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bismuth germanium oxide (bi4ge3o12, bgo) scintillation crystals are widely used as detectors in the fields of particle physics and astrophysics due to their high density, and thus higher efficiency for gamma-ray detection. owing to their good chemical stability, they can be used in any environment. for rare-event searc... | a method to measure the quenching factor for recoil energy of oxygen in bismuth germanium oxide scintillators |
proper interpretation of past, current, and future data on lepton-nucleus reactions requires a clear separation between quantum electrodynamics and strong interaction effects inside the nucleus. first studies of qed in-medium lepton dynamics have set a theoretical framework to derive electron-nucleus and (anti)neutrino... | broadening of particle distributions in electron-, neutrino-, and antineutrino-nucleus scattering from qed interactions |
since many of the dark-sector particles interact with standard model (sm) particles in multiple ways, they can appear in experimental facilities where sm particles appear in abundance. in this study, we explore a particular class of longer-lived mediators that are produced from photons, charged mesons, neutral mesons, ... | longer-lived mediators from charged mesons and photons at neutrino experiments |
we investigate the inelastic signatures of dark matter-nucleus interactions, explicitly focusing on the ramifications of polarization, dark matter splitting, and the migdal effect. direct detection experiments, crucial for testing the existence of dark matter, encounter formidable obstacles such as indomitable neutrino... | probing inelastic signatures of dark matter detection via polarized nucleus |
in this work, we introduce the theoretical framework of the phonon-mediated migdal effect for neutrino-nucleus scattering in semiconductors, considering both the standard model and the presence of the neutrino magnetic moment. we calculate the rate of electron excitation resulting from the migdal effect and observe a s... | migdal effect of phonon-mediated neutrino nucleus scattering in semiconductor detectors |
we investigate the enhancement of dark sector particle production within the scattering dominant regime. these particles typically exhibit a slight mixing with standard model particles through various portals, allowing for their generation through in-medium oscillation from standard model particle sources. our analysis... | amplifying non-resonant production of dark sector particles in scattering dominance regime |
in certain conditions a macroscopic quantum-mechanical scattering may occur, which may lead to a coherent cross-section on a macroscopic scale in a monocrystal. the conditions are satisfied by neutrinos, but not satisfied by other projectiles, with a higher cross-section. this may explain weber-type experiments of neut... | macroscopic quantum-mechanical scattering |
there are profound connections between neutrino physics and nuclear experiments. exceptionally precise measurements of single and double beta-decay spectra illuminate the scale and nature of neutrino mass and may finally answer the question of whether neutrinos are their own antimatter counterparts. neutrino-nucleus sc... | experimental neutrino physics in a nuclear landscape |
the icecube neutrino observatory deployed 5160 digital optical modules (doms) in a cubic kilometer of deep, glacial ice below the geographic south pole, recording the cherenkov light of passing charged particles. while the optical properties of the undisturbed ice are nowadays well understood, the properties of the ref... | a model independent parametrization of the optical properties of the refrozen icecube drill holes |
solar neutrino measurements have recently reached a level of sensitivity such that cno fluxes can now be experimentally determined. while these first measurements are still only sensitive to the higher energy neutrinos resulting from the β+ decays of 15o produced by the 14n(p ,γ )15o reaction, future measurements will ... | absolute cross section of the 12c(p ,γ )13n reaction |
a portable monoenergetic 24 kev neutron source based on the 124sb-9be photoneutron reaction and an iron filter has been constructed and characterized. the coincidence of the neutron energy from sbbe and the low interaction cross-section with iron (mean free path up to 29 cm) makes pure iron specially suited to shield a... | a portable and monoenergetic 24 kev neutron source based on 124sb-9be photoneutrons and an iron filter |
introduction: the recent discovery of coherent elastic neutrino-nucleus scattering (cevns) has created new opportunities to detect and study neutrinos. the interaction cross section in cevns scales quadratically with the number of neutrons, making heavy-nuclei targets such as active lead-based detectors ideal. lead per... | lead perovskites as ceνns detectors |
the elastic and inelastic neutral current ν (ν ¯) scattering off the polarized nucleon is discussed. the inelastic scattering concerns the single-pion production process. we show that the spin asymmetries' measurement can help to distinguish between neutrino and antineutrino neutral current scattering processes. the sp... | neutral current neutrino and antineutrino scattering off the polarized nucleon |
inverse muon decay (νμe-→νeμ- ) is a promising tool to constrain neutrino fluxes with energies eν≥10.9 gev . radiative corrections introduce percent-level distortions to energy spectra of outgoing muons and depend on experimental details. in this paper, we calculate radiative corrections to the scattering processes νμe... | radiative corrections to inverse muon decay for accelerator neutrinos |
we present an analysis on the sensitivity to the active-sterile neutrino mixing with germanium (ge) and silicon (si) detectors in the context of the proposed coherent elastic neutrino-nucleus experiment in india. the study has been carried out with 3 (active )+1 (sterile ) neutrino oscillation model. it is observed tha... | sterile neutrino searches with reactor antineutrinos using coherent neutrino-nucleus scattering experiments |
at leading order in weak and electromagnetic couplings, cross sections for (anti)neutrino-nucleon elastic scattering are determined by vector and axial-vector form factors. radiative corrections in the standard model, and potential new physics contributions beyond the standard model, generate additional operators with ... | invariant amplitudes, unpolarized cross sections, and polarization asymmetries in neutrino-nucleon elastic scattering |
complete monte carlo (mc) simulation of a neutrino experiment typically involves the lengthy and cpu-intensive process of integrating models of incoming neutrino fluxes, event generation, and detector setup. we describe a fast, geometry-independent, genie-based system known as nusmear which provides preliminary simulat... | nusmear: fast simulation of energy smearing and angular smearing for neutrino-nucleon scattering events in the genie event generator |
the detection of coherent elastic neutrino-nucleus scattering (ce$\nu$ns) opens new possibilities for neutrino physics within and beyond the standard model. following the initial discovery in 2017, several experimental attempts have emerged allowing this reaction channel to be studied with the full repertoire of modern... | coherent elastic neutrino-nucleus scattering -- first constraints/observations and future potential |
we suggest an empirical rule-of-thumb for calculating the cross sections of charged-current quasielastic (ccqe) and ccqe-like interactions of neutrinos and antineutrinos with nuclei. the approach is based on the standard relativistic fermi-gas model and on the notion of neutrino energy dependent axial-vector mass of th... | running axial mass of the nucleon as a phenomenological tool for calculating qe neutrino-nucleus cross sections |
we discuss cross sections for $\nu_{\tau}$ and ${\overline \nu}_{\tau}$ production from the direct $d_s^{\pm} \to \nu_{\tau}/{\overline \nu}_{\tau}$ and chain $d_s^{\pm} \to \tau^+/\tau^- \to \nu_{\tau}/{\overline \nu}_{\tau}$ decays in $p\!+^{96}\!\mathrm{mo}$ scattering with proton beam $e_{\mathrm{lab}}$ = 400 gev \... | production of \\nu_{\\tau} neutrinos and {/line \\nu}_{\\tau} antineutrinos - elaborate calculation for a fixed target experiment ship |
the public galprop code gives a fully numerical solution for the spectrum of cosmic rays propagating through a linear galactic wind directed outward from the galactic plane in the framework of a cylindrical diffusion model. alternatively, for the linear galactic wind case, we present a semianalytical solution of the tw... | diffusion of cosmic antiprotons generated throughout the dark matter halo-a semianalytical solution for a linear galactic wind model |
we consider anisotropic diffusion of galactic cosmic rays in the galactic magnetic field, using the jansson-farrar model for the field. in this paper we investigate the influence of source position on the cosmic ray flux at earth in two ways: [1] by considering the contribution from cosmic ray sources located in differ... | the contribution of nearby supernova remnants on the cosmic ray flux at earth |
the origin and nature of the ultrahigh energy cosmic rays (uhecrs) are still unknown. however, great progress has been achieved in past years due to the observations performed by the pierre auger observatory and telescope array. above $10^{18}$ ev the observed energy spectrum presents two features: a hardening of the s... | implications of gamma-ray and neutrino observations on source models of ultrahigh energy cosmic rays |
using a setup for testing a prototype for a satellite-borne cosmic-ray ion detector, we have operated a stack of scintillator and silicon detectors on top of the princess sirindhorn neutron monitor (psnm), an nm64 detector at 2560-m altitude at doi inthanon, thailand (18.59∘n, 98.49∘e). monte carlo simulations have ind... | measurement and simulation of the neutron propagation time distribution inside a neutron monitor |
cosmic rays are nowadays a crucial tool to study the astrophysics of extreme objects in the universe, the cosmic environmental plasma (both galactic and extra-galactic), the physics of nuclear interactions or the properties of elementary particles at very high energies and even cosmological problems such as the dark ma... | cosmic-ray propagation and production of secondary particles in the galaxy |
at very high energies (vhe), the emission of $\gamma$ rays is dominated by discrete sources. due to the limited resolution and sensitivity of current-generation instruments, only a small fraction of the total galactic population of vhe $\gamma$-ray sources has been detected significantly. the larger part of the populat... | exploring the population of galactic very-high-energy gamma-ray sources |
we study the effects of drift motions and the advection by a galactic wind on the propagation of cosmic rays in the galaxy. we employ a simplified magnetic field model, based on (and similar to) the jansson-farrar model for the galactic magnetic field. diffusion is allowed to be anisotropic. the relevant equations are ... | the effects of drift and winds on the propagation of galactic cosmic rays |
cosmic rays (crs) are an integral component of the interstellar medium, producing broadband emission while interacting with other galactic matter components like the interstellar gas or magnetic fields. in addition to observations, numerical simulations of cr propagation through the galaxy help to increase the level of... | cosmic-ray propagation under consideration of a spatially resolved source distribution |
high-velocity clouds moving towards the disc will reach the galactic plane and will inevitably collide with the disc. in these collisions, a system of two shocks is produced, one propagating through the disc and the other develops within the cloud. the shocks produced within the clouds in these interactions have veloci... | gamma-rays from reaccelerated cosmic rays in high-velocity clouds colliding with the galactic disc |
the dark matter particle explorer (dampe) has been undergoing a stable on-orbit operation for more than 6 yr and acquired observations of over 11 billion events. a better understanding of the overall radiation environment of the dampe orbit is crucial for both simulation data production and flight data analysis. in thi... | a study on monte carlo simulation of the radiation environment above gev at the dampe orbit |
cosmic rays are charged particles accelerated in supernova shocks, exerting pressure on gas and heating it. as these effects can alter both the star formation and the multiphase structure of galaxies, they are likely an important feedback channel in galaxy evolution. using radiation-magneto-hydrodynamics simulations of... | the role of cosmic ray feedback in the evolution of galaxies |
the center of the milky way is a prime site to search for signals of dark matter (dm) annihilation due to its proximity and expected high concentration of dm. the amplification of the dispersion velocity of dm particles in the galactic center (gc), caused by baryonic contraction and feedback, makes this particular regi... | tev gamma-ray sensitivity to velocity-dependent dark matter models in the galactic center |
m-dwarf stars have been preferred targets of exoplanet search due to the favourable parameters of the system for remote characterisation. however, planets in the habitable zones of these stars are expecting to experience intense radiation. we present the increase project (influence of strong stellar particle events and... | effect of energetic particles on the atmosphere of terrestrial exoplanets |
detailed measurements of the spectral structure of cosmic-ray electrons and positrons from 10.6 gev to 7.5 tev are presented from over 7 years of observations with the calorimetric electron telescope (calet) on the international space station. the instrument, consisting of a charge detector, an imaging calorimeter, and... | direct measurement of the spectral structure of cosmic-ray electrons+positrons in the tev region with calet on the international space station |
electron and positron fluxes in cosmic rays are currently measured with unprecedented precision by ams-02 up to tev energies, and represent unique probes for the local properties of our galaxy. the interpretation of their spectra is at present still debated, especially for the excess of positrons above 10 gev. the hypo... | constraints on the positron emission from pulsar populations with ams-02 data |
observations of oh+ are used to infer the interstellar cosmic ray ionization rate in diffuse atomic clouds, thereby constraining the propagation of cosmic rays through and the shielding by interstellar clouds, as well as the low energy cosmic ray spectrum. in regions where the h2-to-h number density ratio is low, disso... | dissociative recombination of rotationally cold oh+ and its implications for the cosmic ray ionization rate in diffuse clouds |
when high-energy particles originating from space penetrate the atmosphere, they may interact with atoms and molecules, initiating air showers composed of secondary and tertiary particles propagating towards the ground. they can cause ionization of the atmosphere and contribute to the radiation dose at low altitudes. t... | the atmospheric influence on cosmic-ray-induced ionization and absorbed dose rates |
in the standard picture of cosmic ray transport the propagation of charged cosmic rays through turbulent magnetic fields is described as a random walk with cosmic rays scattering on magnetic field turbulence. this is in good agreement with the highly isotropic cosmic ray arrival directions as this diffusion process eff... | cosmic ray small-scale anisotropies in slab turbulence |
with tantalizing evidence of the recent e-rosita mission, re-discovering very soft x-rays and extreme-ultraviolet (euv) radiation from a cluster of galaxies or its environment, the question of the origin of cluster euv excess is revisited in this work. it will be shown that the gas temperature, density, and frozen-in m... | a model of euv emission from clusters of galaxies |
cosmic rays represent one of the most important energy transformation processes of the universe. they bring information about the surrounding universe, our galaxy, and very probably also the extragalactic space, at least at the highest observed energies. more than one century after their discovery, we have no definitiv... | measurement of energy spectrum and elemental composition of pev cosmic rays: open problems and prospects |
the alpha magnetic spectrometer (ams) is a cosmic ray detector operating onboard the international space station since may 2011 conducting a unique, long-duration mission of fundamental physics research in space. the physics objectives include the precise studies of the origin of dark matter, antimatter, and cosmic ray... | the ams experiment on the international space station |
recent studies have indicated that cosmic ray acceleration by a first-order fermi process in magnetic reconnection current sheets can be efficient enough in the surrounds of compact sources. in this work, we discuss this acceleration mechanism operating in the core region of galactic black hole binaries (or microquasar... | a magnetic reconnection model for explaining the multiwavelength emission of the microquasars cyg x-1 and cyg x-3 |
recently, active galactic nuclei (agn) have been proposed as "standardizable candles," thanks to an observed nonlinear relation between their x-ray and optical-ultraviolet (uv) luminosities, which provides an independent measurement of their distances. in this paper, we use these observables for the first time to estim... | testing f (r ) gravity models with quasar x-ray and uv fluxes |
the study of cosmic expansion history and the late time cosmic acceleration from observational data depends on the nuisance parameters associated with the data. for example, the absolute peak magnitude of type ia supernova associated with the type ia supernova observations and the comoving sound horizon at the baryon d... | minimal model-dependent constraints on cosmological nuisance parameters and cosmic curvature from combinations of cosmological data |
we probed the dynamical mass profiles of ten galaxy clusters from the highest x-ray flux galaxy cluster sample (hiflugcs) using galaxy kinematics. we numerically solved the spherical jeans equation and parameterize the dynamical mass profile and the galaxy velocity anisotropy profile using two general functions to ensu... | measuring galaxy cluster mass profiles into the low-acceleration regime with galaxy kinematics |
radio relics are synchrotron emission found on the periphery of galaxy clusters. from the position and the morphology, it is often believed that the relics are generated by cosmic-ray (cr) electrons accelerated at shocks through a diffusive shock acceleration (dsa) mechanism. however, some radio relics have harder spec... | turbulent cosmic-ray reacceleration at radio relics and halos in clusters of galaxies |
spatially compact stellar profiles and old stellar populations have established compact elliptical galaxies (cegs) as local analogs of the high-redshift “red nuggets” thought to represent the progenitors of today’s early-type galaxies (etgs). to address whether the structure of the dark matter (dm) halo in a ceg also r... | the extremely high dark matter halo concentration of the relic compact elliptical galaxy mrk 1216 |
next-generation optical imaging surveys will revolutionize the observations of weak gravitational lensing by galaxy clusters and provide stringent constraints on growth of structure and cosmic acceleration. in these experiments, accurate modelling of covariance matrices of cluster weak lensing plays the key role in obt... | covariance matrices for galaxy cluster weak lensing: from virial regime to uncorrelated large-scale structure |
the intracluster medium (icm) is expected to experience on average about three passages of weak shocks with low sonic mach numbers, m ≲ 3, during the formation of galaxy clusters. both protons and electrons could be accelerated to become high energy cosmic rays (crs) at such icm shocks via diffusive shock acceleration ... | diffusive shock acceleration by multiple weak shocks |
we report a discovery of a double radio relic in the cluster merger zwcl1447.2+2619 (z = 0.376) with ugmrt observations at 420 mhz and 700 mhz. the linear sizes of the northern and southern relics are ~0.3 mpc and ~1.2 mpc, respectively, which is consistent with the theoretical expectation that a larger relic is produc... | discovery of a double radio relic in zwcl1447.2+2619: a rare testbed for shock-acceleration models with a peculiar surface-brightness ratio |
massive stars blow powerful winds and eventually explode as supernovae. by doing so, they inject energy and momentum in the circumstellar medium, which is pushed away from the star and piles up to form a dense and expanding shell of gas. the effect is larger when many massive stars are grouped together in bound cluster... | cosmic rays from star clusters |
following evidence for an east-west elongated virial ring around the coma galaxy cluster in a ∼220 gev veritas mosaic, we search for corresponding signatures in >gev γ-rays from fermi-large area telescope (lat), and in soft, ∼0.1 kev x-rays from rosat. for the ring elongation and orientation inferred from veritas, w... | evidence for an x-ray to gamma-ray virial shock signal from the coma cluster |
we use 1d and 3d two-fluid cosmic ray (cr) hydrodynamic simulations to investigate the role of crs in the vicinity of a compact young star cluster. we model a self-gravitating cloud (density profile ρ∝r-1), include important thermal and non-thermal processes, and explore two different cr injection scenarios. we show th... | constraining cosmic ray acceleration in young star clusters using multi-wavelength observations |
it has often been thought that the northern radio relic in the galaxy cluster ciza j2242.8+5301 (the "sausage" cluster) is associated with cosmic ray (cr) electrons that are accelerated at a shock through the diffusive shock acceleration (dsa) mechanism. however, recent radio observations have shown that the radio spec... | turbulent cosmic ray reacceleration and the curved radio spectrum of the radio relic in the sausage cluster |
we propose semi-analytic models for the electron momentum distribution in weak shocks that accounts for both in situ acceleration and re-acceleration through diffusive shock acceleration (dsa). in the former case, a small fraction of incoming electrons is assumed to be reflected at the shock ramp and pre-accelerated to... | semi-analytic models for electron acceleration in weak icm shocks |
observations of diffuse radio emission in galaxy clusters indicate that cosmic-ray electrons are accelerated on ∼ mpc scales. however, protons appear to be accelerated less efficiently since their associated hadronic γ-ray emission has not yet been detected. inspired by recent particle-in-cell simulations, we study the... | studying the effect of shock obliquity on the γ-ray and diffuse radio emission in galaxy clusters |
while it is well known that cosmic rays (crs) can gain energy from turbulence via second-order fermi acceleration, how this energy transfer affects the turbulent cascade remains largely unexplored. here, we show that damping and steepening of the compressive turbulent power spectrum are expected once the damping time $... | cosmic-ray drag and damping of compressive turbulence |
sagittarius a* (sgr a*) is a potential very high energy (vhe) γ-ray and cosmic-ray source. we examine limits to gap-type particle acceleration in the magnetosphere of sgr a*, showing that in the current phase of activity proton acceleration to pev energies is possible, with injection powers into the environment usually... | constraining cosmic-ray acceleration in the magnetospheric gaps of sgr a* |
galaxy clusters accrete mass through large-scale, strong, structure-formation shocks. such a virial shock is thought to deposit fractions ξe and ξb of the thermal energy in cosmic-ray electrons (cres) and magnetic fields, respectively, thus generating a leptonic virial ring. however, the expected synchrotron signal was... | synchrotron emission from virial shocks around stacked ovro-lwa galaxy clusters |
radio relics are diffuse synchrotron sources that illuminate shock waves in the intracluster medium. in recent years, radio telescopes have provided detailed observations about relics. consequently, cosmological simulations of radio relics need to provide a similar amount of detail. in this methodological work, we incl... | modelling the energy spectra of radio relics |
the debate on the nature of the gamma-ray emission from young supernova remnants is still open. ascribing such emission to hadronic rather than leptonic processes would provide an evidence for the acceleration of protons and nuclei, and this fact would fit with the very popular (but not proven) paradigm that supernova ... | gamma-ray emission from young supernova remnants: hadronic or leptonic? |
we perform spatial and spectral analyses of the lmc gamma-ray emission collected over 66 months by the fermi gamma-ray space telescope. in our spatial analysis, we model the lmc cosmic-ray distribution and gamma-ray production using observed maps of the lmc interstellar medium, star formation history, interstellar radi... | spatial and spectral modeling of the gamma-ray distribution in the large magellanic cloud |
supernova remnants (snrs) are prime candidates for efficient particle acceleration up to the knee in the cosmic ray particle spectrum. in this work we present a new method for a systematic search for new tev-emitting snr shells in 2864 hours of h.e.s.s. phase i data used for the h.e.s.s. galactic plane survey. this new... | discovery of new tev supernova remnant shells in the galactic plane with h.e.s.s. |
galaxy clusters are known to host many active galaxies (agns) with radio jets, which could expand to form radio bubbles with relativistic electrons in the intracluster medium (icm). it has been suggested that fossil relativistic electrons contained in remnant bubbles from extinct radio galaxies can be re-accelerated to... | re-acceleration of fossil electrons by shocks encountering hot bubbles in the outskirts of galaxy clusters |
we report on results of our upgraded giant metrewave radio telescope (ugmrt) observations for an early-stage merging galaxy cluster, ciza j1358.9-4750 (ciza1359), in band-3 (300-500 mhz). we achieved the image dynamic range of ~38000 using the direction dependent calibration and found a candidate of diffuse radio emiss... | diffuse radio source candidate in ciza j1358.9-4750 |
amongst the population of tev gamma-ray sources detected with the high energy stereoscopic system (h.e.s.s.) in the galactic plane, clearly identified supernova remnant (snr) shells constitute a small but precious source class. tev-selected snrs are prime candidates for sources of efficient cosmic-ray acceleration. in ... | search for new supernova remnant shells in the galactic plane with h.e.s.s. |
we report on the search for steady point-like sources of neutral particles around 1018 ev between 2008 and 2013 may with the scintillator sd of the telescope array experiment. we found overall no significant point-like excess above 0.5 eev in the northern sky. subsequently, we also searched for coincidence with the fer... | a northern sky survey for point-like sources of eev neutral particles with the telescope array experiment |
cosmic rays (crs) play an important role in many astrophysical systems. acting on plasma scales to galactic environments, crs are usually modelled as a fluid, using the cr energy density as the evolving quantity. this method comes with the flaw that the corresponding cr evolution equation is not in conservative form as... | comparing energy and entropy formulations for cosmic ray hydrodynamics |
it is recently proposed that cosmic rays generate a seed magnetic field in the early universe. in this paper, we propose another generation mechanism of magnetic fields by cosmic rays, which is the biermann battery driven by resistive heating induced by the streaming of cosmic rays. this mechanism is dominant in small-... | biermann battery powered by resistive heating induced by cosmic ray streaming |
the ultrarelativistic generalized lorentzian quasi-equilibrium thermodynamic energy distribution is tentatively applied to the energy spectrum of galactic cosmic ray fluxes. it is found that the inferred power law slopes contain a component which evolves with cosmic ray energy in steps of thirds, resembling the sequenc... | the differential cosmic ray energy flux in the light of an ultrarelativistic generalized lorentzian thermodynamics |
we present the results of suzaku and chandra observations of the galaxy cluster rxc j1053.7+5453 (z = 0.0704), which contains a radio relic. the radio relic is located at a distance of ∼540 kpc from the x-ray peak toward the west. we measured the temperature of this cluster for the first time. the resultant temperature... | suzaku and chandra observations of the galaxy cluster rxc j1053.7+5453 with a radio relic |
experimental evidence has accumulated to indicate that wakefield acceleration (wfa) accompanies intense and sometimes coherent emission of radiation such as from betatron radiation. the investigation of this issue has additional impetus nowadays because we are learning (1) there is an additional acceleration process of... | high energy photon emission from wakefields |
the large gap between a galactic dark matter subhalo's velocity and its own gravitational binding velocity creates the situation that small subhalos can be evaporated before dark matter thermalize with baryons due to the low binding velocity. in case dark matter acquires an electromagnetic dipole moment, the survival o... | soft scattering evaporation of dark matter subhalos by inner galactic gases |
it is suggested that the decline with energy of the boron-to-carbon abundance ratio in galactic cosmic rays is due, in part, to a correlation between the maximum energy attainable by shock acceleration in a given region of the galactic disk and the grammage traversed before escape. in this case the energy dependence of... | an alternative explanation of the varying boron-to-carbon ratio in galactic cosmic rays |
supernova remnants are supposed to be the most possible sources of cosmic rays. however, alternative sources of cosmic rays, such as an active galactic nucleus, gamma-ray bursts, and pulsars, have not be excluded. in this study, we investigate the possibility of cosmic rays being generated by pulsars. the pulsar is sim... | particles accelerated in hertzian magnetic dipole field of a pulsar |
superclusters and galaxy clusters offer a wide range of astrophysical science topics with regards to studying the evolution and distribution of galaxies, intra-cluster magnetization mediums, cosmic ray accelerations and large scale diffuse radio sources all in one observation. recent developments in new radio telescope... | third-generation calibrations for meerkat observation |
the dependence of the cosmic ray intensity on galactocentric distance is known to be much less rapid than that of the thought-to-be sources: supernova remnants. this is an old problem ('the radial gradient problem') which has led to a number of possible 'scenarios'. here, we use recent data on the supernova remnant's r... | the radial gradient of cosmic ray intensity in the galaxy |
we examine the new galactic supernova remnant (snr) candidate, g23.11+0.18, as seen by the murchison widefield array radio telescope. we describe the morphology of the candidate and find a spectral index of -0.63 ± 0.05 in the 70-170 mhz domain. coincident tev gamma-ray detection in high energy stereoscopic system (hes... | a supernova remnant counterpart for hess j1832-085 |
recent discovery of fast blue optical transients (fbots)—a new class of energetic transient sources—can shed light on the long-standing problem of supernova—long gamma-ray burst connections. a distinctive feature of such objects is the presence of modestly relativistic outflows which place them in between the non-relat... | particle acceleration in mildly relativistic outflows of fast energetic transient sources |
one of the primary current astrobiological goals is to understand the limits of microbial resistance to extraterrestrial conditions. much attention is paid to ionizing radiation, since it can prevent the preservation and spread of life outside the earth. the aim of this research was to study the impact of accelerated h... | the responses of the black fungus cryomyces antarcticus to high doses of accelerated helium ions radiation within martian regolith simulants and their relevance for mars |
an introduction is given to a meeting on the role of massive and stellar black holes in powering non-thermal activity in a rich variety of cosmic sources. relevant properties of magnetized, spinning black holes are summarized and their observational expression, within galactic nuclei, in terms of radio loudness and fan... | black holes as cosmic dynamos |
based on the collective linear and nonlinear processes in a magnetized plasma surrounding the black hole at the galactic center (gc), an acceleration mechanism is proposed to explain the recent detection/discovery of pev protons. in a two-stage process, the gravitation energy is first converted to the electrical energy... | on the rotationally driven pevatron in the center of the milky way |
galaxy clusters are the largest and most massive bound objects resulting from cosmic hierarchical structure formation. baryons account for somewhat more than 10% of that mass, with roughly 90% of the baryonic matter distributed throughout the clusters as hot ($t>1$ kev), high-$\beta$, very weakly collisional plasma;... | plasma 2020 - intracluster medium plasmas |
hessj1826-130 is an unidentified hard spectrum source discovered by h.e.s.s. along the galactic plane, the spectral index being γ = 1.6 with an exponential cut-off at about 12 tev. while the source does not have a clear counterpart at longer wavelengths, the very hard spectrum emission at tev energies implies that elec... | hess j1826-130: a very hard γ-ray spectrum source in the galactic plane |
supernovae (sne) are the dominant source of chemical enrichment of galaxies, and they are an important source of energy to heat the interstellar medium and accelerate cosmic rays. our knowledge of sne in the milky way is based mostly on the study of galactic supernova remnants (snrs), providing an (incomplete) record t... | the radial supernova remnant distribution in the galaxy |
we report the emergence of a new h i 21-cm absorption at zabs = 1.172 635 in the damped lyα absorber (dla) towards the γ-ray blazar pks 2355-106 (zem~1.639) using science verification observations (2020 june) from the meerkat absorption line survey (mals). since 2006, this dla is known to show a narrow h i 21-cm absorp... | emergence of a new h i 21-cm absorption component at z 1.1726 towards the γ-ray blazar pks 2355-106 |
pair cascades from millisecond pulsars (msps) may be a primary source of galactic electrons and positrons that contribute to the increase in positron flux above 10 gev as observed by pamela and ams-02. the fermi large area telescope (lat) has increased the number of detected gamma-ray msps tremendously. light curve mod... | the millisecond pulsar contribution to the rising positron fraction |
context. the diffusive shock acceleration mechanism has been widely accepted as the acceleration mechanism for galactic cosmic rays. while self-consistent hybrid simulations have shown how power-law spectra are produced, detailed information on the interplay of diffusive particle motion and the turbulent electromagneti... | cosmic-ray acceleration at collisionless astrophysical shocks using monte-carlo simulations |
we consider cosmic ray (cr) modified shocks with both streaming and diffusion in the two-fluid description. previously, numerical codes were unable to incorporate streaming in this demanding regime, and have never been compared against analytic solutions. first, we find a new analytic solution highly discrepant in acce... | fluid simulations of cosmic ray modified shocks |
the x-ray emission from the knots of the kiloparsec scale jet of active galactic nuclei (agn) suggests the high energy emission process is different from the radio/optical counterpart. interpretation based on the inverse compton scattering of cosmic microwave photons has been ruled out through fermi γ-ray observations ... | advection of accelerated electrons in radio/x-ray knots of agn jets |
we investigate the production of magnetic flux from rotating black holes in active galactic nuclei (agns) and compare it with the upper limit of ultrahigh energy cosmic ray (uhecr) luminosities, calculated from observed integral flux of gev-tev gamma rays for nine uhecr agn sources. we find that, for the expected range... | luminosity of ultrahigh energy cosmic rays and bounds on magnetic luminosity of radio-loud active galactic nuclei |
in this paper, we study centrifugal acceleration of particles moving along a prescribed rotating curved trajectories. we consider the physical system embedded in an isotropic photon field and study the influence of the photon drag force on the acceleration process. for this purpose, we study three major configurations ... | centrifugal acceleration in the isotropic photon field |
in this paper, we study relativistic dynamics of charged particles corotating with prescribed trajectories, having the shape of dipolar magnetic field lines. in particular, we consider the role of the drag force caused by the photon field the forming of equilibrium positions of the charged particles. alongside a single... | 3d study of centrifugal acceleration in isotropic photon fields |
with enzo simulations run on the jülich supercomputers, we have investigated the evolution of magnetic fields in the largest cosmic structures (namely galaxy clusters and filaments connecting them) with unprecedented dynamical range. these simulations revealed the full development of the small-scale dynamo in eulerian ... | a song of shocks and dynamo: numerical studies of a galaxy cluster merger in the himag project |
the process of stationary acceleration of protons by an electric field in the electromagnetic field of active galactic nuclei, including the regions of the magnetosphere of a supermassive black hole and a relativistic jet, is considered. the process of collisionless acceleration of the proton as a component of ultrahig... | acceleration of the high energy protons in an active galactic nuclei |
we give an overview of the agile γ-ray satellite scientific highlights. agile is an italian space agency (asi) mission devoted to observations in the 30mev-50gev γ-ray energy range, with simultaneous x-ray imaging in the 18-60kev band. launched in april 2007, the agile satellite has completed its tenth year of operatio... | agile results on relativistic outflows above 100mev |
a major feature of the energy spectrum of the cosmic radiation above 10$^{19}$ ev is the increasing fraction of heavy nuclei with respect to light nuclei. this fact, along with other simple assumptions, is adopted to calculate the energy spectrum of the cosmic radiation up to 2.4$\times$10$^{21}$ ev. the predicted spec... | the energy spectrum of ultraheavy nuclei above 10$^{20}$ ev |
astrophysical shocks are known to accelerate particles to high relativistic velocities. this process requires the particles to repeatedly cross the shock, a process that can only occur if the particle is reflected by the local magnetic field. such particles are observed on earth as cosmic rays. this phenomenon has been... | diffusive shock acceleration of cosmic rays in low-mach galaxy cluster shocks. |
recent observations found that electrons are accelerated to ∼10 gev and emit synchrotron hard x-rays in two magnetic white dwarfs (wds), also known as cataclysmic variables (cvs). in nova outbursts of wds, multi-gev gamma-rays were detected, implying that protons are accelerated to 100 gev or higher. in recent optical ... | evidence for gev cosmic rays from white dwarfs in the local cosmic ray spectra and in the gamma-ray emissivity of the inner galaxy |
we study a scenario in which the fermi bubbles are formed through a galactocentric outflow of gas and pre-accelerated cosmic-rays (cr). we take into account cr energy losses due to proton-proton interactions with the gas present in the bubbles, and calculate the associated gamma-ray emission. we find that crs diffusing... | galactic cosmic-rays in a breeze |
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