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the hybrid design of the pierre auger observatory allows for the measurement of the properties of extensive air showers initiated by ultra-high energy cosmic rays with unprecedented precision. by using an array of prototype underground muon detectors, we have performed the first direct measurement, by the auger collaboration, of the muon content of air showers between 2 ×1017 and 2 ×1018 ev. we have studied the energy evolution of the attenuation-corrected muon density, and compared it to predictions from air shower simulations. the observed densities are found to be larger than those predicted by models. we quantify this discrepancy by combining the measurements from the muon detector with those from the auger fluorescence detector at 1017.5ev and 1018ev . we find that, for the models to explain the data, an increase in the muon density of 38 % ±4 %(12 %) ±18%21 % for epos-lhc, and of 50 %(53 %) ±4 %(13 %) ±20%23 % for qgsjetii-04, is respectively needed. | direct measurement of the muonic content of extensive air showers between 2 ×1017 and 2 ×1018 ev at the pierre auger observatory |
we propose a mechanism of elementary thermal dark matter with a mass up to 1 014 gev , within a standard cosmological history, whose relic abundance is determined solely by its interactions with the standard model, without violating the perturbative unitarity bound. the dark matter consists of many nearly degenerate particles which scatter with the standard model bath in a nearest-neighbor chain, and maintain chemical equilibrium with the standard model bath by in-equilibrium decays and inverse decays. the phenomenology includes super heavy elementary dark matter and heavy relics that decay at various epochs in the cosmological history, with implications for the cosmic microwave background, structure formation, and cosmic ray experiments. | superheavy thermal dark matter |
the astro-h mission was designed and developed through an international collaboration of jaxa, nasa, esa, and the csa. it was successfully launched on february 17, 2016, and then named hitomi. during the in-orbit verification phase, the on-board observational instruments functioned as expected. the intricate coolant and refrigeration systems for soft x-ray spectrometer (sxs, a quantum micro-calorimeter) and soft x-ray imager (sxi, an x-ray ccd) also functioned as expected. however, on march 26, 2016, operations were prematurely terminated by a series of abnormal events and mishaps triggered by the attitude control system. these errors led to a fatal event: the loss of the solar panels on the hitomi mission. the x-ray astronomy recovery mission (or, xarm) is proposed to regain the key scientific advances anticipated by the international collaboration behind hitomi. xarm will recover this science in the shortest time possible by focusing on one of the main science goals of hitomi,"resolving astrophysical problems by precise high-resolution x-ray spectroscopy".1 this decision was reached after evaluating the performance of the instruments aboard hitomi and the mission's initial scientific results, and considering the landscape of planned international x-ray astrophysics missions in 2020's and 2030's. hitomi opened the door to high-resolution spectroscopy in the x-ray universe. it revealed a number of discrepancies between new observational results and prior theoretical predictions. yet, the resolution pioneered by hitomi is also the key to answering these and other fundamental questions. the high spectral resolution realized by xarm will not offer mere refinements; rather, it will enable qualitative leaps in astrophysics and plasma physics. xarm has therefore been given a broad scientific charge: "revealing material circulation and energy transfer in cosmic plasmas and elucidating evolution of cosmic structures and objects". to fulfill this charge, four categories of science objectives that were defined for hitomi will also be pursued by xarm; these include (1) structure formation of the universe and evolution of clusters of galaxies; (2) circulation history of baryonic matters in the universe; (3) transport and circulation of energy in the universe; (4) new science with unprecedented high resolution x-ray spectroscopy. in order to achieve these scientific objectives, xarm will carry a 6 × 6 pixelized x-ray micro-calorimeter on the focal plane of an x-ray mirror assembly, and an aligned x-ray ccd camera covering the same energy band and a wider field of view. this paper introduces the science objectives, mission concept, and observing plan of xarm. | concept of the x-ray astronomy recovery mission |
the flux of unstable secondary cosmic ray nuclei, produced by spallation processes in the interstellar medium, can be used to constrain the residence time of cosmic rays inside the galaxy. among them, 10be is especially useful because of its relatively long half-life of 1.39 myr. in the framework of the diffusive halo model we describe cosmic ray transport taking into account all relevant interaction channels and accounting for the decay of unstable secondary nuclei. we then compare our results with the data collected by the alpha magnetic spectrometer (ams-02) on board the international space station for the flux ratios be/c, b/c, be/o, b/o, c/o and be/b as well as c, n and o absolute fluxes. these measurements, and especially the be/b ratio, allow us to single out the flux of 10be and infer a best fit propagation time of crs in the galaxy. our results show that, if the cross sections for the production of secondary elements through spallation are taken at face value, ams-02 measurements are compatible with the standard picture based on cr diffusion in a halo of size h ≳5 kpc . taking into account the uncertainties in the cross sections, this conclusion becomes less reliable, although still compatible with the standard picture. implications of our findings for alternative models of cr transport are discussed. | ams-02 beryllium data and its implication for cosmic ray transport |
we analyze the distribution of arrival directions of ultra-high-energy cosmic rays recorded at the pierre auger observatory in 10 years of operation. the data set, about three times larger than that used in earlier studies, includes arrival directions with zenith angles up to 80°, thus covering from -90{}^\circ to +45{}^\circ in declination. after updating the fraction of events correlating with the active galactic nuclei (agns) in the véron-cetty and véron catalog, we subject the arrival directions of the data with energies in excess of 40 eev to different tests for anisotropy. we search for localized excess fluxes, self-clustering of event directions at angular scales up to 30°, and different threshold energies between 40 and 80 eev. we then look for correlations of cosmic rays with celestial structures both in the galaxy (the galactic center and galactic plane) and in the local universe (the super-galactic plane). we also examine their correlation with different populations of nearby extragalactic objects: galaxies in the 2mrs catalog, agns detected by swift-bat, radio galaxies with jets, and the centaurus a (cen a) galaxy. none of the tests show statistically significant evidence of anisotropy. the strongest departures from isotropy (post-trial probability ∼ 1.4%) are obtained for cosmic rays with e\gt 58 eev in rather large windows around swift agns closer than 130 mpc and brighter than 1044 erg s-1 (18° radius), and around the direction of cen a (15° radius). | searches for anisotropies in the arrival directions of the highest energy cosmic rays detected by the pierre auger observatory |
the greenland ice sheet (gis) contains the equivalent of 7.4 metres of global sea-level rise. its stability in our warming climate is therefore a pressing concern. however, the sparse proxy evidence of the palaeo-stability of the gis means that its history is controversial (compare refs 2 and 3 to ref. 4). here we show that greenland was deglaciated for extended periods during the pleistocene epoch (from 2.6 million years ago to 11,700 years ago), based on new measurements of cosmic-ray-produced beryllium and aluminium isotopes (10be and 26al) in a bedrock core from beneath an ice core near the gis summit. models indicate that when this bedrock site is ice-free, any remaining ice is concentrated in the eastern greenland highlands and the gis is reduced to less than ten per cent of its current volume. our results narrow the spectrum of possible gis histories: the longest period of stability of the present ice sheet that is consistent with the measurements is 1.1 million years, assuming that this was preceded by more than 280,000 years of ice-free conditions. other scenarios, in which greenland was ice-free during any or all pleistocene interglacials, may be more realistic. our observations are incompatible with most existing model simulations that present a continuously existing pleistocene gis. future simulations of the gis should take into account that greenland was nearly ice-free for extended periods under pleistocene climate forcing. | greenland was nearly ice-free for extended periods during the pleistocene |
the cumulative emission resulting from hadronic cosmic-ray interactions in star-forming galaxies (sfgs) has been proposed as the dominant contribution to the astrophysical neutrino flux at tev to pev energies reported by icecube. the same particle interactions also inevitably create γ-ray emission that could be detectable as a component of the extragalactic γ-ray background (egb), which is now measured with the fermi-lat in the energy range from 0.1 to 820 gev. new studies of the blazar flux distribution at γ-ray energies above 50 gev place an upper bound on the residual non-blazar component of the egb. we show that these results are in strong tension with models that consider sfgs as the dominant source of the diffuse neutrino backgrounds. a characteristic spectral index for parent cosmic rays in starburst galaxies of γsb ≃ 2.3 for {dn}/{de}\propto {e}-{{{γ }}{sb}} is consistent with the observed scaling relation between γ-ray and ir luminosity for sfgs, the bounds from the non-blazar egb, and the observed γ-ray spectra of individual starbursts, but underpredicts the icecube data by approximately an order of magnitude. | evidence against star-forming galaxies as the dominant source of icecube neutrinos |
since the detection of the methylidyne radical (ch) in the interstellar medium nearly 80 y ago, about 200 molecules ranging from molecular hydrogen to fullerenes have been identified in interstellar and circumstellar environments, but the synthesis of complex organic molecules (coms)--organics containing several atoms of carbon, hydrogen, nitrogen, and oxygen--has remained elusive to date. here, we provide compelling evidence via laboratory experiments, computations, and modeling that the synthesis of coms is driven by a cosmic-ray-triggered nonequilibrium chemistry within interstellar ices at temperatures as low as 10 k. these fundamental reaction mechanisms are of major significance to facilitate an understanding of the origin and evolution of the molecular universe. | a study of interstellar aldehydes and enols as tracers of a cosmic ray-driven nonequilibrium synthesis of complex organic molecules |
traditional direct searches for dark matter, looking for nuclear recoils in deep underground detectors, are challenged by an almost complete loss of sensitivity for light dark matter particles. consequently, there is a significant effort in the community to devise new methods and experiments to overcome these difficulties, constantly pushing the limits of the lowest dark matter mass that can be probed this way. from a model-building perspective, the scattering of sub-gev dark matter on nucleons essentially must proceed via new light mediator particles, given that collider searches place extremely stringent bounds on contact-type interactions. here we present an updated compilation of relevant limits for the case of a scalar mediator, including a new estimate of the near-future sensitivity of the na62 experiment as well as a detailed evaluation of the model-specific limits from big bang nucleosynthesis. we also derive updated and more general limits on dm particles upscattered by cosmic rays, applicable to arbitrary energy- and momentum dependences of the scattering cross section. finally we stress that dark matter self-interactions, when evaluated beyond the common s-wave approximation, place stringent limits independently of the dark matter production mechanism. these are, for the relevant parameter space, generically comparable to those that apply in the commonly studied freeze-out case. we conclude that the combination of existing (or expected) constraints from accelerators and astrophysics, combined with cosmological requirements, puts robust limits on the maximally possible nuclear scattering rate. in most regions of parameter space these are at least competitive with the best projected limits from currently planned direct detection experiments. | direct detection and complementary constraints for sub-gev dark matter |
the interaction of ultra-high-energy cosmic rays (uhecrs) with pervasive photon fields generates associated cosmogenic fluxes of neutrinos and photons due to photohadronic and photonuclear processes taking place in the intergalactic medium. we perform a fit of the uhecr spectrum and composition measured by the pierre auger observatory for four source emissivity scenarios: power-law redshift dependence with one free parameter, active galactic nuclei, gamma-ray bursts, and star formation history. we show that negative source emissivity evolution is favoured if we treat the source evolution as a free parameter. in all cases, the best fit is obtained for relatively hard spectral indices and low maximal rigidities, for compositions at injection dominated by intermediate nuclei (nitrogen and silicon groups). in light of these results, we calculate the associated fluxes of neutrinos and photons. finally, we discuss the prospects for the future generation of high-energy neutrino and gamma-ray observatories to constrain the sources of uhecrs. | cosmogenic photon and neutrino fluxes in the auger era |
sub-gev dark matter candidates are of increasing interest, because long-favored candidates such as gev-scale weakly interacting massive particles have not been detected. for low-mass dark matter, model-independent constraints are weak or nonexistent. we show that for such candidates, because the number density is high, cosmic ray propagation can be affected by elastic scattering with dark matter. we call this type of search "reverse direct detection," because dark matter is the target and standard model particles are the beam. using a simple propagation model for galactic cosmic rays, we calculate how dark matter affects cosmic ray spectra at earth, and set new limits on the dark matter-proton and dark matter-electron cross sections. for protons, our limit is competitive with cosmological constraints, but is independent. for electrons, our limit covers masses not yet probed, and improves on cosmological constraints by one to two orders of magnitude. we comment on how future work can significantly improve the sensitivity of cosmic-ray probes of dark matter interactions. | reverse direct detection: cosmic ray scattering with light dark matter |
the hubble constant h 0 and matter density ω mof the universe are measured using the latest γ-ray attenuation results from fermi-lat and cerenkov telescopes. this methodology is based upon the fact that the extragalactic background light supplies opacity for very high energy photons via photon-photon interaction. the amount of γ-ray attenuation along the line of sight depends on the expansion rate and matter content of the universe. this novel strategy results in a value of {h}0={67.4}-6.2+6.0 km s-1 mpc-1 and {{{ω }}}m={0.14}-0.07+0.06. these estimates are independent and complementary to those based on the distance ladder, cosmic microwave background (cmb), clustering with weak lensing, and strong lensing data. we also produce a joint likelihood analysis of our results from γ-rays and those from more mature methodologies, excluding the cmb, yielding a combined value of h 0 = 66.6 ± 1.6 km s-1 mpc-1 and ω m= 0.29 ± 0.02. | a new measurement of the hubble constant and matter content of the universe using extragalactic background light γ-ray attenuation |
high-resolution spectroscopy in soft x-rays will open a new window to map multiphase gas in galaxy clusters and probe physics of the intracluster medium (icm), including chemical enrichment histories, circulation of matter and energy during large-scale structure evolution, stellar and black hole feedback, halo virialization, and gas mixing processes. an ev-level spectral resolution, large field-of-view, and effective area are essential to separate cluster emissions from the galactic foreground and efficiently map the cluster outskirts. several mission concepts that meet these criteria have been proposed recently, e.g., lem, hubs, and superdios. this theoretical study explores what information on icm physics could be recovered with such missions and the associated challenges. we emphasize the need for a comprehensive comparison between simulations and observations to interpret the high-resolution spectroscopic observations correctly. using line emission mapper (lem) characteristics as an example, we demonstrate that it enables the use of soft x-ray emission lines (e.g., o vii/viii and fe-l complex) from the cluster outskirts to measure the thermodynamic, chemical, and kinematic properties of the gas up to $r_{200}$ and beyond. by generating mock observations with full backgrounds, analysing their images/spectra with observational approaches, and comparing the recovered characteristics with true ones from simulations, we develop six key science drivers for future missions, including the exploration of multiphase gas in galaxy clusters (e.g., temperature fluctuations, phase-space distributions), metallicity, icm gas bulk motions and turbulence power spectra, icm-cosmic filament interactions, and advances for cluster cosmology. | mapping the intracluster medium in the era of high-resolution x-ray spectroscopy |
the diffuse extragalactic background light (ebl) is formed by ultraviolet (uv), optical, and infrared (ir) photons mainly produced by star formation processes over the history of the universe and contains essential information about galaxy evolution and cosmology. here, we present a new determination of the evolving ebl spectral energy distribution using a novel approach purely based on galaxy data aiming to reduce current uncertainties on the higher redshifts and ir intensities. our calculations use multiwavelength observations from the uv to the far-ir of a sample of approximately 150 000 galaxies detected up to z ~ 6 in the five fields of the cosmic assembly near-infrared deep extragalactic legacy survey from the hubble space telescope. this is one of the most comprehensive and deepest multiwavelength galaxy data sets ever obtained. these unprecedented resources allow us to derive the overall ebl evolution up to z ~ 6 and its uncertainties. our results agree with cosmic observables estimated from galaxy surveys and γ-ray attenuation such as monochromatic luminosity densities, including those in the far-ir, and star formation rate densities, also at the highest redshifts. optical depths from our ebl approximation, which will be robust at high redshifts and for γ-rays up to tens of tev, will be reported in a companion paper. | an observational determination of the evolving extragalactic background light from the multiwavelength hst/candels survey in the fermi and cta era |
we have recently discovered a smooth vacuum-wormhole solution of the first-order equations of general relativity. here, we obtain the corresponding multiple-vacuum-wormhole solution. assuming that our world is essentially minkowski spacetime with a large number of these vacuum-defect wormholes inserted, there is then another flat spacetime with opposite spatial orientation, which may be called a "mirror" world. we briefly discuss some phenomenological aspects and point out that there will be no significant vacuum-cherenkov radiation in our world, so that ultrahigh-energy cosmic rays do not constrain the typical size and separation of the wormhole mouths (different from the constraints obtained for a single minkowski spacetime with similar defects). other signatures from a "gas" of vacuum-defect wormholes are mentioned, including a possible time machine. | vacuum-defect wormholes and a mirror world |
the small-scale dynamo (ssd) amplifies weak magnetic fields exponentially fast via kinetic motions. while there exist well-established theories for ssds in incompressible flows, many astrophysical ssds operate in supersonic turbulence. to understand the impact of compressibility on amplified magnetic fields, we perform an extensive set of visco-resistive ssd simulations, covering a wide range of sonic mach number $\mathcal{m}$, hydrodynamic reynolds number re, and magnetic prandtl number pm. we develop robust methods for measuring kinetic and magnetic energy dissipation scales $\ell_\nu$ and $\ell_\eta$, as well as the scale at which magnetic fields are strongest $\ell_p$ during the kinematic phase of these simulations. we show that $\ell_\nu/\ell_\eta \sim$ pm$^{1/2}$ is a universal feature in the kinematic phase of pm $\geq 1$ ssds, regardless of $\mathcal{m}$ or re, and we confirm earlier predictions that ssds operating in incompressible plasmas (either $\mathcal{m} \leq 1$ or re $<$ re$_{\rm crit} \approx 100$) concentrate magnetic energy at the smallest scales allowed by magnetic dissipation, $\ell_p \sim \ell_\eta$, and produce fields organised with field strength and field-line curvature inversely correlated. however, we show that these predictions fail for compressible ssds ($\mathcal{m} > 1$ and re $>$ re$_{\rm crit}$), where shocks concentrate magnetic energy in large-scale, over-dense, coherent structures, with size $\ell_p \sim (\ell_{\rm turb} / \ell_{\rm shock})^{1/3} \ell_\eta \gg \ell_\eta$, where $\ell_{\rm shock} \sim \mathcal{m}^2 / [$re $ (\mathcal{m} - 1)^2]$ is shock width, and $\ell_{\rm turb}$ is the turbulent outer scale; magnetic field-line curvature becomes almost independent of the field strength. we discuss the implications for galaxy mergers and for cosmic-ray transport models in the interstellar medium that are sensitive to field-line curvature statistics. | fundamental mhd scales -- ii: the kinematic phase of the supersonic small-scale dynamo |
neutrinos are the most elusive particles in the universe, capable of traveling nearly unimpeded across it. despite the vast amount of data collected, a long-standing and unsolved issue is still the association of high-energy neutrinos with the astrophysical sources that originate them. among the candidate sources of neutrinos, there are blazars, a class of extragalactic sources powered by supermassive black holes that feed highly relativistic jets, pointed toward earth. previous studies appear controversial, with several efforts claiming a tentative link between high-energy neutrino events and individual blazars, and others putting into question such relation. in this work, we show that blazars are unambiguously associated with high-energy astrophysical neutrinos at an unprecedented level of confidence, i.e., a chance probability of 6 × 10-7. our statistical analysis provides the observational evidence that blazars are astrophysical neutrino factories and hence, extragalactic cosmic-ray accelerators. | beginning a journey across the universe: the discovery of extragalactic neutrino factories |
we summarize and reanalyze observations bearing on missing galactic baryons, where we propose a consistent picture for halo gas in l ≳ l* galaxies. the hot x-ray-emitting halos are detected to 50-70 kpc, where typically m hot(<50 kpc) ∼ 5 × 109 m ⊙, and with density n ∝ r -3/2. when extrapolated to r 200, the gas mass is comparable to the stellar mass, but about half of the baryons are still missing from the hot phase. if extrapolated to 1.7r 200-3r 200, the ratio of baryon to dark matter approaches the cosmic value. significantly flatter density profiles are unlikely for r < 50 kpc, and they are disfavored but not ruled out for r > 50 kpc. for the milky way, the hot halo metallicity lies in the range 0.3-1 solar for r < 50 kpc. planck measurements of the thermal sunyaev-zel’dovich (sz) effect toward stacked luminous galaxies (primarily early type) indicate that most of their baryons are hot, are near the virial temperature, and extend beyond r 200. this stacked sz signal is nearly an order of magnitude larger than that inferred from the x-ray observations of individual (mostly spiral) galaxies with m * > 1011.3 m ⊙. this difference suggests that the hot halo properties are distinct for early- and late-type galaxies, possibly due to different evolutionary histories. for the cooler gas detected in uv absorption line studies, we argue that there are two absorption populations: extended halos, and disks extending to ∼50 kpc, containing most of this gas, and with masses a few times lower than the stellar masses. such extended disks are also seen in 21 cm h i observations and in simulations. | the extended distribution of baryons around galaxies |
the development of automated solutions to pattern recognition problems is important in many areas of scientific research and human endeavour. this paper describes the implementation of the pandora software development kit, which aids the process of designing, implementing and running pattern recognition algorithms. the pandora application programming interfaces ensure simple specification of the building-blocks defining a pattern recognition problem. the logic required to solve the problem is implemented in algorithms. the algorithms request operations to create or modify data structures and the operations are performed by the pandora framework. this design promotes an approach using many decoupled algorithms, each addressing specific topologies. details of algorithms addressing two pattern recognition problems in high energy physics are presented: reconstruction of events at a high-energy e+e- linear collider and reconstruction of cosmic ray or neutrino events in a liquid argon time projection chamber. | the pandora software development kit for pattern recognition |
we have obtained estimates for the cosmic-ray ionization rate (crir) in the galactic disk, using a detailed model for the physics and chemistry of diffuse interstellar gas clouds to interpret previously published measurements of the abundance of four molecular ions: arh+, oh+, {{{h}}}2{{{o}}}+, and {{{h}}}3+. for diffuse atomic clouds at galactocentric distances in the range {r}g∼ 4{--}9 {kpc}, observations of arh+, oh+, and {{{h}}}2{{{o}}}+ imply a mean primary crir of (2.2+/- 0.3) \exp [({r}0-{r}g)/4.7 {kpc}]× {10}-16 {{{s}}}-1 per hydrogen atom, where {r}0=8.5 {kpc}. within diffuse molecular clouds observed toward stars in the solar neighborhood, measurements of {{{h}}}3+ and h2 imply a primary crir of (2.3+/- 0.6)× {10}-16 {{{s}}}-1 per h atom, corresponding to a total ionization rate per h2 molecule of (5.3+/- 1.1)× {10}-16 {{{s}}}-1, in good accord with previous estimates. these estimates are also in good agreement with a rederivation, presented here, of the crir implied by recent observations of carbon and hydrogen radio recombination lines along the sight line to cas a. here, our best-fit estimate for the primary crir is 2.9× {10}-16 {{{s}}}-1 per h atom. our results show marginal evidence that the crir in diffuse molecular clouds decreases with cloud extinction, {a}{{v}}({tot}), with a best-fit dependence \propto {a}{{v}}{({tot})}-1 for {a}{{v}}({tot})≥slant 0.5. | the cosmic-ray ionization rate in the galactic disk, as determined from observations of molecular ions |
we present rest-frame near-ir (nir) luminosities and stellar masses for a large and uniformly selected population of gamma-ray burst (grb) host galaxies using deep spitzer space telescope imaging of 119 targets from the swift grb host galaxy legacy survey spanning 0.03 < z < 6.3, and we determine the effects of galaxy evolution and chemical enrichment on the mass distribution of the grb host population across cosmic history. we find a rapid increase in the characteristic nir host luminosity between z ∼ 0.5 and z ∼ 1.5, but little variation between z ∼ 1.5 and z ∼ 5. dust-obscured grbs dominate the massive host population but are only rarely seen associated with low-mass hosts, indicating that massive star-forming galaxies are universally and (to some extent) homogeneously dusty at high redshift while low-mass star-forming galaxies retain little dust in their interstellar medium. comparing our luminosity distributions with field surveys and measurements of the high-z mass-metallicity relation, our results have good consistency with a model in which the grb rate per unit star formation is constant in galaxies with gas-phase metallicity below approximately the solar value but heavily suppressed in more metal-rich environments. this model also naturally explains the previously reported “excess” in the grb rate beyond z ≳ 2 metals stifle grb production in most galaxies at z < 1.5 but have only minor impact at higher redshifts. the metallicity threshold we infer is much higher than predicted by single-star models and favors a binary progenitor. our observations also constrain the fraction of cosmic star formation in low-mass galaxies undetectable to spitzer to be small at z < 4. | the swift grb host galaxy legacy survey. ii. rest-frame near-ir luminosity distribution and evidence for a near-solar metallicity threshold |
the lhaaso collaboration has reported their observation of very high energy photons (eγmax≃18 tev ) from the gamma-ray burst grb221009a. the sterile neutrino that involves both mixing and a transition magnetic moment may be a viable explanation for these high energy photon events. however, we demonstrate that such a solution is strongly disfavored by the cosmic microwave background and big bang nucleosynthesis in standard cosmology. | can sterile neutrinos explain the very high energy photons from grb221009a? |
the pierre auger observatory, located on a vast, high plain in western argentina, is the world's largest cosmic ray observatory. the objectives of the observatory are to probe the origin and characteristics of cosmic rays above $10^{17}$ ev and to study the interactions of these, the most energetic particles observed in nature. the auger design features an array of 1660 water-cherenkov particle detector stations spread over 3000 km$^2$ overlooked by 24 air fluorescence telescopes. in addition, three high elevation fluorescence telescopes overlook a 23.5 km$^2$, 61-detector infilled array with 750 m spacing. the observatory has been in successful operation since completion in 2008 and has recorded data from an exposure exceeding 40,000 km$^2$ sr yr. this paper describes the design and performance of the detectors, related subsystems and infrastructure that make up the auger observatory. | the pierre auger cosmic ray observatory |
we derive constraints on the thermal and ionization states of the intergalactic medium (igm) at redshift ≈ 9.1 using new upper limits on the 21-cm power spectrum measured by the lofar radio telescope and a prior on the ionized fraction at that redshift estimated from recent cosmic microwave background (cmb) observations. we have used results from the reionization simulation code grizzly and a bayesian inference framework to constrain the parameters which describe the physical state of the igm. we find that, if the gas heating remains negligible, an igm with ionized fraction ≳0.13 and a distribution of the ionized regions with a characteristic size ≳ 8 h-1 comoving megaparsec (mpc) and a full width at half-maximum (fwhm) ≳16 h-1 mpc is ruled out. for an igm with a uniform spin temperature ts ≳ 3 k, no constraints on the ionized component can be computed. if the large-scale fluctuations of the signal are driven by spin temperature fluctuations, an igm with a volume fraction ≲0.34 of heated regions with a temperature larger than cmb, average gas temperature 7-160 k, and a distribution of the heated regions with characteristic size 3.5-70 h-1 mpc and fwhm of ≲110 h-1 mpc is ruled out. these constraints are within the 95 per cent credible intervals. with more stringent future upper limits from lofar at multiple redshifts, the constraints will become tighter and will exclude an increasingly large region of the parameter space. | constraining the intergalactic medium at z ≈ 9.1 using lofar epoch of reionization observations |
we present new chandra constraints on the x-ray luminosity functions (xlfs) of x-ray binary (xrb) populations, as well as their scaling relations, for a sample of 38 nearby galaxies (d = 3.4-29 mpc). our galaxy sample is drawn primarily from the spitzer infrared nearby galaxies survey (sings) and contains a wealth of chandra (5.8 ms total) and multiwavelength data, allowing for star formation rates (sfrs) and stellar masses (m ⋆) to be measured on subgalactic scales. we divided the 2478 x-ray-detected sources into 21 subsamples in bins of specific sfr (ssfr ≡ sfr/m ⋆) and constructed xlfs. to model the xlf dependence on ssfr, we fit a global xlf model, containing contributions from high-mass xrbs (hmxbs), low-mass xrbs (lmxbs), and background sources from the cosmic x-ray background that respectively scale with sfr, m ⋆, and sky area. we find an hmxb xlf that is more complex in shape than previously reported and an lmxb xlf that likely varies with ssfr, potentially due to an age dependence. when applying our global model to xlf data for each individual galaxy, we discover a few galaxy xlfs that significantly deviate from our model beyond statistical scatter. most notably, relatively low-metallicity galaxies have an excess of hmxbs above ≈1038 erg s-1, and elliptical galaxies that have relatively rich populations of globular clusters (gcs) show excesses of lmxbs compared to the global model. additional modeling of how the xrb xlf depends on stellar age, metallicity, and gc specific frequency is required to sufficiently characterize the xlfs of galaxies. | x-ray binary luminosity function scaling relations for local galaxies based on subgalactic modeling |
in the context of self-interacting dark matter as a solution for the small-scale structure problems, we consider the possibility that dark matter could have been produced without being in thermal equilibrium with the standard model bath. we discuss one by one the following various dark matter production regimes of this kind: freeze-in, reannihilation and dark freeze-out. we exemplify how these mechanisms work in the context of the particularly simple hidden vector dark matter model. in contrast to scenarios where there is thermal equilibrium with the standard model bath, we find two regimes which can easily satisfy all the laboratory and cosmological constraints. these are dark freeze-out with 3-to-2 annihilations and freeze-in via a light mediator. in the first regime, different temperatures in the visible and the dark matter sectors allow us to avoid the constraints coming from cosmic structure formation as well as the use of non-perturbative couplings to reproduce the observed relic density. for the second regime, different couplings are responsible for dark matter relic density and self-interactions, permitting to surpass bbn, x-ray, cmb and direct detection constraints. | production regimes for self-interacting dark matter |
gamma-ray bursts (grbs) are the most luminous explosions in and can be detectable out to the edge of the universe. they have long been thought to be able to extend the hubble diagram to very high redshifts. several correlations between temporal or spectral properties and grb luminosities have been proposed to make grbs cosmological tools. however, those correlations cannot be properly standardized. in this paper, we select a long-grb sample with x-ray plateau phases produced by electromagnetic dipole emissions from central newborn magnetars. a tight correlation is found between the plateau luminosity and the end time of the plateau in the x-ray afterglows out to the redshift z = 5.91. we standardize these long-grb x-ray light curves to a universal behavior through this correlation, with a luminosity dispersion of 0.5 dex. the derived distance-redshift relation of grbs is in agreement with the standard λcdm model both at low and high redshifts. the evidence for an accelerating universe from this grb sample is 3σ, which is the highest statistical significance from grbs to date. | standardized long gamma-ray bursts as a cosmic distance indicator |
we propose a flavored u(1)eμ neutrino mass and dark matter (dm) model to explain the recent dark matter particle explorer (dampe) data, which feature an excess on the cosmic ray electron plus positron flux around 1.4 tev. only the first two lepton generations of the standard model are charged under the new u(1)eμ gauge symmetry. a vector-like fermion ψ, which is our dm candidate, annihilates into e± and μ± via the new gauge boson z‧ exchange and accounts for the dampe excess. we have found that the data favors a ψ mass around 1.5 tev and a z‧ mass around 2.6 tev, which can potentially be probed by the next generation lepton colliders and dm direct detection experiments. | a model explaining neutrino masses and the dampe cosmic ray electron excess |
gamma-ray bursts (grbs) are the most luminous explosions in the universe, which within seconds release energy comparable to what the sun releases in its entire lifetime. the field of grbs has developed rapidly and matured over the past decades. written by a leading researcher, this text presents a thorough treatment of every aspect of the physics of grbs. it starts with an overview of the field and an introduction to grb phenomenology. after laying out the basics of relativity, relativistic shocks, and leptonic and hadronic radiation processes, the volume covers all topics related to grbs, including a general theoretical framework, afterglow and prompt emission models, progenitor, central engine, multi-messenger aspects (cosmic rays, neutrinos, and gravitational waves), cosmological connections, and broader impacts on fundamental physics and astrobiology. it is suitable for advanced undergraduates, graduate students, and experienced researchers in the field of grbs and high-energy astrophysics in general. | the physics of gamma-ray bursts |
we present an all-sky search for muon neutrinos produced during the prompt γ-ray emission of 1172 gamma-ray bursts (grbs) with the icecube neutrino observatory. the detection of these neutrinos would constitute evidence for ultra-high-energy cosmic-ray (uhecr) production in grbs, as interactions between accelerated protons and the prompt γ-ray field would yield charged pions, which decay to neutrinos. a previously reported search for muon neutrino tracks from northern hemisphere grbs has been extended to include three additional years of icecube data. a search for such tracks from southern hemisphere grbs in five years of icecube data has been introduced to enhance our sensitivity to the highest energy neutrinos. no significant correlation between neutrino events and observed grbs is seen in the new data. combining this result with previous muon neutrino track searches and a search for cascade signature events from all neutrino flavors, we obtain new constraints for single-zone fireball models of grb neutrino and uhecr production. | extending the search for muon neutrinos coincident with gamma-ray bursts in icecube data |
one of the most promising ways to probe intergalactic magnetic fields (igmfs) is through gamma rays produced in electromagnetic cascades initiated by high-energy gamma rays or cosmic rays in the intergalactic space. because the charged component of the cascade is sensitive to magnetic fields, gamma-ray observations of distant objects such as blazars can be used to constrain igmf properties. ground-based and space-borne gamma-ray telescopes deliver spectral, temporal, and angular information of high-energy gamma-ray sources, which carries imprints of the intervening magnetic fields. this provides insights into the nature of the processes that led to the creation of the first magnetic fields and into the phenomena that impacted their evolution. here we provide a detailed description of how gamma-ray observations can be used to probe cosmic magnetism. we review the current status of this topic and discuss the prospects for measuring igmfs with the next generation of gamma-ray observatories. | the gamma-ray window to intergalactic magnetism |
cosmic probes of fundamental physics take two primary forms: very high energy particles (cosmic rays, neutrinos, and gamma rays) and gravitational waves. already today, these probes give access to fundamental physics not available by any other means, helping elucidate the underlying theory that completes the standard model. the last decade has witnessed a revolution of exciting discoveries such as the detection of high-energy neutrinos and gravitational waves. the scope for major developments in the next decades is dramatic, as we detail in this report. | report of the topical group on cosmic probes of fundamental physics for for snowmass 2021 |
we present comprehensive analyses of faint dropout galaxies up to z ~ 10 with the first full-depth data set of the a2744 lensing cluster and parallel fields observed by the hubble frontier fields (hff) program. we identify 54 dropouts at z ~ 5-10 in the hff fields and enlarge the size of the z ~ 9 galaxy sample obtained to date. although the number of highly magnified (μ ~ 10) galaxies is small because of the tiny survey volume of strong lensing, our study reaches the galaxies' intrinsic luminosities comparable to the deepest-field hudf studies. we derive uv luminosity functions with these faint dropouts, carefully evaluating by intensive simulations the combination of observational incompleteness and lensing effects in the image plane, including magnification, distortion, and multiplication of images, with the evaluation of mass model dependencies. our results confirm that the faint-end slope, α, is as steep as -2 at z ~ 6-8 and strengthen the evidence for the rapid decrease of uv luminosity densities, ρuv, at z > 8 from the large z ~ 9 sample. we examine whether the rapid ρuv decrease trend can be reconciled with the large thomson scattering optical depth, τe, measured by cosmic microwave background experiments, allowing a large space of free parameters, such as an average ionizing photon escape fraction and a stellar-population-dependent conversion factor. no parameter set can reproduce both the rapid ρuv decrease and the large τ e . it is possible that the ρuv decrease moderates at z >~ 11, that the free parameters significantly evolve toward high z, or that there exist additional sources of reionization such as x-ray binaries and faint active galactic nuclei. | hubble frontier fields first complete cluster data: faint galaxies at z ~ 5-10 for uv luminosity functions and cosmic reionization |
we demonstrate that a population of active galactic nuclei (agn) can describe the observed spectrum of ultra-high-energy cosmic rays (uhecrs) at and above the ankle, and that the dominant contribution comes from low-luminosity bl lacertae objects. an additional, subdominant contribution from high-luminosity agn is needed to improve the description of the composition observables, leading to a substantial neutrino flux that peaks at exaelectronvolt (eev) energies. we also find that different properties for the low- and high-luminosity agn populations are required; a possibly similar baryonic loading can already be excluded from current icecube neutrino observatory observations. we also show that the flux of neutrinos emitted from within the sources should outshine the cosmogenic neutrinos produced during the propagation of uhecrs. this result has profound implications for the ultra-high-energy (∼eev ) neutrino experiments, since additional search strategies can be used for source neutrinos compared to cosmogenic neutrinos, such as stacking searches, flare analyses, and multimessenger follow-ups. | active galactic nuclei jets as the origin of ultrahigh-energy cosmic rays and perspectives for the detection of astrophysical source neutrinos at eev energies |
the cosmic-ray database, crdb, has been gathering cosmic-ray data for the community since 2013. we present a new release, crdb v4.1, providing many new quantities and data sets, with several improvements made on the code and web interface, and with new visualisation tools. crdb relies on the mysql database management system, jquery and table-sorter libraries for queries and sorting, and php web pages and ajax protocol for displays. a rest interface enables user queries from command line or scripts. a new (pip-installable) crdb python library is developed and extensive jupyter notebook examples are provided. this release contains cosmic-ray dipole anisotropy data, high-energy p ¯ /p upper limits, some unpublished lee and aesop lepton time series, many more ultra-high energy data, and a few missing old data sets. it also includes high-precision data from the last three years, in particular the hundreds of thousands ams-02 and pamela data time series (time-dependent plots are now enabled). all these data are shown in a gallery of plots, which can be easily reproduced from the public notebook examples. crdb contains 316,126 data points from 504 publications, in 4111 sub-experiments from 131 experiments. | a cosmic-ray database update: crdb v4.1 |
recurrent novae are repeating thermonuclear explosions in the outer layers of white dwarfs, due to the accretion of fresh material from a binary companion. the shock generated when ejected material slams into the companion star’s wind can accelerate particles. we report very-high-energy (vhe; ≳100 giga–electron volts) gamma rays from the recurrent nova rs ophiuchi, up to 1 month after its 2021 outburst, observed using the high energy stereoscopic system (h.e.s.s.). the temporal profile of vhe emission is similar to that of lower-energy giga–electron volt emission, indicating a common origin, with a 2-day delay in peak flux. these observations constrain models of time-dependent particle energization, favoring a hadronic emission scenario over the leptonic alternative. shocks in dense winds provide favorable environments for efficient acceleration of cosmic rays to very high energies. | time-resolved hadronic particle acceleration in the recurrent nova rs ophiuchi |
transverse momentum spectra (pt) of charged particles including π±, k± and (anti-)protons measured by alice experiment in the pt range of 0.1-2.5 gev/c and |η | < 0.5 are studied in pp collisions at √{s } = 900 gev using modified hagedorn function with embedded transverse flow velocity and are compared to the predictions of epos-lhc, pythia, qgsjet and sibyll models. we find that the average transverse flow velocity (βt) decreases with increasing the mass of the particle, while the kinetic freeze-out temperature (t0) extracted from the function increases with the particle's mass. the former varies from (0.36 ± 0.01) c to (0.25 ± 0.01) c for π± to protons, while the latter from (76 ± 6) mev to (95 ± 5) mev, respectively. the fit of the models predictions also yields the same values for t0 and βt as the experimental data. the only difference is in the values of n and n0 which yields different values for different models. the epos-lhc, pythia and qgsjet models reproduce the data in most of the pt range for π±, epos-lhc and sibyll for k± up to 1.5 gev/c and epos-lhc for protons up to 1.6 gev/c. the model simulations also reproduced the behavior of increasing average transverse momentum with mass reported by the alice experiment. | study of pt spectra of light particles using modified hagedorn function and cosmic rays monte carlo event generators in proton-proton collisions at √{s } = 900 gev |
contributions of the pierre auger collaboration to the 36th international cosmic ray conference (icrc 2019), 24 july - 1 august 2019, madison, wisconsin, usa. | the pierre auger observatory: contributions to the 36th international cosmic ray conference (icrc 2019) |
we present the evolution of the 21-cm signal from cosmic dawn and the epoch of reionization in an upgraded model including three subtle effects of ly α radiation: ly α heating, cmb heating (mediated by ly α photons), and multiple scattering of ly α photons. taking these effects into account, we explore a wide range of astrophysical models and quantify the impact of these processes on the global 21-cm signal and its power spectrum. we find that ly α heating raises the gas temperature by up to $\mathcal {o}(100)$ degrees (cmb heating adds a few more degrees) in models with weak x-ray heating, thus suppressing the predicted 21-cm signals. varying the astrophysical parameters broadly in an attempt to cover the full plausible range of models, we find that in the upgraded model the absorption trough of the global signal reaches a lowest possible floor of -165 mk at redshifts z ≈ 15-19. this is in contrast with the predictions for a pure adiabatically cooling universe, for which the deepest possible absorption is a monotonically decreasing function of cosmic time and is -178 mk at z = 19 and -216 mk at z = 15, dropping to even lower values at lower redshifts. with ly α and cmb heating included we also observe a strong suppression in the low-redshift power spectra, with the maximum possible power (evaluated over the ensemble of models) attenuated by a factor of 6.6 at z = 9 and k = 0.1 mpc-1. finally, we find that at high redshifts corresponding to cosmic dawn, the multiple scattering of ly α photons leads to an amplification of the power spectrum by a factor of ~2-3 in all models. | the subtlety of ly α photons: changing the expected range of the 21-cm signal |
as the largest virialized structures in the universe, galaxy clusters continue to grow and accrete matter from the cosmic web. due to the low gas density in the outskirts of clusters, measurements are very challenging, requiring extremely sensitive telescopes across the entire electromagnetic spectrum. observations using x-rays, the sunyaev-zeldovich effect, and weak lensing and galaxy distributions from the optical band, have over the last decade helped to unravel this exciting new frontier of cluster astrophysics, where the infall and virialization of matter takes place. here, we review the current state of the art in our observational and theoretical understanding of cluster outskirts, and discuss future prospects for exploration using newly planned and proposed observatories. | the physics of galaxy cluster outskirts |
we review progress in high-energy cosmic ray physics focusing on recent experimental results and models developed for their interpretation. emphasis is put on the propagation of charged cosmic rays, covering the whole range from ∼(20-50) gv, i.e. the rigidity when solar modulations can be neglected, up to the highest energies observed. we discuss models aiming to explain the anomalies in galactic cosmic rays, the knee, and the transition from galactic to extragalactic cosmic rays. | cosmic ray models |
a majority of the γ-ray emission from star-forming galaxies is generated by the interaction of high-energy cosmic rays with the interstellar gas and radiation fields. star-forming galaxies are expected to contribute to both the extragalactic γ-ray background and the icecube astrophysical neutrino flux. using roughly 10 yr of γ-ray data taken by the fermi large area telescope, in this study we constrain the γ-ray properties of star-forming galaxies. we report the detection of 11 bona fide γ-ray-emitting galaxies and 2 candidates. moreover, we show that the cumulative γ-ray emission of below-threshold galaxies is also significantly detected at ∼5σ confidence. the γ-ray luminosity of resolved and unresolved galaxies is found to correlate with the total (8-1000 μm) infrared luminosity as previously determined. above 1 gev, the spectral energy distribution of resolved and unresolved galaxies is found to be compatible with a power law with a photon index of ≈2.2-2.3. finally, we find that star-forming galaxies account for roughly 5% and 3% of the extragalactic γ-ray background and the icecube neutrino flux, respectively. | the γ-ray emission of star-forming galaxies |
liquid argon time projection chambers (lartpcs) are now a standard detector technology for making accelerator neutrino measurements, due to their high material density, precise tracking, and calorimetric capabilities. an electric field (e-field) is required in such detectors to drift ionization electrons to the anode where they are collected. the e-field of a tpc is often approximated to be uniform between the anode and the cathode planes. however, significant distortions can appear from effects such as mechanical deformations, electrode failures, or the accumulation of space charge generated by cosmic rays. the latter effect is particularly relevant for detectors placed near the earth's surface and with large drift distances and long drift time. to determine the e-field in situ, an ultraviolet (uv) laser system is installed in the microboone experiment at fermi national accelerator laboratory. the purpose of this system is to provide precise measurements of the e-field, and to make it possible to correct for 3d spatial distortions due to e-field non-uniformities. here we describe the methodology developed for deriving spatial distortions, the drift velocity and the e-field from uv-laser measurements. | a method to determine the electric field of liquid argon time projection chambers using a uv laser system and its application in microboone |
the theoretical motivation for exotic stable massive particles (smps) and the results of smp searches at non-collider facilities are reviewed. smps are defined such that they would be sufficiently long-lived so as to still exist in the cosmos either as big bang relics or secondary collision products, and sufficiently massive such that they are typically beyond the reach of any conceivable accelerator-based experiment. the discovery of smps would address a number of important questions in modern physics, such as the origin and composition of dark matter and the unification of the fundamental forces. this review outlines the scenarios predicting smps and the techniques used at non-collider experiments to look for smps in cosmic rays and bound in matter. the limits so far obtained on the fluxes and matter densities of smps which possess various detection-relevant properties such as electric and magnetic charge are given. | non-collider searches for stable massive particles |
first results of a cosmic-ray electron and positron spectrum from 10 gev to 3 tev is presented based upon observations with the calet instrument on the international space station starting in october, 2015. nearly a half million electron and positron events are included in the analysis. calet is an all-calorimetric instrument with total vertical thickness of 30 x0 and a fine imaging capability designed to achieve a large proton rejection and excellent energy resolution well into the tev energy region. the observed energy spectrum over 30 gev can be fit with a single power law with a spectral index of -3.152 ±0.016 (stat+syst ). possible structure observed above 100 gev requires further investigation with increased statistics and refined data analysis. | energy spectrum of cosmic-ray electron and positron from 10 gev to 3 tev observed with the calorimetric electron telescope on the international space station |
the present white paper is submitted as part of the "snowmass" process to help inform the long-term plans of the united states department of energy and the national science foundation for high-energy physics. it summarizes the science questions driving the ultra-high-energy cosmic-ray (uhecr) community and provides recommendations on the strategy to answer them in the next two decades. | ultra high energy cosmic rays the intersection of the cosmic and energy frontiers |
gamma-ray bursts (grbs) are considered as promising sources of ultra-high-energy cosmic rays (uhecrs) due to their large power output. observing a neutrino flux from grbs would offer evidence that grbs are hadronic accelerators of uhecrs. previous icecube analyses, which primarily focused on neutrinos arriving in temporal coincidence with the prompt gamma-rays, found no significant neutrino excess. the four analyses presented in this paper extend the region of interest to 14 days before and after the prompt phase, including generic extended time windows and targeted precursor searches. grbs were selected between 2011 may and 2018 october to align with the data set of candidate muon-neutrino events observed by icecube. no evidence of correlation between neutrino events and grbs was found in these analyses. limits are set to constrain the contribution of the cosmic grb population to the diffuse astrophysical neutrino flux observed by icecube. prompt neutrino emission from grbs is limited to ≲1% of the observed diffuse neutrino flux, and emission on timescales up to 104 s is constrained to 24% of the total diffuse flux. | searches for neutrinos from gamma-ray bursts using the icecube neutrino observatory |
we present low frequency array observations of the coma cluster field at 144 mhz. the cluster hosts one of the most famous radio halos, a relic, and a low surface brightness bridge. we detect new features that allow us to make a step forward in the understanding of particle acceleration in clusters. the radio halo extends for more than 2 mpc, which is the largest extent ever reported. to the northeast of the cluster, beyond the coma virial radius, we discover an arc-like radio source that could trace particles accelerated by an accretion shock. to the west of the halo, coincident with a shock detected in the x-rays, we confirm the presence of a radio front, with different spectral properties with respect to the rest of the halo. we detect a radial steepening of the radio halo spectral index between 144 and 342 mhz, at ~30' from the cluster center, that may indicate a non-constant re-acceleration time throughout the volume. we also detect a mild steepening of the spectral index toward the cluster center. for the first time, a radial change in the slope of the radio-x-ray correlation is found, and we show that such a change could indicate an increasing fraction of cosmic-ray versus thermal energy density in the cluster outskirts. finally, we investigate the origin of the emission between the relic and the source ngc 4789, and we argue that ngc 4789 could have crossed the shock originating the radio emission visible between its tail and the relic. | the coma cluster at lofar frequencies. ii. the halo, relic, and a new accretion relic |
cosmic ray probes are an emerging technology to continuously monitor soil water content at a scale significant to land surface processes. however, the application of this method is hampered by its susceptibility to the presence of aboveground biomass. here we present a simple empirical framework to account for moderation of fast neutrons by aboveground biomass in the calibration. the method extends the n0-calibration function and was developed using an extensive data set from a network of 10 cosmic ray probes located in the rur catchment, germany. the results suggest a 0.9% reduction in fast neutron intensity per 1 kg of dry aboveground biomass per m2 or per 2 kg of biomass water equivalent per m2. we successfully tested the novel vegetation correction using temporary cosmic ray probe measurements along a strong gradient in biomass due to deforestation, and using the cosmic, and the hmf method as independent soil water content retrieval algorithms. the extended n0-calibration function was able to explain 95% of the overall variability in fast neutron intensity. | an empirical vegetation correction for soil water content quantification using cosmic ray probes |
an efficient method for calculating inclusive conventional and prompt atmospheric leptons fluxes is presented. the coupled cascade equations are solved numerically by formulating them as matrix equation. the presented approach is very flexible and allows the use of different hadronic interaction models, realistic parametrizations of the primary cosmic-ray flux and the earth's atmosphere, and a detailed treatment of particle interactions and decays. the power of the developed method is illustrated by calculating lepton flux predictions for a number of different scenarios. | calculation of conventional and prompt lepton fluxes at very high energy |
composition and spectra of galactic cosmic rays (crs) are vital for studies of high-energy processes in a variety of environments and on different scales, for interpretation of γ-ray and microwave observations, for disentangling possible signatures of new phenomena, and for understanding of our local galactic neighborhood. since its launch, ams-02 has delivered outstanding-quality measurements of the spectra of $\bar{p}$ , ${e}^{\pm }$ , and nuclei: 1h-8o, 10ne, 12mg, 14si. these measurements resulted in a number of breakthroughs; however, spectra of heavier nuclei and especially low-abundance nuclei are not expected until later in the mission. meanwhile, a comparison of published ams-02 results with earlier data from heao-3-c2 indicates that heao-3-c2 data may be affected by undocumented systematic errors. utilizing such data to compensate for the lack of ams-02 measurements could result in significant errors. in this paper we show that a fraction of heao-3-c2 data match available ams-02 measurements quite well and can be used together with voyager 1 and ace-cris data to make predictions for the local interstellar spectra (lis) of nuclei that are not yet released by ams-02. we are also updating our already-published lis to provide a complete set from 1h-28ni in the energy range from 1 mev nucleon-1 to ∼100-500 tev nucleon-1, thus covering 8-9 orders of magnitude in energy. our calculations employ the galprop-helmod framework, which has proved to be a reliable tool in deriving the lis of cr $\bar{p}$ , e-, and nuclei 1h-8o. | inference of the local interstellar spectra of cosmic-ray nuclei z ≤ 28 with the galprop-helmod framework |
we discuss implications that can be obtained by searches for neutrinos from the brightest gamma-ray burst (grb), grb 221009a. we derive constraints on grb model parameters such as the cosmic-ray loading factor and dissipation radius, taking into account both neutrino spectra and effective areas. the results are strong enough to constrain proton acceleration near the photosphere, and we find that the single burst limits are comparable to those from stacking analysis. quasi-thermal neutrinos from subphotospheres and ultra-high-energy neutrinos from external shocks are not yet constrained. we show that gev-tev neutrinos originating from neutron collisions are detectable, and urge dedicated analysis on these neutrinos with deepcore and icecube as well as orca and km3net. | neutrinos from the brightest gamma-ray burst? |
this manuscript gives an up-to-date and comprehensive overview of the effects of energetic particle precipitation (epp) onto the whole atmosphere, from the lower thermosphere/mesosphere through the stratosphere and troposphere, to the surface. the paper summarizes the different sources and energies of particles, principally galactic cosmic rays (gcrs), solar energetic particles (seps) and energetic electron precipitation (eep). all the proposed mechanisms by which epp can affect the atmosphere are discussed, including chemical changes in the upper atmosphere and lower thermosphere, chemistry-dynamics feedbacks, the global electric circuit and cloud formation. the role of energetic particles in earth's atmosphere is a multi-disciplinary problem that requires expertise from a range of scientific backgrounds. to assist with this synergy, summary tables are provided, which are intended to evaluate the level of current knowledge of the effects of energetic particles on processes in the entire atmosphere. | energetic particle influence on the earth's atmosphere |
several groups have analyzed the publicly available fermi-lat data and have reported a spatially extended γ ray excess of around 1-3 gev from the region surrounding the galactic center that might originate from annihilation of dark-matter particles with a rest mass mχ∼30 -40 gev . in this work we examine the role of the diffuse galactic gamma-ray emission templates played in suppressing the gev excess. for such a purpose, we adopt in total 128 background templates that were generated by ackermann et al. [astrophys. j. 750, 3 (2012)] in the study of the fermi-lat observations of the diffuse gamma-ray emission considering the effects of cosmic rays and the interstellar medium. the possible gev excess, assumed to follow the spatial distribution of the prompt gamma rays produced in the annihilation of dark-matter particles taking a generalized navarro-frenk-white profile with an inner slope α =1.2 , has been analyzed in some regions of interest. the introduction of such an additional component centered at the galactic center is found to have improved the goodness of fit to the data significantly in all background template models regardless of whether the excess spectrum is fixed or not. our results thus suggest that the presence of a statistically significant gev excess in the inner galaxy is robust, though its spectrum depends on the diffuse galactic gamma-ray emission model adopted in the analysis. the possible physical origin of the gev excess component is discussed and, in the dark-matter model, the annihilation cross section of such particles is evaluated. | gev excess in the milky way: the role of diffuse galactic gamma-ray emission templates |
in recent years, exciting developments have taken place in the identification of the role of cosmic rays in star-forming environments. observations from radio to infrared wavelengths and theoretical modelling have shown that low-energy cosmic rays (<1 tev) play a fundamental role in shaping the chemical richness of the interstellar medium, determining the dynamical evolution of molecular clouds. in this review we summarise in a coherent picture the main results obtained by observations and by theoretical models of propagation and generation of cosmic rays, from the smallest scales of protostars and circumstellar discs, to young stellar clusters, up to galactic and extragalactic scales. we also discuss the new fields that will be explored in the near future thanks to new generation instruments, such as: cta, for the γ -ray emission from high-mass protostars; ska and precursors, for the synchrotron emission at different scales; and elt/hires, jwst, and ariel, for the impact of cosmic rays on exoplanetary atmospheres and habitability. | impact of low-energy cosmic rays on star formation |
we present a search for a neutrino signal from dark matter self-annihilations in the milky way using the icecube neutrino observatory (icecube). in 1005 days of data we found no significant excess of neutrinos over the background of neutrinos produced in atmospheric air showers from cosmic ray interactions. we derive upper limits on the velocity averaged product of the dark matter self-annihilation cross section and the relative velocity of the dark matter particles < σ _{ {a}}v> . upper limits are set for dark matter particle candidate masses ranging from 10 gev up to 1 tev while considering annihilation through multiple channels. this work sets the most stringent limit on a neutrino signal from dark matter with mass between 10 and 100 gev, with a limit of 1.18\cdot 10^{-23} { cm}^3 {s}^{-1} for 100 gev dark matter particles self-annihilating via τ ^+τ ^- to neutrinos (assuming the navarro-frenk-white dark matter halo profile). | search for neutrinos from dark matter self-annihilations in the center of the milky way with 3 years of icecube/deepcore |
galaxy groups are more than an intermediate scale between clusters and halos hosting individual galaxies, they are crucial laboratories capable of testing a range of astrophysics from how galaxies form and evolve to large scale structure (lss) statistics for cosmology. cosmological hydrodynamic simulations of groups on various scales offer an unparalleled testing ground for astrophysical theories. widely used cosmological simulations with ∼(100 mpc)3 volumes contain statistical samples of groups that provide important tests of galaxy evolution influenced by environmental processes. larger volumes capable of reproducing lss while following the redistribution of baryons by cooling and feedback are the essential tools necessary to constrain cosmological parameters. higher resolution simulations can currently model satellite interactions, the processing of cool (t≈104‑5 k) multi-phase gas, and non-thermal physics including turbulence, magnetic fields and cosmic ray transport. we review simulation results regarding the gas and stellar contents of groups, cooling flows and the relation to the central galaxy, the formation and processing of multi-phase gas, satellite interactions with the intragroup medium, and the impact of groups for cosmological parameter estimation. cosmological simulations provide evolutionarily consistent predictions of these observationally difficult-to-define objects, and have untapped potential to accurately model their gaseous, stellar and dark matter distributions. | simulating groups and the intragroup medium: the surprisingly complex and rich middle ground between clusters and galaxies |
at the core of some of the most important problems in plasma physics—from controlled nuclear fusion to the acceleration of cosmic rays—is the challenge to describe nonlinear, multiscale plasma dynamics. the development of reduced plasma models that balance between accuracy and complexity is critical to advancing theoretical comprehension and enabling holistic computational descriptions of these problems. here we report the data-driven discovery of accurate reduced plasma models, in the form of partial differential equations, directly from first-principles particle-in-cell simulations. we achieve this by using an integral formulation of sparsity-based model-discovery techniques and show that this is crucial to robustly identify the governing equations in the presence of discrete particle noise. we demonstrate the potential of this approach by recovering the fundamental hierarchy of plasma physics models—from the vlasov equation to magnetohydrodynamics. our findings show that this data-driven methodology offers a promising route to accelerate the development of reduced theoretical models of complex nonlinear plasma phenomena and to design computationally efficient algorithms for multiscale plasma simulations. | data-driven discovery of reduced plasma physics models from fully kinetic simulations |
we report on electrostatic measurements made on board the european space agency mission lisa pathfinder. detailed measurements of the charge-induced electrostatic forces exerted on free-falling test masses (tms) inside the capacitive gravitational reference sensor are the first made in a relevant environment for a space-based gravitational wave detector. employing a combination of charge control and electric-field compensation, we show that the level of charge-induced acceleration noise on a single tm can be maintained at a level close to 1.0 fm s-2 hz-1 /2 across the 0.1-100 mhz frequency band that is crucial to an observatory such as the laser interferometer space antenna (lisa). using dedicated measurements that detect these effects in the differential acceleration between the two test masses, we resolve the stochastic nature of the tm charge buildup due to interplanetary cosmic rays and the tm charge-to-force coupling through stray electric fields in the sensor. all our measurements are in good agreement with predictions based on a relatively simple electrostatic model of the lisa pathfinder instrument. | charge-induced force noise on free-falling test masses: results from lisa pathfinder |
we use adversarial network architectures together with the wasserstein distance to generate or refine simulated detector data. the data reflect two-dimensional projections of spatially distributed signal patterns with a broad spectrum of applications. as an example, we use an observatory to detect cosmic ray-induced air showers with a ground-based array of particle detectors. first we investigate a method of generating detector patterns with variable signal strengths while constraining the primary particle energy. we then present a technique to refine simulated time traces of detectors to match corresponding data distributions. with this method we demonstrate that training a deep network with refined data-like signal traces leads to a more precise energy reconstruction of data events compared to training with the originally simulated traces. | generating and refining particle detector simulations using the wasserstein distance in adversarial networks |
in the last few years the method of cosmic-ray neutron sensing (crns) has gained popularity among hydrologists, physicists, and land-surface modelers. the sensor provides continuous soil moisture data, averaged over several hectares and tens of decimeters in depth. however, the signal still may contain unidentified features of hydrological processes, and many calibration datasets are often required in order to find reliable relations between neutron intensity and water dynamics. recent insights into environmental neutrons accurately described the spatial sensitivity of the sensor and thus allowed one to quantify the contribution of individual sample locations to the crns signal. consequently, data points of calibration and validation datasets are suggested to be averaged using a more physically based weighting approach. in this work, a revised sensitivity function is used to calculate weighted averages of point data. the function is different from the simple exponential convention by the extraordinary sensitivity to the first few meters around the probe, and by dependencies on air pressure, air humidity, soil moisture, and vegetation. the approach is extensively tested at six distinct monitoring sites: two sites with multiple calibration datasets and four sites with continuous time series datasets. in all cases, the revised averaging method improved the performance of the crns products. the revised approach further helped to reveal hidden hydrological processes which otherwise remained unexplained in the data or were lost in the process of overcalibration. the presented weighting approach increases the overall accuracy of crns products and will have an impact on all their applications in agriculture, hydrology, and modeling. | improving calibration and validation of cosmic-ray neutron sensors in the light of spatial sensitivity |
we report on measurements of the all-particle cosmic ray energy spectrum and composition in the pev to eev energy range using 3 years of data from the icecube neutrino observatory. the icetop detector measures cosmic ray induced air showers on the surface of the ice, from which the energy spectrum of cosmic rays is determined by making additional assumptions about the mass composition. a separate measurement is performed when icetop data are analyzed in coincidence with the high-energy muon energy loss information from the deep in-ice icecube detector. in this measurement, both the spectrum and the mass composition of the primary cosmic rays are simultaneously reconstructed using a neural network trained on observables from both detectors. the performance and relative advantages of these two distinct analyses are discussed, including the systematic uncertainties and the dependence on the hadronic interaction models, and both all-particle spectra as well as individual spectra for elemental groups are presented. | cosmic ray spectrum and composition from pev to eev using 3 years of data from icetop and icecube |
magnetars are slowly rotating neutron stars that possess the strongest magnetic fields ($10^{14}-10^{15} \mathrm{g}$) known in the cosmos. they display a range of transient high-energy electromagnetic activity. the brightest and most energetic of these events are the gamma-ray bursts (grbs) known as magnetar giant flares (mgfs), with isotropic energy $e\approx10^{44}-10^{46} \mathrm{erg}$. there are only seven detections identified as mgfs to date: three unambiguous events occurred in our galaxy and the magellanic clouds, and the other four mgf candidates are associated with nearby star-forming galaxies. as all seven identified mgfs are bright at earth, additional weaker events remain unidentified in archival data. we conducted a search of the fermi gamma-ray burst monitor (gbm) database for candidate extragalactic mgfs and, when possible, collected localization data from the interplanetary network (ipn) satellites. our search yielded one convincing event, grb 180128a. ipn localizes this burst with ngc 253, commonly known as the sculptor galaxy. this event is the second mgf in modern astronomy to be associated with this galaxy and the first time two bursts are associated with a single galaxy outside our own. here, we detail the archival search criteria that uncovered this event and its spectral and temporal properties, which are consistent with expectations for a mgf. we also discuss the theoretical implications and finer burst structures resolved from various binning methods. our analysis provides observational evidence for an eighth identified mgf. | grb 180128a: a second magnetar giant flare candidate from the sculptor galaxy |
we introduce the prism interstellar medium (ism) model for thermochemistry and its implementation in the ramses-rtz code. the model includes a non-equilibrium primordial, metal, and molecular chemistry network for 115 species coupled to on-the-fly multifrequency radiation transport. prism accurately accounts for the dominant ism cooling and heating processes in the low-density regime (i.e. $\rho<10^5\ {\rm cm^{-3}}$), including photoheating, photoelectric heating, h$_2$ heating/cooling, cosmic-ray heating, h/he cooling, metal-line cooling, co cooling, and dust cooling (recombination and gas-grain collisions). we validate the model by comparing 1d equilibrium simulations across six dex in metallicity to existing 1d ism models in the literature. we apply prism to high-resolution (4.5 pc) isolated dwarf galaxy simulations that include state-of-the-art models for star formation and stellar feedback to take an inventory of which cooling and heating processes dominate each different gas phase of a galaxy and to understand the importance of non-equilibrium effects. we show that most of the ism gas is either close to thermal equilibrium or exhibits a slight cooling instability, while from a chemical perspective, the non-equilibrium electron fraction is often more than three times higher or lower than the equilibrium value, which impacts cooling, heating, and observable emission lines. electron enhancements are attributed to recombination lags while deficits are shown to be due to rapid cosmic-ray heating. the prism model and its coupling to ramses-rtz is applicable to a wide variety of astrophysical scenarios, from cosmological simulations to isolated giant molecular clouds, and is particularly useful for understanding how changes to ism physics impact observable quantities such as metallic emission lines. | prism: a non-equilibrium, multiphase interstellar medium model for radiation hydrodynamics simulations of galaxies |
cosmic rays are energetic charged particles from extraterrestrial sources, with the highest-energy events thought to come from extragalactic sources. their arrival is infrequent, so detection requires instruments with large collecting areas. in this work, we report the detection of an extremely energetic particle recorded by the surface detector array of the telescope array experiment. we calculate the particle’s energy as 244±29 stat. −76+51syst. exa–electron volts (~40 joules). its arrival direction points back to a void in the large-scale structure of the universe. possible explanations include a large deflection by the foreground magnetic field, an unidentified source in the local extragalactic neighborhood, or an incomplete knowledge of particle physics. | an extremely energetic cosmic ray observed by a surface detector array |
complex organic molecules (coms) have been observed not only in the hot cores surrounding low- and high-mass protostars, but also in cold dark clouds. therefore, it is interesting to understand how such species can be formed without the presence of embedded energy sources. we present new laboratory experiments on the low-temperature solid state formation of three complex molecules - methyl formate (hc(o)och3), glycolaldehyde (hc(o)ch2oh) and ethylene glycol (h2c(oh)ch2oh) - through recombination of free radicals formed via h-atom addition and abstraction reactions at different stages in the co→h2co→ch3oh hydrogenation network at 15 k. the experiments extend previous co hydrogenation studies and aim at resembling the physical-chemical conditions typical of the co freeze-out stage in dark molecular clouds, when h2co and ch3oh form by recombination of accreting co molecules and h-atoms on ice grains. we confirm that h2co, once formed through co hydrogenation, not only yields ch3oh through ongoing h-atom addition reactions, but is also subject to h-atom-induced abstraction reactions, yielding co again. in a similar way, h2co is also formed in abstraction reactions involving ch3oh. the dominant methanol h-atom abstraction product is expected to be ch2oh, while h-atom additions to h2co should at least partially proceed through ch3o intermediate radicals. the occurrence of h-atom abstraction reactions in ice mantles leads to more reactive intermediates (hco, ch3o and ch2oh) than previously thought, when assuming sequential h-atom addition reactions only. this enhances the probability to form coms through radical-radical recombination without the need of uv photolysis or cosmic rays as external triggers. | h-atom addition and abstraction reactions in mixed co, h2co and ch3oh ices - an extended view on complex organic molecule formation |
we investigate the possibility that blazars in the roma-bzcat multifrequency catalogue of blazars (5bzcat) are sources of the high-energy astrophysical neutrinos detected by the icecube neutrino observatory, as recently suggested by buson et al. although we can reproduce their ~4.5σ result, which applies to 7 yr of neutrino data in the southern sky, we find no significant correlation with 5bzcat sources when extending the search to the northern sky, where icecube is most sensitive to astrophysical signals. to further test this scenario, we use a larger sample consisting of 10 yr of neutrino data recently released by the icecube collaboration, this time finding no significant correlation in neither the southern nor the northern sky. these results suggest that the strong correlation reported by buson et al. using 5bzcat could be due to a statistical fluctuation and possibly the spatial and flux nonuniformities in the blazar sample. we perform some additional correlation tests using the more uniform, flux-limited, and blazar-dominated radio fundamental catalogue and find a ~3.2σ equivalent p-value when correlating it with the 7 yr southern neutrino sky. however, this correlation disappears completely when extending the analysis to the northern sky and when analyzing 10 yr of all-sky neutrino data. our findings support a scenario where the contribution of the whole blazar class to the icecube signal is relevant but not dominant, in agreement with most previous studies. | correlating high-energy icecube neutrinos with 5bzcat blazars and rfc sources |
multi-messenger astrophysics, a long-anticipated extension to traditional multiwavelength astronomy, has emerged over the past decade as a distinct discipline providing unique and valuable insights into the properties and processes of the physical universe. these insights arise from the inherently complementary information carried by photons, gravitational waves, neutrinos and cosmic rays about individual cosmic sources and source populations. this complementarity is the reason why multi-messenger astrophysics is much more than just the sum of the parts. in this review article, we survey the current status of multi-messenger astrophysics, highlighting some exciting results, and discussing the major follow-up questions they have raised. key recent achievements include the measurement of the spectrum of ultrahigh-energy cosmic rays out to the highest observable energies; the discovery of the diffuse high-energy neutrino background; the first direct detections of gravitational waves and the use of gravitational waves to characterize merging black holes and neutron stars in strong-field gravity; and the identification of the first joint electromagnetic plus gravitational wave and electromagnetic plus high-energy neutrino multi-messenger sources. we discuss the rationales for the next generation of multi-messenger observatories, and outline a vision of the most likely future directions for this exciting and rapidly growing field. | multi-messenger astrophysics |
context. the presence of dust in the interstellar medium has profound consequences on the chemical composition of regions where stars are forming. recent observations show that many species formed onto dust are populating the gas phase, especially in cold environments where uv- and cosmic-ray-induced photons do not account for such processes.aims: the aim of this paper is to understand and quantify the process that releases solid species into the gas phase, the so-called chemical desorption process, so that an explicit formula can be derived that can be included in astrochemical models.methods: we present a collection of experimental results of more than ten reactive systems. for each reaction, different substrates such as oxidized graphite and compact amorphous water ice were used. we derived a formula for reproducing the efficiencies of the chemical desorption process that considers the equipartition of the energy of newly formed products, followed by classical bounce on the surface. in part ii of this study we extend these results to astrophysical conditions.results: the equipartition of energy correctly describes the chemical desorption process on bare surfaces. on icy surfaces, the chemical desorption process is much less efficient, and a better description of the interaction with the surface is still needed.conclusions: we show that the mechanism that directly transforms solid species into gas phase species is efficient for many reactions. | dust as interstellar catalyst. i. quantifying the chemical desorption process |
fast radio bursts (frbs) are cosmic sources emitting millisecond-duration radio bursts. although several hundreds frbs have been discovered, their physical nature and central engine remain unclear. the variations of faraday rotation measure and dispersion measure, due to local environment, are crucial clues to understanding their physical nature. the recent observations on the rotation measure of frb 20201124a show a significant variation on a day time scale. intriguingly, the oscillation of rotation measure supports that the local contribution can change sign, which indicates the magnetic field reversal along the line of sight. here we present a physical model that explains observed characteristics of frb 20201124a and proposes that repeating signal comes from a binary system containing a magnetar and a be star with a decretion disk. when the magnetar approaches the periastron, the propagation of radio waves through the disk of the be star naturally leads to the observed varying rotation measure, depolarization, large scattering timescale, and faraday conversion. this study will prompt to search for frb signals from be/x-ray binaries. | repeating fast radio burst 20201124a originates from a magnetar/be star binary |
ams-02 has reached the sensitivity to probe canonical thermal wimps by their annihilation into antiprotons. due to the high precision of the data, uncertainties in the astrophysical background have become the most limiting factor for indirect dark matter detection. in this work we systematically quantify and—where possible—reduce uncertainties in the antiproton background. we constrain the propagation of charged cosmic rays through the combination of antiproton, b/c and positron data. cross section uncertainties are determined from a wide collection of accelerator data and are—for the first time ever—fully taken into account. this allows us to robustly constrain even subdominant dark matter signals through their spectral properties. for a standard nfw dark matter profile we are able to exclude thermal wimps with masses up to 570 gev which annihilate into bottom quarks. while we confirm a reported excess compatible with dark matter of mass around 80 gev, its local (global) significance only reaches 2.2 σ (1.1 σ) in our analysis. | a precision search for wimps with charged cosmic rays |
the arcade2 and lwa1 experiments have claimed an excess over the cosmic microwave background (cmb) at low radio frequencies. if the cosmological high-redshift contribution to this radio background is between 0.1 per cent and 22 per cent of the cmb at 1.42 ghz, it could explain the tentative edges low-band detection of the anomalously deep absorption in the 21-cm signal of neutral hydrogen. we use the upper limit on the 21-cm signal from the epoch of reionization (z = 9.1) based on 141 h of observations with lofar to evaluate the contribution of the high-redshift universe to the detected radio background. marginalizing over astrophysical properties of star-forming haloes, we find (at 95 per cent cl) that the cosmological radio background can be at most 9.6 per cent of the cmb at 1.42 ghz. this limit rules out strong contribution of the high-redshift universe to the arcade2 and lwa1 measurements. even though lofar places limit on the extra radio background, excess of 0.1-9.6 per cent over the cmb (at 1.42 ghz) is still allowed and could explain the edges low-band detection. we also constrain the thermal and ionization state of the gas at z = 9.1, and put limits on the properties of the first star-forming objects. we find that, in agreement with the limits from edges high-band data, lofar data constrain scenarios with inefficient x-ray sources, and cases where the universe was ionized by stars in massive haloes only. | tight constraints on the excess radio background at z = 9.1 from lofar |
after the identification of the gamma-ray blazar txs 0506+056 as the first compelling icecube neutrino source candidate, we perform a systematic analysis of all high-energy neutrino events satisfying the icecube realtime trigger criteria. we find one additional known gamma-ray source, the blazar gb6 j1040+0617, in spatial coincidence with a neutrino in this sample. the chance probability of this coincidence is 30% after trial correction. for the first time, we present a systematic study of the gamma-ray flux, spectral and optical variability, and multiwavelength behavior of gb6 j1040+0617 and compare it to txs 0506+056. we find that txs 0506+056 shows strong flux variability in the fermi-large area telescope gamma-ray band, being in an active state around the arrival of icecube-170922a, but in a low state during the archival icecube neutrino flare in 2014/15. in both cases the spectral shape is statistically compatible (≤2σ) with the average spectrum showing no indication of a significant relative increase of a high-energy component. while the association of gb6 j1040+0617 with the neutrino is consistent with background expectations, the source appears to be a plausible neutrino source candidate based on its energetics and multiwavelength features, namely a bright optical flare and modestly increased gamma-ray activity. finding one or two neutrinos originating from gamma-ray blazars in the given sample of high-energy neutrinos is consistent with previously derived limits of neutrino emission from gamma-ray blazars, indicating the sources of the majority of cosmic high-energy neutrinos remain unknown. | investigation of two fermi-lat gamma-ray blazars coincident with high-energy neutrinos detected by icecube |
we report the evidence for the existence of the universal, continuous turbulent cascade of velocity fluctuations with kolmogorov -5/3 slope spanning 6 orders of length scales, from $10^4$ pc down to $10^{-2}$ pc. this was achieved by applying our innovative technique of separating density and velocity fluctuations to a set of spectroscopic surveys featuring various galactic spectral lines. this unified velocity cascade involves different interstellar phases from diffuse galactic media to dense self-gravitating clouds and persists despite interstellar phase transitions. however, the turbulent density fluctuations do not show this universality as the value of the spectral slope changes in different interstellar phases. this agrees with the expectation of compressible turbulence theory and demonstrates that the density is only an indirect tracer of interstellar turbulence. we report that the density fluctuations for clouds and filaments that are preferentially parallel to magnetic fields exhibit the spectral slope of -2. the universal grand turbulent velocity cascade that is established in our paper has significant implications for key galactic physical processes, including star formation, cosmic ray transport etc. we anticipate our result to be a starting point for in vitro models of multiphase interstellar turbulence studies with a significant impact for modeling of spiral galaxies. | turbulent universal galactic kolmogorov velocity cascade over 6 decades |
super-kamiokande (sk) can search for weakly interacting massive particles (wimps) by detecting neutrinos produced from wimp annihilations occurring inside the sun. in this analysis, we include neutrino events with interaction vertices in the detector in addition to upward-going muons produced in the surrounding rock. compared to the previous result, which used the upward-going muons only, the signal acceptances for light (few-gev /c2-200 -gev /c2 ) wimps are significantly increased. we fit 3903 days of sk data to search for the contribution of neutrinos from wimp annihilation in the sun. we found no significant excess over expected atmospheric-neutrino background and the result is interpreted in terms of upper limits on wimp-nucleon elastic scattering cross sections under different assumptions about the annihilation channel. we set the current best limits on the spin-dependent wimp-proton cross section for wimp masses below 200 gev /c2 (at 10 gev /c2 , 1.49 ×10-39 cm2 for χ χ →b b ¯ and 1.31 ×10-40 cm2 for χ χ →τ+τ- annihilation channels), also ruling out some fraction of wimp candidates with spin-independent coupling in the few-gev /c2 mass range. | search for neutrinos from annihilation of captured low-mass dark matter particles in the sun by super-kamiokande |
precision cosmology is crucial to understand the different energy components in the universe and their evolution through cosmic time. gravitational wave sources are standard sirens that can accurately map out distances in the universe. together with the source redshift information, we can then probe the expansion history of the universe. we explore the capabilities of various gravitational-wave detector networks to constrain different cosmological models while employing separate waveform models for inspiral and post-merger part of the gravitational wave signal from equal mass binary neutron stars. we consider two different avenues to measure the redshift of a gravitational-wave source: first, we examine an electromagnetic measurement of the redshift via either a kilonova or a gamma ray burst detection following a binary neutron star merger (the electromagnetic counterpart method); second, we estimate the redshift from the gravitational-wave signal itself from the adiabatic tides between the component stars characterized by the tidal love number, to provide a second mass-scale and break the mass-redshift degeneracy (the counterpart-less method). we find that the electromagnetic counterpart method is better suited to measure the hubble constant while the counterpart-less method places more stringent bounds on other cosmological parameters. in the era of next-generation gravitational-wave detector networks, both methods achieve sub-percent measurement of the hubble constant $h_0$ after one year of observations. the dark matter energy density parameter $\omega_{\rm m}$ in the $\lambda$cdm model can be measured at percent-level precision using the counterpart method, whereas the counterpart-less method achieves sub-percent precision. we, however, do not find the postmerger signal to contribute significantly to these precision measurements. | cosmography with bright and love sirens |
neutrinos in the cosmic ray flux with energies near 1 eev and above are detectable with the surface detector array (sd) of the pierre auger observatory. we report here on searches through auger data from 1 january 2004 until 20 june 2013. no neutrino candidates were found, yielding a limit to the diffuse flux of ultrahigh energy neutrinos that challenges the waxman-bahcall bound predictions. neutrino identification is attempted using the broad time structure of the signals expected in the sd stations, and is efficiently done for neutrinos of all flavors interacting in the atmosphere at large zenith angles, as well as for "earth-skimming" neutrino interactions in the case of tau neutrinos. in this paper the searches for downward-going neutrinos in the zenith angle bins 60°-75° and 75°-90° as well as for upward-going neutrinos, are combined to give a single limit. the 90% c.l. single-flavor limit to the diffuse flux of ultrahigh energy neutrinos with an e-2 spectrum in the energy range 1.0 ×1 017 ev - 2.5 ×1 019 ev is eν2d nν/d eν<6.4 ×10-9 gev cm-2 s-1 sr-1 . | improved limit to the diffuse flux of ultrahigh energy neutrinos from the pierre auger observatory |
we describe a method used to calibrate the position- and time-dependent response of the microboone liquid argon time projection chamber anode wires to ionization particle energy loss. the method makes use of crossing cosmic-ray muons to partially correct anode wire signals for multiple effects as a function of time and position, including cross-connected tpc wires, space charge effects, electron attachment to impurities, diffusion, and recombination. the overall energy scale is then determined using fully-contained beam-induced muons originating and stopping in the active region of the detector. using this method, we obtain an absolute energy scale uncertainty of 2% in data. we use stopping protons to further refine the relation between the measured charge and the energy loss for highly-ionizing particles. this data-driven detector calibration improves both the measurement of total deposited energy and particle identification based on energy loss per unit length as a function of residual range. as an example, the proton selection efficiency is increased by 2% after detector calibration. | calibration of the charge and energy loss per unit length of the microboone liquid argon time projection chamber using muons and protons |
using the latest upper limits on the 21-cm power spectrum at z ≈ 9.1 from the low frequency array (lofar), we explore the regions of parameter space which are inconsistent with the data. we use 21cmmc, a monte carlo markov chain sampler of 21cmfast which directly forward models the three dimensional (3d) cosmic 21-cm signal in a fully bayesian framework. we use the astrophysical parametrization from 21cmfast, which includes mass-dependent star formation rates and ionizing escape fractions as well as soft-band x-ray luminosities to place limits on the properties of the high-z galaxies. further, we connect the disfavoured regions of parameter space with existing observational constraints on the epoch of reionization such as ultra-violet (uv) luminosity functions, background uv photoionization rate, intergalactic medium (igm) neutral fraction, and the electron scattering optical depth. we find that all models exceeding the 21-cm signal limits set by lofar at z ≈ 9.1 are excluded at ≳2σ by other probes. finally, we place limits on the igm spin temperature from lofar, disfavouring at 95 per cent confidence spin temperatures below ∼2.6 k across an igm neutral fraction range of $0.15 \lesssim \bar{x}_{\rm h\, \rm {\small i}} \lesssim 0.6$ . note, these limits are only obtained from 141 h of data in a single redshift bin. with tighter upper limits, across multiple redshift bins expected in the near future from lofar, more viable models will be ruled out. our approach demonstrates the potential of forward modelling tools such as 21cmmc in combining 21-cm observations with other high-z probes to constrain the astrophysics of galaxies. | interpreting lofar 21-cm signal upper limits at z ≈ 9.1 in the context of high-z galaxy and reionization observations |
the thermal sunyaev-zel'dovich (tsz) effect is one of the recent probes of cosmology and large-scale structures. we update constraints on cosmological parameters from galaxy clusters observed by the planck satellite in a first attempt to combine cluster number counts and the power spectrum of hot gas; we used a new value of the optical depth and, at the same time, sampling on cosmological and scaling-relation parameters. we find that in the λcdm model, the addition of a tsz power spectrum provides small improvements with respect to number counts alone, leading to the 68% c.l. constraints ωm = 0.32 ± 0.02, σ8 = 0.76 ± 0.03, and σ8(ωm/0.3)1/3 = 0.78 ± 0.03 and lowering the discrepancy with results for cosmic microwave background (cmb) primary anisotropies (updated with the new value of τ) to ≃1.8σ on σ8. we analysed extensions to the standard model, considering the effect of massive neutrinos and varying the equation of state parameter for dark energy. in the first case, we find that the addition of the tsz power spectrum helps in improving cosmological constraints with respect to number count alone results, leading to the 95% upper limit ∑ mν < 1.88 ev. for the varying dark energy equation of state scenario, we find no important improvements when adding tsz power spectrum, but still the combination of tsz probes is able to provide constraints, producing w = -1.0 ± 0.2. in all cosmological scenarios, the mass bias to reconcile cmb and tsz probes remains low at (1 - b) ≲ 0.67 as compared to estimates from weak lensing and x-ray mass estimate comparisons or numerical simulations. | constraints from thermal sunyaev-zel'dovich cluster counts and power spectrum combined with cmb |
we present novel constraints on cosmic-ray propagation in the galaxy using the recent precise measurements of proton and helium spectra from ams-02, together with preliminary ams-02 data on the antiproton over proton ratio. to explore efficiently the large (up to 11-dimensional) parameter space we employ the nested-sampling algorithm as implemented in the multinest package, interfaced with the galprop code to compute the model-predicted spectra. we use voyager proton and helium data, sampling the local interstellar spectra, to constrain the solar modulation potential. we find that the turbulence of the galactic magnetic field is well constrained, i.e., δ =0.3 0-0.02+0.03(stat )-0.04+0.10(sys ) , with uncertainties dominated by systematic effects. systematic uncertainties are determined checking the robustness of the results to the minimum rigidity cut used to fit the data (from 1 gv to 5 gv), to the propagation scenario (convection vs no convection), and to the uncertainties in the knowledge of the antiproton production cross section. convection and reacceleration are found to be degenerate and not well constrained singularly when using data above 5 gv. using data above 1 gv reacceleration is required, va=25 ±2 km /s , although this value might be significantly affected by the low-energy systematic uncertainty in the solar modulation. in a forthcoming companion paper, we investigate the constraints imposed by ams-02 measurements on lithium, boron, and carbon. | galactic cosmic-ray propagation in the light of ams-02: analysis of protons, helium, and antiprotons |
the proposed arianna-200 neutrino detector, located at sea-level on the ross ice shelf, antarctica, consists of 200 autonomous and independent detector stations separated by 1 kilometer in a uniform triangular mesh, and serves as a pathfinder mission for the future icecube-gen2 project. the primary science mission of arianna-200 is to search for sources of neutrinos with energies greater than 10^17 ev, complementing the reach of icecube. an arianna observation of a neutrino source would provide strong insight into the enigmatic sources of cosmic rays. arianna observes the radio emission from high energy neutrino interactions in the antarctic ice. among radio based concepts under current investigation, arianna-200 would uniquely survey the vast majority of the southern sky at any instant in time, and an important region of the northern sky, by virtue of its location on the surface of the ross ice shelf in antarctica. the broad sky coverage is specific to the moore's bay site, and makes arianna-200 ideally suited to contribute to the multi-messenger thrust by the us national science foundation, windows on the universe - multi-messenger astrophysics, providing capabilities to observe explosive sources from unknown directions. the arianna architecture is designed to measure the angular direction to within 3 degrees for every neutrino candidate, which too plays an important role in the pursuit of multi-messenger observations of astrophysical sources. | white paper: arianna-200 high energy neutrino telescope |
first, i benchmark existing methods of calculating subsurface 26al, 10be, and 14c production rates due to cosmic-ray muons against published calibration data from bedrock cores and mine excavations. this shows that methods based on downward propagation of the surface muon energy spectrum fit calibration data adequately. of these methods, one that uses a simpler geographic scaling method based on energy-dependent attenuation of muons in the atmosphere appears to fit calibration data better than a more complicated one that uses the results of a global particle transport model to estimate geographic variation in the surface muon energy spectrum. second, i show that although highly simplified and computationally much cheaper exponential function approximations for subsurface production rates are not globally adequate for accurate production rate estimates at arbitrary location and depth, they can be used with acceptable accuracy for many exposure-dating and erosion-rate-estimation applications. | production rate calculations for cosmic-ray-muon-produced 10be and 26al benchmarked against geological calibration data |
the scale difference between point in situ soil moisture measurements and low resolution satellite products limits the quality of any validation efforts in heterogeneous regions. cosmic ray neutron probes (crnp) could be an option to fill the scale gap between both systems, as they provide area-average soil moisture within a 150–250 m radius footprint. in this study, we evaluate differences and similarities between crnp observations, and surface soil moisture products from the advanced microwave scanning radiometer 2 (amsr2), the metop-a/b advanced scatterometer (ascat), the soil moisture active and passive (smap), the soil moisture and ocean salinity (smos), as well as simulations from the global land data assimilation system version 2 (gldas2). six crnps located on five continents have been selected as test sites: the rur catchment in germany, the cosmos sites in arizona and california (usa), and kenya, one cosmoz site in new south wales (australia), and a site in karnataka (india). standard validation scores as well as the triple collocation (tc) method identified smap to provide a high accuracy soil moisture product with low noise or uncertainties as compared to crnps. the potential of crnps for satellite soil moisture validation has been proven; however, biomass correction methods should be implemented to improve its application in regions with large vegetation dynamics. | validation of spaceborne and modelled surface soil moisture products with cosmic-ray neutron probes |
recent years have seen increased theoretical and experimental effort towards the first-ever detection of cosmic-ray antideuterons, in particular as an indirect signature of dark matter annihilation or decay. in contrast to indirect dark matter searches using positrons, antiprotons, or γ-rays, which suffer from relatively high and uncertain astrophysical backgrounds, searches with antideuterons benefit from very suppressed conventional backgrounds, offering a potential breakthrough in unexplored phase space for dark matter. this article is based on the first dedicated cosmic-ray antideuteron workshop, which was held at ucla in june 2014. it reviews broad classes of dark matter candidates that result in detectable cosmic-ray antideuteron fluxes, as well as the status and prospects of current experimental searches. the coalescence model of antideuteron production and the influence of antideuteron measurements at particle colliders are discussed. this is followed by a review of the modeling of antideuteron propagation through the magnetic fields, plasma currents, and molecular material of our galaxy, the solar system, the earth's geomagnetic field, and the atmosphere. finally, the three ongoing or planned experiments that are sensitive to cosmic-ray antideuterons, bess, ams-02, and gaps, are detailed. as cosmic-ray antideuteron detection is a rare event search, multiple experiments with orthogonal techniques and backgrounds are essential. therefore, the combination of ams-02 and gaps antideuteron searches is highly desirable. many theoretical and experimental groups have contributed to these studies over the last decade, this review aims to provide the first coherent discussion of the relevant dark matter theories that antideuterons probe, the challenges to predictions and interpretations of antideuteron signals, and the experimental efforts toward cosmic antideuteron detection. | review of the theoretical and experimental status of dark matter identification with cosmic-ray antideuterons |
we present predictions for the prompt-neutrino flux arising from the decay of charmed mesons and baryons produced by the interactions of high-energy cosmic rays in the earth's atmosphere, making use of a qcd approach on the basis of the general-mass variable-flavor-number scheme for the description of charm hadroproduction at nlo, complemented by a consistent set of fragmentation functions. we compare the theoretical results to those already obtained by our and other groups with different theoretical approaches. we provide comparisons with the experimental results obtained by the icecube collaboration in two different analyses and we discuss the implications for parton distribution functions. | prompt neutrinos from atmospheric charm in the general-mass variable-flavor-number scheme |
we explore the observational implications of a model in which primordial black holes (pbhs) with a broad birth mass function ranging in mass from a fraction of a solar mass to ~106 m ⊙, consistent with current observational limits, constitute the dark matter (dm) component in the universe. the formation and evolution of dark matter and baryonic matter in this pbh-λ cold dark matter (λcdm) universe are presented. in this picture, pbh-dm mini-halos collapse earlier than in standard λcdm, baryons cool to form stars at z ~ 15-20, and growing pbhs at these early epochs start to accrete through bondi capture. the volume emissivity of these sources peaks at z ~ 20 and rapidly fades at lower redshifts. as a consequence, pbh dm could also provide a channel to make early black hole seeds and naturally account for the origin of an underlying dm halo-host galaxy and central black hole connection that manifests as the m bh-σ correlation. to estimate the luminosity function and contribution to integrated emission power spectrum from these high-redshift pbh-dm halos, we develop a halo occupation distribution model. in addition to tracing the star formation and reionization history, it permits us to evaluate the cosmic infrared and x-ray backgrounds. we find that accretion onto pbhs/active galactic nuclei successfully accounts for the detected backgrounds and their cross-correlation, with the inclusion of an additional ir stellar emission component. detection of the deep ir source count distribution by the james webb space telescope could reveal the existence of this population of high-redshift star-forming and accreting pbh dm. | exploring the high-redshift pbh-λcdm universe: early black hole seeding, the first stars and cosmic radiation backgrounds |
the physics of cosmic ray (cr) transport remains a key uncertainty in assessing whether crs can produce galaxy-scale outflows consistent with observations. in this paper, we elucidate the physics of cr-driven galactic winds for cr transport dominated by diffusion. a companion paper considers cr streaming. we use analytic estimates validated by time-dependent spherically symmetric simulations to derive expressions for the mass-loss rate, momentum flux, and speed of cr-driven galactic winds, suitable for cosmological-scale or semi-analytic models of galaxy formation. for cr diffusion coefficients κ ≳ r0ci, where r0 is the base radius of the wind and ci is the isothermal gas sound speed, the asymptotic wind energy flux is comparable to that supplied to crs, and the outflow rapidly accelerates to supersonic speeds. by contrast, for κ ≲ r0ci, cr-driven winds accelerate more slowly and lose most of their energy to gravity, a cr analogue of photon-tired stellar winds. given cr diffusion coefficients estimated using fermi gamma-ray observations of pion decay, we predict mass-loss rates in cr-driven galactic winds of the order of the star formation rate for dwarf and disc galaxies. the dwarf galaxy mass-loss rates are small compared to the mass-loadings needed to reconcile the stellar and dark matter halo mass functions. for nuclear starbursts (e.g. m82, arp 220), cr diffusion and pion losses suppress the cr pressure in the galaxy and the strength of cr-driven winds. we discuss the implications of our results for interpreting observations of galactic winds and for the role of crs in galaxy formation. | the physics of galactic winds driven by cosmic rays i: diffusion |
phenomenological models of cosmic ray (cr) transport in the milky way can reproduce a wide range of observations assuming that crs scatter off of magnetic-field fluctuations with spectrum ∝ k-δ and δ ~ [1.4, 1.67]. we study the extent to which such models can be reconciled with current microphysical theories of cr transport, specifically self-confinement due to the streaming instability and/or extrinsic turbulence due to a cascade of magnetohydrodynamic (mhd) fast modes. we first review why it is that on their own neither theory is compatible with observations. we then highlight that cr transport is a strong function of local plasma conditions in the multiphase interstellar medium, and may be diffusive due to turbulence in some regions and streaming due to self-confinement in others. a multiphase combination of scattering mechanisms can in principle reproduce the main trends in the proton spectrum and the boron-to-carbon ratio. however, models with a combination of scattering by self-excited waves and fast-mode turbulence require significant fine-tuning due to fast-mode damping, unlike phenomenological models that assume undamped kolmogorov turbulence. the assumption that fast modes follow a weak cascade is also not well justified theoretically, as the weak cascade is suppressed by wave steepening and weak-shock dissipation even in subsonic turbulence. these issues suggest that there may be a significant theoretical gap in our understanding of mhd turbulence. we discuss a few topics at the frontier of mhd turbulence theory that bear on this (possible) gap and that may be relevant for cr scattering. | reconciling cosmic ray transport theory with phenomenological models motivated by milky-way data |
understanding the physical mechanisms that control galaxy formation is a fundamental challenge in contemporary astrophysics. recent advances in the field of astrophysical feedback strongly suggest that cosmic rays (crs) may be crucially important for our understanding of cosmological galaxy formation and evolution. the appealing features of crs are their relatively long cooling times and relatively strong dynamical coupling to the gas. in galaxies, crs can be close to equipartition with the thermal, magnetic, and turbulent energy density in the interstellar medium, and can be dynamically very important in driving large-scale galactic winds. similarly, crs may provide a significant contribution to the pressure in the circumgalactic medium. in galaxy clusters, crs may play a key role in addressing the classic cooling flow problem by facilitating efficient heating of the intracluster medium and preventing excessive star formation. overall, the underlying physics of cr interactions with plasmas exhibit broad parallels across the entire range of scales characteristic of the interstellar, circumgalactic, and intracluster media. here we present a review of the state-of-the-art of this field and provide a pedagogical introduction to cosmic ray plasma physics, including the physics of wave-particle interactions, acceleration processes, cr spatial and spectral transport, and important cooling processes. the field is ripe for discovery and will remain the subject of intense theoretical, computational, and observational research over the next decade with profound implications for the interpretation of the observations of stellar and supermassive black hole feedback spanning the entire width of the electromagnetic spectrum and multi-messenger data. | cosmic ray feedback in galaxies and galaxy clusters |
a galaxy cluster acts as a cosmic telescope over background galaxies but also as a cosmic microscope magnifying the imperfections of the lens. the diverging magnification of lensing caustics enhances the microlensing effect of substructure present within the lensing mass. fine-scale structure can be accessed as a moving background source brightens and disappears when crossing these caustics. the recent discovery of a distant lensed star near the einstein radius of the galaxy cluster macsj1149.5+2223 allows a rare opportunity to reach subsolar-mass microlensing through a supercritical column of cluster matter. here we compare these observations with high-resolution ray-tracing simulations that include stellar microlensing set by the observed intracluster starlight and also primordial black holes that may be responsible for the recently observed ligo events. we explore different scenarios with microlenses from the intracluster medium and black holes, including primordial ones, and examine strategies to exploit these unique alignments. we find that the best constraints on the fraction of compact dark matter (dm) in the small-mass regime can be obtained in regions of the cluster where the intracluster medium plays a negligible role. this new lensing phenomenon should be widespread and can be detected within modest-redshift lensed galaxies so that the luminosity distance is not prohibitive for detecting individual magnified stars. high-cadence hubble space telescope monitoring of several such optimal arcs will be rewarded by an unprecedented mass spectrum of compact objects that can contribute to uncovering the nature of dm. | dark matter under the microscope: constraining compact dark matter with caustic crossing events |
the origin of two large peaks in the atmospheric radiocarbon (14c) concentration at ad 774/5 and 993/4 is still debated. there is consensus, however, that these features can only be explained by an increase in the atmospheric 14c production rate due to an extraterrestrial event. here we provide evidence that these peaks were most likely produced by extreme solar events, based on several new annually resolved 10be measurements from both arctic and antarctic ice cores. using ice core 36cl data in pair with 10be, we further show that these solar events were characterized by a very hard energy spectrum with high fluxes of solar protons with energy above 100 mev. these results imply that the larger of the two events (ad 774/5) was at least five times stronger than any instrumentally recorded solar event. our findings highlight the importance of studying the possibility of severe solar energetic particle events. | multiradionuclide evidence for the solar origin of the cosmic-ray events of ᴀᴅ 774/5 and 993/4 |
the origins of high-energy astrophysical neutrinos remain a mystery despite extensive searches for their sources. we present constraints from seven years of icecube neutrino observatory muon data on the neutrino flux coming from the galactic plane. this flux is expected from cosmic-ray interactions with the interstellar medium or near localized sources. two methods were developed to test for a spatially extended flux from the entire plane, both of which are maximum likelihood fits but with different signal and background modeling techniques. we consider three templates for galactic neutrino emission based primarily on gamma-ray observations and models that cover a wide range of possibilities. based on these templates and in the benchmark case of an unbroken {e}-2.5 power-law energy spectrum, we set 90% confidence level upper limits, constraining the possible galactic contribution to the diffuse neutrino flux to be relatively small, less than 14% of the flux reported in aartsen et al. above 1 tev. a stacking method is also used to test catalogs of known high-energy galactic gamma-ray sources. | constraints on galactic neutrino emission with seven years of icecube data |
we present a detailed study of the large-scale anisotropies of cosmic rays with energies above 4 eev measured using the pierre auger observatory. for the energy bins [4, 8] eev and e ≥ 8 eev, the most significant signal is a dipolar modulation in r.a. at energies above 8 eev, as previously reported. in this paper we further scrutinize the highest-energy bin by splitting it into three energy ranges. we find that the amplitude of the dipole increases with energy above 4 eev. the growth can be fitted with a power law with index β = 0.79 ± 0.19. the directions of the dipoles are consistent with an extragalactic origin of these anisotropies at all the energies considered. additionally, we have estimated the quadrupolar components of the anisotropy: they are not statistically significant. we discuss the results in the context of the predictions from different models for the distribution of ultrahigh-energy sources and cosmic magnetic fields. | large-scale cosmic-ray anisotropies above 4 eev measured by the pierre auger observatory |
we update predictions for lepton fluxes from the hadroproduction of charm quarks in the scattering of primary cosmic rays with the earth's atmosphere. the calculation of charm-pair hadroproduction applies the latest results from perturbative qcd through next-to-next-to-leading order and modern parton distributions, together with estimates on various sources of uncertainties. our predictions for the lepton fluxes turn out to be compatible, within the uncertainty band, with recent results in the literature. however, by taking into account contributions neglected in previous works, our total uncertainties are much larger. the predictions are crucial for the interpretation of results from neutrino experiments like icecube, when disentangling signals of neutrinos of astrophysical origin from the atmospheric background. | lepton fluxes from atmospheric charm revisited |
we discuss baryogenesis in scenarios where the universe is reheated to temperatures ≲100 gev by the decay of long-lived massive particles into energetic sm particles. before its thermalization, the center-of-mass energy in collisions between such a particle and a particle from the ambient plasma can be higher than the typical sphaleron mass, even if the temperature of the plasma itself is much lower. optimistic estimates for the high energy enhancement of the sphaleron cross section suggest that successful baryogenesis is possible for reheating temperatures as low as 0.1-1 gev. with a simple extension of the sm, sufficient baryon production should be achieved by enhancing the w-boson coupling even if more pessimistic results for the sphaleron rate are correct. in both cases, if the two to many sphaleron reaction is significant enough for the baryogenesis, the same process can be probed in collider and cosmic-ray experiments. complementing such experimental tests, a significantly improved understanding of the two to many sphaleron rate in the nonperturbative coupling regime is mandatory to determine whether this scenario is viable. finally, we briefly discuss the possible origin of the required c p violation. | high energy sphalerons for baryogenesis at low temperatures |
opportunities for searches for phenomena beyond the standard model (bsm) using heavy-ions beams at high energies are outlined. different bsm searches proposed in the last years in collisions of heavy ions, mostly at the large hadron collider, are summarized. a few concrete selected cases are reviewed including searches for axion-like particles, anomalous τ electromagnetic moments, magnetic monopoles, and dark photons. expectations for the achievable sensitivities of these searches in the coming years are given. studies of cp violation in hot and dense qcd matter and connections to ultrahigh-energy cosmic rays physics are also mentioned. | opportunities for new physics searches with heavy ions at colliders |
intriguing signals with excesses over expected backgrounds have been observed in many astrophysical and terrestrial settings, which could potentially have a dark matter origin. astrophysical excesses include the galactic center gev gamma-ray excess detected by the fermi gamma-ray space telescope, the ams antiproton and positron excesses, and the 511 and 3.5 kev x-ray lines. direct detection excesses include the dama/libra annual modulation signal, the xenon1t excess, and low-threshold excesses in solid state detectors. we discuss avenues to resolve these excesses, with actions the field can take over the next several years. | snowmass2021 cosmic frontier white paper: puzzling excesses in dark matter searches and how to resolve them |
this white paper discusses the current landscape and prospects for experiments sensitive to particle dark matter processes producing photons and cosmic rays. much of the gamma-ray sky remains unexplored on a level of sensitivity that would enable the discovery of a dark matter signal. currently operating gev-tev observatories, such as fermi-lat, atmospheric cherenkov telescopes, and water cherenkov detector arrays continue to target several promising dark matter-rich environments within and beyond the galaxy. soon, several new experiments will continue to explore, with increased sensitivity, especially extended targets in the sky. this paper reviews the several near-term and longer-term plans for gamma-ray observatories, from mev energies up to hundreds of tev. similarly, the x-ray sky has been and continues to be monitored by decade-old observatories. upcoming telescopes will further bolster searches and allow new discovery space for lines from, e.g., sterile neutrinos and axion-photon conversion. furthermore, this overview discusses currently operating cosmic-ray probes and the landscape of future experiments that will clarify existing persistent anomalies in cosmic radiation and spearhead possible new discoveries. finally, the article closes with a discussion of necessary cross section measurements that need to be conducted at colliders to reduce substantial uncertainties in interpreting photon and cosmic-ray measurements in space. | snowmass2021 cosmic frontier: the landscape of cosmic-ray and high-energy photon probes of particle dark matter |
sub-gev dark matter particles can annihilate or decay producing e ± pairs which upscatter the low-energy photon fields in the galaxy and generate an x-ray emission (via the inverse compton effect). using x-ray data from xmm-newton, integral, nustar and suzaku, we derive new constraints on this class of dark matter (dm). in the annihilation case, our new bounds are the strongest available for dm masses above 180 mev, reaching <σv> ≲ 10-28 cm3/s for m dm ≃ 1 gev. in the decay case, our bounds are the strongest to date over a large fraction of the considered mass range, constraining τ ≳ 1028 s for m dm ≃ 1 gev and improving by up to 3 orders of magnitude upon existing limits. | putting all the x in one basket: updated x-ray constraints on sub-gev dark matter |
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