values are in tension with those found at pierre auger observatory but agree with results from other cosmic ray observatories based in the northern hemisphere. | depth of shower maximum and mass composition of cosmic rays from 50 pev to 2 eev measured with the lofar radio telescope |
we report the demonstration of a low-power pixelated readout system designed for three-dimensional ionization charge detection and digital readout of liquid argon time projection chambers (lartpcs) . unambiguous 3d charge readout was achieved using a custom-designed system-on-a-chip asic (larpix) to uniquely instrument each pad in a pixelated array of charge-collection pads. the larpix asic, manufactured in 180 nm bulk cmos, provides 32 channels of charge-sensitive amplification with self-triggered digitization and multiplexed readout at temperatures from 80 k to 300 k . using an 832-channel larpix-based readout system with 3 mm spacing between pads, we demonstrated low-noise (0<50 e- rms equivalent noise charge) and very low-power (<100 μw/channel) ionization signal detection and readout . the readout was used to successfully measure the three-dimensional ionization distributions of cosmic rays passing through a lartpc, free from the ambiguities of existing projective techniques. the system design relies on standard printed circuit board manufacturing techniques, enabling scalable and low-cost production of large-area readout systems using common commercial facilities. this demonstration overcomes a critical technical obstacle for operation of lartpcs in high-occupancy environments, such as the near detector site of the deep underground neutrino experiment (dune) . | larpix: demonstration of low-power 3d pixelated charge readout for liquid argon time projection chambers |
a recent analysis of supernova ia (sn ia) data claims a "marginal" ( 3σ) evidence for a cosmic acceleration. this result has been complemented with a non-accelerating rh = ct cosmology, which was presented as a valid alternative to the λcdm model. in this paper we use the same analysis to show that non-marginal evidence for acceleration is truly found. we compare the standard friedmann models to the rh = ct cosmology by complementing sn ia data with baryon acoustic oscillations, gamma ray bursts, and observational hubble datasets. we also study the power-law model, which is a functional generalisation of rh = ct. we find that the evidence for late-time acceleration cannot be refuted at a 4.56σ confidence level from sn ia data alone, and at an even stronger confidence level (5.38σ) from our joint analysis. in addition, the non-accelerating rh = ct model fails to statistically compare with the λcdm, having a δ(aic) 30. | strong evidence for an accelerating universe |
the origin of ultrahigh energy cosmic rays (uhecrs) is still unknown. it has recently been proposed that uhecr anisotropies can be attributed to starburst galaxies or active galactic nuclei. we suggest that the latter is more likely and that giant-lobed radio galaxies such as centaurus a and fornax a can explain the data. | fornax a, centaurus a, and other radio galaxies as sources of ultrahigh energy cosmic rays |
we study the thermalization, injection, and acceleration of ions with different mass/charge ratios, a /z , in nonrelativistic collisionless shocks via hybrid (kinetic ions-fluid electrons) simulations. in general, ions thermalize to a postshock temperature proportional to a . when diffusive shock acceleration is efficient, ions develop a nonthermal tail whose extent scales with z and whose normalization is enhanced as (a /z )2 so that incompletely ionized heavy ions are preferentially accelerated. we discuss how these findings can explain observed heavy-ion enhancements in galactic cosmic rays. | chemical enhancements in shock-accelerated particles: ab initio simulations |
we present an efficient algorithm to follow spectral evolution of cosmic rays (cr) coupled with an mhd system on eulerian grids. the algorithm is designed for studies of cr energy spectrum evolution in mhd simulations of a galactic interstellar medium. the base algorithm for cr transport relies on the two-moment piece-wise power-law method, known also as coarse-grained momentum finite volume (cgmv), for solving the fokker-planck cr transport equation, with a low number of momentum bins extending over several decades of the momentum coordinate. we propose an extension of the cgmv with a novel feature that allows momentum boundaries to change in response to cr momentum gains or losses near the extremes of the population distribution. our extension involves a special treatment of momentum bins containing spectral cutoff. contrary to the regular bins of fixed width, those bins have variable width, and their outer edges coincide with spectral cutoffs. the cutoff positions are estimated from the particle number density and energy density in the outer bins for an assumed small value of an additional parameter representing the smallest physically significant level of cr spectral energy density. we performed a series of elementary tests to validate the algorithm and demonstrated, whenever possible, that results of the test simulations correspond, with a reasonable accuracy, to the results of analogous analytical solutions. in a more complex test of the galactic cr-driven wind problem, we obtained results consistent with expectations regarding the effects of advection, diffusion, adiabatic, and synchrotron cooling of a cr population. | implementation of cosmic ray energy spectrum (cresp) algorithm in piernik mhd code. i. spectrally resolved propagation of cosmic ray electrons on eulerian grids |
the ionizing radiation properties of a fission fragment rocket engine concept are described in the context of a crewed mars mission. this propulsion system could achieve very high specific impulses (>106 s) at a high power density (>kw/kg), utilizing micron-sized fissile fuel particles suspended in an aerogel matrix. the fission core is located within the bore of an electromagnet and external neutron moderator material. the low-density aerogel allows for radiative cooling of fuel particles while minimizing collisional losses with the fission fragments, leading to a more efficient use of fissile fuel in producing thrust compared to previous concepts. this paper presents the estimates of the steady-state ionizing radiation equivalent dose to the astronaut crew from both external (e.g., galactic cosmic rays) and internal (reactor) sources. the spacecraft design includes a centrifugation concept where the transit habitation module rotates around the spacecraft's center of mass, providing artificial gravity to the crew and the separation distance to the nuclear core. we find that the fission fragment propulsion system combined with centrifugation could lead to reduced transit time, reduced equivalent radiation doses, and a reduced risk of long-term exposure to micro-g environments. such a high-specific impulse propulsion system would enable other crewed fast transit, high delta-v interplanetary missions with payload mass fractions much greater than those of alternative propulsion architecture (chemical and solar electric). | radiation characteristics of an aerogel-supported fission fragment rocket engine for crewed interplanetary missions |
cosmic-ray neutron sensing (crns) has become an effective method to measure soil moisture at a horizontal scale of hundreds of metres and a depth of decimetres. recent studies proposed operating crns in a network with overlapping footprints in order to cover root-zone water dynamics at the small catchment scale and, at the same time, to represent spatial heterogeneity. in a joint field campaign from september to november 2020 (jfc-2020), five german research institutions deployed 15 crns sensors in the 0.4 km2 wüstebach catchment (eifel mountains, germany). the catchment is dominantly forested (but includes a substantial fraction of open vegetation) and features a topographically distinct catchment boundary. in addition to the dense crns coverage, the campaign featured a unique combination of additional instruments and techniques: hydro-gravimetry (to detect water storage dynamics also below the root zone); ground-based and, for the first time, airborne crns roving; an extensive wireless soil sensor network, supplemented by manual measurements; and six weighable lysimeters. together with comprehensive data from the long-term local research infrastructure, the published data set (available at https://doi.org/10.23728/b2share.756ca0485800474e9dc7f5949c63b872; heistermann et al., 2022) will be a valuable asset in various research contexts: to advance the retrieval of landscape water storage from crns, wireless soil sensor networks, or hydrogravimetry; to identify scale-specific combinations of sensors and methods to represent soil moisture variability; to improve the understanding and simulation of land-atmosphere exchange as well as hydrological and hydrogeological processes at the hillslope and the catchment scale; and to support the retrieval of soil water content from airborne and spaceborne remote sensing platforms. | soil moisture observation in a forested headwater catchment: combining a dense cosmic-ray neutron sensor network with roving and hydrogravimetry at the tereno site wüstebach |
cosmic-ray neutron sensing (crns) is a powerful technique for retrieving representative estimates of soil water content at a horizontal scale of hectometres (the "field scale") and depths of tens of centimetres ("the root zone"). this study demonstrates the potential of the crns technique to obtain spatio-temporal patterns of soil moisture beyond the integrated volume from isolated crns footprints. we use data from an observational campaign carried out between may and july 2019 that featured a dense network of more than 20 neutron detectors with partly overlapping footprints in an area that exhibits pronounced soil moisture gradients within one square kilometre. the present study is the first to combine these observations in order to represent the heterogeneity of soil water content at the sub-footprint scale as well as between the crns stations. first, we apply a state-of-the-art procedure to correct the observed neutron count rates for static effects (heterogeneity in space, e.g. soil organic matter) and dynamic effects (heterogeneity in time, e.g. barometric pressure). based on the homogenized neutron data, we investigate the robustness of a calibration approach that uses a single calibration parameter across all crns stations. finally, we benchmark two different interpolation techniques for obtaining spatio-temporal representations of soil moisture: first, ordinary kriging with a fixed range; second, spatial interpolation complemented by geophysical inversion ("constrained interpolation"). to that end, we optimize the parameters of a geostatistical interpolation model so that the error in the forward-simulated neutron count rates is minimized, and suggest a heuristic forward operator to make the optimization problem computationally feasible. comparison with independent measurements from a cluster of soil moisture sensors (soilnet) shows that the constrained interpolation approach is superior for representing horizontal soil moisture gradients at the hectometre scale. the study demonstrates how a crns network can be used to generate coherent, consistent, and continuous soil moisture patterns that could be used to validate hydrological models or remote sensing products. | spatio-temporal soil moisture retrieval at the catchment scale using a dense network of cosmic-ray neutron sensors |
space-based gravitational wave detection will be carried out by the laser interferometer space antenna (lisa), a joint european space agency and nasa collaboration. the configuration of this antenna will include three identical spacecraft in a triangular formation separated by 2.5×106km, flying in a drag-free formation around free-falling test masses. charging of the test masses by cosmic ray fluxes and solar energetic particles must be compensated by photons that contain more energy than the effective work function of gold (4.3±0.4ev). the uv photons will be provided by algan light emitting diodes, which must operate reliably for the duration of the mission. we have tested a large number (96 for dc and pulsed testing, more than 200 for all tests) of uv leds over a period of up to 600 days to characterize their performance over a wide range of operating conditions, assessing the lifetime performance under dc (1–80ma drive current) and pulsed conditions (500–100 000 pulses per second) and temperatures ranging from 20 to 80°c. degradation of uv light output is faster at elevated temperatures and dc conditions. preselection of leds based on initial spectral ratio of peak-to-midgap emission and ideality factor provides a positive correlation with subsequent reliability. the uv leds used for lisa will need to support 2 years of cruise and commissioning plus a 4-year baseline science mission. | deep uv algan led reliability for long duration space missions |
cosmic-ray neutron sensing (crs) is a unique approach to measure soil moisture at field scale filling the gap of current methodologies. however, crs signal is affected by all the hydrogen pools on the land surface and understanding their relative importance plays an important role for the application of the method e.g., validation of remote sensing products and data assimilation. in this study, a soil moisture scaling approach is proposed to estimate directly the correct crs soil moisture based on the soil moisture profile measured at least in one position within the field. the approach has the advantage to avoid the need to introduce one correction for each hydrogen contribution and to estimate indirectly all the related time-varying hydrogen pools. based on the data collected in three crop seasons, the scaling approach shows its ability to identify and to quantify the seasonal biomass water equivalent. additionally, the analysis conducted at sub-daily time resolution is able to quantify the daily vertical redistribution of the water biomass and the rainfall interception, showing promising applications of the crs method also for these types of measurements. overall, the study underlines how not only soil moisture but all the specific hydrological processes in the soil-plant-atmosphere continuum should be considered for a proper evaluation of the crs signal. for this scope, the scaling approach reveals to be a simple and pragmatic analysis that can be easily extended to other experimental sites. | a scaling approach for the assessment of biomass changes and rainfall interception using cosmic-ray neutron sensing |
we present a novel interpretation of the γ -ray diffuse emission measured by fermi-lat and h.e.s.s. in the galactic center (gc) region and the galactic ridge (gr). in the first part we perform a data-driven analysis based on pass8 fermi-lat data: we extend down to a few gev the spectra measured by h.e.s.s. and infer the primary cosmic-ray (cr) radial distribution between 0.1 and 3 tev. in the second part we adopt a cr transport model based on a position-dependent diffusion coefficient. such behavior reproduces the radial dependence of the cr spectral index recently inferred from the fermi-lat observations. we find that the bulk of the gr emission can be naturally explained by the interaction of the diffuse steady-state galactic cr sea with the gas present in the central molecular zone. although we confirm the presence of a residual radial-dependent emission associated with a central source, the relevance of the large-scale diffuse component prevents to claim a solid evidence of gc pevatrons. | diffuse cosmic rays shining in the galactic center: a novel interpretation of h.e.s.s. and fermi-lat γ -ray data |
based on new and published cosmic-ray exposure chronologies, we show that glacier extent in the tropical andes and the north atlantic regions (tanar) varied in-phase on millennial timescales during the holocene, distinct from other regions. glaciers experienced an early holocene maximum extent, followed by a strong mid-holocene retreat and a re-advance in the late holocene. we further explore the potential forcing of tanar glacier variations using transient climate simulations. since the atlantic meridional overturning circulation (amoc) evolution is poorly represented in these transient simulations, we develop a semi-empirical model to estimate the "amoc-corrected" temperature and precipitation footprint at regional scales. we show that variations in the amoc strength during the holocene are consistent with the observed glacier changes. our findings highlight the need to better constrain past amoc behavior, as it may be an important driver of tanar glacier variations during the holocene, superimposed on other forcing mechanisms. | in-phase millennial-scale glacier changes in the tropics and north atlantic regions during the holocene |
cosmic ray neutron sensing (crns) has become a promising method for soil water content (swc) monitoring. stationary crns offers hectare-scale average swc measurements at fixed locations maintenance-free and continuous in time, while car-borne crns roving can reveal spatial swc patterns at medium scales, but only on certain survey days. the novel concept of a permanent mobile crns system on rails promises to combine the advantages of both methods, while its technical implementation, data processing and interpretation raised a new level of complexity. this study introduced a fully automatic crns rail-borne system as the first of its kind, installed within the locomotive of a cargo train. data recorded from september 2021 to july 2022 along an ∼9 km railway segment were analyzed, as repeatedly used by the train, supported by local swc measurements (soil samples and dielectric methods), car-borne and stationary crns. the results revealed consistent spatial swc patterns and temporary variation along the track at a daily resolution. the observed variability was mostly related to surface features, seasonal dynamics and different responses of the railway segments to wetting and drying periods, while some variations were related to measurement uncertainties. the achieved medium scale of swc mapping could support large scale hydrological modeling and detection of environmental risks, such as droughts and wildfires. hence, rail-borne crns has the chance to become a central tool of continuous swc monitoring for larger scales (≤10-km), with the additional benefit of providing root-zone soil moisture, potentially even in sub-daily resolution. | toward large-scale soil moisture monitoring using rail-based cosmic ray neutron sensing |
context. under cosmic irradiation, the interstellar water ice mantles evolve towards a compact amorphous state. crystalline ice amorphisation was previously monitored mainly in the kev to hundreds of kev ion energies.aims: we experimentally investigate heavy ion irradiation amorphisation of crystalline ice, at high energies closer to true cosmic rays, and explore the water-ice sputtering yield.methods: we irradiated thin crystalline ice films with mev to gev swift ion beams, produced at the ganil accelerator. the ice infrared spectral evolution as a function of fluence is monitored with in-situ infrared spectroscopy (induced amorphisation of the initial crystalline state into a compact amorphous phase).results: the crystalline ice amorphisation cross-section is measured in the high electronic stopping-power range for different temperatures. at large fluence, the ice sputtering is measured on the infrared spectra, and the fitted sputtering-yield dependence, combined with previous measurements, is quadratic over three decades of electronic stopping power.conclusions: the final state of cosmic ray irradiation for porous amorphous and crystalline ice, as monitored by infrared spectroscopy, is the same, but with a large difference in cross-section, hence in time scale in an astrophysical context. the cosmic ray water-ice sputtering rates compete with the uv photodesorption yields reported in the literature. the prevalence of direct cosmic ray sputtering over cosmic-ray induced photons photodesorption may be particularly true for ices strongly bonded to the ice mantles surfaces, such as hydrogen-bonded ice structures or more generally the so-called polar ices. experiments performed at the grand accélérateur national d'ions lourds (ganil) caen, france. part of this work has been financed by the french insu-cnrs programme "physique et chimie du milieu interstellaire" (pcmi) and the anr iglias. | heavy ion irradiation of crystalline water ice. cosmic ray amorphisation cross-section and sputtering yield |
in this study, our primary objective is to compare the properties of smbh and their host galaxies between type 1 and type 2 agn. in our analysis, we use x-ray detected sources in two fields, namely the efeds and the cosmos-legacy. to classify the x-ray sources, we perform sed fitting analysis, using the cigale code. ensuring the robustness of our analysis is paramount, and to achieve this, we impose stringent selection criteria. thus, only sources with extensive photometric data across the optical, near- and mid-infrared part of the spectrum and reliable host galaxy properties and classifications were included. the final sample consists of 3,312 agn, of which 3\,049 are classified as type 1 and 263 as type 2. the sources span a redshift range of $\rm 0.5<z<3.5$ and encompass a wide range of l$_x$, falling within $\rm 42<log,[l_{x,2-10kev}(ergs^{-1})]<46$. our results show that type 2 agn exhibit a tendency to inhabit more massive galaxies, by $0.2-0.3$\,dex, compared to type 1 sources. type 2 agn also display, on average, lower specific black hole accretion rates, a proxy of the eddington ratio, compared to type 1 agn. these differences persist across all redshifts and l$_x$ considered within our dataset. moreover, our analysis uncovers, that type 2 sources tend to have lower star-formation rates compared to 1 agn, at $\rm z<1$. this picture reverses at $\rm z>2$ and $\rm log,[l_{x,2-10kev}(ergs^{-1})]>44$. similar patterns emerge when we categorize agn based on their x-ray obscuration levels ($n_h$). however, in this case, the observed differences are pronounced only for low-to-intermediate l$_x$ agn and are also sensitive to the $\rm n_h$ threshold applied for the agn classification. these comprehensive findings enhance our understanding of the intricate relationships governing agn types and their host galaxy properties across diverse cosmic epochs and luminosity regimes. | the properties of supermassive black holes and their host galaxies for type 1 and 2 agn in the efeds and cosmos fields |
the primary mission of the arianna ultra-high energy neutrino telescope is to uncover astrophysical sources of neutrinos with energies greater than 1016 ev. a pilot array, consisting of seven arianna stations located on the surface of the ross ice shelf in antarctica, was commissioned in november 2014. we report on the search for astrophysical neutrinos using data collected between november 2014 and february 2019. a straight-forward template matching analysis yielded no neutrino candidates, with a signal efficiency of 79%. we find a 90% confidence upper limit on the diffuse neutrino flux of e2φ=1.7× 10-6 gev cm-2s-1sr-1 for a decade wide logarithmic bin centered at a neutrino energy of 1018,ev, which is an order of magnitude improvement compared to the previous limit reported by the arianna collaboration. the arianna stations, including purpose built cosmic-ray stations at the moore's bay site and demonstrator stations at the south pole, have operated reliably. sustained operation at two distinct sites confirms that the flexible and adaptable architecture can be deployed in any deep ice, radio quiet environment. we show that the scientific capabilities, technical innovations, and logistical requirements of arianna are sufficiently well understood to serve as the basis for large area radio-based neutrino telescope with a wide field-of-view. | a search for cosmogenic neutrinos with the arianna test bed using 4.5 years of data |
we study sub-gev dark matter (dm) particles that may annihilate or decay into standard model (sm) particles producing an electron-positron cascade that results in positronium bound state formation after energy losses. this comprises an exotic injection component in the milky way that leaves an imprint in the 511 kev photon line due to the decay of positronium into two photons. in this work, we use $\sim16$~yr of spi spectrometer data from the integral satellite to constrain dm properties. we include three major novelties in our study: i) we account for positron diffusion and propagation, as well as positron losses due to annihilation in flight and other energy losses, ii) we include the free electron density suppression away from the galactic plane and iii) we derive limits for decaying dm for the first time with spi data. we show that the predicted longitude and latitude profiles change significantly for different dm masses, contrary to what has previously been assumed. in addition, we find that the limits derived from this new set of spi data are the strongest on sub-gev dm to date across almost the entire dm mass range considered (from mev to a few gev), excluding cross-sections down to $10^{-32}$ cm$^3$ s$^{-1} \, \, (\text{for} \,\, m_{\chi}\sim1 \,\text{mev}) \lesssim \langle \sigma v\rangle \lesssim10^{-26}$ cm$^3$ s$^{-1} \, \, (m_{\chi}\sim5\,\text{gev})$ and lifetimes up to $10^{29}\, \textrm{s} \, (m_{\chi}\sim1\,\text{mev})\lesssim \tau \lesssim 10^{27}\,\textrm{s}$ ($m_{\chi}\sim5$~gev), whilst considering best-fit cosmic ray (cr) propagation and diffusion parameters. these limits surpass even the most stringent complementary cosmological and astrophysical limits over most of the mass range considered. | new 511 kev line data provides strongest sub-gev dark matter constraints |
cosmic rays (crs) in starburst galaxies produce high-energy gamma-rays by colliding with the dense interstellar medium. arp 220 is the nearest ultraluminous infrared galaxy that has star formation at extreme levels, so it has long been predicted to emit high-energy gamma-rays. however, no evidence of gamma-ray emission was found despite intense search efforts. here we report the discovery of high-energy gamma-ray emission above 200 mev from arp 220 at a confidence level of ∼6.3σ using 7.5 years of fermi large area telescope observations. the gamma-ray emission shows no significant variability over the observation period and it is consistent with the quasi-linear scaling relation between the gamma-ray luminosity and total infrared luminosity for star-forming galaxies, suggesting that these gamma-rays arise from cr interactions. as the high-density medium of arp 220 makes it an ideal cr calorimeter, the gamma-ray luminosity can be used to measure the efficiency of powering crs by supernova (sn) remnants given a known supernova rate in arp 220. we find that this efficiency is about 4.2 ± 2.6% for crs above 1 gev. | first detection of gev emission from an ultraluminous infrared galaxy: arp 220 as seen with the fermi large area telescope |
muons produced in atmospheric cosmic ray showers account for the by far dominant part of the event yield in large-volume underground particle detectors. the icecube detector, with an instrumented volume of about a cubic kilometer, has the potential to conduct unique investigations on atmospheric muons by exploiting the large collection area and the possibility to track particles over a long distance. through detailed reconstruction of energy deposition along the tracks, the characteristics of muon bundles can be quantified, and individual particles of exceptionally high energy identified. the data can then be used to constrain the cosmic ray primary flux and the contribution to atmospheric lepton fluxes from prompt decays of short-lived hadrons. in this paper, techniques for the extraction of physical measurements from atmospheric muon events are described and first results are presented. the multiplicity spectrum of tev muons in cosmic ray air showers for primaries in the energy range from the knee to the ankle is derived and found to be consistent with recent results from surface detectors. the single muon energy spectrum is determined up to pev energies and shows a clear indication for the emergence of a distinct spectral component from prompt decays of short-lived hadrons. the magnitude of the prompt flux, which should include a substantial contribution from light vector meson di-muon decays, is consistent with current theoretical predictions. the variety of measurements and high event statistics can also be exploited for the evaluation of systematic effects. in the course of this study, internal inconsistencies in the zenith angle distribution of events were found which indicate the presence of an unexplained effect outside the currently applied range of detector systematics. the underlying cause could be related to the hadronic interaction models used to describe muon production in air showers. | characterization of the atmospheric muon flux in icecube |
kascade-grande, the extension of the multi-detector setup of kascade, was devoted to measure the properties of extensive air showers initiated by high-energy cosmic rays in the primary energy range of 1 pev up to 1 eev. the observations of the energy spectrum and mass composition of cosmic rays contribute with great detail to the understanding of the transition from galactic to extragalactic origin of cosmic rays, and furthermore to validate the properties of hadronic interaction models in the air shower development. although the experiment is fully dismantled, the analysis of the entire kascade-grande data set continues. we have recently investigated the impact of different post-lhc hadronic interaction models, qgsjetii-04, epos-lhc, sibyll 2.3d, on air shower predictions in terms of the reconstructed spectra of heavy and light primary masses, including systematic uncertainties. in addition, the conversely discussed evolution of the muon content of high-energy air showers in the atmosphere is compared with the predictions of different interaction models. in this contribution, the latest results from the kascade-grande measurements will be discussed. | latest analysis results from the kascade-grande data |
aims: the identification of pevatrons, hadronic particle accelerators reaching the knee of the cosmic ray spectrum (few × 1015 ev), is crucial to understand the origin of cosmic rays in the galaxy. we provide an update on the unidentified source hess j1702-420, a promising pevatron candidate.methods: we present new observations of hess j1702-420 made with the high energy stereoscopic system (h.e.s.s.), and processed using improved analysis techniques. the analysis configuration was optimized to enhance the collection area at the highest energies. we applied a three-dimensional likelihood analysis to model the source region and adjust non thermal radiative spectral models to the γ-ray data. we also analyzed archival fermi large area telescope data to constrain the source spectrum at γ-ray energies > 10 gev.results: we report the detection of γ-rays up to 100 tev from a specific region of hess j1702-420, which is well described by a new source component called hess j1702-420a that was separated from the bulk of tev emission at a 5.4σ confidence level. the power law γ-ray spectrum of hess j1702-420a extends with an index of γ = 1.53 ± 0.19stat ± 0.20sys and without curvature up to the energy band 64−113 tev, in which it was detected by h.e.s.s. at a 4.0σ confidence level. this makes hess j1702-420a a compelling candidate site for the presence of extremely high energy cosmic rays. with a flux above 2 tev of (2.08 ± 0.49stat ± 0.62sys) × 10−13 cm−2 s−1 and a radius of (0.06 ± 0.02stat ± 0.03sys)°, hess j1702-420a is outshone - below a few tens of tev - by the companion hess j1702-420b. the latter has a steep spectral index of γ = 2.62 ± 0.10stat ± 0.20sys and an elongated shape, and it accounts for most of the low-energy hess j1702-420 flux. simple hadronic and leptonic emission models can be well adjusted to the spectra of both components. remarkably, in a hadronic scenario, the cut-off energy of the particle distribution powering hess j1702-420a is found to be higher than 0.5 pev at a 95% confidence level.conclusions: for the first time, h.e.s.s. resolved two components with significantly different morphologies and spectral indices, both detected at > 5σ confidence level, whose combined emissions result in the source hess j1702-420. we detected hess j1702-420a at a 4.0σ confidence level in the energy band 64−113 tev, which brings evidence for the source emission up to 100 tev. in a hadronic emission scenario, the hard γ-ray spectrum of hess j1702-420a implies that the source likely harbors pev protons, thus becoming one of the most solid pevatron candidates detected so far in h.e.s.s. data. however, a leptonic origin of the observed tev emission cannot be ruled out either. | evidence of 100 tev γ-ray emission from hess j1702-420: a new pevatron candidate |
the cosmic origin of the elements, the fundamental chemical building blocks of the universe, is still uncertain. binary interactions play a key role in the evolution of many massive stars, yet their impact on chemical yields is poorly understood. using the mesa stellar evolution code, we predict the chemical yields ejected in wind mass loss and the supernovae of single and binary-stripped stars. we do this with a large 162-isotope nuclear network at solar metallicity. we find that binary-stripped stars are more effective producers of the elements than single stars, due to their increased mass loss and an increased chance to eject their envelopes during a supernova. this increased production by binaries varies across the periodic table, with f and k being more significantly produced by binary-stripped stars than single stars. we find that the 12c/13c could be used as an indicator of the conservativeness of mass transfer, as 13c is preferentially ejected during mass transfer while 12c is preferentially ejected during wind mass loss. we identify a number of gamma-ray-emitting radioactive isotopes that may be used to help constrain progenitor and explosion models of core-collapse supernovae with next-generation gamma-ray detectors. for single stars we find that 44v and 52mn are strong probes of the explosion model, while for binary-stripped stars it is 48cr. our findings highlight that binary-stripped stars are not equivalent to two single stars and that detailed stellar modeling is needed to predict their final nucleosynthetic yields. | nucleosynthesis of binary-stripped stars |
cosmic rays with energies above $10^{19}$ ev, observed in 1999-2004 by the high resolution fly's eye (hires) experiment in the stereoscopic mode, were found to correlate with directions to distant bl lac type objects (bl lacs), suggesting non-standard neutral particles travelling for cosmological distances without attenuation. this effect could not be tested by newer experiments because of their inferior angular resolution. the distribution in the sky of bl lacs associated with cosmic rays was found to deviate from isotropy, which might give a clue to the interpretation of the observed anomaly. however, previous studies made use of a sample of bl lacs which was anisotropic by itself, thus complicating these interpretations. here, we use a recently compiled isotropic sample of bl lacs and the same hires data to confirm the presence of correlations and to strengthen the case for the local large-scale structure pattern in the distribution of the correlated events in the sky. further tests of the anomaly await new precise cosmic-ray data. | anomalous cosmic-ray correlations revisited with a complete full-sky sample of bl lac type objects |
the strong cosmic censorship conjecture, which states that the evolution of generic initial data will always produce a globally hyperbolic spacetime, is hard to be tested by astronomical observations. in this paper, we study the appearance of the regular black hole without mass inflation, which violates the strong cosmic censorship conjecture. since the cauchy horizon is stable, the photons entering the two horizons of the regular black hole in the preceding companion universe can come out from the white hole in our universe. these rays create a novel multi-ring structure, which is significantly different from the image of the schwarzschild black hole. this serves a potential method to test the strong cosmic censorship conjecture. | the appearance of the regular black hole with a stable cauchy horizon |
we report a first detection, at very high significance ($25\sigma$), of the cross-correlation between cosmic shear and the diffuse x-ray background, using data from the dark energy survey and the rosat satellite. the x-ray cross-correlation signal is sensitive to the distribution of the surrounding gas in dark matter haloes. this allows us to use our measurements to place constraints on key physical parameters that determine the impact of baryonic effects in the matter power spectrum. in particular, we determine the mass of haloes in which feedback has expelled half of their gas content on average to be $\log_{10}(m_c/m_\odot)=13.643^{+0.081}_{-0.12}$, and the polytropic index of the gas to be $\gamma = 1.231^{+0.015}_{-0.011}$. this represents a first step in the direct use of x-ray cross-correlations to obtain improved constraints on cosmology and the physics of the intergalactic gas. | x-ray - cosmic shear cross-correlations: first detection and constraints on baryonic effects |
the first data from the lhc run 2 have shown a possible excess in diphoton events with invariant mass ∼750 gev , suggesting the existence of a new resonance which may decay dominantly into dark matter (dm) particles. we show in a simple model that the reported diphoton excess at the lhc is consistent with another photon excess, the 2 gev excess in cosmic gamma-ray fluxes towards the galactic center observed by the fermi-lat. both the excesses can be simultaneously explained by a ∼60 gev scalar dm particle annihilating dominantly into two gluons with a typical thermal annihilation cross section, which leads to the prediction of a width-to-mass ratio γ /m ≈o (10-2) of the resonance. the upper limit on the dijet search at lhc run 1 leads to a lower limit on the predicted cross section for dm annihilating into γ γ final states ⟨σ v ⟩γ γ≳o (10-30) cm3 s-1 . both the predictions can be tested by the lhc, fermi-lat, and future experiments. | 750 gev diphoton excess and a dark matter messenger at the galactic center |
cosmic rays hitting the solar atmosphere generate neutrinos that interact and oscillate in the sun and oscillate on the way to earth. these neutrinos could potentially be detected with neutrino telescopes and will be a background for searches for neutrinos from dark matter annihilation in the sun. we calculate the flux of neutrinos from these cosmic ray interactions in the sun and also investigate the interactions near a detector on earth that give rise to muons. we compare this background with both regular earth-atmospheric neutrinos and signals from dark matter annihilation in the sun. our calculation is performed with an event-based monte carlo approach that should be suitable as a simulation tool for experimental collaborations. our program package is released publicly along with this paper. | neutrinos from cosmic ray interactions in the sun |
the probe of extreme multi-messenger astrophysics (poemma) mission is being designed to establish charged-particle astronomy with ultra-high energy cosmic rays (uhecrs) and to observe cosmogenic tau neutrinos (ctns). the study of uhecrs and ctns from space will yield orders-of-magnitude increase in statistics of observed uhecrs at the highest energies, and the observation of the cosmogenic flux of neutrinos for a range of uhecr models. these observations should solve the long-standing puzzle of the origin of the highest energy particles ever observed, providing a new window onto the most energetic environments and events in the universe, while studying particle interactions well beyond accelerator energies. the discovery of ctns will help solve the puzzle of the origin of uhecrs and begin a new field of astroparticle physics with the study of neutrino properties at ultra-high energies. | poemma: probe of extreme multi-messenger astrophysics |
analysis of radio signals from cosmic-ray induced air showers has been shown to be a reliable method to extract shower parameters such as primary energy and depth of shower maximum. the required detailed air shower simulations take 1 to 3 days of cpu time per shower for a few hundred antennas. with nearly 60,000 antennas envisioned to be used for air shower studies at the square kilometre array (ska), simulating all of these would come at unreasonable costs. we present an interpolation algorithm to reconstruct the full pulse time series at any position in the radio footprint, from a set of antennas simulated on a polar grid. relying on fourier series representations and cubic splines, it significantly improves on existing linear methods. we show that simulating about 200 antennas is sufficient for high-precision analysis in the ska era, including e.g. interferometry which relies on accurate pulse shapes and timings. we therefore propose the interpolation algorithm and its implementation as a useful extension of radio simulation codes, to limit computational effort while retaining accuracy. | a high-precision interpolation method for pulsed radio signals from cosmic-ray air showers |
feedback mediated by cosmic rays (crs) is an important process in galaxy formation. because crs are long-lived and because they are transported along the magnetic field lines independently of any gas flow, they can efficiently distribute their feedback energy within the galaxy. we present an in-depth investigation of (i) how crs launch galactic winds from a disc that is forming in a $10^{11} \, \rm {m}_\odot$ halo and (ii) the state of cr transport inside the galactic wind. to this end, we use the arepo moving-mesh code and model cr transport with the two-moment description of cr hydrodynamics. this model includes the cr interaction with the gyroresonant alfvén waves that enable us to self-consistently calculate the cr diffusion coefficient and cr transport speeds based on coarse-grained models for plasma physical effects. this delivers insight into key questions such as whether the effective cr transport is streaming-like or diffusive-like, how the cr diffusion coefficient and transport speed change inside the circumgalactic medium, and to what degree the two-moment approximation is needed to faithfully capture these effects. we find that the cr-diffusion coefficient reaches a steady state in most environments with the notable exception of our newly discovered alfvén-wave dark regions where the toroidal wind magnetic field is nearly perpendicular to the cr pressure gradient so that crs are unable to excite the gyroresonant alfvén waves. however, cr transport itself cannot reach a steady state and is not well described by either the cr streaming paradigm, the cr diffusion paradigm, or a combination of both. | cosmic-ray-driven galactic winds: transport modes of cosmic rays and alfvén-wave dark regions |
observations of ionized carbon at 158 μm ([c ii]) from luminous star-forming galaxies at z ∼ 0 show that their ratios of [c ii] to far-infrared (fir) luminosity are systematically lower than those of more modestly star-forming galaxies. in this paper, we provide a theory for the origin of this so-called [c ii] deficit in galaxies. our model treats the interstellar medium as a collection of clouds with radially stratified chemical and thermal properties, which are dictated by the clouds' volume and surface densities, as well as the interstellar radiation and cosmic ray fields to which they are exposed. [c ii] emission arises from the outer, h i-dominated layers of clouds, and from regions where the hydrogen is h2 but the carbon is predominantly c+. in contrast, the most shielded regions of clouds are dominated by co, and produce little [c ii] emission. this provides a natural mechanism to explain the observed [c ii]-star formation relation: galaxies' star formation rates are largely driven by the surface densities of their clouds. as this rises, so does the fraction of gas in the co-dominated phase that produces little [c ii] emission. our model further suggests that the apparent offset in the [c ii]-fir relation for high-z sources compared to those at present epoch may arise from systematically larger gas masses at early times: a galaxy with a large gas mass can sustain a high star formation rate even with a relatively modest surface density, allowing copious [c ii] emission to coexist with rapid star formation. | a physical model for the [c ii]-fir deficit in luminous galaxies |
the energetic proton, electron, and alpha detector (epead) and high energy proton and alpha detector (hepad) instruments on the geostationary operational environmental satellite (goes) spacecraft have served over many years as monitors of the solar particle intensities, surveying the sun and measuring in situ its effect on the near-earth solar-terrestrial environment. however, the reconstruction of the differential energy spectra is affected by large uncertainties related to the poor energy resolution, the small geometrical factor, and the high contamination by out-of-acceptance particles. in this work, the high-quality data set from the payload for antimatter matter exploration and light-nuclei astrophysics (pamela) space mission is used to calibrate the high-energy (>80 mev) proton channels of the epead and the hepad sensors on board the goes 13 and 15, bringing the measured spectral intensities inline with those registered by pamela. suggested corrections significantly reduce the uncertainties on the response of goes detectors, thus improving the reliability of the spectroscopic observations of solar energetic particle events. | calibration of the goes 13/15 high-energy proton detectors based on the pamela solar energetic particle observations |
secondary messengers such as neutrinos and photons are expected to be produced in interactions of ultra-high-energy cosmic rays (uhecrs) with extragalactic background photons. their propagation could be altered by the effects of lorentz invariance violation. in this work, we have developed an extension of the simprop code that includes some lorentz-violating scenarios affecting the propagation of neutrinos. we present the corresponding expected cosmogenic neutrino fluxes for three different astrophysical scenarios for the production of uhecrs. these results can be used to put constraints on the scale of lorentz violation in the neutrino sector. | testing lorentz invariance violation using cosmogenic neutrinos |
context. the spectrum of cosmic ray protons and electrons released by supernova remnants throughout their evolution is poorly known because of the difficulty in accounting for particle escape and confinement downstream of a shock front, where both adiabatic and radiative losses are present. since electrons lose energy mainly through synchrotron losses, it is natural to ask whether the spectrum released into the interstellar medium may be different from that of their hadronic counterpart. independent studies of cosmic ray transport through the galaxy require that the source spectrum of electrons and protons be very different. therefore, the above question acquires a phenomenological relevance.aims: here we calculate the spectrum of cosmic ray protons released during the evolution of supernovae of different types, accounting for the escape from the upstream region and for adiabatic losses of particles advected downstream of the shock and liberated at later times. the same calculation is carried out for electrons, where in addition to adiabatic losses we take the radiative losses suffered behind the shock into account. these electrons are dominated by synchrotron losses in the magnetic field, which most likely is self-generated by cosmic rays accelerated at the shock.methods: we use standard temporal evolution relations for supernova shocks expanding in different types of interstellar media together with an analytic description of particle acceleration and magnetic field amplification to determine the density and spectrum of cosmic ray particles. their evolution in time is derived by numerically solving the equation describing advection with adiabatic and radiative losses for electrons and protons. the flux from particles continuously escaping the supernova remnants is also accounted for.results: the magnetic field in the post-shock region is calculated by using an analytic treatment of the magnetic field amplification due to nonresonant and resonant streaming instability and their saturation. the resulting field is compared with the available set of observational results concerning the dependence of the magnetic field strength upon shock velocity. we find that when the field is the result of the growth of the cosmic-ray-driven nonresonant instability alone, the spectrum of electrons and protons released by a supernova remnant are indeed different; however, such a difference becomes appreciable only at energies ≳100−1000 gev, while observations of the electron spectrum require such a difference to be present at energies as low as ∼10 gev. an effect at such low energies requires substantial magnetic field amplification in the late stages of supernova remnant evolution (shock velocity ≪1000 km s−1); this may not be due to streaming instability but rather hydrodynamical processes. we comment on the feasibility of such conditions and speculate on the possibility that the difference in spectral shape between electrons and protons may reflect either some unknown acceleration effect or additional energy losses in cocoons around the sources. | cosmic ray protons and electrons from supernova remnants |
aragats solar neutron telescope (asnt) is a unique instrument allowing to measure the energy spectra of electrons accelerated and multiplied in the strong electric fields of the atmosphere. we describe the instrument setup, its operation condition, software, and hardware triggers. we present energy spectra of a very large thunderstorm ground enhancement (tge) event observed on 6 october 2021. the detector response function, algorithm to recover energy spectra from the energy release histograms also are presented. the spectra recovery procedure is verified by simulation of the response function of the sevan detector, operating nearby asnt. sevan is a stacked 3 layered detector, interlayered by lead filters registering both charged and neutral species of cosmic rays. the simulated and measured count rates of all 3 layers of the sevan detector show good agreement within 20%. | measurements of energy spectra of relativistic electrons and gamma-rays from avalanches developed in the thunderous atmosphere with aragats solar neutron telescope |
light neutralinos could be copiously produced from the decays of mesons generated in cosmic-ray air showers. these neutralinos can be long-lived particles in the context of r -parity violating (rpv) supersymmetric models, implying that they could be capable of reaching the surface of the earth and decay within the instrumental volume of large neutrino detectors. in this article, we use atmospheric neutrino data from the super-kamiokande experiment to derive novel constraints for the rpv couplings involved in the production of long-lived light neutralinos from the decays of charged d -mesons and kaons. our results highlight the potential of neutrino detectors to search for long-lived particles, by demonstrating that it is possible to explore regions of parameter space that are not yet constrained by any fixed-target nor collider experiments. | searching for light long-lived neutralinos at super-kamiokande |
cosmic rays (crs) are thought to be an important feedback mechanism in star-forming galaxies. they can provide an important source of pressure support and possibly drive outflows. we perform multidimensional cr magnetohydrodynamic simulations including transport by streaming and diffusion to investigate wind launching from an initially hydrostatic atmosphere by crs. we estimate a characteristic eddington limit on the cr flux for which the cr force exceeds gravity and compare it to simulated systems. scaling our results to conditions in star-forming galaxies, we find that crs are likely to contribute to driving outflows for a broad range of star formation environments. we quantify the momentum and energy transfer between crs and gas, along with the associated mass outflow rates under different assumptions about the relative importance of streaming and diffusion for transport. in simulations with streaming, we observe the growth and saturation of the cr acoustic instability, but the crs and gas remain well coupled, with cr momentum transferred efficiently to the gas even when this instability is present. higher cr fluxes transfer more energy to the gas and drive stronger outflows. when streaming is present, most of the transferred energy takes the form of alfvén wave heating of the gas, raising its pressure and internal energy, with a lower fractional contribution to the kinetic energy of the outflow. we also consider runs with radiative cooling, which modifies gas temperature and pressure profiles but does not seem to have a large impact on the mass outflow for super-eddington cr fluxes. | the launching of cosmic ray-driven outflows |
we consider axions coupled to nucleons and photons only through the nucleon electric-dipole moment (edm) portal. this coupling is a model-independent feature of qcd axions, which solve the strong c p problem, and might arise as well in more general axionlike particle setups. we revise the supernova (sn) axion emission induced by the nucleon edm coupling and refine accordingly the sn 1987a bound. furthermore, we calculate the axion flux from a future galactic sn and show that it might produce a peculiar and potentially detectable gamma-ray signal in a large underground neutrino detector such as the proposed hyper-kamiokande. the possibility to detect such a signal offers a way to search for an oscillating nucleon edm complementary to caspere, without relying on the assumption that axions are a sizeable component of the dark matter. furthermore, if axions from sn produce an observable signal, they could also lead to an amount of cosmological extra radiation observable in future cosmic surveys. | axion signatures from supernova explosions through the nucleon electric-dipole portal |
our limited understanding of the physical properties of matter at ultra-high density, high proton/neutron number asymmetry, and low temperature is presently one of the major outstanding problems in physics. as matter in this extreme state is known to only exist stably in the cores of neutron stars (nss), complementary measurements from electromagnetic and gravitational wave astrophysical observations of nss, combined with terrestrial laboratory constraints and further theoretical investigations, hold the promise to provide important insight into the properties of matter in a region of the quantum chromodynamics phase space that is otherwise inaccessible. this multidisciplinary endeavor imposes the following requirements for facilities and resources in the upcoming decade and beyond: * a next generation of gravitational wave detectors to uncover more double ns and neutron star-black hole mergers; * sensitive radio telescopes to find the most massive and fastest spinning nss; * large-area, high-time-resolution and/or high angular resolution x-ray telescopes to constrain the ns mass-radius relation; * suitable laboratory facilities for nuclear physics experiments to constrain the dense matter equation of state; * funding resources for theoretical studies of matter in this regime; * the availability of modern large-scale high performance computing infrastructure. the same facilities and resources would also enable significant advances in other high-profile fields of inquiry in modern physics such as the nature of dark matter, alternative theories of gravity, nucleon superfluidity and superconductivity, as well as an array of astrophysics, including but not limited to stellar evolution, nucleosynthesis, and primordial black holes. | snowmass 2021 cosmic frontier white paper: the dense matter equation of state and qcd phase transitions |
we study the destruction and modification of icy interstellar objects by cosmic rays and gas collisions. using the cosmic-ray flux measured in the local interstellar medium as well as inferred from gamma-ray observations at the different galactocentric radii, we find that cosmic-ray erosion is significant for interstellar objects made of common types of ices. interestingly, cosmic-ray heating might destroy icy interstellar objects very efficiently such that the initial size of an n$_2$ fragment as suggested by \citet{jackson2021} to explain the composition of `oumuamua should be at least 0.5 km in size in order to survive the journey of about 0.5 gyr in the ism and might be even larger if it originated from a region with an enhanced cosmic-ray flux. this implies an initial n$_2$ mass that is at least an order of magnitude larger than the final value, exacerbating the n$_2$ mass budget deficiency for explaining `oumuamua. the erosion time due to cosmic-ray heating and gas collisions also allows us to set approximate limits on the initial size for other types of icy interstellar objects, e.g. composed of co, co$_2$, or ch$_4$. for a given initial size, we constrain the maximum distance to the birth site for interstellar objects with different speeds. we also find that cosmic-ray and gas heating could entirely modify the ice structure before destroying interstellar objects. | erosion of icy interstellar objects by cosmic rays and implications for `oumuamua |
low-energy cosmic rays (up to the gev energy domain) play a crucial role in the physics and chemistry of the densest phase of the interstellar medium. unlike interstellar ionising radiation, they can penetrate large column densities of gas, and reach molecular cloud cores. by maintaining there a small but not negligible gas ionisation fraction, they dictate the coupling between the plasma and the magnetic field, which in turn affects the dynamical evolution of clouds and impacts on the process of star and planet formation. the cosmic-ray ionisation of molecular hydrogen in interstellar clouds also drives the rich interstellar chemistry revealed by observations of spectral lines in a broad region of the electromagnetic spectrum, spanning from the submillimetre to the visual band. some recent developments in various branches of astrophysics provide us with an unprecedented view on low-energy cosmic rays. accurate measurements and constraints on the intensity of such particles are now available both for the very local interstellar medium and for distant interstellar clouds. the interpretation of these recent data is currently debated, and the emerging picture calls for a reassessment of the scenario invoked to describe the origin and/or the transport of low-energy cosmic rays in the galaxy. | low-energy cosmic rays: regulators of the dense interstellar medium |
clusters of galaxies are the largest gravitationally bound systems in the universe. their dynamics are dominated by dark matter (dm), which makes them among the best targets for indirect dm searches. we analyze 12 years of data collected by the fermi large area telescope (fermi-lat) in the direction of 49 clusters of galaxies selected for their proximity to the earth and their high x-ray flux, which makes them the most promising targets. we first create physically motivated models for the dm density around each cluster considering different assumptions for the substructure distribution. then we perform a combined search for a γ -ray signal in the fermi-lat data between 500 mev and 1 tev. we find a signal of γ rays potentially associated with dm that is at a statistical significance of 2.5 σ -3.0 σ when considering a slope for the subhalo mass distribution α =1.9 and minimum mass of mmin=10-6m⊙ . the best-fit dm mass and annihilation cross sections for a b b ¯ annihilation channel are mχ=40 - 60 gev and ⟨σ v ⟩=(2 - 4 )×10-25 cm3/s . when we consider α =2.0 and mmin=10-9m⊙ , the best fit of the cross section reduces to ⟨σ v ⟩=(4 - 10 )×10-26 cm3/s . for both dm substructure models there is a tension between the values of ⟨σ v ⟩ that we find and the upper limits obtained with the nondetection of a γ -ray flux from milky way dwarf spheroidal galaxies. this signal is thus more likely associated with γ rays produced in the intracluster region by cosmic rays colliding with gas and photon fields. | constraining the dark matter contribution of γ rays in clusters of galaxies using fermi-lat data |
the description of the tempo-spatial evolution of the composition of cosmic gas on galactic scales is called 'modelling galactic chemical evolution'. it aims to use knowledge about sources of nucleosynthesis and how they change the composition of interstellar gas, following the formation of stars and the ejection of products from nuclear fusion during their evolution and terminating explosions. sources of nucleosynthesis are diverse: stars with hydrostatic nuclear burning eject some of the products, and core-collapse supernovae add ejecta. binary interactions lead to sources such as thermonuclear supernovae and kilonovae. tracing ejecta from sources, with their different frequencies and environments, through the interstellar medium and successive star formation cycles is the goal of model descriptions. a variety of formalisms exist, from analytical through semi-analytical, numerical or stochastic approaches, gradually making descriptions of compositional evolution of cosmic matter more realistic, teaching us about the astrophysical processes involved in this complex aspect of our universe. radioactive isotopes add important ingredients to such modelling: the intrinsic clock of the radioactive decay process adds a new aspect to the modelling algorithms that leads to different constraints on the important unknowns of star formation activity and interstellar transports. several prominent examples illustrate how modelling the abundances of radioactive isotopes and their evolution have resulted in new lessons; among these are the galaxy-wide distribution of 26al and 60fe, the radioactive components of cosmic rays, the interpretations of terrestrial deposits of 60fe and 244pu, and the radioactive-decay daughter isotopes that were found in meteorites and characterise the birth environment of our solar system. | cosmic radioactivity and galactic chemical evolution |
understanding the anisotropy of ultra high-energy cosmic rays (uhecrs) is crucial for unraveling the origins and propagation mechanisms of these enigmatic particles. in this work, we studied the dipolar anisotropy of uhecrs in the diffusive regime by considering three cosmological models: the standard $\lambda$cdm model, $f(r)$ gravity power-law model and the starobinsky model. this work aims to see the role of the $f(r)$ gravity theory in understanding the anisotropy of uhecrs without condoning the standard cosmology. we found that the amplitude of the dipolar anisotropy is sensitive to these cosmological models, with the $f(r)$ power-law model predicting the largest amplitude, while the $\lambda$cdm model predicting the smallest amplitude at most of the energies in the range considered. the predicted amplitude of the starobinsky model lies within the range of the $\lambda$cdm one. this work not only provides a way for exploration of uhecrs anisotropy within different cosmological contexts but also may pave the way for new avenues of research at the intersection of high-energy astrophysics. | anisotropies of diffusive ultra-high energy cosmic rays in $f(r)$ gravity theory |
photonuclear reactions of light nuclei below a mass of a =60 are planned to be studied experimentally and theoretically with the pandora (photo-absorption of nuclei and decay observation for reactions in astrophysics) project. two experimental methods, virtual photon excitation by proton scattering and real photo absorption by a high-brilliance γ -ray beam produced by laser compton scattering, will be applied to measure the photoabsorption cross sections and decay branching ratio of each decay channel as a function of the photon energy. several nuclear models, e.g. anti-symmetrized molecular dynamics, mean-field and beyond-mean-field models, a large-scale shell model, and ab initio models, will be employed to predict the photonuclear reactions. the uncertainty in the model predictions will be evaluated based on the discrepancies between the model predictions and experimental data. the data and predictions will be implemented in the general reaction calculation code, talys. the results will be applied to the simulation of the photo-disintegration process of ultra-high-energy cosmic rays in inter-galactic propagation. | pandora project for the study of photonuclear reactions below a =60 |
we present the measurement of the energy dependence of the boron flux in cosmic rays and its ratio to the carbon flux in an energy interval from 8.4 gev /n to 3.8 tev /n based on the data collected by the calorimetric electron telescope (calet) during ∼6.4 yr of operation on the international space station. an update of the energy spectrum of carbon is also presented with an increase in statistics over our previous measurement. the observed boron flux shows a spectral hardening at the same transition energy e0∼200 gev /n of the c spectrum, though b and c fluxes have different energy dependences. the spectral index of the b spectrum is found to be γ =-3.047 ±0.024 in the interval 25 <e <200 gev /n . the b spectrum hardens by δ γb=0.25 ±0.12 , while the best fit value for the spectral variation of c is δ γc=0.19 ±0.03 . the b /c flux ratio is compatible with a hardening of 0.09 ±0.05 , though a single power-law energy dependence cannot be ruled out given the current statistical uncertainties. a break in the b /c ratio energy dependence would support the recent ams-02 observations that secondary cosmic rays exhibit a stronger hardening than primary ones. we also perform a fit to the b /c ratio with a leaky-box model of the cosmic-ray propagation in the galaxy in order to probe a possible residual value λ0 of the mean escape path length λ at high energy. we find that our b /c data are compatible with a nonzero value of λ0, which can be interpreted as the column density of matter that cosmic rays cross within the acceleration region. | cosmic-ray boron flux measured from 8.4 gev /n to 3.8 tev /n with the calorimetric electron telescope on the international space station |
$\it{context.}$ various high-energy phenomena in the universe are associated with blazars, powerful active galaxies with jets pointing to the observer. novel results relating blazars to high-energy neutrinos, cosmic rays, and even possible manifestations of new particle physics, are often based on statistical analyses of blazar samples, and uniform sky coverage is important for many of these studies. $\it{aims.}$ here, we construct a uniform full-sky catalog of blazars selected by their optical emission. $\it{methods.}$ we define criteria of isotropy, making a special effort to cover the galactic plane region, and compile an isotropic sample of blazars with gaia optical magnitudes $g<18^{\rm m}$, corrected for the galactic absorption. the sources are taken from full-sky samples selected by parsec-scale radio emission or by high-energy gamma-ray flux, both being known to efficiently select blazar-like objects. $\it{results.}$ we present a catalog of 651 optically bright blazars, uniformly distributed in the sky, together with their radio, optical, x-ray and gamma-ray fluxes, and an isotropic sample of 336 confirmed bl lac type objects. $\it{conclusions.}$ this catalog may be used in future statistical studies of energetic neutrinos, cosmic rays and gamma rays. | an isotropic full-sky sample of optically selected blazars |
there are two classes of gamma-ray transients with a duration shorter than 2 seconds. one consists of cosmic short gamma-ray bursts (grbs) taking place in the deep universe via the neutron star mergers, and the other is the magnetar giant flares (gfs) with energies of $\sim 10^{44}-10^{46}$ erg from ``nearby" galaxies. though the magnetar gfs and the short grbs have rather similar temporal and spectral properties, their energies ($e_{\rm \gamma,iso}$) are different by quite a few orders of magnitude and hence can be distinguished supposing the host galaxies have been robustly identified. the newly observed grb 231115a has been widely discussed as a new gf event for its high probability of being associated with m82. here we conduct a detailed analysis of its prompt emission observed by fermi-gbm, and compare the parameters with existing observations. the prompt gamma-ray radiation properties of grb 231115a, if associated with m82, nicely follow the $e_{\rm p,z}-e_{\gamma,\rm iso}$ relation of the gfs, where $e_{\rm p,z}$ is the peak energy of the gamma-ray spectrum after the redshift ($z$) correction. to be a short grb, the reshift needs to be $\sim 1$. though such a chance is low, the available x-ray/gev observation upper limits are not stringent enough to further rule out this possibility. we have also discussed the prospect of convincingly establishing the magnetar origin of grb 231115a-like events in the future. | grb 231115a: a nearby magnetar giant flare or a cosmic short gamma-ray burst? |
while from the energetic point of view supernova remnants are viable sources of galactic cosmic rays (crs), the issue of whether they can accelerate protons up to a few pev remains unsolved. here we discuss particle acceleration at the forward shock of supernovae, and discuss the possibility that the current of escaping particles may excite a non-resonant instability that in turn leads to the formation of resonant modes that confine particles close to the shock, thereby increasing the maximum energy. this mechanism is at work throughout the expansion of the supernova explosion, from the ejecta dominated (ed) phase to the sedov-taylor (st) phase. the transition from one stage to the other reflects in a break in the spectrum of injected particles. because of their higher explosion rate, we focus our work on type ii sne expanding in the slow, dense wind, produced by the red super-giant progenitor stars. when the explosion occurs in such winds, the transition between the ed and the st phase is likely to take place within a few tens of years. the highest energies are reached at even earlier times, when, however, a small fraction of the mass of ejecta has been processed. as a result, the spectrum of accelerated particles shows a break in the slope, at an energy that is the maximum energy (em) achieved at the beginning of the st phase. above this characteristic energy, the spectrum becomes steeper but remains a power law rather than developing an exponential cutoff. an exponential cut is eventually present at much higher energies but it does not have a phenomenological relevance. we show that for parameters typical of type ii supernovae, em for protons can easily reach values in the pev range, confirming that type ii snrs are the best candidate sources for crs at the knee. from the point of view of implications of this scenario on the measured particle spectra, we have tried to fit kascade-grande, argo -ybj and yac1-tibet array data with our model but we could not find any combination of the parameters that could explain all data sets. indeed the recent measurement of the proton and helium spectra in the knee region, with the argo-ybj and yac1-tibet array, has made the situation very confused. these measurements suggest that the knee in the light component is at ∼ 650 tev, appreciably below the knee in the overall spectrum. on one hand this finding would resolve the problem of reaching very high energies in supernovae, but on the other it would open a critical issue in the transition region between galactic and extragalactic crs. | on the cosmic ray spectrum from type ii supernovae expanding in their red giant presupernova wind |
the cosmogenic radionuclides 7be and 10be are useful tracers for atmospheric transport studies. combining 7be and 10be measurements with an atmospheric transport model can not only improve our understanding of the radionuclide transport and deposition processes but also provide an evaluation of the transport process in the model. to simulate these aerosol tracers, it is critical to evaluate the influence of radionuclide production uncertainties on simulations. here we use the geos-chem chemical transport model driven by the modern-era retrospective analysis for research and applications, version 2 (merra-2) reanalysis to simulate 7be and 10be with the state-of-the-art production rate from the crac:be (cosmic ray atmospheric cascade: beryllium) model considering realistic spatial geomagnetic cutoff rigidities (denoted as p16spa). we also perform two sensitivity simulations: one with the default production rate in geos-chem based on an empirical approach (denoted as lp67) and the other with the production rate from the crac:be but considering only geomagnetic cutoff rigidities for a geocentric axial dipole (denoted as p16). the model results are comprehensively evaluated with a large number of measurements including surface air concentrations and deposition fluxes. the simulation with the p16spa production can reproduce the absolute values and temporal variability of 7be and 10be surface concentrations and deposition fluxes on annual and sub-annual scales, as well as the vertical profiles of air concentrations. the simulation with the lp67 production tends to overestimate the absolute values of 7be and 10be concentrations. the p16 simulation suggests less than 10 % differences compared to p16spa but a significant positive bias (∼18 %) in the 7be deposition fluxes over east asia. we find that the deposition fluxes are more sensitive to the production in the troposphere and downward transport from the stratosphere. independent of the production models, surface air concentrations and deposition fluxes from all simulations show similar seasonal variations, suggesting a dominant meteorological influence. the model can also reasonably simulate the stratosphere-troposphere exchange process of 7be and 10be by producing stratospheric contribution and 10be/7be ratio values that agree with measurements. finally, we illustrate the importance of including the time-varying solar modulations in the production calculation, which significantly improve the agreement between model results and measurements, especially at mid-latitudes and high latitudes. reduced uncertainties in the production rates, as demonstrated in this study, improve the utility of 7be and 10be as aerosol tracers for evaluating and testing transport and scavenging processes in global models. for future geos-chem simulations of 7be and 10be, we recommend using the p16spa (versus default lp67) production rate. | simulations of 7be and 10be with the geos-chem global model v14.0.2 using state-of-the-art production rates |
next-generation neutrino telescopes with substantially improved sensitivity are required to pinpoint the sources of the diffuse astrophysical neutrino flux detected by icecube and uncover the century-old puzzle of cosmic-ray origins. a detector near the equator will provide a unique viewpoint of the neutrino sky, complementing icecube and other neutrino telescopes in the northern hemisphere. here we present results from an expedition to the northeastern region of the south china sea, in the western pacific ocean. a favourable neutrino telescope site was found on an abyssal plain at a depth of ~3.5 km. at depths below 3 km, the sea current speed, water absorption and scattering lengths for cherenkov light were measured to be vc < 10 cm s−1, λabs ≈ 27 m and λsca ≈ 63 m, respectively. accounting for these measurements, we present the design and expected performance of a next-generation neutrino telescope, tropical deep-sea neutrino telescope (trident). with its advanced photon-detection technology and large dimensions, trident expects to observe the icecube steady source candidate ngc 1068 with 5σ significance within 1 year of operation. this level of sensitivity will open a new arena for diagnosing the origin of cosmic rays and probing fundamental physics over astronomical baselines. | a multi-cubic-kilometre neutrino telescope in the western pacific ocean |
the icarus-t600 detector is a 760-ton liquid argon time projection chamber (lartpc) currently operating at fermilab as the far detector in the short baseline neutrino (sbn) program. the sbn program is composed of three lartpcs with a central goal of testing the sterile neutrino hypothesis. after operating for 3-years in the gran sasso underground laboratory, the icarus detector was shipped to cern where it was outfitted with 360 8" photomultiplier tubes (pmts) for a new optical detection system. the pmt system detects fast scintillation light from charged particles interacting in the liquid argon, generating the trigger signal for the full detector and allows 3d reconstruction of events. now operating at shallow depth, the detector is exposed to a high flux of cosmic rays that can fake neutrino interactions. to mitigate this effect a cosmic ray tagger (crt) and a 3-meter-thick concrete were installed. precise timing information from both the pmt and crt subsystems can help to identify whether an interaction originated from inside or outside of the icarus cryostat. this paper reviews a method for cosmogenic background reduction and timing calibration of the crt and pmt light detection systems in icarus. | light detection and cosmic rejection in the icarus lartpc at fermilab |
cosmic-ray protons accumulate for cosmological times in clusters of galaxies because their typical radiative and diffusive escape times are longer than the hubble time. their hadronic interactions with protons of the intra-cluster medium generate secondary electrons, gamma rays, and neutrinos. in light of the high-energy neutrino events recently discovered by the icecube neutrino observatory, for which galaxy clusters have been suggested as possible sources, and the forthcoming results from the fermi gamma-ray survey, we here estimate the contribution from galaxy clusters to the diffuse gamma-ray and neutrino backgrounds. we modelled the cluster population by means of their mass function, using a phenomenological luminosity-mass relation applied to all clusters, as well as a detailed semi-analytical model. in the latter model, we divide clusters into cool-core/non-cool-core, and loud/quiet subsamples, as suggested by observations, and model the cosmic-ray proton population according to state-of-the-art hydrodynamic numerical simulations. additionally, we consider observationally-motivated values for the cluster magnetic field. this is a crucial parameter since the observed radio counts of clusters need to be respected owing to synchrotron emission by secondary electrons. for a choice of parameters respecting current constraints from radio to gamma rays, and assuming a proton spectral index of -2, we find that hadronic interactions in clusters contribute less than 10% to the icecube flux and much less to the total extragalactic gamma-ray background observed by fermi. they account for less than 1% for spectral indices ≤-2. the high-energy neutrino flux observed by icecube can be reproduced without violating radio constraints only if a very hard (and speculative) spectral index >-2 is adopted. however, this scenario is in tension with the high-energy icecube data, which seems to suggest a spectral energy distribution of the neutrino flux that decreases with the particle energy. we prove that icecube should be able to test our most optimistic scenarios for spectral indices ≥-2.2 by stacking a few nearby massive galaxy clusters. in the case of proton-photon interactions in clusters, we find that very likely protons do not reach sufficiently high energies to produce neutrinos in these environments. we argue that our results are optimistic because of our assumptions and that clusters of galaxies cannot make any relevant contribution to the extragalactic gamma-ray and neutrino backgrounds in any realistic scenario. finally, we find that the cluster contribution to the angular fluctuations in the gamma-ray background is subdominant, less than 10% on sub-degree scales. | high-energy gamma-ray and neutrino backgrounds from clusters of galaxies and radio constraints |
several attempts have been made to obtain a radiographic image inside volcanoes using cosmic-ray muons (muography). muography is expected to resolve highly heterogeneous density profiles near the surface of volcanoes. however, several prior works have failed to make clear observations due to contamination by background noise. the background contamination leads to an overestimation of the muon flux and consequently a significant underestimation of the density in the target mountains. to investigate the origin of the background noise, we performed a monte carlo simulation. the main components of the background noise in muography are found to be low-energy protons, electrons and muons in case of detectors without particle identification and with energy thresholds below 1 gev. this result was confirmed by comparisons with actual observations of nuclear emulsions. this result will be useful for detector design in future works, and in addition some previous works of muography should be reviewed from the view point of background contamination. | monte carlo simulation for background study of geophysical inspection with cosmic-ray muons |
we present here designs for a staged implementation of an orbiting debris remediation system comprised of a super-wide field-of-view telescope (euso) and a novel high efficiency fibre-based laser system (can). initial proof of concept stages will operate from the international space station (iss) where the euso telescope has been designed for operation as a detector of ultra-high energy cosmic rays. equipped with 2.5 m optics and a field of view of ±30°, the euso telescope can also be utilised for the detection of high velocity fragmentation debris in orbit near the iss. further tracking, characterisation and remediation are to be performed by a can laser system operating in tandem with the euso telescope. for full scale versions of both instruments, the range of the detection/removal operation can be as large as 100 km. utilising a step-by-step approach of increasing scale we present an analysis of implementation of: 1) proof of principle demonstration of the detection by a mini-euso and operation of 100-fibre can laser technology as an iss based prototype, 2) technical demonstrator of debris-removal that consists of the euso telescope for the detection and a 10,000 fibre can laser for tracking and impulse delivery for debris re-entry, and 3) a free-flyer mission dedicated to debris remediation in a polar orbit with the altitude near 800 km. the integration of the two novel technologies aboard the iss amounts to a novel approach as an immediate response to the serious space debris problem with the existing platform of iss. | demonstration designs for the remediation of space debris from the international space station |
cosmic ray antiprotons provide a powerful tool to probe dark matter annihilations in our galaxy. the sensitivity of this important channel is, however, diluted by sizable uncertainties in the secondary antiproton background. in this work, we improve the calculation of secondary antiproton production with a particular focus on the high energy regime. we employ the most recent collider data and identify a substantial increase of antiproton cross sections with energy. this increase is driven by the violation of feynman scaling as well as by an enhanced strange hyperon production. the updated antiproton production cross sections are made publicly available for independent use in cosmic ray studies. in addition, we provide the correlation matrix of cross section uncertainties for the ams-02 experiment. at high energies, the new cross sections improve the compatibility of the ams-02 data with a pure secondary origin of antiprotons in cosmic rays. | cosmic ray antiprotons at high energies |
local interstellar spectra (lis) of primary cosmic ray (cr) nuclei, such as helium, oxygen, and mostly primary carbon are derived for the rigidity range from 10 mv to ∼200 tv using the most recent experimental results combined with the state-of-the-art models for cr propagation in the galaxy and in the heliosphere. two propagation packages, galprop and helmod, are combined into a single framework that is used to reproduce direct measurements of cr species at different modulation levels, and at both polarities of the solar magnetic field. the developed iterative maximum-likelihood method uses galprop-predicted lis as input to helmod, which provides the modulated spectra for specific time periods of the selected experiments for model-data comparison. the interstellar and heliospheric propagation parameters derived in this study are consistent with our prior analyses using the same methodology for propagation of cr protons, helium, antiprotons, and electrons. the resulting lis accommodate a variety of measurements made in the local interstellar space (voyager 1) and deep inside the heliosphere at low (ace/cris, heao-3) and high energies (pamela, ams-02). | deciphering the local interstellar spectra of primary cosmic-ray species with helmod |
we report the results of our analysis of the publicly available data obtained by the large area telescope (lat) on board the fermi satellite towards the direction of the young massive star cluster westerlund 2. we found significant extended γ-ray emission in the vicinity of westerlund 2 with a hard power-law energy spectrum extending from 1 to 250 gev with a photon index of 2.0 ± 0.1. we argue that amongst several alternatives, the luminous stars in westerlund 2 are likely sites of acceleration of particles responsible for the diffuse γ-ray emission of the surrounding interstellar medium. in particular, the young star cluster westerlund 2 can provide sufficient non-thermal energy to account for the γ-ray emission. in this scenario, since the γ-ray production region is significantly larger than the area occupied by the star cluster, we conclude that the γ-ray production is caused by hadronic interactions of accelerated protons and nuclei with the ambient gas. in that case, the total energy budget in relativistic particles is estimated of the order of 1050 erg. | diffuse γ-ray emission in the vicinity of young star cluster westerlund 2 |
context. features in the spectra of primary cosmic rays (crs) provide invaluable information on the propagation of these particles in the galaxy. in the rigidity region around a few hundred gv, these features have been measured in the proton and helium spectra by the pamela experiment and later confirmed with a higher significance by ams-02. we investigate the implications of these data sets for the scenario in which crs propagate under the action of self-generated waves.aims: we show that the recent data on the spectrum of protons and helium nuclei as collected with ams-02 and voyager are in very good agreement with the predictions of a model in which the transport of galactic crs is regulated by self-generated waves. we also study the implications of the scenario for the boron-to-carbon ratio: although a good overall agreement is found, at high energy we find marginal support for a (quasi) energy independent contribution from the grammage, which we argue may come from the sources themselves.methods: the transport equation for both primary and secondary nuclei is solved together with an equation for the evolution of the self-generated waves and a background of pre-existing waves. the solution for this system of nonlinear equations is found with an iterative method elaborated by the same authors in a previous work on this topic.results: a break in the spectra of all nuclei is found at a rigidity of a few hundred gv, as a result of a transition from self-generated waves to pre-existing waves with a kolmogorov power spectrum. neither the slope of the diffusion coefficient, nor its normalization are free parameters. moreover, at rigidities below a few gv, crs are predicted to be advected with the self-generated waves at the local alfvén speed. this effect, predicted in our previous work, provides an excellent fit to the voyager data on the proton and helium spectra at low energies, providing additional support to the model. | nonlinear cosmic ray galactic transport in the light of ams-02 and voyager data |
relativistic jets from blazars are known to be sources of very high energy gamma rays (vhegrs). during their propagation in the intergalactic space, vhegrs interact with pervasive cosmological photon fields such as the extragalactic background light (ebl) and the cosmic microwave background (cmb), producing electron-positron pairs. these pairs can upscatter cmb/ebl photons to high energies via inverse compton (ic) scattering, thereby continuing the cascade process. this is often used to set limits on intergalactic magnetic fields (igmfs). however, the picture may change if plasma instabilities, arising due to the interaction of the pairs with the intergalactic medium (igm), cool down the electrons/positrons faster than inverse compton scattering. as a consequence, the kinetic energy lost by the pairs to the igm could cause a hardening in the observed gamma-ray spectrum at energies below ∼100 gev. here, we study several types and models of instabilities and assess their impact for interpreting observations of distant blazars. our results suggest that plasma instabilities can describe the spectra of some blazars and mimic the effects of igmfs, depending on parameters such as intrinsic spectrum of the object, the density and temperature of the igm, and the luminosity of the beam. on the other hand, we find that for our fiducial set of parameters plasma instabilities do not have a major impact on the spectra of some of the blazars studied. therefore, they may be used for constraining igmfs. | the impact of plasma instabilities on the spectra of tev blazars |
in 15 years of data taking, the pierre auger observatory has observed no events beyond 1 011.3 gev . this null result translates into an upper bound on the flux of ultrahigh-energy cosmic rays, implying j (>1 011.3 gev )<3.6 ×10-5 km-2 sr-1 yr-1 , at the 90% c.l. we interpret this bound as a constraint on extreme-energy photons originating in the decay super-heavy dark matter (shdm) particles clustered in the galactic halo. armed with this constraint, we derive the strongest lower limit on the lifetime of hadronically decaying shdm particles with masses in the range 1 014≲mx/gev ≲1016. we also explore the capability of nasa's future probe of extreme multi-messenger astrophysics mission to search for shdm signals. | hunting for superheavy dark matter with the highest-energy cosmic rays |
cosmic ray (cr) electrons reveal key insights into the non-thermal physics of the interstellar medium (ism), galaxies, galaxy clusters, and active galactic nuclei by means of their inverse compton (ic) γ-ray emission and synchrotron emission in magnetic fields. while magnetohydrodynamical (mhd) simulations with cr protons capture their dynamical impact on these systems, only few computational studies include cr electron physics because of the short cooling time-scales and complex hysteresis effects, which require a numerically expensive, high-resolution spectral treatment. since cr electrons produce important non-thermal observational signatures, such a spectral cr electron treatment is important to link mhd simulations to observations. we present an efficient post-processing code for cosmic ray electron spectra that are evolved in time (crest) on lagrangian tracer particles. the cr electron spectra are very accurately evolved on comparably large mhd time-steps owing to an innovative hybrid numerical-analytical scheme. crest is coupled to the cosmological mhd code arepo and treats all important aspects of spectral cr electron evolution such as adiabatic expansion and compression, coulomb losses, radiative losses in form of ic, bremsstrahlung and synchrotron processes, diffusive shock acceleration and reacceleration, fermi-ii reacceleration, and secondary electron injection. after showing various code validations of idealized one-zone simulations, we study the coupling of crest to mhd simulations. we demonstrate that the cr electron spectra are efficiently and accurately evolved in shock-tube and sedov-taylor blast wave simulations. this opens up the possibility to produce self-consistent synthetic observables of non-thermal emission processes in various astrophysical environments. | evolution of cosmic ray electron spectra in magnetohydrodynamical simulations |
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