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high-energy γ-rays of interstellar origin are produced by the interaction of cosmic-ray (cr) particles with the diffuse gas and radiation fields in the galaxy. the main features of this emission are well understood and are reproduced by existing cr propagation models employing 2d galactocentric cylindrically symmetrical geometry. however, the high-quality data from instruments like the fermi large area telescope reveal significant deviations from the model predictions on few to tens of degrees scales, indicating the need to include the details of the galactic spiral structure and thus requiring 3d spatial modeling. in this paper, the high-energy interstellar emissions from the galaxy are calculated using the new release of the galprop code employing 3d spatial models for the cr source and interstellar radiation field (isrf) densities. three models for the spatial distribution of cr sources are used that are differentiated by their relative proportion of input luminosity attributed to the smooth disk or spiral arms. two isrf models are developed based on stellar and dust spatial density distributions taken from the literature that reproduce local near- to far-infrared observations. the interstellar emission models that include arms and bulges for the cr source and isrf densities provide plausible physical interpretations for features found in the residual maps from high-energy γ-ray data analysis. the 3d models for cr and isrf densities provide a more realistic basis that can be used for the interpretation of the nonthermal interstellar emissions from the galaxy. | high-energy gamma rays from the milky way: three-dimensional spatial models for the cosmic-ray and radiation field densities in the interstellar medium |
the bulk propagation speed of gev-energy cosmic rays is limited by frequent scattering off hydromagnetic waves. most galaxy evolution simulations that account for this confinement assume the gas is fully ionized and cosmic rays are well coupled to alfvén waves; however, multiphase density inhomogeneities, frequently underresolved in galaxy evolution simulations, induce cosmic-ray collisions and ionization-dependent transport driven by cosmic-ray decoupling and elevated streaming speeds in partially neutral gas. how do cosmic rays navigate and influence such a medium, and can we constrain this transport with observations? in this paper, we simulate cosmic-ray fronts impinging upon idealized, partially neutral clouds and lognormally distributed clumps, with and without ionization-dependent transport. with these high-resolution simulations, we identify cloud interfaces as crucial regions where cosmic-ray fronts can develop a stairstep pressure gradient sufficient to collisionlessly generate waves, overcome ion-neutral damping, and exert a force on the cloud. we find that the acceleration of cold clouds is hindered by only a factor of a few when ionization-dependent transport is included, with additional dependencies on magnetic field strength and cloud dimensionality. we also probe how cosmic rays sample the background gas and quantify collisional losses. hadronic gamma-ray emission maps are qualitatively different when ionization-dependent transport is included, but the overall luminosity varies by only a small factor, as the short cosmic-ray residence times in cold clouds are offset by the higher densities that cosmic rays sample. | cosmic-ray transport, energy loss, and influence in the multiphase interstellar medium |
classical novae are cataclysmic binary star systems in which the matter of a companion star is accreted on a white dwarf1,2. accumulation of hydrogen in a layer eventually causes a thermonuclear explosion on the surface of the white dwarf3, brightening the white dwarf to ~105 solar luminosities and triggering ejection of the accumulated matter. novae provide the extreme conditions required to accelerate particles, electrons or protons, to high energies. here we present the detection of gamma rays by the magic telescopes from the 2021 outburst of rs ophiuchi, a recurrent nova with a red giant companion, which allowed us to accurately characterize the emission from a nova in the 60 gev to 250 gev energy range. the theoretical interpretation of the combined fermi lat and magic data suggests that protons are accelerated to hundreds of gigaelectronvolts in the nova shock. such protons should create bubbles of enhanced cosmic ray density, of the order of 10 pc, from the recurrent novae. | proton acceleration in thermonuclear nova explosions revealed by gamma rays |
although many high-energy neutrinos detected by the icecube telescope are believed to have an extraterrestrial origin, their astrophysical sources remain a mystery. recently, an unprecedented discovery of a high-energy muon neutrino event coincident with a multiwavelength flare from a blazar, txs 0506 +056 , shed some light on the origin of the neutrinos. it is usually believed that a blazar is produced by a relativistic jet launched from an accreting supermassive black hole (smbh). here, we show that the high-energy neutrino event can be interpreted by the inelastic hadronuclear interactions between the accelerated cosmic-ray protons in the relativistic jet and the dense gas clouds in the vicinity of the smbh. such a scenario only requires a moderate proton power in the jet, which could be much smaller than that required in the conventional hadronic model which instead calls upon the photomeson process. meanwhile, the flux of the multiwavelength flare from the optical to gamma-ray band can be well explained by invoking a second radiation zone in the jet at a larger distance to the smbh. in our model, the neutrino emission lasts a shorter time than the multiwavelength flare, so the neutrino event is not necessarily correlated with the flare, but it is probably accompanied by a spectrum hardening above a few giga-electron-volt (gev). | hadronuclear interpretation of a high-energy neutrino event coincident with a blazar flare |
recent models for the large-scale galactic magnetic fields in the literature have been largely constrained by synchrotron emission and faraday rotation measures. we use three different but representative models to compare their predicted polarized synchrotron and dust emission with that measured by the planck satellite. we first update these models to match the planck synchrotron products using a common model for the cosmic-ray leptons. we discuss the impact on this analysis of the ongoing problems of component separation in the planck microwave bands and of the uncertain cosmic-ray spectrum. in particular, the inferred degree of ordering in the magnetic fields is sensitive to these systematic uncertainties, and we further show the importance of considering the expected variations in the observables in addition to their mean morphology. we then compare the resulting simulated emission to the observed dust polarization and find that the dust predictions do not match the morphology in the planck data but underpredict the dust polarization away from the plane. we modify one of the models to roughly match both observables at high latitudes by increasing the field ordering in the thin disc near the observer. though this specific analysis is dependent on the component separation issues, we present the improved model as a proof of concept for how these studies can be advanced in future using complementary information from ongoing and planned observational projects. | planck intermediate results. xlii. large-scale galactic magnetic fields |
the differential cross sections for inclusive neutral pions as a function of transverse and longitudinal momentum in the very forward-rapidity region have been measured at the lhc with the lhc forward detector in proton-proton collisions at √{s }=2.76 and 7 tev and in proton-lead collisions at nucleon-nucleon center-of-mass energies of √{snn}=5.02 tev . such differential cross sections in proton-proton collisions are compatible with the hypotheses of limiting fragmentation and feynman scaling. comparing proton-proton with proton-lead collisions, we find a sizable suppression of the production of neutral pions in the differential cross sections after subtraction of ultraperipheral proton-lead collisions. this suppression corresponds to the nuclear modification factor value of about 0.1-0.3. the experimental measurements presented in this paper provide a benchmark for the hadronic interaction monte carlo simulation codes that are used for the simulation of cosmic ray air showers. | measurements of longitudinal and transverse momentum distributions for neutral pions in the forward-rapidity region with the lhcf detector |
the brightest long gamma-ray burst (grb) detected so far by the swift-bat and fermi-gbm telescopes, grb 221009a, provides an unprecedented opportunity for understanding the high-energy processes in extreme transient phenomena. we find that the conventional leptonic models for the afterglow emission from this source, synchrotron and synchrotron-self-compton, have difficulties explaining the observation of ≳10 tev γ rays (as high as 18 tev) by the lhaaso detector. we modeled the γ-ray spectrum estimated in the energy range 0.1-1 gev by the fermi-lat detector. the flux predicted by our leptonic models is severely attenuated at > 1 tev due to γγ pair production with extragalactic background light, and hence an additional component is required at ≳10 tev. ultrahigh-energy cosmic rays can be accelerated in the grb blast wave, and their propagation induces an electromagnetic cascade in the extragalactic medium. the line-of-sight component of this flux can explain the emission at ≳10 tev detected by lhaaso, which requires a fraction of the grb blast wave energy to be in ultrahigh-energy cosmic rays. this could be an indication of ultrahigh-energy cosmic-ray acceleration in grbs. | ultrahigh-energy cosmic-ray signature in grb 221009a |
we report the observation of new properties of primary iron (fe) cosmic rays in the rigidity range 2.65 gv to 3.0 tv with 0.62 ×106 iron nuclei collected by the alpha magnetic spectrometer experiment on the international space station. above 80.5 gv the rigidity dependence of the cosmic ray fe flux is identical to the rigidity dependence of the primary cosmic ray he, c, and o fluxes, with the fe /o flux ratio being constant at 0.155 ±0.006 . this shows that unexpectedly fe and he, c, and o belong to the same class of primary cosmic rays which is different from the primary cosmic rays ne, mg, and si class. | properties of iron primary cosmic rays: results from the alpha magnetic spectrometer |
detections of non-gravitational interactions of massive dark matter (dm) with visible sector so far have given null results. the dm may communicate with the ordinary matter only through gravitational interaction. besides, the majority of traditional direct detections have poor sensitivities for light dm because of the small recoil energy. thanks to the high energy cosmic rays (crs), the light dm can be boosted by scattering with crs and thus may be detected in the ongoing experiments. in this work, we derive the exclusion limits on the cosmic ray boosted sub-gev dm with gravitational mediator from the xenon1t data. it turns out that a sizable region of such a cosmic ray boosted dm can be excluded by the current data. | cosmic ray boosted sub-gev gravitationally interacting dark matter in direct detection |
the fermi-lat data accumulated over 7 years of γ -ray observations, together with the high resolution gas (co & hi) and the dust opacity maps, are used to study the emissivity of γ -rays induced by interactions of cosmic rays (crs) with the interstellar medium. based on the dust opacity templates, the γ -ray emissivity was measured for 36 segments of the galactic plane. furthermore, the γ -ray emissivity was evaluated in six galactocentric rings. both the absolute emissivity and the energy spectra of γ -rays derived in the interval 0.2-100 gev show significant variations along the galactic plane. the density of crs, derived under the assumption that γ -rays are predominately produced in cr interactions with the interstellar gas, is characterized by a strong radial dependence. in the inner galaxy the cr density substantially exceeds the density in the outer parts of the galaxy: by a factor of a few at 10 gev, and by more than an order of magnitude at 1 tev. remarkably, the energy distribution of crs appears to be substantially harder than the energy spectrum obtained from direct measurements of local crs. at the same time, the flux and the energy spectrum of multi-gev protons derived from γ -ray data in the outskirts of the galaxy is quite close to the measurements of local crs. | radial distribution of the diffuse γ -ray emissivity in the galactic disk |
the observation of long-lived particles at the lhc would reveal physics beyond the standard model, could account for the many open issues in our understanding of our universe, and conceivably point to a more complete theory of the fundamental interactions. such long-lived particle signatures are fundamentally motivated and can appear in virtually every theoretical construct that address the hierarchy problem, dark matter, neutrino masses and the baryon asymmetry of the universe. we describe in this document a large detector, mathusla, located on the surface above an hl-lhc $pp$ interaction point, that could observe long-lived particles with lifetimes up to the big bang nucleosynthesis limit of 0.1 s. we also note that its large detector area allows mathusla to make important contributions to cosmic ray physics. because of the potential for making a major breakthrough in our conceptual understanding of the universe, long-lived particle searches should have the highest level of priority. | mathusla: a detector proposal to explore the lifetime frontier at the hl-lhc |
without additional heating, radiative cooling of the halo gas of massive galaxies (milky way-mass and above) produces cold gas or stars exceeding that observed. heating from active galactic nucleus (agn) jets is likely required, but the jet properties remain unclear. this is particularly challenging for galaxy simulations, where the resolution is orders-of-magnitude insufficient to resolve jet formation and evolution. on such scales, the uncertain parameters include the jet energy form [kinetic, thermal, cosmic ray (cr)]; energy, momentum, and mass flux; magnetic fields; opening angle; precession; and duty cycle. we investigate these parameters in a $10^{14}\, {\rm m}_{\odot }$ halo using high-resolution non-cosmological magnetohydrodynamic simulations with the fire-2 (feedback in realistic environments) stellar feedback model, conduction, and viscosity. we explore which scenarios qualitatively meet observational constraints on the halo gas and show that cr-dominated jets most efficiently quench the galaxy by providing cr pressure support and modifying the thermal instability. mildly relativistic (~mev or ~1010k) thermal plasma jets work but require ~10 times larger energy input. for fixed energy flux, jets with higher specific energy (longer cooling times) quench more effectively. for this halo mass, kinetic jets are inefficient at quenching unless they have wide opening or precession angles. magnetic fields also matter less except when the magnetic energy flux reaches ≳ 1044 erg s-1 in a kinetic jet model, which significantly widens the jet cocoon. the criteria for a successful jet model are an optimal energy flux and a sufficiently wide jet cocoon with a long enough cooling time at the cooling radius. | which agn jets quench star formation in massive galaxies? |
the 13c (α ,n ) 16o reaction is the main neutron source for the slow-neutron-capture process in asymptotic giant branch stars and for the intermediate process. direct measurements at astrophysical energies in above-ground laboratories are hindered by the extremely small cross sections and vast cosmic-ray-induced background. we performed the first consistent direct measurement in the range of ec .m .=0.24 to 1.9 mev using the accelerators at the china jinping underground laboratory and sichuan university. our measurement covers almost the entire intermediate process gamow window in which the large uncertainty of the previous experiments has been reduced from 60% down to 15%, eliminates the large systematic uncertainty in the extrapolation arising from the inconsistency of existing datasets, and provides a more reliable reaction rate for the studies of the slow-neutron-capture and intermediate processes along with the first direct determination of the alpha strength for the near-threshold state. | deep underground laboratory measurement of 13c (α ,n ) 16o in the gamow windows of the s and i processes |
we present a solution for the ultraviolet - submillimetre (submm) interstellar radiation fields (isrfs) of the milky way (mw), derived from modelling cobe, iras and planck maps of the all-sky emission in the near-, mid-, far-infrared and submm. the analysis uses the axisymmetric radiative transfer model that we have previously implemented to model the panchromatic spectral energy distributions (seds) of star-forming galaxies in the nearby universe, but with a new methodology allowing for optimization of the radial and vertical geometry of stellar emissivity and dust opacity, as deduced from the highly resolved emission seen from the vantage point of the sun. as such, this is the first self-consistent model of the broad-band continuum emission from the mw. in this paper, we present model predictions for the spatially integrated sed of the mw as seen from the sun, showing good agreement with the data, and give a detailed description of the solutions for the distribution of isrfs, as well as their physical origin, throughout the volume of the galaxy. we explore how the spatial and spectral distributions of our new predictions for the isrf in the mw affects the amplitude and spectral distributions of the gamma rays produced via inverse compton scattering for cosmic ray (cr) electrons situated at different positions in the galaxy, as well as the attenuation of the gamma rays due to interactions of the gamma-ray photons with photons of the isrf. we also compare and contrast our solutions for the isrf with those incorporated in the galprop package used for modelling the high-energy emission from cr in the mw. | a radiation transfer model for the milky way: i. radiation fields and application to high-energy astrophysics★ |
low-background searches for astrophysical neutrino sources anywhere in the sky can be performed using cascade events induced by neutrinos of all flavors interacting in icecube with energies as low as ∼1 tev. previously we showed that, even with just two years of data, the resulting sensitivity to sources in the southern sky is competitive with icecube and antares analyses using muon tracks induced by charge current muon neutrino interactions—especially if the neutrino emission follows a soft energy spectrum or originates from an extended angular region. here, we extend that work by adding five more years of data, significantly improving the cascade angular resolution, and including tests for point-like or diffuse galactic emission to which this data set is particularly well suited. for many of the signal candidates considered, this analysis is the most sensitive of any experiment to date. no significant clustering was observed, and thus many of the resulting constraints are the most stringent to date. in this paper we will describe the improvements introduced in this analysis and discuss our results in the context of other recent work in neutrino astronomy. | search for sources of astrophysical neutrinos using seven years of icecube cascade events |
we present a measurement of the extragalactic background light (ebl) based on a joint likelihood analysis of 32 gamma-ray spectra for 12 blazars in the redshift range z = 0.03-0.944, obtained by the magic telescopes and fermi-lat. the ebl is the part of the diffuse extragalactic radiation spanning the ultraviolet, visible, and infrared bands. major contributors to the ebl are the light emitted by stars through the history of the universe, and the fraction of it that was absorbed by dust in galaxies and re-emitted at longer wavelengths. the ebl can be studied indirectly through its effect on very high energy photons that are emitted by cosmic sources and absorbed via γγ interactions during their propagation across cosmological distances. we obtain estimates of the ebl density in good agreement with state-of-the-art models of the ebl production and evolution. the 1σ upper bounds, including systematic uncertainties, are between 13 per cent and 23 per cent above the nominal ebl density in the models. no anomaly in the expected transparency of the universe to gamma-rays is observed in any range of optical depth. we also perform a wavelength-resolved ebl determination, which results in a hint of an excess of ebl in the 0.18-0.62 μ m range relative to the studied models, yet compatible with them within systematics. | measurement of the extragalactic background light using magic and fermi-lat gamma-ray observations of blazars up to z = 1 |
context. the vertical diffusive halo size of the galaxy, l, is a key parameter for dark matter indirect searches. it can be better determined thanks to recent ams-02 data.aims: we set constraints on l from be/b and 10be/be data, and we performed a consistency check with positron data. we detail the dependence of be/b and 10be/be on l and forecast on which energy range better data would be helpful for future l improvements.methods: we used usine v3.5 for the propagation of nuclei, and e+ were calculated with the pinching method.results: the current ams-02 be/b (∼3% precision) and ace-cris 10be/be (∼10% precision) data bring similar and consistent constraints on l. the ams-02 be/b data alone constrain l = 5-2+3 kpc at a 68% confidence level (spanning different benchmark transport configurations), a range for which most models do not overproduce positrons. future experiments need to deliver percent-level accuracy on 10be/9be anywhere below 10 gv to further constrain l.conclusions: forthcoming ams-02, helix, and pamela 10be/9be results will further test and possibly tighten the limits derived here. elemental ratios involving radioactive species with different lifetimes (e.g. al/mg and cl/ar) are also awaited to provide complementary and robuster constraints. | galactic halo size in the light of recent ams-02 data |
we investigate the effects of population iii (pop iii) stars and their remnants on the cosmological 21-cm global signal. by combining a semi-analytic model of pop iii star formation with a global 21-cm simulation code, we investigate how x-ray and radio emission from accreting pop iii black holes may affect both the timing and depth of the 21-cm absorption feature that follows the initial onset of star formation during the cosmic dawn. we compare our results to the findings of the edges experiment, which has reported the first detection of a cosmic 21-cm signal. in general, we find that our fiducial pop iii models, which have peak star formation rate densities of ∼10-4 m⊙ yr-1 mpc-3 between z ∼ 10 and z ∼ 15, are able to match the timing of the edges signal quite well, in contrast to models that ignore pop iii stars. to match the unexpectedly large depth of the edges signal without recourse to exotic physics, we vary the parameters of emission from accreting black holes (formed as pop iii remnants) including the intrinsic strength of x-ray and radio emission as well as the local column density of neutral gas. we find that models with strong radio emission and relatively weak x-ray emission can self-consistently match the edges signal, though this solution requires fine-tuning. we are only able to produce signals with sharp features similar to the edges signal if the pop iii imf is peaked narrowly around $140 \, \mathrm{m}_\odot$ . | the effects of population iii radiation backgrounds on the cosmological 21-cm signal |
the seven approximately earth-sized transiting planets in the trappist-1 system provide a unique opportunity to explore habitable- and nonhabitable-zone small planets within the same system. its habitable-zone exoplanets—due to their favorable transit depths—are also worlds for which atmospheric transmission spectroscopy is within reach with the hubble space telescope (hst) and james webb space telescope (jwst). we present here an independent reduction and analysis of two hst wide field camera 3 (wfc3) near-infrared transit spectroscopy data sets for six planets (b through g). utilizing our physically motivated detector charge-trap correction and a custom cosmic-ray correction routine, we confirm the general shape of the transmission spectra presented by de wit et al. our data reduction approach leads to a 25% increase in the usable data and reduces the risk of confusing astrophysical brightness variations (e.g., flares) with instrumental systematics. no prominent absorption features are detected in any individual planet’s transmission spectra; by contrast, the combined spectrum of the planets shows a suggestive decrease around 1.4 μm similar to an inverted water absorption feature. including transit depths from k2, the speculoos-south observatory, and spitzer, we find that the complete transmission spectrum is fully consistent with stellar contamination owing to the transit light source effect. these spectra demonstrate how stellar contamination can overwhelm planetary absorption features in low-resolution exoplanet transit spectra obtained by hst and jwst and also highlight the challenges in combining multi-epoch observations for planets around rapidly rotating spotted stars. | the near-infrared transmission spectra of trappist-1 planets b, c, d, e, f, and g and stellar contamination in multi-epoch transit spectra |
spectral distortions in the cosmic microwave background over the 40-200 mhz band are imprinted by neutral hydrogen in the intergalactic medium prior to the end of reionization. this signal, produced in the redshift range z = 6-34 at the rest-frame wavelength of 21 cm, has not been detected yet; and a poor understanding of high-redshift astrophysics results in a large uncertainty in the expected spectrum. the saras 2 radiometer was purposely designed to detect the sky-averaged 21 cm signal. the instrument, deployed at the timbaktu collective (southern india) in 2017 april-june, collected 63 hr of science data, which were examined for the presence of the cosmological 21 cm signal. in our previous work, the first-light data from the saras 2 radiometer were analyzed with bayesian likelihood-ratio tests using 264 plausible astrophysical scenarios. in this paper we reexamine the data using an improved analysis based on the frequentist approach and forward-modeling. we show that saras 2 data reject 20 models, out of which 15 are rejected at a significance >5σ. all the rejected models share the scenario of inefficient heating of the primordial gas by the first population of x-ray sources, along with rapid reionization. joint astronomy program, indian institute of science, bangalore 560012, india. | saras 2 constraints on global 21 cm signals from the epoch of reionization |
the most powerful persistent accelerators in the universe are jetted active galaxies. blazars, galaxies whose jets are directed towards earth, dominate the extragalactic γ-ray sky. still, most of the highest-energy particle accelerators probably elude detection. these extreme blazars, whose radiated energy can peak beyond 10 tev, are ideal targets to study particle acceleration and radiative processes, and may provide links to cosmic rays and astrophysical neutrinos. the growing number of extreme blazars observed at teraelectronvolt energies has been critical for the emergence of γ-ray cosmology, including measurements of the extragalactic background light, tight bounds on the intergalactic magnetic field, and constraints on exotic physics at energies inaccessible with human-made accelerators. tremendous progress has been achieved over the past decade, which bodes well for the future, particularly with the deployment of the cherenkov telescope array. | progress in unveiling extreme particle acceleration in persistent astrophysical jets |
the origin of extragalactic magnetic fields is still poorly understood. based on a dedicated suite of cosmological magneto-hydrodynamical simulations with the enzo code we have performed a survey of different models that may have caused present-day magnetic fields in galaxies and galaxy clusters. the outcomes of these models differ in cluster outskirts, filaments, sheets and voids and we use these simulations to find observational signatures of magnetogenesis. with these simulations, we predict the signal of extragalactic magnetic fields in radio observations of synchrotron emission from the cosmic web, in faraday rotation, in the propagation of ultra high energy cosmic rays, in the polarized signal from fast radio bursts at cosmological distance and in spectra of distant blazars. in general, primordial scenarios in which present-day magnetic fields originate from the amplification of weak (⩽ng ) uniform seed fields result in more homogeneous and relatively easier to observe magnetic fields than astrophysical scenarios, in which present-day fields are the product of feedback processes triggered by stars and active galaxies. in the near future the best evidence for the origin of cosmic magnetic fields will most likely come from a combination of synchrotron emission and faraday rotation observed at the periphery of large-scale structures. | simulations of extragalactic magnetic fields and of their observables |
we use kinetic hybrid simulations (kinetic ions-fluid electrons) to characterize the fraction of ions that are accelerated to non-thermal energies at non-relativistic collisionless shocks. we investigate the properties of the shock discontinuity and show that shocks propagating almost along the background magnetic field (quasi-parallel shocks) reform quasi-periodically on ion cyclotron scales. ions that impinge on the shock when the discontinuity is the steepest are specularly reflected. this is a necessary condition for being injected, but it is not sufficient. also, by following the trajectories of reflected ions, we calculate the minimum energy needed for injection into diffusive shock acceleration, as a function of the shock inclination. we construct a minimal model that accounts for the ion reflection from quasi-periodic shock barrier, for the fraction of injected ions, and for the ion spectrum throughout the transition from thermal to non-thermal energies. this model captures the physics relevant for ion injection at non-relativistic astrophysical shocks with arbitrary strengths and magnetic inclinations, and represents a crucial ingredient for understanding the diffusive shock acceleration of cosmic rays. | simulations and theory of ion injection at non-relativistic collisionless shocks |
the past decade has brought impressive advances in the astrophysics of cosmic rays (crs) and multiwavelength astronomy, thanks to the new instrumentation launched into space and built on the ground. modern technologies employed by those instruments provide measurements with unmatched precision, enabling searches for subtle signatures of dark matter and new physics. understanding the astrophysical backgrounds to better precision than the observed data is vital in moving to this new territory. a state-of-the-art cr propagation code, called galprop, is designed to address exactly this challenge. having 25 yr of development behind it, the galprop framework has become a de facto standard in the astrophysics of crs, diffuse photon emissions (radio to γ-rays), and searches for new physics. galprop uses information from astronomy, particle physics, and nuclear physics to predict crs and their associated emissions self-consistently, providing a unifying modeling framework. the range of its physical validity covers 18 orders of magnitude in energy, from sub-kev to pev energies for particles and from μev to pev energies for photons. the framework and the data sets are public and are extensively used by many experimental collaborations and by thousands of individual researchers worldwide for interpretation of their data and for making predictions. this paper details the latest release of the galprop framework and updated cross sections, further developments of its initially auxiliary data sets for models of the interstellar medium that grew into independent studies of the galactic structure-distributions of gas, dust, radiation, and magnetic fields-as well as the extension of its modeling capabilities. example applications included with the distribution illustrating usage of the new features are also described. | the galprop cosmic-ray propagation and nonthermal emissions framework: release v57 |
we report the first detection of a tev γ -ray flux from the solar disk (6.3 σ ), based on 6.1 years of data from the high altitude water cherenkov (hawc) observatory. the 0.5-2.6 tev spectrum is well fit by a power law, d n /d e =a (e /1 tev )-γ , with a =(1.6 ±0.3 )×10-12 tev-1 cm-2 s-1 and γ =3.62 ±0.14 . the flux shows a strong indication of anticorrelation with solar activity. these results extend the bright, hard gev emission from the disk observed with fermi-lat, seemingly due to hadronic galactic cosmic rays showering on nuclei in the solar atmosphere. however, current theoretical models are unable to explain the details of how solar magnetic fields shape these interactions. hawc's tev detection thus deepens the mysteries of the solar-disk emission. | discovery of gamma rays from the quiescent sun with hawc |
we first apply singular spectrum analysis (ssa) to the international sunspot number (1849-2015) and the count of polar faculae (1906-2006). the ssa method finds 22-, 11-, and 5.5-year components as the first eigenvectors of these solar activity proxies. we next apply ssa to the 10 madden-julian oscillation (mjo; 1978-2016) indices. the first, most intense component ssa finds in all mjo indices has either a period of 5.5 or 11 years. the longer-term modulation of amplitude is on the order of one third of the total variation. the 5.5-year ssa component 1 of most mjo indices moreover follows the decreasing amplitude of solar cycles. we then apply ssa to climate indices pacific decadal oscillation, el nino southern oscillation precipitation index, arctic oscillation, atlantic multidecadal oscillation, tropical southern atlantic oscillation, western hemisphere warm pool, and brazil and sahel rainfalls. we find that the first ssa eigenvectors are all combinations of rather pure 11, 5.5, and 3.6-year pseudo-cycles. the 5.5-year component is frequently observed and is particularly important and sharp in the series in which it appears. all these periods have long been attributed to solar activity, and this by itself argues for the existence of a strong link between solar activity and climate. the mechanisms of coupling must be complex and probably nonlinear but they remain to be fully understood (uv radiation, solar wind, and galactic cosmic rays being the most promising candidates). we propose as a first step a kuramoto model of nonlinear coupling that generates phase variations compatible with the observed ones. | a solar signature in many climate indices |
a high-energy muon neutrino event, icecube-170922a, was recently discovered in both spatial and temporal coincidence with a gamma-ray flare of the blazar txs 0506+056. it has been shown with standard one-zone models that neutrinos can be produced in the blazar jet via hadronic interactions, but with a flux that is mostly limited by the x-ray data. in this work, we explore the neutrino production from txs 0506+056 by invoking two physically distinct emission zones in the jet, with an inner blob inside of or close to the broad-line region (blr) and an outer one well beyond the blr. using the doppler-boosted radiation of the blr as the target photon field, the inner zone accounts for the neutrino and gamma-ray emission via pγ interactions and inverse compton scattering, respectively, while the outer zone produces the optical and x-ray emission via synchrotron and synchrotron self-compton processes. the different conditions of the two zones allow us to suppress the x-ray emission from the electromagnetic cascade, and set a much higher upper limit on the muon neutrino flux (i.e., ∼10-11 erg cm-2 s-1) than in one-zone models. we compare our scenario in detail with one-zone models discussed in the literature, and argue that differentiating between such scenarios will become possible with next-generation neutrino telescopes, such as icecube-gen2. | a two-zone model for blazar emission: implications for txs 0506+056 and the neutrino event icecube-170922a |
new data are reported from the operation of a 2 liter c3f8 bubble chamber in the snolab underground laboratory, with a total exposure of 211.5 kg days at four different energy thresholds below 10 kev. these data show that c3f8 provides excellent electron-recoil and alpha rejection capabilities at very low thresholds. the chamber exhibits an electron-recoil sensitivity of <3.5 ×1 0-10 and an alpha rejection factor of >98.2 %. these data also include the first observation of a dependence of acoustic signal on alpha energy. twelve single nuclear recoil event candidates were observed during the run. the candidate events exhibit timing characteristics that are not consistent with the hypothesis of a uniform time distribution, and no evidence for a dark matter signal is claimed. these data provide the most sensitive direct detection constraints on wimp-proton spin-dependent scattering to date, with significant sensitivity at low wimp masses for spin-independent wimp-nucleon scattering. | dark matter search results from the pico-2l c3f8 bubble chamber |
we introduce the swift gamma-ray burst host galaxy legacy survey (“shoals”), a multi-observatory high-redshift galaxy survey targeting the largest unbiased sample of long-duration gamma-ray burst (grb) hosts yet assembled (119 in total). we describe the motivations of the survey and the development of our selection criteria, including an assessment of the impact of various observability metrics on the success rate of afterglow-based redshift measurement. we briefly outline our host galaxy observational program, consisting of deep spitzer/irac imaging of every field supplemented by similarly deep, multicolor optical/near-ir photometry, plus spectroscopy of events without preexisting redshifts. our optimized selection cuts combined with host galaxy follow-up have so far enabled redshift measurements for 110 targets (92%) and placed upper limits on all but one of the remainder. about 20% of grbs in the sample are heavily dust obscured, and at most 2% originate from z\gt 5.5. using this sample, we estimate the redshift-dependent grb rate density, showing it to peak at z∼ 2.5 and fall by at least an order of magnitude toward low (z = 0) redshift, while declining more gradually toward high (z∼ 7) redshift. this behavior is consistent with a progenitor whose formation efficiency varies modestly over cosmic history. our survey will permit the most detailed examination to date of the connection between the grb host population and general star-forming galaxies, directly measure evolution in the host population over cosmic time and discern its causes, and provide new constraints on the fraction of cosmic star formation occurring in undetectable galaxies at all redshifts. | the swift gamma-ray burst host galaxy legacy survey. i. sample selection and redshift distribution |
we present a new cosmological analysis of the galaxy clusters in the planck mmf3 cosmology sample with a cosmic microwave background (cmb) lensing calibration of the cluster masses. as demonstrated by planck, galaxy clusters detected via the sunyaev-zel'dovich (sz) effect offer a powerful way to constrain cosmological parameters such as ωm and σ8. determining the absolute cluster mass scale is, however, difficult, and some recent calibrations have yielded cosmological constraints in apparent tension with constraints in the λcdm model derived from the power spectra of the primary cmb anisotropies. in order to calibrate the absolute mass scale of the full planck cluster sample, we remeasure the masses of all 433 clusters through their weak lensing signature in the cmb temperature anisotropies as measured by planck. we perform a joint bayesian analysis of the cluster counts and masses taking as input the estimated cluster masses, sz signal-to-noise ratios, and redshifts. our analysis properly accounts for selection effects in the construction of the cluster sample. we find σ8(ωm/0.33)0.25 = 0.765 ± 0.035 and 1-b_{sz} = 0.71 ± 0.10, where the mass bias factor 1-b_{sz} relates cluster mass to the sz mass that appears in the x-ray-calibrated cluster scaling relations. we find no evidence for tension with the planck primary cmb constraints on λcdm model parameters. | cosmological constraints from planck galaxy clusters with cmb lensing mass bias calibration |
the nature of cosmic ray (cr) transport in the milky way remains elusive. the predictions of current microphysical cr transport models in magnetohydrodynamic (mhd) turbulence are drastically different from what is observed. these models usually focus on mhd turbulence with a strong guide field and ignore the impact of turbulent intermittency on particle propagation. this motivates our studying the alternative regime of large-amplitude turbulence with δb/b0 ≫ 1, in which intermittent small-scale magnetic field reversals are ubiquitous. we study particle transport in such turbulence by integrating trajectories in stationary snapshots. to quantify spatial diffusion, we use a set-up with continuous particle injection and escape, which we term the turbulent leaky box. we find that particle transport is very different from the strong guide-field case. low-energy particles are better confined than high-energy particles, despite less efficient pitch-angle isotropization at small energies. in the limit of weak guide field, energy-dependent confinement is driven by the energy-dependent (in)ability to follow reversing magnetic field lines exactly and by the scattering in regions of 'resonant curvature', where the field line bends on a scale that is of the order of the local particle gyro-radius. we derive a heuristic model of particle transport in magnetic folds that approximately reproduces the energy dependence of transport found numerically. we speculate that cr propagation in the galaxy is regulated by the intermittent field reversals highlighted here and discuss the implications of our findings for cr transport in the milky way. | cosmic ray transport in large-amplitude turbulence with small-scale field reversals |
recently, the icecube collaboration reported first evidence for the astrophysical neutrinos. observation corresponds to the total astrophysical neutrino flux of the order of 3 × 10-8 gev cm-2 s-1 sr-1 in a pev energy range [1]. active galactic nuclei (agn) are natural candidate sources for such neutrinos. to model the neutrino creation in agns, we study photopion production processes on the radiation field of the shakura-sunyaev accretion discs in the black hole vicinity. we show that this model can explain the detected neutrino flux and at the same time avoids the existing constraints from the gamma-ray and cosmic-ray observations. | neutrinos in icecube from active galactic nuclei |
superheavy dark matter may show its presence in high-energy neutrino signals detected on earth. from the latest results of icecube, we could set the strongest lower bound on the lifetime of dark matter beyond 100 tev around 1028 s. the excess around a pev is noticed and may be interpreted as the first signal of dark matter even though further confirmation and dedicated searches are invited. | superheavy dark matter and icecube neutrino signals: bounds on decaying dark matter |
context. the alpha magnetic spectrometer (ams-02) measured several secondary-to-primary ratios enabling a detailed study of galactic cosmic-ray transport.aims: we constrain previously derived benchmark scenarios (based on ams-02 b/c data only) using other secondary-to-primary ratios to test the universality of transport and the presence of a low-rigidity diffusion break.methods: we use the 1d thin disc/thick halo propagation model of usine v3.5 and a χ2 minimisation accounting for a covariance matrix of errors (ams-02 systematics) and nuisance parameters (cross-sections and solar modulation uncertainties).results: the combined analysis of ams-02 li/c, be/c, and b/c strengthens the case for a diffusion slope of δ = 0.50 ± 0.03 with a low-rigidity break or upturn of the diffusion coefficient at gv rigidities. our simple model can successfully reproduce all considered data (li/c, be/c, b/c, n/o, and 3he/4he), although several issues remain: (i) the quantitative agreement depends on the assumptions made on the poorly constrained correlation lengths of ams-02 data systematics; (ii) combined analyses are very sensitive to production cross-sections, and we find post-fit values differing by ∼5 - 15% from their most likely values (roughly within currently estimated nuclear uncertainties); (iii) two very distinct regions of the parameter space remain viable, either with reacceleration and convection, or with purely diffusive transport.conclusions: to take full benefit of combined analyses of ams-02 data, better nuclear data and a better handle on energy correlations in the data systematic are required. ams-02 data on heavier species are eagerly awaited to explore cosmic-ray propagation scenarios further. | combined analysis of ams-02 (li,be,b)/c, n/o, 3he, and 4he data |
we use the spectral synthesis code cloudy to tabulate the properties of gas for an extensive range in redshift (z = 0-9), temperature (log t[k] = 1-9.5), metallicity (log z/z⊙ = -4 - +0.5, z = 0), and density ($\log n_{\mathrm{h}}[\, \mathrm{cm}^{-3}] = -8$ - +6). this therefore includes gas with properties characteristic of the interstellar, circumgalactic, and intergalactic media. the gas is exposed to a redshift-dependent uv/x-ray background, while for the self-shielded lower-temperature gas (i.e. ism gas), an interstellar radiation field and cosmic rays are added. the radiation field is attenuated by a density- and temperature-dependent column of gas and dust. motivated by the observed star formation law, this gas column density also determines the intensity of the interstellar radiation field and the cosmic ray density. the ionization balance, molecule fractions, cooling rates, line emissivities, and equilibrium temperatures are calculated self-consistently. we include dust, cosmic rays, and the interstellar radiation field step-by-step to study their relative impact. these publicly available tables are ideal for hydrodynamical simulations. they can be used stand alone or coupled to a non-equilibrium network for a subset of elements. the release includes a c routine to read in and interpolate the tables, as well as an easy-to-use python graphical user interface to explore the tables. | radiative cooling rates, ion fractions, molecule abundances, and line emissivities including self-shielding and both local and metagalactic radiation fields |
context. as the number of complex organic molecules (coms) detected in the interstellar medium increases, it becomes even more important to place meaningful constraints on the origins and formation pathways of such chemical species. the molecular cloud sagittarius b2(n) is host to several hot molecular cores in the early stage of star formation, where a great variety of coms are detected in the gas phase. given its exposure to the extreme conditions of the galactic center (gc) region, sgr b2(n) is one of the best targets to study the impact of environmental conditions on the production of coms.aims: our main goal is to characterize the physico-chemical evolution of sgr b2(n)'s sources in order to explain their chemical differences and constrain their environmental conditions.methods: the chemical composition of sgr b2(n)'s hot cores, n2, n3, n4, and n5 is derived by modeling their 3 mm emission spectra extracted from the exploring molecular complexity with alma (emoca) imaging spectral line survey performed with the atacama large millimeter/submillimeter array (alma). we derived the density distribution in the envelope of the sources based on the masses computed from the alma dust continuum emission maps. we used the radiative transfer code radmc-3d to compute temperature profiles and inferred the current luminosity of the sources based on the com rotational temperatures derived from population diagrams. we used published results of 3d radiation-magnetohydrodynamical (rmhd) simulations of high-mass star formation to estimate the time evolution of the source properties. we employed the astrochemical code magickal to compute time-dependent chemical abundances in the sources and to investigate how physical properties and environmental conditions influence the production of coms.results: the analysis of the abundances of 11 coms detected toward sgr b2(n2-n5) reveals that n3 and n5 share a similar chemical composition while n2 differs significantly from the other sources. we estimate the current luminosities of n2, n3, n4, and n5 to be 2.6 × 105 l⊙, 4.5 × 104 l⊙, 3.9 × 105 l⊙, and 2.8 × 105 l⊙, respectively. we find that astrochemical models with a cosmic-ray ionization rate of 7 × 10-16 s-1 best reproduce the abundances with respect to methanol of ten coms observed toward sgr b2(n2-n5). we also show that coms still form efficiently on dust grains with minimum dust temperatures in the prestellar phase as high as 15 k, but that minimum temperatures higher than 25 k are excluded.conclusions: the chemical evolution of sgr b2(n2-n5) strongly depends on their physical history. a more realistic description of the hot cores' physical evolution requires a more rigorous treatment with rmhd simulations tailored to each hot core. | the complex chemistry of hot cores in sgr b2(n): influence of cosmic-ray ionization and thermal history |
we build a new model for the global 21-cm signal that is calibrated to measurements of the high-z galaxy luminosity function (lf) and further tuned to match the thomson scattering optical depth of the cosmic microwave background, τe. assuming that the z ≲ 8 galaxy population can be smoothly extrapolated to higher redshifts, the recent decline in best-fitting values of τe and the inefficient heating induced by x-ray binaries (the presumptive sources of the high-z x-ray background) imply that the entirety of cosmic reionization and reheating occurs at z ≲ 12. in contrast to past global 21-cm models, whose z ∼ 20 (ν ∼ 70 mhz) absorption features and strong ∼25 mk emission features were driven largely by the assumption of efficient early star formation and x-ray heating, our new models peak in absorption at ν ∼ 110 mhz at depths ∼-160 mk and have negligible emission components. current uncertainties in the faint-end of the lf, binary populations in star-forming galaxies, and uv and x-ray escape fractions introduce ∼20 mhz (∼50 mk) deviations in the trough's frequency (amplitude), while emission signals remain weak (≲10 mk) and are confined to ν ≳ 140 mhz. these predictions, which are intentionally conservative, suggest that the detection of a 21-cm absorption minimum at frequencies below ∼90 mhz and/or emission signals stronger than ∼10mk at ν ≲ 140 mhz would provide strong evidence for `new' sources at high redshifts, such as population iii stars and their remnants. | the global 21-cm signal in the context of the high- z galaxy luminosity function |
neutron star mergers are the canonical multimessenger events: they have been observed through photons for half a century, gravitational waves since 2017, and are likely to be sources of neutrinos and cosmic rays. studies of these events enable unique insights into astrophysics, particles in the ultrarelativistic regime, the heavy element enrichment history through cosmic time, cosmology, dense matter, and fundamental physics. uncovering this science requires vast observational resources, unparalleled coordination, and advancements in theory and simulation, which are constrained by our current understanding of nuclear, atomic, and astroparticle physics. this review begins with a summary of our current knowledge of these events, the expected observational signatures, and estimated detection rates for the next decade. i then present the key observations necessary to advance our understanding of these sources, followed by the broad science this enables. i close with a discussion on the necessary future capabilities to fully utilize these enigmatic sources to understand our universe. | neutron star mergers and how to study them |
we introduce a python package that provides simple and unified access to a collection of datasets from fundamental physics research—including particle physics, astroparticle physics, and hadron- and nuclear physics—for supervised machine learning studies. the datasets contain hadronic top quarks, cosmic-ray-induced air showers, phase transitions in hadronic matter, and generator-level histories. while public datasets from multiple fundamental physics disciplines already exist, the common interface and provided reference models simplify future work on cross-disciplinary machine learning and transfer learning in fundamental physics. we discuss the design and structure and line out how additional datasets can be submitted for inclusion. as showcase application, we present a simple yet flexible graph-based neural network architecture that can easily be applied to a wide range of supervised learning tasks. we show that our approach reaches performance close to dedicated methods on all datasets. to simplify adaptation for various problems, we provide easy-to-follow instructions on how graph-based representations of data structures, relevant for fundamental physics, can be constructed and provide code implementations for several of them. implementations are also provided for our proposed method and all reference algorithms. | shared data and algorithms for deep learning in fundamental physics |
we use analytical calculations and time-dependent spherically symmetric simulations to study the properties of isothermal galactic winds driven by cosmic rays (crs) streaming at the alfvén velocity. the simulations produce time-dependent flows permeated by strong shocks; we identify a new linear instability of sound waves that sources these shocks. the shocks substantially modify the wind dynamics, invalidating previous steady state models: the cr pressure pc has a staircase-like structure with dpc/dr ≃ 0 in most of the volume, and the time-averaged cr energetics are in many cases better approximated by pc ∝ ρ1/2, rather than the canonical pc ∝ ρ2/3. accounting for this change in cr energetics, we analytically derive new expressions for the mass-loss rate, momentum flux, wind speed, and wind kinetic power in galactic winds driven by cr streaming. we show that streaming crs are ineffective at directly driving cold gas out of galaxies, though cr-driven winds in hotter ism phases may entrain cool gas. for the same physical conditions, diffusive cr transport (paper i) yields mass-loss rates that are a few-100 times larger than streaming transport, and asymptotic wind powers that are a factor of ≃4 larger. we discuss the implications of our results for galactic wind theory and observations; strong shocks driven by cr-streaming-induced instabilities produce gas with a wide range of densities and temperatures, consistent with the multiphase nature of observed winds. we also quantify the applicability of the isothermal gas approximation for modelling streaming crs and highlight the need for calculations with more realistic thermodynamics. | the physics of galactic winds driven by cosmic rays - ii. isothermal streaming solutions |
we theoretically show that a single free electron in circular motion radiates an electromagnetic wave possessing helical phase structure, which is closely related to orbital angular momentum carried by it. we experimentally demonstrate it by interference and double-slit diffraction experiments on radiation from relativistic electrons in spiral motion. our results indicate that photons carrying orbital angular momentum should be created naturally by cyclotron/synchrotron radiations or compton scatterings in various situations in cosmic space. we propose promising laboratory vortex photon sources in various wavelengths ranging from radio wave to gamma-rays. | helical phase structure of radiation from an electron in circular motion |
the deep extragalactic visible legacy survey (devils) is a large spectroscopic campaign at the anglo-australian telescope (aat) aimed at bridging the near and distant universe by producing the highest completeness survey of galaxies and groups at intermediate redshifts (0.3 < z < 1.0). our sample consists of ∼60 000 galaxies to y < 21.2 mag, over ∼6 deg2 in three well-studied deep extragalactic fields (cosmic origins survey field, cosmos; extended chandra deep field south, ecdfs; and the x-ray multi-mirror mission large-scale structure region, xmm-lss - all large synoptic survey telescope deep-drill fields). this paper presents the broad experimental design of devils. our target sample has been selected from deep visible and infrared survey telescope for astronomy (vista) y-band imaging (vista deep extragalactic observations, video and ultravista), with photometry measured by profound. photometric star/galaxy separation is done on the basis of near-infrared colours and has been validated by visual inspection. to maximize our observing efficiency for faint targets, we employ a redshift feedback strategy, which continually updates our target lists, feeding back the results from the previous night's observations. we also present an overview of the initial spectroscopic observations undertaken in late 2017 and early 2018. | deep extragalactic visible legacy survey (devils): motivation,design, and target catalogue |
we report a quasi-differential upper limit on the extremely-high-energy (ehe) neutrino flux above $5\times 10^{6}$ gev based on an analysis of nine years of icecube data. the astrophysical neutrino flux measured by icecube extends to pev energies, and it is a background flux when searching for an independent signal flux at higher energies, such as the cosmogenic neutrino signal. we have developed a new method to place robust limits on the ehe neutrino flux in the presence of an astrophysical background, whose spectrum has yet to be understood with high precision at pev energies. a distinct event with a deposited energy above $10^{6}$ gev was found in the new two-year sample, in addition to the one event previously found in the seven-year ehe neutrino search. these two events represent a neutrino flux that is incompatible with predictions for a cosmogenic neutrino flux and are considered to be an astrophysical background in the current study. the obtained limit is the most stringent to date in the energy range between $5 \times 10^{6}$ and $5 \times 10^{10}$ gev. this result constrains neutrino models predicting a three-flavor neutrino flux of $e_\nu^2\phi_{\nu_e+\nu_\mu+\nu_\tau}\simeq2\times 10^{-8}\ {\rm gev}/{\rm cm}^2\ \sec\ {\rm sr}$ at $10^9\ {\rm gev}$. a significant part of the parameter-space for ehe neutrino production scenarios assuming a proton-dominated composition of ultra-high-energy cosmic rays is excluded. | differential limit on the extremely-high-energy cosmic neutrino flux in the presence of astrophysical background from nine years of icecube data |
lorentz invariance violation (liv) can change the threshold behavior predicted by special relativity and cause threshold anomalies which affect the propagation of cosmic photons. in this work, we focus on the threshold anomaly effect on cosmic photon attenuations by extragalactic background light (ebl) and discuss how to identify liv from observations of very high energy (vhe) photons propagated from long distance in the universe. we point out that the large high altitude air shower observatory (lhaaso), one of the most sensitive gamma-ray detector arrays currently operating at tev and pev energies, is an ideal facility for performing such liv searching. we apply the proposed strategy to discuss the newly observed gamma-ray burst grb 221009a to demonstrate the predictive ability of our suggestions. | searching lorentz invariance violation from cosmic photon attenuation |
we explore the effects of the expected higher cosmic ray (cr) ionization rates {\zeta }{cr} on the abundances of carbon monoxide (co), atomic carbon (c), and ionized carbon (c+) in the h2 clouds of star-forming galaxies. the study of bisbas et al. is expanded by (a) using realistic inhomogeneous giant molecular cloud (gmc) structures, (b) a detailed chemical analysis behind the cr-induced destruction of co, and (c) exploring the thermal state of cr-irradiated molecular gas. crs permeating the interstellar medium with {\zeta }{cr}≳ 10× ({galactic}) are found to significantly reduce the [co]/[h2] abundance ratios throughout the mass of a gmc. co rotational line imaging will then show much clumpier structures than the actual ones. for {\zeta }{cr}≳ 100 × (galactic) this bias becomes severe, limiting the usefulness of co lines for recovering structural and dynamical characteristics of h2-rich galaxies throughout the universe, including many of the so-called main-sequence galaxies where the bulk of cosmic star formation occurs. both c+ and c abundances increase with rising {\zeta }{cr}, with c remaining the most abundant of the two throughout h2 clouds, when {\zeta }{cr}∼ (1-100) × (galactic). c+ starts to dominate for {\zeta }{cr}≳ {10}3 × (galactic). the thermal state of the gas in the inner and denser regions of gmcs is invariant with {t}{gas}∼ 10 {{k}} for {\zeta }{cr}∼ (1-10) × (galactic). for {\zeta }{cr}∼ {10}3 × (galactic) this is no longer the case and {t}{gas}∼ 30{--}50 {{k}} are reached. finally, we identify oh as the key species whose t gas-sensitive abundance could mitigate the destruction of co at high temperatures. | cosmic-ray induced destruction of co in star-forming galaxies |
active galactic nuclei (agns) play a central role in solving the decades-old cooling-flow problem. although there is consensus that agns provide the energy to prevent catastrophically large star formation, one major problem remains: how is the agn energy thermalized in the intracluster medium (icm)? we perform a suite of three-dimensional magnetohydrodynamical adaptive mesh refinement simulations of agn feedback in a cool core cluster including cosmic rays (crs). crs are supplied to the icm via collimated agn jets and subsequently disperse in the magnetized icm via streaming, and interact with the icm via hadronic, coulomb, and streaming instability heating. we find that cr transport is an essential model ingredient at least within the context of the physical model considered here. when streaming is included, (i) crs come into contact with the ambient icm and efficiently heat it, (ii) streaming instability heating dominates over coulomb and hadronic heating, (iii) the agn is variable and the atmosphere goes through low-/high-velocity dispersion cycles, and, importantly, (iv) cr pressure support in the cool core is very low and does not demonstrably violate observational constraints. however, when streaming is ignored, cr energy is not efficiently spent on the icm heating and cr pressure builds up to a significant level, creating tension with the observations. overall, we demonstrate that cr heating is a viable channel for the agn energy thermalization in clusters and likely also in ellipticals, and that crs play an important role in determining agn intermittency and the dynamical state of cool cores. | cosmic-ray feedback heating of the intracluster medium |
the dark matter particle explorer (dampe) is a spaceborne astroparticle physics experiment, launched on 17 december 2015. dampe will identify possible dark matter signatures by detecting electrons and photons in the 5 gev-10 tev energy range. it will also measure the flux of nuclei up to 100 tev, for the study of the high energy cosmic ray origin and propagation mechanisms. dampe is composed of four sub-detectors: a plastic strip scintillator, a silicon-tungsten tracker-converter (stk), a bgo imaging calorimeter and a neutron detector. the stk is composed of six tracking planes of 2 orthogonal layers of single-sided micro-strip detectors, for a total detector surface of ca. 7 m2. the stk has been extensively tested for space qualification. also, numerous beam tests at cern have been done to study particle detection at silicon module level, and at full detector level. after description of the dampe payload and its scientific mission, we will describe the stk characteristics and assembly. we will then focus on some results of single ladder performance tests done with particle beams at cern. | the dampe silicon-tungsten tracker |
by looking at the kinetic sunyaev-zeldovich effect (ksz) in planck nominal mission data, we present a significant detection of baryons participating in large-scale bulk flows around central galaxies (cgs) at redshift z ≈ 0.1. we estimate the pairwise momentum of the ksz temperature fluctuations at the positions of the central galaxy catalogue (cgc) samples extracted from sloan digital sky survey (sdss-dr7) data. for the foreground-cleaned sevem, smica, nilc, and commander maps, we find 1.8-2.5σ detections of the ksz signal, which are consistent with the ksz evidence found in individualplanck raw frequency maps, although lower than found in the wmap-9yr w-band (3.3σ). we further reconstruct the peculiar velocity field from the cg density field, and compute for the first time the cross-correlation function between ksz temperature fluctuations and estimates of cg radial peculiar velocities. this correlation function yields a 3.0-3.7σ detection of the peculiar motion of extended gas on mpc scales in flows correlated up to distances of 80-100 h-1 mpc. both the pairwise momentum estimates and the ksz temperature-velocity field correlation find evidence for ksz signatures out to apertures of 8 arcmin and beyond, corresponding to a physical radius of >1 mpc, more than twice the mean virial radius of halos. this is consistent with the predictions from hydrodynamical simulations that most of the baryons are outside the virialized halos. we fit a simple model, in which the temperature-velocity cross-correlation is proportional to the signal seen in a semi-analytic model built upon n-body simulations, and interpret the proportionality constant as an effective optical depth to thomson scattering. we find τt = (1.4 ± 0.5) × 10-4; the simplest interpretation of this measurement is that much of the gas is in a diffuse phase, which contributes little signal to x-ray or thermal sunyaev-zeldovich observations. | planck intermediate results. xxxvii. evidence of unbound gas from the kinetic sunyaev-zeldovich effect |
we forecast the number of galaxy clusters that can be detected via the thermal sunyaev-zel'dovich (tsz) signals by future cosmic microwave background (cmb) experiments, primarily the wide area survey of the cmb-s4 experiment but also cmb-s4's smaller de-lensing survey and the proposed cmb-hd experiment. we predict that cmb-s4 will detect 75,000 clusters with its wide survey of f sky = 50% and 14,000 clusters with its deep survey of f sky = 3%. of these, approximately 1350 clusters will be at z ≥ 2, a regime that is difficult to probe by optical or x-ray surveys. we assume cmb-hd will survey the same sky as the s4-wide, and find that cmb-hd will detect three times more overall and an order of magnitude more z ≥ 2 clusters than cmb-s4. these results include galactic and extragalactic foregrounds along with atmospheric and instrumental noise. using cmb-cluster lensing to calibrate the cluster tsz-mass scaling relation, we combine cluster counts with primary cmb to obtain cosmological constraints for a two-parameter extension of the standard model (λcdm + ∑mν+ w 0). in addition to constraining σ(w 0) to ≲1%, we find that both surveys can enable a ~2.5-4.5σ detection of ∑mν , substantially strengthening cmb-only constraints. we also study the evolution of the intracluster medium by modeling the cluster virialization v(z) and find tight constraints from cmb-s4, with further factors of three to four improvement for cmb-hd. | constraining cluster virialization mechanism and cosmology using thermal-sz-selected clusters from future cmb surveys |
the abundance of massive galaxy clusters is a powerful probe of departures from general relativity (gr) on cosmic scales. despite current stringent constraints placed by stellar and galactic tests, on larger scales alternative theories of gravity such as f(r) can still work as effective theories. here we present constraints on two popular models of f(r), hu-sawicki and "designer," derived from a fully self-consistent analysis of current samples of x-ray selected clusters and accounting for all the covariances between cosmological and astrophysical parameters. using cluster number counts in combination with recent data from the cosmic microwave background (cmb) and the cmb lensing potential generated by large scale structures, as well as with other cosmological constraints on the background expansion history and its mean matter density, we obtain the upper bounds log10|fr 0|<-4.79 and log10b0<-3.75 at the 95.4% confidence level, for the hu-sawicki (with n =1 ) and designer models, respectively. the robustness of our results derives from high-quality cluster growth data for the most massive clusters known out to redshifts z ∼0.5, a tight control of systematic uncertainties including an accurate and precise mass calibration from weak gravitational lensing data, and the use of the full shape of the halo mass function over the mass range of our data. | new constraints on f(r) gravity from clusters of galaxies |
cosmic-ray interactions with the atmosphere produce a flux of neutrinos in all directions with energies extending above the tev scale1. the earth is not a fully transparent medium for neutrinos with energies above a few tev, as the neutrino-nucleon cross-section is large enough to make the absorption probability non-negligible2. since absorption depends on energy and distance travelled, studying the distribution of the tev atmospheric neutrinos passing through the earth offers an opportunity to infer its density profile3-7. this has never been done, however, due to the lack of relevant data. here we perform a neutrino-based tomography of the earth using actual data—one-year of through-going muon atmospheric neutrino data collected by the icecube telescope8. using only weak interactions, in a way that is completely independent of gravitational measurements, we are able to determine the mass of the earth and its core, its moment of inertia, and to establish that the core is denser than the mantle. our results demonstrate the feasibility of this approach to study the earth's internal structure, which is complementary to traditional geophysics methods. neutrino tomography could become more competitive as soon as more statistics is available, provided that the sources of systematic uncertainties are fully under control. | neutrino tomography of earth |
if dark matter has mass lower than around 1 gev, it will not impart enough energy to cause detectable nuclear recoils in many direct-detection experiments. however, if dark matter is upscattered to high energy by collisions with cosmic rays, it may be detectable in both direct-detection experiments and neutrino experiments. we report the results of a dedicated search for boosted dark matter upscattered by cosmic rays, using ∼14.6 solar days of data from the prospect reactor antineutrino experiment. we show that such a flux of upscattered dark matter would display characteristic diurnal sidereal modulation, and use this to set new experimental constraints on sub-gev dark matter exhibiting large interaction cross sections. | limits on sub-gev dark matter from the prospect reactor antineutrino experiment |
context. scaling relations link the physical properties of clusters at cosmic scales. they are used to probe the evolution of large-scale structure, estimate observables of clusters, and constrain cosmological parameters through cluster counts.aims: we investigate the scaling relations between x-ray observables of the clusters detected in the efeds field using spectrum-roentgen-gamma/erosita observations taking into account the selection effects and the distributions of observables with cosmic time.methods: we extract x-ray observables (lx, lbol, t, mgas, yx) within r500 for the sample of 542 clusters in the efeds field. by applying detection and extent likelihood cuts, we construct a subsample of 265 clusters with a contamination level of <10% (including agns and spurious fluctuations) to be used in our scaling relations analysis. the selection function based on the state-of-the-art simulations of the erosita sky is fully accounted for in our work.results: we provide the x-ray observables in the core-included <r500 and core-excised 0.15 r500-r500 apertures for 542 galaxy clusters and groups detected in the efeds field. additionally, we present our best-fit results for the normalization, slope, redshift evolution, and intrinsic scatter parameters of the x-ray scaling relations between lx - t, lx - mgas, lx - yx, lbol - t, lbol - mgas, lbol - yx, and mgas - t. we find that the best-fit slopes significantly deviate from the self-similar model at a >4σ confidence level, but our results are nevertheless in good agreement with the simulations including non-gravitational physics, and the recent results that take into account selection effects.conclusions: the strong deviations we find from the self-similar scenario indicate that the non-gravitational effects play an important role in shaping the observed physical state of clusters. this work extends the scaling relations to the low-mass, low-luminosity galaxy cluster and group regime using efeds observations, demonstrating the ability of erosita to measure emission from the intracluster medium out to r500 with survey-depth exposures and constrain the scaling relations in a wide mass-luminosity-redshift range. the lists of best-fit electron density model parameters (table 1) of efeds clusters and x-ray observable measurements (table 2) are available at the cds via anonymous ftp to cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/j/a+a/661/a7 or can be found at https://erosita.mpe.mpg.de/edr/erositaobservations/catalogues | the erosita final equatorial-depth survey (efeds). x-ray properties and scaling relations of galaxy clusters and groups |
the pamela cosmic-ray detector was launched on june 15th 2006 on board the russian resurs-dk1 satellite, and during ten years of nearly continuous data-taking it has observed new interesting features in cosmic rays (crs). in a decade of operation it has provided plenty of scientific data, covering different issues related to cosmic-ray physics. its discoveries might change our basic vision of the mechanisms of production, acceleration and propagation of cosmic rays in the galaxy. the antimatter measurements, focus of the experiment, have set strong constraints to the nature of dark matter. search for signatures of more exotic processes (such as the ones involving strange quark matter) was also pursued. furthermore, the long-term operation of the instrument had allowed a constant monitoring of the solar activity during its maximum and a detailed and prolonged study of the solar modulation, improving the comprehension of the heliosphere mechanisms. pamela had also measured the radiation environment around the earth, and it detected for the first time the presence of an antiproton radiation belt surrounding our planet. the operation of resurs-dk1 was terminated in 2016. in this article we will review the main features of the pamela instrument and its constructing phases. the main part of the article will be dedicated to the summary of the most relevant pamela results over a decade of observation. | ten years of pamela in space |
in this paper we investigate the phenomenology of the electron flavored dirac dark matter with two types of portal interactions. we analyze constraints from the electron magnetic moment anomaly, lhc searches of singly charged scalar, dark matter relic abundance as well as direct and indirect detections. our study shows that the available parameter space is quite constrained, but there are parameter space that is compatible with the current data. we further show that the dampe cosmic ray electron excess, which indicates cosmic ray excess at around 1.5 tev, can be interpreted as the annihilation of dark matter into electron positron pairs in this model. | electron flavored dark matter |
the diffusive paradigm for the transport of galactic cosmic rays is central to our understanding of the origin of these high energy particles. however, it is worth recalling that the normalization, energy dependence, and spatial extent of the diffusion coefficient in the interstellar medium are fitted to the data and typically are not derived from more basic principles. here, we discuss a scenario in which the diffusion properties of cosmic rays are derived from a combination of wave self-generation and advection from the galactic disc, where the sources of cosmic rays are assumed to be located. we show for the first time that a halo naturally arises from these phenomena, with a size of a few kiloparsecs, compatible with the value that typically best fits observations in simple parametric approaches to cosmic ray diffusion. we also show that transport in such a halo results in a hardening in the spectra of primary cosmic rays at ∼300 gv . | origin of the cosmic ray galactic halo driven by advected turbulence and self-generated waves |
the 21-cm signal holds the key to understanding the first structure formation during cosmic dawn. theoretical progress over the last decade has focused on simulations of this signal, given the non-linear and non-local relation between initial conditions and observables (21 cm or reionization maps). here, instead, we propose an effective and fully analytical model for the 21-cm signal during cosmic dawn. we take advantage of the exponential-like behaviour of the local star-formation rate density (sfrd) against densities at early times to analytically find its correlation functions including non-linearities. the sfrd acts as the building block to obtain the statistics of radiative fields (x-ray and lyman α fluxes), and therefore the 21-cm signal. we implement this model as the public python package zeus21. this code can fully predict the 21-cm global signal and power spectrum in ~1 s, with negligible memory requirements. when comparing against state-of-the-art semi-numerical simulations from 21cmfast we find agreement to $\sim 10~{{\ \rm per\ cent}}$ precision in both the 21-cm global signal and power spectra, after accounting for a (previously missed) underestimation of adiabatic fluctuations in 21cmfast. zeus21 is modular, allowing the user to vary the astrophysical model for the first galaxies, and interfaces with the cosmological code class, which enables searches for beyond standard-model cosmology in 21-cm data. this represents a step towards bringing 21-cm to the era of precision cosmology. | an effective model for the cosmic-dawn 21-cm signal |
theseus, one of the two space mission concepts being studied by esa as candidates for next m5 mission within its comsic vision programme, aims at fully exploiting gamma-ray bursts (grb) to solve key questions about the early universe, as well as becoming a cornerstone of multi-messenger and time-domain astrophysics. by investigating the first billion years of the universe through high-redshift grbs, theseus will shed light on the main open issues in modern cosmology, such as the population of primordial low mass and luminosity galaxies, sources and evolution of cosmic re-ionization, sfr and metallicity evolution up to the "cosmic dawn" and across pop-iii stars. at the same time, the mission will provide a substantial advancement of multi-messenger and time-domain astrophysics by enabling the identification, accurate localisation and study of electromagnetic counterparts to sources of gravitational waves and neutrinos, which will be routinely detected in the late `20s and early `30s by the second and third generation gravitational wave (gw) interferometers and future neutrino detectors, as well as of all kinds of grbs and most classes of other x/gamma-ray transient sources. under all these respects, theseus will provide great synergies with future large observing facilities in the multi-messenger domain. a guest observer programme, comprising target of opportunity (too) observations, will expand the science return of the mission, to include, e.g., solar system minor bodies, exoplanets, and agn. | the theseus space mission: science goals, requirements and mission concept |
it has been shown that a realistic level of magnetization of dense molecular cloud cores can suppress the formation of a rotationally supported disc (rsd) through catastrophic magnetic braking in the axisymmetric ideal mhd limit. in this study, we present conditions for the formation of rsds through non-ideal mhd effects computed self-consistently from an equilibrium chemical network. we find that removing from the standard mrn distribution the large population of very small grains (vsgs) of ∼ 10 å to few 100 å that dominate the coupling of the bulk neutral matter to the magnetic field increases the ambipolar diffusivity by ∼ 1-2 orders of magnitude at densities below 1010/cm-3. the enhanced ambipolar diffusion (ad) in the envelope reduces the amount of magnetic flux dragged by the collapse into the circumstellar disc-forming region. therefore, magnetic braking is weakened and more angular momentum can be retained. with continuous high angular momentum inflow, rsds of tens of au are able to form, survive, and even grow in size, depending on other parameters including cosmic ray ionization rate, magnetic field strength, and rotation speed. some discs become self-gravitating and evolve into rings in our 2d (axisymmetric) simulations, which have the potential to fragment into (close) multiple systems in 3d. we conclude that disc formation in magnetized cores is highly sensitive to chemistry, especially to grain sizes. a moderate grain coagulation/growth to remove the large population of vsgs, either in the prestellar phase or during free-fall collapse, can greatly promote ad and help formation of tens of au rsds. | protostellar disc formation enabled by removal of small dust grains |
during a tidal disruption event, a star is torn apart by the tidal forces of a supermassive black hole, with about 50% of the star's mass eventually accreted by the black hole. the resulting flare can, in extreme cases of super-eddington mass accretion, result in a relativistic jet1-4. while tidal disruption events have been theoretically proposed as sources of high-energy cosmic rays5,6 and neutrinos7-14, stacking searches indicate that their contribution to the diffuse extragalactic neutrino flux is very low15. however, a recent association of a track-like astrophysical neutrino (icecube-191001a16) with a tidal disruption event (at2019dsg17) indicates that some tidal disruption events can accelerate cosmic rays to petaelectronvolt energies. here we introduce a phenomenological concordance scenario with a relativistic jet to explain this association: an expanding cocoon progressively obscures the x-rays emitted by the accretion disk, while at the same time providing a sufficiently intense external target of backscattered x-rays for the production of neutrinos via proton-photon interactions. we also reproduce the delay (relative to the peak) of the neutrino emission by scaling the production radius with the black-body radius. our energetics and assumptions for the jet and the cocoon are compatible with expectations from numerical simulations of tidal disruption events. | a concordance scenario for the observed neutrino from a tidal disruption event |
active galactic nuclei inject large amounts of energy into their host galaxies and surrounding environment, shaping their properties and evolution1,2. in particular, active-galactic-nuclei jets inflate cosmic-ray lobes, which can rise buoyantly as light `bubbles' in the surrounding medium3, displacing and heating the encountered thermal gas and thus halting its spontaneous cooling. these bubbles have been identified in a wide range of systems4,5. however, due to the short synchrotron lifetime of electrons, the most advanced phases of their evolution have remained observationally unconstrained, preventing us from fully understand their coupling with the external medium, and thus active galactic nuclei feedback. simple subsonic hydrodynamic models6,7 predict that the pressure gradients, naturally present around the buoyantly rising bubbles, transform them into toroidal structures, resembling mushroom clouds in a stratified atmosphere. the way and timescales on which these tori will eventually disrupt depend on various factors including magnetic fields and plasma viscosity8,9. here we report observations below 200 mhz, sensitive to the oldest radio-emitting particles, showing the late evolution of multiple generations of cosmic-ray active-galactic-nuclei bubbles in a galaxy group with unprecedented level of detail. the bubbles' buoyancy power can efficiently offset the radiative cooling of the intragroup medium. however, the bubbles still have not thoroughly mixed with the thermal gas, after hundreds of million years, probably under the action of magnetic fields. | a snapshot of the oldest active galactic nuclei feedback phases |
the h i gas content is a key ingredient in galaxy evolution, the study of which has been limited to moderate cosmological distances for individual galaxies due to the weakness of the hyperfine h i 21 cm transition. here we present a new approach that allows us to infer the h i gas mass m hi of individual galaxies up to z ≈ 6, based on a direct measurement of the [c ii]-to-h i conversion factor in star-forming galaxies at z ≳ 2 using γ-ray burst afterglows. by compiling recent [c ii]-158 μm emission line measurements we quantify the evolution of the h i content in galaxies through cosmic time. we find that m hi starts to exceed the stellar mass m ⋆ at z ≳ 1, and increases as a function of redshift. the h i fraction of the total baryonic mass increases from around 20% at z = 0 to about 60% at z ~ 6. we further uncover a universal relation between the h i gas fraction m hi/m ⋆ and the gas-phase metallicity, which seems to hold from z ≈ 6 to z = 0. the majority of galaxies at z > 2 are observed to have h i depletion times, t dep,hi = m hi/sfr, less than ≈2 gyr, substantially shorter than for z ~ 0 galaxies. finally, we use the [c ii]-to-h i conversion factor to determine the cosmic mass density of h i in galaxies, ρ hi, at three distinct epochs: z ≈ 0, z ≈ 2, and z ~ 4-6. these measurements are consistent with previous estimates based on 21 cm h i observations in the local universe and with damped lyα absorbers (dlas) at z ≳ 2, suggesting an overall decrease by a factor of ≈5 in ρ hi(z) from the end of the reionization epoch to the present. | measuring the h i content of individual galaxies out to the epoch of reionization with [c ii] |
scientists have explored how energetic particles such as solar energetic particles and cosmic rays move through a magnetized plasma such as the interplanetary and interstellar medium since more than five decades. from a theoretical point of view, this topic is difficult because the particles experience complicated interactions with turbulent magnetic fields. besides turbulent fields, there are also large scale or mean magnetic fields breaking the symmetry in such systems and one has to distinguish between transport of particles parallel and perpendicular with respect to such mean fields. in standard descriptions of transport phenomena, one often assumes that the transport in both directions is normal diffusive but non-diffusive transport was found in more recent work. this is in particular true for early and intermediate times where the diffusive regime is not yet reached. in recent years researchers employed advanced numerical tools in order to simulate the motion of those particles through the aforementioned systems. nevertheless, the analytical description of the problem discussed here is of utmost importance since analytical forms of particle transport parameters need to be known in several applications such as solar modulation studies or investigations of shock acceleration. the latter process is directly linked to the question of what the sources of high energy cosmic rays are, a problem which is considered to be one of the most important problems of the sciences of the 21st century. the present review article discusses analytical theories developed for describing particle transport across a large scale magnetic field as well as field line random walk. a heuristic approach explaining the basic physics of perpendicular transport is also presented. simple analytical forms for the perpendicular diffusion coefficient are proposed which can easily be incorporated in numerical codes for solar modulation or shock acceleration studies. test-particle simulations are also discussed together with a comparison with analytical results. several applications such as cosmic ray propagation and diffusive shock acceleration are also part of this review. | perpendicular transport of energetic particles in magnetic turbulence |
co is commonly used as a tracer of the total gas mass in both the interstellar medium and in protoplanetary disks. recently, there has been much debate about the utility of co as a mass tracer in disks. observations of co in protoplanetary disks reveal a range of co abundances, with measurements of low co to dust mass ratios in numerous systems. one possibility is that carbon is removed from co via chemistry. however, the full range of physical conditions conducive to this chemical reprocessing is not well understood. we perform a systematic survey of the time dependent chemistry in protoplanetary disks for 198 models with a range of physical conditions. we vary dust grain size distribution, temperature, comic-ray and x-ray ionization rates, disk mass, and initial water abundance, detailing what physical conditions are necessary to activate the various co depletion mechanisms in the warm molecular layer. we focus our analysis on the warm molecular layer in two regions: the outer disk (100 au) well outside the co snowline and the inner disk (19 au) just inside the midplane co snowline. after 1 myr, we find that the majority of models have a co abundance relative to h2 less than 10-4 in the outer disk, while an abundance less than 10-5 requires the presence of cosmic-rays. inside the co snowline, significant depletion of co only occurs in models with a high cosmic-ray rate. if cosmic-rays are not present in young disks, it is difficult to chemically remove carbon from co. additionally, removing water prior to co depletion impedes the chemical processing of co. chemical processing alone cannot explain current observations of low co abundances. other mechanisms must also be involved. | unlocking co depletion in protoplanetary disks. i. the warm molecular layer |
we report on the effects of cosmic rays (crs) on the abundance of co in h2 clouds under conditions typical for star-forming galaxies in the universe. we discover that this most important molecule for tracing h2 gas is very effectively destroyed in ism environments with cr energy densities {{u}cr}∼ (50-{{10}3})× {{u}cr,gal}, a range expected in numerous star-forming systems throughout the universe. this density-dependent effect operates volumetrically rather than only on molecular cloud surfaces (i.e., unlike fuv radiation that also destroys co), and is facilitated by (a) the direct destruction of co by crs and (b) a reaction channel activated by cr-produced he+. the effect we uncover is strong enough to render milky-way-type giant molecular clouds very co-poor (and thus co-untraceable), even in ism environments with rather modestly enhanced average cr energy densities of {{u}cr}∼ (10-50)× {{u}cr,gal}. we conclude that the cr-induced destruction of co in molecular clouds, unhindered by dust absorption, is perhaps the single most important factor controlling the co-visibility of molecular gas in vigorously star-forming galaxies. we anticipate that a second-order effect of this co destruction mechanism will be to make the h2 distribution in the gas-rich disks of such galaxies appear much clumpier in co j = 1-0, 2-1 line emission than it actually is. finally we give an analytical approximation of the co/h2 abundance ratio as a function of gas density and cr energy density for use in galaxy-size or cosmological hydrodynamical simulations, and propose some key observational tests. | effective destruction of co by cosmic rays: implications for tracing h2 gas in the universe |
we discuss limits on the noise strength parameter in mass-proportional-coupled wave-function collapse models implied by bulk heating effects and examine the role of the noise power spectrum in comparing experiments of different types. this comparison utilizes a calculation of the rate of heating through phonon excitation implied by a general noise power spectrum λ (ω ) . we find that, in the standard heating formula, the reduction rate λ is replaced by λeff=2/3 π3 /2 ∫d3w e-w⃗2w⃗2λ ( ωl(w ⃗/rc) ) , with ωl(q ⃗) being the longitudinal acoustic-phonon frequency as a function of wave number q ⃗, and with rc being the noise correlation length. hence if the noise power spectrum is cut off below ωl(| q ⃗|∼rc-1) , the bulk heating rate is sharply reduced, allowing compatibility with current experimental results. we suggest possible new bulk heating experiments that can be performed subject to limits placed by natural heating from radioactivity and cosmic rays. the proposed experiments exploit the vanishing of thermal transport in the low-temperature limit. | bulk heating effects as tests for collapse models |
a new reconstruction of the heliospheric modulation potential for galactic cosmic rays is presented for the neutron monitor era, since 1951. the new reconstruction is based on an updated methodology in comparison to previous reconstructions: (1) the use of the new-generation neutron monitor yield function; (2) the use of the new model of the local interstellar spectrum, employing in particular direct data from the distant missions; and (3) the calibration of the neutron monitor responses to direct measurements of the cosmic ray spectrum performed by the payload for antimatter matter exploration and light-nuclei astrophysics (pamela) spaceborne spectrometer over 47 time intervals during 2006-2010. the reconstruction is based on data from six standard nm64-type neutron monitors (apatity, inuvik, kergulen, moscow, newark, and oulu) since 1965 and two international geophysical year-type ground-based detectors (climax and mount washington) for 1951-1964. the new reconstruction, along with the estimated uncertainties is tabulated in the paper. the presented series forms a benchmark record of the cosmic ray variability (in the energy range between 1 and 30 gev) for the last 60 years and can be used in long-term studies in the fields of solar, heliospheric, and solar-terrestrial physics. | heliospheric modulation of cosmic rays during the neutron monitor era: calibration using pamela data for 2006-2010 |
we report the result of a search for sterile neutrinos with the latest cosmological observations. both cases of massless and massive sterile neutrinos are considered in the λ cdm cosmology. the cosmological observations used in this work include the planck 2015 temperature and polarization data, the baryon acoustic oscillation data, the hubble constant direct measurement data, the planck sunyaev-zeldovich cluster counts data, the planck lensing data, and the cosmic shear data. we find that the current observational data give a hint of the existence of massless sterile neutrino (as dark radiation) at the 1.44σ level, and the consideration of an extra massless sterile neutrino can indeed relieve the tension between observations and improve the cosmological fit. for the case of massive sterile neutrino, the observations give a rather tight upper limit on the mass, which implies that actually a massless sterile neutrino is more favored. our result is consistent with the recent result of neutrino oscillation experiment done by the daya bay and minos collaborations, as well as the recent result of cosmic ray experiment done by the icecube collaboration. | a search for sterile neutrinos with the latest cosmological observations |
the most promising variation of the standard siren technique combines gravitational-wave (gw) data for binary neutron star (bns) mergers with redshift measurements enabled by their electromagnetic (em) counterparts, to constrain cosmological parameters such as h0, ωm, and w0. here we evaluate the near- and long-term prospects of multimessenger cosmology in the era of future gw observatories: advanced ligo plus (a+, 2025), voyager-like detectors (2030s), and cosmic explorer-like detectors (2035 and beyond). we show that the bns horizon distance of ≈ 700 mpc for a+ is well matched to the sensitivity of the vera c. rubin observatory (vro) for kilonova detections. we find that one year of joint a+ and vro observations will constrain the value of h0 to percent-level precision, given a small investment of vro time dedicated to target-of-opportunity gw follow-up. in the voyager era, the bns-kilonova observations begin to constrain ωm with an investment of a few percent of vro time. with the larger bns horizon distance in the cosmic explorer era, on-axis short gamma-ray bursts (sgrbs) and their afterglows (though accompanying only some of the gw-detected mergers) supplant kilonovae as the most promising counterparts for redshift identification. we show that five years of joint observations with cosmic explorer-like facilities and a next-generation gamma-ray satellite with localization capabilities similar to that presently possible with swift could constrain both ωm and w0 to 15%-20%. we therefore advocate for a robust target-of-opportunity (too) program with vro, and a wide-field gamma-ray satellite with improved sensitivity in the 2030s, to enable standard siren cosmology with next-generation gravitational-wave facilities. | a program for multimessenger standard siren cosmology in the era of ligo a+, rubin observatory, and beyond |
we recently proposed a method to constrain s -wave annihilating mev dark matter from a combination of the voyager 1 and the ams-02 data on cosmic-ray electrons and positrons. voyager 1 actually provides an unprecedented probe of dark matter annihilation to cosmic rays down to ∼10 mev in an energy range where the signal is mostly immune to uncertainties in cosmic-ray propagation. in this article, we derive for the first time new constraints on p -wave annihilation down to the mev mass range using cosmic-ray data. to proceed, we derive a self-consistent velocity distribution for the dark matter across the milky way by means of the eddington inversion technique and its extension to anisotropic systems. as inputs, we consider state-of-the-art galactic mass models including baryons and constrained on recent kinematic data. they allow for both a cored or a cuspy halo. we then calculate the flux of cosmic-ray electrons and positrons induced by p -wave annihilating dark matter and obtain very stringent limits in the mev mass range, robustly excluding cross sections greater than ∼10-22 cm3/s (including theoretical uncertainties), about 5 orders of magnitude better than current cmb constraints. this limit assumes that dark matter annihilation is the sole source of cosmic rays and could therefore be made even more stringent when reliable models of astrophysical backgrounds are included. | robust cosmic-ray constraints on p -wave annihilating mev dark matter |
in this work we use the newly reported boron-to-carbon ratio (b/c) from ams-02 and the time-dependent proton fluxes from pamela and ams-02 to constrain the source and propagation parameters of cosmic rays in the milky way. a linear correlation of the solar modulation parameter with solar activities is assumed to account for the time-varying cosmic ray fluxes. a comprehensive set of propagation models, with or without reacceleration or convection, has been discussed and compared. we find that only the models with reacceleration can self-consistently fit both the proton and b/c data. the rigidity dependence slope of the diffusion coefficient, δ , is found to be about 0.38-0.50 for the diffusion-reacceleration models. the plain diffusion and diffusion-convection models fit the data poorly. we compare different model predictions of the positron and antiproton fluxes with the data. we find that the diffusion-reacceleration models overproduce low energy positrons, while nonreacceleration models give better fit to the data. as for antiprotons, reacceleration models tend to underpredict low energy antiproton fluxes, unless a phenomenological modification of the velocity dependence of the diffusion coefficient is applied. our results suggest that there could be important differences of the propagation for nuclei and leptons, in either the milky way or the solar heliosphere. | propagation of cosmic rays in the ams-02 era |
astrophysical neutrinos are powerful tools for investigating the fundamental properties of particle physics through their flavor content. in this letter, we perform the first general new physics study on ultrahigh energy neutrino flavor content by introducing effective operators. we find that, at the current limits on these operators, new physics terms cause maximal effects on the flavor content; however, the flavor content on the earth is confined to a region related to the assumed initial flavor content. furthermore, we conclude that a precise measure of the flavor content on the earth will provide orders of magnitude improvement on new physics bounds. finally, we discuss the current best fits of flavor content of the icecube data and their interplay with new physics scenarios. | effect of new physics in astrophysical neutrino flavor |
for the first time a proper comparison of the average depth of shower maximum (xmax) published by the pierre auger and telescope array observatories is presented. the xmax distributions measured by the pierre auger observatory were fit using simulated events initiated by four primaries (proton, helium, nitrogen and iron). the primary abundances which best describe the auger data were simulated through the telescope array (ta) middle drum (md) fluorescence and surface detector array. the simulated events were analyzed by the ta collaboration using the same procedure as applied to their data. the result is a simulated version of the auger data as it would be observed by ta. this analysis allows a direct comparison of the evolution of < xmax > with energy of both data sets. the < xmax > measured by ta-md is consistent with a preliminary simulation of the auger data through the ta detector and the average difference between the two data sets was found to be (2.9 ± 2.7 (stat.) ± 18 (syst.)) g/cm2. | report of the working group on the composition of ultra high energy cosmic rays |
for space observatories, the glitches caused by high energy phonons created by the interaction of cosmic ray particles with a detector substrate lead to dead time during observation. mitigating the impact of cosmic rays is therefore an important requirement for detectors to be used in future space missions. in order to investigate possible solutions, we carry out a systematic study by testing four large arrays of microwave kinetic inductance detectors (mkids), each consisting of ∼960 pixels and fabricated on monolithic 55 mm × 55 mm × 0.35 mm si substrates. we compare the response to cosmic ray interactions in our laboratory for different detector arrays: a standard array with only the mkid array as reference, an array with a low tc superconducting film as a phonon absorber on the opposite side of the substrate, and arrays with mkids on membranes. the idea is that the low tc layer down converts the phonon energy to values below the pair breaking threshold of the mkids, and the membranes isolate the sensitive part of the mkids from phonons created in the substrate. we find that the dead time can be reduced up to a factor of 40 when compared to the reference array. simulations show that the dead time can be reduced to below 1% for the tested detector arrays when operated in a spacecraft in an l2 or a similar far-earth orbit. the technique described here is also applicable and important for large superconducting qubit arrays for future quantum computers. | mitigation of cosmic ray effect on microwave kinetic inductance detector arrays |
context. the tibet asγ and lhaaso collaborations recently reported the observation of a γ-ray diffuse emission with energy up to the pev level from the galactic plane.aims: we discuss the relevance of non-uniform cosmic-ray transport scenarios and the implications of these results for cosmic-ray physics.methods: we used the dragon and hermes codes to build high-resolution maps and spectral distributions of that emission for several representative models under the condition that they reproduce a wide set of local cosmic-ray data up to 100 pev.results: we show that the energy spectra measured by tibet asγ, lhaaso, argo-ybj, and fermi-lat in several regions of interest in the sky can all be reasonably described in terms of the emission arising by the galactic cosmic-ray "sea". we also show that all our models are compatible with icetop γ-ray upper limits.conclusions: we compare the predictions of conventional and space-dependent transport models with those data sets. although the fermi-lat, argo-ybj, and lhaaso preliminary data slightly favor this scenario, due to the still large experimental errors, the poorly known source spectral shape at the highest energies, the potential role of spatial fluctuations in the leptonic component, and a possible larger-than-expected contamination due to unresolved sources, a solid confirmation requires further investigations. we discuss which measurements will be most relevant in order to resolve the remaining degeneracy. | galactic diffuse gamma rays meet the pev frontier |
gravitational wave (gw) events, produced by the coalescence of binary neutron stars (bnss), can be treated as the standard sirens to probe the expansion history of the universe, if their redshifts can be determined from electromagnetic (em) observations. for the high-redshift (z ≳ 0.1) events, the short γ-ray bursts (sgrbs) and the afterglows are always considered as the primary em counterparts. in this paper, by investigating various models of sgrbs and afterglows, we discuss the rates and distributions of the multimessenger observations of bns mergers using gw detectors in the second-generation (2g), 2.5g, and 3g era with detectable sgrbs and afterglows. for instance, for the cosmic explorer gw detector, the rate is about 300-3500 yr-1 with a gecam-like detector for γ-ray emissions and an lsst/wfst detector for optical afterglows. in addition, we find that these events have redshifts z ≲ 2 and inclination angles ι ≲ 20°. these results justify the rough estimation in previous works. considering these events as standard sirens to constrain the equation-of-state parameters of dark energy w0 and wa, we obtain the potential constraints of δw0 ≃ 0.02-0.05 and δwa ≃ 0.1-0.4. | multimessenger detection rates and distributions of binary neutron star mergers and their cosmological implications |
indirect searches for dark matter are based on detecting an anomalous flux of photons, neutrinos or cosmic-rays produced in annihilations or decays of dark matter candidates gravitationally accumulated in heavy cosmological objects, like galaxies, the sun or the earth. additionally, evidence for dark matter that can also be understood as indirect can be obtained from early universe probes, like fluctuations of the cosmic microwave background temperature, the primordial abundance of light elements or the hydrogen 21-cm line. the techniques needed to detect these different signatures require very different types of detectors: air shower arrays, gamma- and x-ray telescopes, cherenkov telescopes, neutrino telescopes, radio telescopes or particle detectors in balloons or satellites. although many of these detectors were not originally intended to search for dark matter, they have proven to be unique complementary tools to the direct search efforts. in this review we summarize the current status of indirect searches for dark matter, mentioning also the challenges and limitations that these techniques encounter. | status, challenges and directions in indirect dark matter searches |
observations of the x-ray sky after the next decade will most likely be dominated by athena (advanced telescope for high energy astrophysics), the second large mission of esa's cosmic vision 2015-2035 programme. athena has been conceived to address the "hot and energetic universe" science theme, which focuses on the assembly and evolution of hot baryons in cosmic structures as well as the physics and energetic output generated by accreting super-massive black holes, along with the relationship between the two processes, dubbed cosmic feedback. thanks to its transformational capabilities, athena will enable bringing all of today's xmm-newton's hot science topics to a new stage. in this paper, we summarize the athena science case, science requirements, as well as the expected mission performance, mission concept, and its status. | athena: esa's x-ray observatory for the late 2020s |
non-standard interactions in the propagation of neutrinos in matter can lead to significant deviations from expectations within the standard neutrino oscillation framework and atmospheric neutrino detectors have been considered to set constraints. however, most previous works have focused on relatively low-energy atmospheric neutrino data. here, we consider the one-year high-energy through-going muon data in icecube, which has been already used to search for light sterile neutrinos, to constrain new interactions in the μτ-sector. in our analysis we include several systematic uncertainties on both, the atmospheric neutrino flux and on the detector properties, which are accounted for via nuisance parameters. after considering different primary cosmic-ray spectra and hadronic interaction models, we improve over previous analysis by using the latest data and showing that systematics currently affect very little the bound on the off-diagonal ɛμτ, with the 90% credible interval given by -6 .0 × 10-3 < ɛμτ< 5 .4 × 10-3, comparable to previous results. in addition, we also estimate the expected sensitivity after 10 years of collected data in icecube and study the precision at which non-standard parameters could be determined for the case of ɛμτnear its current bound. | non-standard interactions with high-energy atmospheric neutrinos at icecube |
precision cosmology provides a sensitive probe of extremely weakly coupled states due to thermal freeze-in production, with subsequent decays impacting physics during well-tested cosmological epochs. we explore the cosmological implications of the freeze-in production of a new scalar s via the superrenormalizable higgs portal. if the mass of s is at or below the electroweak scale, peak freeze-in production occurs during the electroweak epoch. we improve the calculation of the freeze-in abundance by including all relevant qcd and electroweak production channels. the resulting abundance and subsequent decay of s is constrained by a combination of x-ray data, cosmic microwave background anisotropies and spectral distortions, neff, and the consistency of big bang nucleosynthesis with observations. these probes constrain technically natural couplings for such scalars from ms∼10 kev all the way to ms∼100 gev . the ensuing constraints are similar in spirit to typical beam dump limits, but extend to much smaller couplings, down to mixing angles as small as θs h∼10-16, and to masses all the way to the electroweak scale. | cosmological beam dump: constraints on dark scalars mixed with the higgs boson |
we compare two techniques for simulation of the propagation of ultra-high-energy cosmic rays (uhecr) in intergalactic space: the monte carlo approach and a method based on solving transport equations in one dimension. for the former, we adopt the publicly available tool crpropa and for the latter, we use the code transportcr, which has been developed by the first author and used in a number of applications, and is made available online with publishing this paper. while the crpropa code is more universal, the transport equation solver has the advantage of a roughly 100 times higher calculation speed. we conclude that the methods give practically identical results for proton or neutron primaries if some accuracy improvements are introduced to the crpropa code. | simulations of ultra-high-energy cosmic rays propagation |
the intergalactic medium is expected to clump on scales down to ${10}^{4}\mbox{--}{10}^{8}$ m⊙ before the onset of reionization. the impact of these small-scale structures on reionization is poorly understood despite the modern understanding that gas clumpiness limits the growth of ${\rm{h}}\,{\rm{ii}}$ regions. we use a suite of radiation-hydrodynamics simulations that capture the $\sim {10}^{4}{m}_{\odot }$ jeans mass of unheated gas to study density fluctuations during reionization. our simulations track the complex ionization and hydrodynamical response of gas in the wake of ionization fronts. the clumping factor of ionized gas (proportional to the recombination rate) rises to a peak value of 5-20 approximately δt = 10 myr after ionization front passage, depending on the incident intensity, redshift, and degree to which the gas had been preheated by the first x-ray sources. the clumping factor reaches its relaxed value of ≈3 by δt = 300 myr. the mean free path of lyman-limit photons evolves in unison, being up to several times shorter in unrelaxed, recently reionized regions compared to those that were reionized much earlier. assessing the impact of this response on the global reionization process, we find that unrelaxed gaseous structures boost the total number of recombinations by ≈50% and lead to spatial fluctuations in the mean free path that persist appreciably for several hundred million years after the completion of reionization. | hydrodynamic response of the intergalactic medium to reionization |
we present an analysis of the first 20 second cadence light curves obtained by the tess space telescope during its extended mission. we find improved precision of 20 second data compared to 2 minute data for bright stars when binned to the same cadence (≈10%-25% better for t ≲ 8 mag, reaching equal precision at t ≈ 13 mag), consistent with pre-flight expectations based on differences in cosmic-ray mitigation algorithms. we present two results enabled by this improvement. first, we use 20 second data to detect oscillations in three solar analogs (γ pav, ζ tuc, and π men) and use asteroseismology to measure their radii, masses, densities, and ages to ≈1%, ≈3%, ≈1%, and ≈20% respectively, including systematic errors. combining our asteroseismic ages with chromospheric activity measurements, we find evidence that the spread in the activity-age relation is linked to stellar mass and thus the depth of the convection zone. second, we combine 20 second data and published radial velocities to recharacterize π men c, which is now the closest transiting exoplanet for which detailed asteroseismology of the host star is possible. we show that π men c is located at the upper edge of the planet radius valley for its orbital period, confirming that it has likely retained a volatile atmosphere and that the "asteroseismic radius valley" remains devoid of planets. our analysis favors a low eccentricity for π men c (<0.1 at 68% confidence), suggesting efficient tidal dissipation (q/k 2,1 ≲ 2400) if it formed via high-eccentricity migration. combined, these early results demonstrate the strong potential of tess 20 second cadence data for stellar astrophysics and exoplanet science. | a 20 second cadence view of solar-type stars and their planets with tess: asteroseismology of solar analogs and a recharacterization of π men c |
in twin higgs models that contain the minimal particle content required to address the little hierarchy problem (i.e., fraternal models), the twin tau has been identified as a promising candidate for dark matter. in this class of scenarios, however, the elastic scattering cross section of the twin tau with nuclei exceeds the bounds from xenon1t and other recent direct detection experiments. in this paper, we propose a modification to the fraternal twin higgs scenario that we call z2fth , incorporating visible and twin hypercharged scalars (with y =2 ) which break twin electromagnetism. this leads to new mass terms for the twin tau that are unrelated to its yukawa coupling, as well as additional annihilation channels via the massive twin photon. we show that these features make it possible for the right-handed twin tau to freeze out with an acceptable thermal relic abundance while scattering with nuclei at a rate that is well below existing constraints. nonetheless, large portions of the currently viable parameter space in this model are within the reach of planned direct detection experiments. the prospects for indirect detection using gamma rays and cosmic-ray antiprotons are also promising in this model. furthermore, if the twin neutrino is light, the predicted deviation of δ neff≈0.1 would be within reach of stage 4 cosmic microwave background experiments. finally, the high luminosity lhc should be able to probe the entire parameter space of the z2fth model through charged scalar searches. we also discuss how searches for long-lived particles are starting to constrain fraternal twin higgs models. | resurrecting the fraternal twin wimp miracle |
we investigate constraints on the abundance of primordial black holes (pbhs) in the mass range 1015- 1017 g using data from the cosmic microwave background (cmb) and mev extragalactic gamma-ray background (egb). hawking radiation from pbhs with lifetime greater than the age of the universe leaves an imprint on the cmb through modification of the ionization history and the damping of cmb anisotropies. using a model for redshift-dependent energy injection efficiencies, we show that a combination of temperature and polarization data from planck provides the strongest constraint on the abundance of pbhs for masses ∼1015- 1016 g , while the egb dominates for masses ≳1016 g . both the cmb and egb now rule out pbhs as the dominant component of dark matter for masses ∼1016- 1017 g . planned mev gamma-ray observatories are ideal for further improving constraints on pbhs in this mass range. | planck constraint on relic primordial black holes |
in this paper we explore the scientific synergies between athena and some of the key multi-messenger facilities that should be operative concurrently with athena. these facilities include ligo a+, advanced virgo+ and future detectors for ground-based observation of gravitational waves (gw), lisa for space-based observations of gw, icecube and km3net for neutrino observations, and cta for very high energy observations. these science themes encompass pressing issues in astrophysics, cosmology and fundamental physics such as: the central engine and jet physics in compact binary mergers, accretion processes and jet physics in super-massive binary black holes (smbbhs) and in compact stellar binaries, the equation of state of neutron stars, cosmic accelerators and the origin of cosmic rays (crs), the origin of intermediate and high-z elements in the universe, the cosmic distance scale and tests of general relativity and the standard model. observational strategies for implementing the identified science topics are also discussed. a significant part of the sources targeted by multi-messenger facilities is of transient nature. we have thus also discussed the synergy of athena with wide-field high-energy facilities, taking theseus as a case study for transient discovery. this discussion covers all the athena science goals that rely on follow-up observations of high-energy transients identified by external observatories, and includes also topics that are not based on multi-messenger observations, such as the search for missing baryons or the observation of early star populations and metal enrichment at the cosmic dawn with gamma-ray bursts (grbs). | athena synergies in the multi-messenger and transient universe |
dark matter particles near the center of a blazar, after being accelerated by the elastic collisions with relativistic electrons and protons in the blazar jet, can be energetic enough to trigger detectable signals at terrestrial detectors. in this work, focusing on the blazars txs 0506+056 and bl lacertae, we derive novel limits on the cross section of the elastic scattering between dark matter and electrons by means of the available super-kamiokande data. thanks to the large blazar-boosted dark matter flux, the limit on the dark matter-electron scattering cross section for dark matter masses below 100 mev can be as low as ~ 10-38 cm2, that is orders of magnitude stronger than the analogous results from galactic cosmic rays. | blazar-boosted dark matter at super-kamiokande |
in this study, we investigate a scenario that dark matter (dm) has only gravitational interaction. in the framework of effective field theory of gravity, we find that dm is still stable at tree level even if there is no symmetry to protect its longevity, but could decay into standard model particles due to gravitational loop corrections. the radiative corrections can lead to both higher- and lower-dimensional effective operators. we also first explore how dm can be produced in the early universe. through gravitational interaction at high temperature, dm is then found to have mass around tev ≲mx ≲1011 gev to get the right relic abundance. when dm decays, it mostly decays into gravitons, which could be tested by current and future cmb experiments. we also estimate the resulting fluxes for cosmic rays, gamma-ray and neutrino. | pure gravitational dark matter, its mass and signatures |
understanding the feedback mechanisms between soil water content (swc) and biomass production is important for sustainable resources management. here we present a new method enabling simultaneous noninvasive measurements of swc and biomass dynamics based on cosmic ray neutron sensing (crns). recently, it was suggested that the neutron ratio (nr) between thermal neutron (tn) and fast neutron (fn) intensity contains information on other hydrogen pools like vegetation, canopy interception, and snow. the aim of this study is to evaluate the accuracy of simultaneous measurements of swc and biomass dynamics during agricultural drought conditions using crns probes. to this end, we instrumented an arable field cropped with sugar beet with crns probes and a wireless in situ swc sensor network. belowground and aboveground biomass were sampled in monthly intervals. we found a linear relationship between nr and the aboveground biomass that allowed to continuously quantify the dry aboveground biomass development throughout the growing season with a root-mean-square error from 0.14 to 0.22 kg/m2. this information was used together with measured belowground biomass to correct for the effect of biomass on swc determination with crns probes, which increased the accuracy of the swc estimates considerably as indicated by the decrease of the root-mean-square error from 0.046 to 0.013 cm3/cm3. we anticipate that future research on the nr can further improve the accuracy of swc and biomass estimates and extend the application of crns to include canopy interception, ponding water, and snow water equivalent estimation for both stationary and roving crns systems. | cosmic ray neutron sensing for simultaneous soil water content and biomass quantification in drought conditions |
for the light relativistic dark matter (dm) boosted by high energy cosmic ray, its scattering cross section with the nucleon is sensitively dependent on the momentum-transfer and such an dependence is caused by the mediator in the scattering. for puffy dm particle with a size, the momentum-transfer dependence can also arise from the dm radius effect. all these momentum-transfer dependences should be considered. in this note we study the direct detection limits on the cosmic ray-boosted puffy dm for a simplified model with a light mediator. for comparison, we first re-derive the direct detection limits on the cosmic ray-boosted point-like dm. we display the limits on various planes of parameters and find that the limits for the cosmic ray-boosted puffy dm are stronger than for the point-like dm. | direct detection of cosmic ray-boosted puffy dark matter |
the 21-cm signal of neutral hydrogen is a sensitive probe of the epoch of reionization (eor), cosmic dawn, and the dark ages. currently, operating radio telescopes have ushered in a data-driven era of 21-cm cosmology, providing the first constraints on the astrophysical properties of sources that drive this signal. however, extracting astrophysical information from the data is highly non-trivial and requires the rapid generation of theoretical templates over a wide range of astrophysical parameters. to this end emulators are often employed, with previous efforts focused on predicting the power spectrum. in this work, we introduce 21cmgem - the first emulator of the global 21-cm signal from cosmic dawn and the eor. the smoothness of the output signal is guaranteed by design. we train neural networks to predict the cosmological signal using a database of ∼30 000 simulated signals which were created by varying seven astrophysical parameters: the star formation efficiency and the minimal mass of star-forming haloes; the efficiency of the first x-ray sources and their spectrum parametrized by spectral index and the low-energy cut-off; the mean-free path of ionizing photons, and the cosmic microwave background optical depth. we test the performance with a set of ∼2000 simulated signals, showing that the relative error in the prediction has an rms of 0.0159. the algorithm is efficient, with a running time per parameter set of 0.16 s. finally, we use the database of models to check the robustness of relations between the features of the global signal and the astrophysical parameters that we previously reported. | emulating the global 21-cm signal from cosmic dawn and reionization |
we use the surface detector of the pierre auger observatory to search for air showers initiated by photons with an energy above $10^{19}$ ev. photons in the zenith angle range from 30$^\circ$ to 60$^\circ$ can be identified in the overwhelming background of showers initiated by charged cosmic rays through the broader time structure of the signals induced in the water-cherenkov detectors of the array and the steeper lateral distribution of shower particles reaching ground. applying the search method to data collected between january 2004 and june 2020, upper limits at 95\% cl are set to an $e^{-2}$ diffuse flux of ultra-high energy photons above $10^{19}$ ev, $2{\times}10^{19}$ ev and $4{\times}10^{19}$ ev amounting to $2.11{\times}10^{-3}$, $3.12{\times}10^{-4}$ and $1.72{\times}10^{-4}$ km$^{-2}$ sr$^{-1}$ yr$^{-1}$, respectively. while the sensitivity of the present search around $2 \times 10^{19}$ ev approaches expectations of cosmogenic photon fluxes in the case of a pure-proton composition, it is one order of magnitude above those from more realistic mixed-composition models. the inferred limits have also implications for the search of super-heavy dark matter that are discussed and illustrated. | search for photons above 10$^{19}$ ev with the surface detector of the pierre auger observatory |
tev-scale particles that couple to the standard model through the weak force represent a compelling class of dark matter candidates. the search for such weakly interacting massive particles has already spanned multiple decades, and whilst it has yet to provide any definitive evidence for their existence, viable parameter space remains. in this paper, we show that the upcoming cherenkov telescope array (cta) has significant sensitivity to uncharted parameter space at the tev mass scale. to do so, we focus on two prototypical dark matter candidates, the wino and higgsino. sensitivity forecasts for both models are performed including the irreducible background from misidentified cosmic rays, as well as a range of estimates for the galactic emissions at tev energies. for each candidate, we find substantial expected improvements over existing bounds from current imaging atmospheric cherenkov telescopes. in detail, for the wino we find a sensitivity improvement of roughly an order of magnitude in ⟨σ v ⟩, whereas for the higgsino we demonstrate that cta has the potential to become the first experiment that has sensitivity to the thermal candidate. taken together, these enhanced sensitivities demonstrate the discovery potential for dark matter at cta in the 1-100 tev mass range. | prospects for detecting heavy wimp dark matter with the cherenkov telescope array: the wino and higgsino |
astrophysical sources of neutrinos detected by large-scale neutrino telescopes remain uncertain. while there exist statistically significant observational indications that a part of the neutrino flux is produced by blazars, numerous theoretical studies suggest also the presence of potential galactic point sources. some of them have been observed in gamma rays above 100 tev. moreover, cosmic-ray interactions in the galactic disk guarantee a diffuse neutrino flux. however, these galactic neutrinos have not been unambiguously detected so far. here we examine whether such a galactic component is present among the observed neutrinos of the highest energies. we analyze public track-like icecube events with estimated neutrino energies above 200 tev. we examine the distribution of arrival directions of these neutrinos in the galactic latitude b with the help of a simple unbinned, nonparametric test statistics, the median ∣b∣ over the sample. this distribution deviates from that implied by the null hypothesis of the neutrino flux isotropy, and is shifted toward lower ∣b∣ with the p-value of 4 × 10-5, corresponding to the statistical significance of 4.1σ. there exists a significant component of the high-energy neutrino flux of galactic origin, matching well the multimessenger expectations from tibet-asγ observations of diffuse galactic gamma rays at hundreds of tev. together with the previously established extragalactic associations, the galactic component we report here implies that the neutrino sky is rich and is composed of contributions from various classes of sources. | galactic contribution to the high-energy neutrino flux found in track-like icecube events |
the cosmic evolution of the chemical elements from the big bang to the present time is driven by nuclear fusion reactions inside stars and stellar explosions. a cycle of matter recurrently re-processes metal-enriched stellar ejecta into the next generation of stars. the study of cosmic nucleosynthesis and this matter cycle requires the understanding of the physics of nuclear reactions, of the conditions at which the nuclear reactions are activated inside the stars and stellar explosions, of the stellar ejection mechanisms through winds and explosions, and of the transport of the ejecta towards the next cycle, from hot plasma to cold, star-forming gas. due to the long timescales of stellar evolution, and because of the infrequent occurrence of stellar explosions, observational studies are challenging, as they have biases in time and space as well as different sensitivities related to the various astronomical methods. here, we describe in detail the astrophysical and nuclear-physical processes involved in creating two radioactive isotopes useful in such studies, $^{26}al$ and $^{60}fe$ . due to their radioactive lifetime of the order of a million years, these isotopes are suitable to characterise simultaneously the processes of nuclear fusion reactions and of interstellar transport. we describe and discuss the nuclear reactions involved in the production and destruction of $^{26}al$ and $^{60}fe$ , the key characteristics of the stellar sites of their nucleosynthesis and their interstellar journey after ejection from the nucleosynthesis sites. this allows us to connect the theoretical astrophysical aspects to the variety of astronomical messengers presented here, from stardust and cosmic-ray composition measurements, through observation of $γ$ rays produced by radioactivity, to material deposited in deep-sea ocean crusts and to the inferred composition of the first solids that have formed in the solar system. we show that considering measurements of the isotopic ratio of $^{26}al$ to $^{60}fe$ eliminate some of the unknowns when interpreting astronomical results, and discuss the lessons learned from these two isotopes on cosmic chemical evolution. this review paper has emerged from an issi-bj team project in 2017-2019, bringing together nuclear physicists, astronomers, and astrophysicists in this inter-disciplinary discussion. | the radioactive nuclei (\\textbf{26}) al and (\\textbf{60}) fe in the cosmos and in the solar system |
the local interstellar spectra (liss) for galactic cosmic rays (crs) cannot be directly observed at the earth below certain energies, because of solar modulation in the heliosphere. with voyager 1 crossing the heliopause in 2012, in situ experimental lis data below 100 mev/nuc can now constrain computed galactic cr spectra. using galactic propagation models, galactic electron, proton, and light nuclei spectra can now be computed more reliably as liss. using the voyager 1 observations made beyond the heliopause, and the observations made by the pamela experiment in earth orbit for the 2009 solar minimum, as experimental constraints, we simultaneously reproduced the cr electron, proton, helium, and carbon observations by implementing the galprop code. below about 30 gev/nuc solar modulation has a significant effect and a comprehensive three-dimensional (3d) numerical modulation model is used to compare the computed spectra with the observed pamela spectra at these energies. subsequently the computed liss can be compared over as wide a range of energies as possible. the simultaneous calculation of cr spectra with a single propagation model allows the liss for positrons, boron, and oxygen to also be inferred. this implementation of the comprehensive galactic propagation model (galprop), alongside a sophisticated solar modulation model to compute cr spectra for comparison with both voyager 1 and pamela observations over a wide energy range, allows us to present new self-consistent liss (and expressions) for electrons, positrons, protons, helium, carbon, boron, and oxygen for the energy range of 3 mev/nuc-100 gev/nuc. | new very local interstellar spectra for electrons, positrons, protons, and light cosmic ray nuclei |
the origin of high-energy cosmic rays, atomic nuclei that continuously impact earth’s atmosphere, is unknown. because of deflection by interstellar magnetic fields, cosmic rays produced within the milky way arrive at earth from random directions. however, cosmic rays interact with matter near their sources and during propagation, which produces high-energy neutrinos. we searched for neutrino emission using machine learning techniques applied to 10 years of data from the icecube neutrino observatory. by comparing diffuse emission models to a background-only hypothesis, we identified neutrino emission from the galactic plane at the 4.5σ level of significance. the signal is consistent with diffuse emission of neutrinos from the milky way but could also arise from a population of unresolved point sources. | observation of high-energy neutrinos from the galactic plane |
local interstellar spectra (lis) of secondary cosmic-ray (cr) nuclei, lithium, beryllium, boron, and partially secondary nitrogen, are derived in the rigidity range from 10 mv to ∼200 tv using the most recent experimental results combined with state-of-the-art models for cr propagation in the galaxy and in the heliosphere. the lithium spectrum appears somewhat flatter at high energies compared to other secondary species, which may imply a primary lithium component. two propagation packages, galprop and helmod, are combined to provide a single framework that is run to reproduce direct measurements of cr species at different modulation levels, and at both polarities of the solar magnetic field. an iterative maximum-likelihood method is developed that uses galprop-predicted lis as input to helmod, which provides the modulated spectra for specific time periods of the selected experiments for the model-data comparison. the proposed lis accommodates the low-energy interstellar spectra measured by voyager 1, the high energy astrophysics observatory-3 (heao-3), and the cosmic ray isotope spectrometer on board of the advanced composition explorer (ace/cris), as well as the high-energy observations by the payload for antimatter matter exploration and light-nuclei astrophysics (pamela), alpha magnetic spectrometer-02 (ams-02), and earlier experiments that are made deep in the heliosphere. the interstellar and heliospheric propagation parameters derived in this study are consistent with our earlier results for propagation of cr protons, helium, carbon, oxygen, antiprotons, and electrons. | deciphering the local interstellar spectra of secondary nuclei with the galprop/helmod framework and a hint for primary lithium in cosmic rays |
numerical solutions of the cosmic-ray (cr) magnetohydrodynamic equations are dogged by a powerful numerical instability, which arises from the constraint that crs can only stream down their gradient. the standard cure is to regularize by adding artificial diffusion. besides introducing ad hoc smoothing, this has a significant negative impact on either computational cost or complexity and parallel scalings. we describe a new numerical algorithm for cr transport, with close parallels to two-moment methods for radiative transfer under the reduced speed of light approximation. it stably and robustly handles cr streaming without any artificial diffusion. it allows for both isotropic and field-aligned cr streaming and diffusion, with arbitrary streaming and diffusion coefficients. cr transport is handled explicitly, while source terms are handled implicitly. the overall time step scales linearly with resolution (even when computing cr diffusion) and has a perfect parallel scaling. it is given by the standard courant condition with respect to a constant maximum velocity over the entire simulation domain. the computational cost is comparable to that of solving the ideal mhd equation. we demonstrate the accuracy and stability of this new scheme with a wide variety of tests, including anisotropic streaming and diffusion tests, cr-modified shocks, cr-driven blast waves, and cr transport in multiphase media. the new algorithm opens doors to much more ambitious and hitherto intractable calculations of cr physics in galaxies and galaxy clusters. it can also be applied to other physical processes with similar mathematical structure, such as saturated, anisotropic heat conduction. | a new numerical scheme for cosmic-ray transport |
the telescope array (ta) observatory utilizes fluorescence detectors and surface detectors (sds) to observe air showers produced by ultra high energy cosmic rays in earth’s atmosphere. cosmic-ray events observed in this way are termed hybrid data. the depth of air shower maximum is related to the mass of the primary particle that generates the shower. this paper reports on shower maxima data collected over 8.5 yr using the black rock mesa and long ridge fluorescence detectors in conjunction with the array of sds. we compare the means and standard deviations of the observed {x}\maxdistributions with monte carlo {x}\maxdistributions of unmixed protons, helium, nitrogen, and iron, all generated using the qgsjet ii-04 hadronic model. we also perform an unbinned maximum likelihood test of the observed data, which is subjected to variable systematic shifting of the data {x}\maxdistributions to allow us to test the full distributions, and compare them to the monte carlo to see which elements are not compatible with the observed data. for all energy bins, qgsjet ii-04 protons are found to be compatible with ta hybrid data at the 95% confidence level after some systematic {x}\maxshifting of the data. three other qgsjet ii-04 elements are found to be compatible using the same test procedure in an energy range limited to the highest energies where data statistics are sparse. | depth of ultra high energy cosmic ray induced air shower maxima measured by the telescope array black rock and long ridge fadc fluorescence detectors and surface array in hybrid mode |
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