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hadronic models of blazar emission constitute an interesting alternative to the more popular leptonic ones. using the bl lac object mrk 421 as a characteristic example, we present two distinct ways of modeling the spectral energy distribution of blazars in the hadronic context, and we discuss the predictions of each va... | consequences of proton acceleration in blazar jets |
among the registered extremely high energy cosmic rays (ehecr, e>10^{20} ev) an event with the highest to date energy of e=3.2\cdot10^{20} ev was detected by the fly's eye experiment (fe event) in 1991. with the use of the back-tracking method for the calculation of the ehecr trajectories in galactic and extragalact... | search for the astrophysical sources of the fly's eye event with the highest to date cosmic ray energy e=3.2\\cdot10^{20} ev |
it has been indicated that low-luminosity active galactic nuclei (llagns) are accelerating high-energy cosmic-ray (cr) protons in their radiatively inefficient accretion flows (riafs). if this is the case, sagittarius a* (sgr a*) should also be generating cr protons, because sgr a* is a llagn. based on this scenario, w... | diffuse gamma-ray emission from the galactic center and implications of its past activities |
in this paper, we study the efficiency of particle acceleration in the magnetospheres of stellar mass black holes. for this purpose, we consider the linearized set of the euler equation, continuity equation and poisson equation, respectively. after introducing the varying relativistic centrifugal force, we show that th... | new mechanism of acceleration of particles by stellar black holes |
using diffusive shock acceleration (dsa) simulations, we have calculated the acceleration of cosmic-ray electrons and the ensuing radio synchrotron emission at weak spherical shocks that are expected to form in the outskirts of galaxy clusters. we demonstrate that, at decelerating spherical shocks, the volume integrate... | radio spectra from shock accelerated electrons in the cluster outskirts |
massive clusters, particularly merging clusters with multiple superposed subhalos, are powerful cosmic telescopes, capable of magnifying high-z galaxies, thus providing a probe of the high-z universe. in addition, merging clusters are excellent laboratories to investigate how the particles that produce cluster-scale di... | jvla and chandra observations of the hst frontier cluster macs j0717.5+3745 |
there are for the galaxies of frii type (like cygnus a) studied a number of hydrodynamic and kinetic processes to transport of magnetized plasma with cosmic rays, and a stratification process of rg-lobe because of ep-cosmic rays. we found that the jet and bow shock in radio galaxies are supported by the processes of ep... | on the p-cosmic rays as mediators of viscous forces that create shock and vortex structures in the radio galaxies |
x-ray binaries are one of the long-standing candidates as the source of galactic cosmic rays and neutrinos. the compact object in a binary system can be the site for cosmic-ray acceleration, while interactions of cosmic rays can happen in the jet of the compact object, the wind, or the companion star's atmosphere, whic... | results from an icecube search for high-energy neutrino emission from x-ray binaries |
while supernova remnants are promising candidates for cosmic ray production, they must produce on average 1050 ergs of energetic particles to sufficiently account for the galactic cosmic ray protons below 3 pev. moreover, supernova remnants that show direct observational evidence for proton accelerations to high energi... | the cosmic ray production of mixed morphology supernova remnant kes 17 |
galaxy clusters are expected to be reservoirs of cosmic rays accelerated by structure formation processes, galaxies, and active galactic nuclei (agn). the detection of diffuse synchrotron radio emission in several clusters confirms the presence of cosmic-ray electrons and magnetic fields permeating the intra-cluster me... | ksp: clusters of galaxies |
since their discovery in 2010, the fermi bubbles have raised a lot of questions such as: what are they? how old are they? how much energy is involved? observations from radio to uv to x-ray have been addressed some of these questions, giving us a new window on energy injection at the galactic center, the growth rate of... | overview of the fermi bubbles |
dark matter is usually considered responsible for the flat rotation curves observed at the outer radii of spiral galaxies. since the existence of dark matter has not been indisputably detected by experiments, magnetic field is sometimes proposed to be substitute for dark matter in explaining the shape of rotation curve... | on the maximum contribution of magnetic field to the rotation curves of dwarf spiral galaxies |
shock waves with low sonic mach number (ms) are induced by mergers and/or flow motions in the hot tenuous plasmas of the intracluster medium (icm). high-energy cosmic ray (cr) protons are expected to be accelerated at quasi-parallel shocks via diffusive shock acceleration (dsa), while proton acceleration is suppressed ... | proton acceleration in intracluster shocks and gamma ray and neutrino emissions from galaxy clusters |
radio relics, mpc-long arc-like structures in the outskirts of galaxy clusters, are believed to arise from relativistic electrons emitting synchrotron radiation in the cluster magnetic field. these features often coincide with shock fronts seen in x-ray observations of the intracluster medium which are produced by merg... | seeding radio relics by turbulent transport of agn bubble material |
galactic outflows play an important role in galactic evolution. despite their importance, a detailed understanding of the physical mechanisms responsible for the driving of these winds is lacking. in an effort to gain more insight into the nature of these flows, we perform global three-dimensional magneto-hydrodynamica... | global mhd simulations of cosmic ray driven galactic winds |
the galactic centre region is unique for its intense activity across the wavebands. the gamma-ray emission here extends up to the highest photon energies so far measured (beyond 10 tev) and spans the central molecular zone (cmz). the general spatial match between the gamma-ray and interstellar gas emission suggests the... | extreme gamma rays from the galactic centre region |
we present a self-consistent model of the fermi bubbles, described as a decelerating outflow of gas and non-thermal particles produced within the galactic center region, on a o(100) myr timescale. motivated by observations, we use an outflow with velocity o(100) km/s, which is slower than velocities used in models desc... | a hadronic model of the fermi bubbles |
low-frequency radio observations recently revealed non-thermal emissionfrom the wolf-rayet bubble g2.4+1.4, proving that cosmic rays areaccelerated in it. we aim to gather data in the x-ray band in orderto better constrain the relativistic electron energy distributionand magnetic field in the bubble shell shocks, givin... | relativistic particle acceleration in the wolf-rayet bubble g2.4+1.4 |
the possible gamma-ray excess in the inner galaxy and the galactic center suggested by fermi-lat observations has triggered great interest in the astro-particle physics community. among its various interpretations have been wimp dark matter annihilations, gamma-ray emission from a population of millisecond pulsars, or ... | the fermi galactic center excess as a signal from bursts of cosmic-rays |
it has been a long-standing question whether supernova remnants (snrs) can account for the acceleration of the bulk of galactic cosmic rays up to the knee in the cosmic ray spectrum. tev-selected snrs are interesting sources to probe this hypothesis and the entire h.e.s.s. phase i data set of the galactic plane, collec... | search for new supernova remnant shells in the galactic plane with h.e.s.s. |
we will present models of the radio synchrotron emission from galactic supernova remnants (snrs) that use current models of galactic magnetic field to simulate snr emission as a function of their position in the galaxy. this work reveals a connection between snrs and their environment and a relationship between the ang... | bilateral symmetry in supernova remnants and the connection to the galactic magnetic field |
using a semi-analytic approach based on the thin-shell approximation, we calculate the long-term evolution of supernova remnants (snrs) while also accounting for the cosmic rays (crs) accelerated at their blast waves. our solution reproduces the results of state-of-the-art fluid simulations across the adiabatic and rad... | effect of cosmic rays on supernova remnant evolution |
g32.4+0.1 is a galactic supernova remnant (snr) that belongs tothe class of snrs that exhibit x-ray spectra that are dominated not bythermal emission but instead by synchrotron radiation. prominent examples of snrs in this class include sn 1006, g266.2-1.2 (vela jr.) and g347.3-0.5, and detailed studies of the synchrot... | new x-ray and radio observations of the synchrotron x-ray-dominated galactic supernova remnant g32.4+0.1 |
astrophysical shocks accelerate particles through the fermi acceleration process, which involves a charged particle repeatedly crossing the shock after being reflected by the local magnetic field and gaining momentum. eventually, the particles reach relativistic speeds and can be observed as cosmic rays. this is a self... | on the contribution of low-mach, high-beta shocks to the cosmic ray spectrum |
we propose a 560 ks observation of a2319 - a nearby, very hot, and the fifth brightest in x-rays, cluster of galaxies - to perform a comprehensive study of plasma physics. our goal is to probe (i) viscosity in the bulk gas through the density fluctuations power spectra on dissipative scales and (ii) thermal conduction ... | how do cosmic plasmas work? insights from the hottest brightest cold front and gas perturbations in a2319 |
possible acute and late risks to the central nervous system from galactic cosmic rays and solar particle events are concerns for human exploration of space. cns risks may include altered cognitive function, impaired balance and motor function, affective behavioral changes, or accelerated late neurodegeneration, all of ... | space radiation: central nervous system risks |
the largest tev source, rx j0852.0-4622 (vela jr.), is one of the few supernova remnants (snrs) with well resolved shell-like morphology at very-high-energy (vhe; e>100 gev) gamma-rays. strong non-thermal emission across the electromagnetic spectrum from radio to vhe gamma-rays, young age and proximity of the remnan... | deep h.e.s.s. observations of the supernova remnant rx j0852.0-4622 |
the super trans-iron galactic element recorder (supertiger) was designed to measure significant statistics particularly for cosmic rays (crs) with charge > 30. these heaviest nuclei are some 10^3-10^5 times rarer than the lighter elements. with the longest science flight to date on a long duration balloon in 2012-13... | supertiger: on the cosmic ray charge frontier |
the cosmic ray dominated fermi bubbles in the milky way are produced either by a starburst or an agn. we can gain further insight into the physics of superbubble by studying similar bubbles around other galaxies. perhaps the best analog is in ngc 3079, which hosts a smaller and probably younger bubble, so offers an eno... | non-thermal x-ray emission from a 'fermi bubble' in an external galaxy |
the ubiquitous turbulence in the interstellar medium (ism) participates in astrophysical processes over a huge dynamic range of scales. understanding the turbulence properties in the multiphase, magnetized, partially ionized, and compressible ism is the fundamental step prior to the studies of the ism physics and other... | the generation, destination, and astrophysical applications of magnetohydrodynamic turbulence |
the impact of galactic superwinds on their galaxies and the intergalacticmedium depends on the driving mechanism, which is controversial. twoleading candidates are thermally driven and cosmic ray-driven winds,which predict different velocity profiles. this will be reflectedin the temperature of the soft x-ray emitting ... | constraining the wind origin in ngc 3079 through x-ray temperature |
stellar feedback remains a key uncertain aspect in galaxy formation and evolution theories. in addition to the mechanical energy injection from fast stellar winds and supernovae of massive stars, their radiative transfer feedback (via direct and indirect/dust-processed radiation pressures and photo-ionization) has also... | feedback from starbursts: 30 dorado as a case study |
if galactic supernova remnants (snrs) are the main producer of cosmicray protons <3 pev, the average remnant must produce ~10^50 ergs ofcosmic rays. however, <10 snrs show observational evidence for cosmicray acceleration, and even fewer produce these particles with therequired energetics. while our recent analys... | the cosmic ray production of mixed morphology supernova remnant kes 17 |
prescriptions for the electron injection into the diffusive shock acceleration process are required in many practical considerations of the cosmic-ray astrophysics, particularly in modeling of the synchrotron emission of astrophysical sources. inspired by the results of our particle-in-cell shock simulations, we assume... | non-linear diffusive shock acceleration: a recipe for electron injection |
we calculate the spectrum of escaping cosmic rays accelerated in the shocks produced by expanding galactic superbubbles powered by supernovae producing a continuous energy outflow in star-forming galaxies. we use the generalized kompaneets equation solutions adapted to expansion in various external density profiles inc... | cosmic rays escaping from galactic superbubbles and application to the fermi bubble |
vela jr. is the brightest steady source in the sky above 1 tev, and is one of the rare class of supernova remnants (snrs) whose shell morphology has been resolved in gamma-rays, with others being rx j1713.7-3946, sn 1006, hess j1731-347, rcw 86, and hess j1534-571. it is thus a remarkable laboratory where we can study ... | x-ray expansion of the southern rim of the vela jr. supernova remnant |
the origin of nonthermal emission observed from a variety of astrophysical objects is still a major unresolved issue in plasma astrophysics. shocks at snrs, with the help of a universal acceleration mechanism (i.e., diffusive shock acceleration; dsa), are widely believed to be the most probable acceleration sites of ga... | electron acceleration in non-relativistic quasi-perpendicular collisionless shocks. |
the first ground-level enhancement of the current solar cycle 25 occurred on 28 october 2021. it was observed by several space-borne and ground-based instruments, specifically neutron monitors. a moderate count-rate increase over the galactic-cosmic ray background was observed by high-altitude polar stations on the sou... | spectral and anisotropy characteristics of the solar protons during ground level enhancement (gle) # 73 on 28 october 2021 derived with neutron monitor data |
star formation is the lynch pin that lies in between the scales of galaxy and planet formation. observational studies of molecular clouds, the sites of star formation, primarly use molecular line emission, providing dynamical and chemical information. two of the key parameters of astrochemical models are far-ultraviole... | the impact of stellar feedback on astrochemistry |
high quality gamma-ray and radio observations of nearby galaxies offer an unprecedented opportunity to quantitatively study the properties of their cosmic ray populations. accounting for various interactions and energy losses, i developed a multi-component, single-zone model of the cosmic ray populations in the central... | cosmic ray interactions in starbursting galaxies |
the magnetic field may play a key role in regulating the extreme galactic center environment. we propose a chandra observation of a distinct 2'-long x-ray thread associated with a bundle of nonthermal radio filaments. this association, together with the detection of the fe 6.7-kev line emission in a suzaku spectrum, pr... | g359.55+0.16: a case of interstellar magnetic reconnection? |
understanding particle acceleration at low-mach number shocks in the intra-cluster medium is an unsolved puzzle. a small fraction of the shock energy could be channeled in the acceleration of cosmic rays, which in the presence of magnetic fields, emit synchrotron radiation and are observed as radio relics. therefore, r... | probing particle acceleration in abell 168 |
due to unusually quiet solar activity conditions during the previous 2009 and 2020 solar minima, record- high levels of galactic cosmic rays (gcrs) were reported. however, anomalous cosmic ray (acr) intensities did not show such extremely high levels. this discrepancy between gcr and acr intensities remains unresolved.... | simulating gcr and acr oxygen intensities during very quiet solar minimum conditions |
the multi-facet nature of the origin of cosmic rays is such that some of the problems currently met in our path to describing available data are due to oversimplified models of cr acceleration and transport, and others to lack of knowledge of the physical processes at work in certain conditions. on the other hand, the ... | galactic cosmic rays |
to date, only a handful of shock fronts are known in merging clusters. a new one was recently reported, coincident with a well-resolved radio relic in rxcj1314-25. the peculiar shape of this shock is an interesting hydrodynamical phenomenon, possibly caused by the rapidly changing gravitational potential and the result... | an m-shaped shock and a multi-branch radio relic in the galaxy cluster rxcj1314-25 |
solar wind shocks and the intracluster medium comprise hot, low-density plasmas with few coulomb collisions. electrons there are not fluid and so gain and exchange energy by interaction with a variety of plasma waves. we explore two mechanisms for electron energization in such plasmas. in 2d kinetic simulations of sola... | electron energization in solar wind shocks and the intracluster medium |
dark matter does not emit light or reflect electromagnetic radiation, but its existence can be inferred from the effects of measurements such as gravity and mass. unveiling the nature of dark matter is one of the biggest mysteries of modern science. exploration of dark matter could give scientists a clearer understandi... | wukong sharpens its eyes and unveils the nature of dark matter |
a new modified-gravity theory, referred to as the unified electro-gravity (ueg) theory, has been recently proposed. the theory introduces a new gravitational field in the presence of an electromagnetic field or radiation, while maintaining the conventional einstein-newtonian gravity in the external region of an electri... | a unified electro-gravity theory to model accelerated expansion of the universe without any dark-energy or dark-matter |
the photos of the pre-flare development observed in the spectral lines of highly ionized iron (sdo aia apparatus) indicate the energy accumulation for a flare in the corona in the pre-flare local (about 1010 cm) high temperature structure. the pre-flare structures in the corona are observed in uv spectral lines of ions... | diagnostics of solar flares by analyzing the spectral line emission of highly ionized iron |
the energy partitioning and magnetic field topology in radio jets from agn on galaxy cluster scales is poorly understood. we present a series of 3d mhd jet simulations with varying energy partitioning in the injected jet between kinetic and magnetic energy. specifically, we highlight the radio observational properties ... | observational signatures from kinetic and magnetic dominant agn jets |
shear flows are ubiquitously present in space and astrophysical plasmas. prominent examples include black hole accretion flows and the relativistic outflows or jets in gamma-ray bursts and active galactic nuclei (agn). fast shear flows can in principle facilitate non-thermal particle acceleration by several means. a ke... | energetic particle acceleration in relativistic astrophysical shear flows |
large-scale galactic winds driven by stellar feedback are one phenomenon that influences the dynamical and chemical evolution of a galaxy, pushing and redistributing material throughout the interstellar medium (ism) and galactic halo. a detailed understanding of the exact physical mechanisms responsible for these winds... | role of turbulent damping in cosmic ray galactic winds |
the parker instability impacts the evolution of galaxies and gas clouds. driven by buoyancy, it describes a feedback loop for warping magnetic fields. as the parker instability evolves, it can cause magnetic field lines to cross and reconnect, accelerating gas bubbles into or away from the disk. how these bubbles form ... | cosmic ray and magnetically driven bubbles in galaxies |
fermi bubbles are giant gamma-ray structures extended north and south of the galactic center with characteristic sizes of the order of 10 kpc discovered by the fermi large area telescope. good correlation between radio and gamma-ray emission in the region covered by fermi bubbles implies the presence of high-energy ele... | fermi bubbles as sources of cosmic rays above 1 pev |
in starburst galaxies, cosmic rays accelerated by supernova interact with the interstellar medium, creating a unique gamma-ray source population. through their interactions with the medium, they undergo energy losses, and are assumed to then escape the medium according to the "leaky box" model. by considering cosmic ra... | modeling cosmic rays in starburst galaxies |
supernova remnants (snrs) are considered to be the primary source of galactic cosmic rays (crs). however, increasing evidence shows that the winds of young massive star clusters (ymcs) may also contribute substantially to cr acceleration. in this poster, we present new results analyzing 14 years of fermi gamma-ray tele... | evaluating stellar winds from young massive star clusters as cosmic-ray acceleration sites using fermi gamma-ray observations |
in this work, we present an x-ray analysis of the nearby merging double-radio-relic cluster abell 3376 (z= 0.046), observed with the suzaku xis instrument. these deep observations (∼380 ks) cover the entire double-relic region in the outskirts of the cluster. the mentioned diffuse radio structures are one of the larges... | x-ray study of the merging double-radio-relic cluster abell 3376 with suzaku |
heliosphere is a bubble occupied by the solar wind plasma and magnetic field in the local interstellar space. the motion of galactic cosmic rays (gcrs) invading into the heliosphere are strongly affected by the electromagnetic structures of the heliosphere. the statistical behavior of the gcrs near and inside the helio... | properties of cosmic ray test particles in global mhd simulation of the heliosphere |
weak shocks with low sonic mach numbers are induced by mergers and/or supersonic flow motions in the hot tenuous intracluster medium (icm). high energy cosmic ray (cr) protons are expected to be accelerated at quasi-parallel shocks via diffusive shock acceleration (dsa). the key element in determining the dsa efficienc... | cosmic ray proton acceleration at weak icm shocks and observational signatures |
cherenkov telescope array (cta) promises to see the high-energy universe with unprecedented sensitivity and angular resolution covering the multi-tev domain. the first part of the thesis concerns the development of a single photoelectron calibration system for the nectarcam camera. the second part aims to understand th... | cherenkov telescope array : development of a calibration system for nectarcam and study of supernova remnants as pevatron candidates |
the question if there is life on other planets has fueled a decade full of exciting discoveries in the field of exo-planet research. the number of known exoplanets has grown beyond 5,000 till today and with the launch of the james webb space telescope, we are now able to probe the atmospheres of the most nearby systems... | galactic cosmic-rays and habitable planets |
we propose to observe bania's clump 2, the densest cloud on the x1 orbits, for 100ks with acis-i. the large-scale molecular clouds in the galactic plane (1 kpc from the galactic center) exhibit 6.4 kev line emission, which is currently thought more likely to originate from mev-gev electron bombardment than from x-ray r... | probing mev-gev electrons in the x-ray regime using molecular cloud bania's clump2 |
the transport of cosmic rays inside their sources and through the galaxy, around sources and during their journey through intergalactic space, may be heavily affected by non-linear effects, namely by 1) bulk motions induced by cosmic ray pressure gradients and 2) generation of magnetic perturbations that in turn modify... | a modern approach to cosmic ray transport in the galaxy |
recurrent novae (rne) undergo episodic eruptions in the form of thermonuclear explosions, due to the accumulation of material accreted by a white dwarf from a binary companion star. the well known rn rs ophiuchi (rs oph) underwent its latest eruption in 2021, triggering numerous follow-up observations, including with t... | efficient cosmic-ray acceleration in the recurrent nova rs ophuichi revealed by h.e.s.s. |
the elemental composition of planetary surfaces can be determined using gamma ray and neutron spectroscopy. most planetary bodies for which nuclear spectroscopy data have been acquired are round, and simple, analytic corrections for measurement geometry can be applied; however, recent measurements of the irregular aste... | shape and topography corrections for planetary nuclear spectroscopy |
supernova remnants (snrs) have long been hypothesized to accelerate galactic cosmic rays. the energy of accelerated protons can be measured if gamma-ray emission arises primarily from inelastic collisions with the surrounding gas through neutral pion decay. here, we constrain the accelerated particle spectrum of both e... | constraining cosmic ray origins through spectral radio breaks in supernova remnants |
we make the first observation-based calculation of the energy that goes into cosmic ray protons versus cosmic ray electrons in shock acceleration during structure formation. we find a ratio of energy in cosmic ray protons to energy in cosmic ray electrons of 0.86. this value, calculated from the nonthermal x-ray compon... | rxte observation of the nonthermal emission from the early stage merger in a1750 |
winds are ubiquitous in galaxies and often feature bubble structures. these wind bubbles are characterized by an external forward shock expanding in the surrounding medium and a wind termination shock separating the cool and fast wind from the hot shocked wind. while the forward shock could not be able to accelerate pa... | particle acceleration in galactic wind bubbles |
cosmic rays (crs) and magnetic fields are important constituents in the current universe. however, the origins of crs and magnetic fields are not yet understood. recently, it is pointed out that the first generation of crs can be accelerated in the supernova remnants of the first stars. based on this expectation, we fo... | magnetic field generation by resistive heating induced by streaming cosmic rays at cosmic dawn |
recent icecube results suggest that the first detection of very high energy astrophysical neutrinos have been accomplished. we consider these results at face value in a galactic origin context. an outflow emission scenario from both the fermi bubble and broader halo region are considered. we motivate that such an inten... | a galactic halo origin of the neutrinos detected by icecube |
x-ray diagnostics of tev (teraelectronvolt) sources continues to be an important tool to identify the nature of newly detected sources as well as to pinpoint the physics processes that are at work in these highly energetic objects. this paper gives a review of recent studies that have been performed on tev sources with... | x-ray observations of galactic h.e.s.s. sources: an update |
neutron monitors (nm) have been for over sixty years powerful instruments for measuring gev-energy solar protons. in that time we have learned much about the nature of ground level enhancements (gle), the signal on the ground from these high energy ions. however, the processes that govern the acceleration of these part... | solar orbiter measurements of the highest energy solar energetic particles-neutron monitors and solar orbiter |
galactic cosmic rays are accelerated in sources situated in the disc of the galaxy, and thereafter move along spiral trajectories, scatter on magnetic inhomogeneities, and consequently diffuse through the interstellar medium and leak away into the intergalactic medium. this process of diffusion essentially erases almos... | cosmic-ray sources as gamma-ray sources |
galaxies and nuclei in dense environment at high redshift provide a good laboratory to investigate accelerated, most extreme evolution of galaxies. the ssa22 proto-cluster at z = 3.1 is known to have a three-dimensional 50 (comoving) mpc-scale filamentary structure, traced by lyα emitters, which makes the field a suita... | alma deep field in the ssa22 proto-cluster at z = 3 |
there is strong evidence from recent experiments that suggest a source of galactic cosmic rays is in superbubble regions and that particles here are accelerated through the shocks from supernova explosions. through further study of ultra-heavy cosmic-rays, those particles with a z >26, we can verify and explore the ... | current and future measurements of ultra-heavy galactic cosmic rays |
we present evidence for jet-like x-ray-emitting features from the nearby pulsar, b2224+65, based on three epochs of chandra x-ray observations, separated by 6 years from each other. this relatively slow rotating pulsar is well known for its extreme velocity of proper motion and associated "guitar"-shaped optical nebula... | x-ray-emitting jet-like features from the fast-moving middle-aged pulsar b2224+65 |
from 2006 to 2016 years on the board of resurs-dk1 satellite pamela and arina cosmic rays experiments was carried out. the main goal of experiments is measurement of galactic component of cosmic rays; it also registers solar particles accelerated in powerful explosive processes on the sun (solar flares) in wide energy ... | solar flare activity in 2006 - 2016 according to pamela and arina spectrometers |
jupiter's radiation belts constitute a multi-component system, trapping high intensities of electrons, protons and heavier ions. we revisit measurements from galileo's heavy ion counter (hic) instrument, a high-quality dataset that extends considerably the energy range covered by galileo/epd and juno/jedi (<10 mev/n... | evidence for local acceleration of heavy >10 mev/n oxygen and sulphur in jupiter's innermost radiation belts |
the review is devoted to consideration of possible observational consequences of modified gravity theories, suggested for explanation of the contemporary accelerated expansion of the universe. the major attention is paid to f(r)-models. it is shown that in systems with rising energy density high frequency and large amp... | instabilities in modified theories of gravity |
supertiger (super trans-iron galactic element recorder) is a long-duration-balloon instrument that completed its first antarctic flight during the 2012-2013 austral summer, spending 55 days at an average float altitude of 125,000 feet. supertiger measured the relative abundances of galactic cosmic-ray (gcr) nuclei with... | analysis progress: supertiger abundances of galactic cosmic rays for the atomic number (z) interval 40 to 56 |
supernova explosions are a major driver of galaxy evolution, and cosmic rays are a major component of that driving. this `cosmic ray feedback' presents a challenging multiscale problem in galaxy simulations. the supernova explosions on small scales (< < 1pc) which accelerate cosmic rays eventually produce the bac... | the large scale impact of localized cosmic ray injection |
spectroscopy in the uv and x-ray can address many of the key questions posited by the 2010 decadal survey and nasa's 2013 astrophysics roadmap: how baryonic matter flows into and out of galaxies over cosmic time, how accreting stars and black holes evolve, and how feedback processes impact their ambient environments an... | curved customized gratings for high energy spectroscopy |
radio shocks in merging galaxy clusters exhibit cosmic-ray acceleration to extreme energies. discrepancies between the shock strengths derived from radio and x-rays may suggest that the standard model of shock acceleration may need to be re-examined. a firm conclusion here requires a sample of mergers with a small view... | chandra observation of newly discovered double radio shocks in abell1838 |
in the period from 2006 to 2016, experiments based on the use of the pamela and arina spectrometers and aimed at detecting cosmic rays were performed on board the resurs-dk1 satellite. although the main goal of these experiments was to study the galactic component of cosmic rays, the instruments in question also detect... | solar flare activity from 2006 to 2016 according to data from the pamela and arina spectrometers |
the origin of the micro-gauss magnetic fields in the igm of galaxy clusters is one of the outstanding problem in modern cosmology. we demonstrate that the cluster accretion shocks are naturally and inevitably generate sub-equipartition magnetic fields from scratch in a two-step process. indeed, accretion shocks acceler... | how did the universe get magnetized? |
in galaxy clusters, the intracluster medium (icm) is expected to host a diffuse, long-lived, and invisible population of ''fossil'' cosmic-ray electrons (cre) with 1-100 mev energies. these cre, if re-accelerated 100x in energy, can contribute to diffuse low-frequency radio synchrotron emission. we study cre scattering... | electron re-acceleration via ion cyclotron waves in the intracluster medium |
the active region ar12673 is appeared near the solar activity minimum and x8.2 flare on the back side of the sun is produced. the energy for the flare is stored in the magnetic field of a current sheet and released in the corona above the active area. the flare is accompanied by a stream of solar cosmic rays that arriv... | the proton solar flare above active region ar12673 on the solar back side |
we present a deep low-frequency study of 3c31, a well-studied fri radio galaxy in the local universe, using the dutch low-frequency array (lofar). our radio continuum observations between 30 and 180 mhz allow us to study the population of cosmic-ray electrons (cre) down to a lorentz factor of 100. we find that in the i... | a low-frequency radio continuum study of the fri radio galaxy 3c31 with lofar |
the gas and dust between stars in galaxies is highly turbulent and magnetized. it is now understood that magnetic fields and turbulence affect many processes of astrophysical interest including star formation, cosmic ray acceleration, and the evolution of structures in the interstellar medium. in this talk, i shall rev... | new diagnostics for turbulence in the multiphase interstellar medium |
quantifying whether supernova remnants (snr) are the primary acceleration source of galactic cosmic rays is a significant problem. snr with a non-thermal dominated spectrum (nd-snr) accelerates particles with high efficiency. therefore, quantitative evaluation of the occurrence rate of nd-snr is essential to quantitati... | universality of non-thermal phenomena in galactic supernova remnants probed by high resolution x-ray spectroscopy |
during the formation of the large-scale structure of the universe, intracluster media (icms), which fills the volume of galaxy clusters and is composed of hot, high-beta plasma, are continuously disturbed by major and minor mergers of clumps as well as infall along filaments of the warm-hot intergalactic medium (whim).... | shock waves and particle acceleration in clusters of galaxies |
we present measurements of the abundances of ultra-heavy (z>29) cosmic rays made by the cris instrument on nasa's advanced composition explorer satellite. the data set corresponds to 6413 days of data collection between december 4, 1997 and may 31, 2016. the charge resolution that we obtain is excellent, exhibiting ... | constraints on galactic cosmic-ray origins from elemental composition measurements |
the observed appearance of the high-energy gamma-ray emission from galactic star clusters is determined by the geometry of the cluster and the distribution of the energy sources inside the cluster. a large number of massive stars with strong winds and supernova explosions lead to the formation of multidirectional plasm... | magnetic field amplification and high-energy emission properties of compact galactic clusters |
the escape model explains the cosmic ray (cr) knee by energy-dependent cr leakage from the milky way, with an excellent fit to all existing data. we test this model calculating the trajectories of individual crs in the galactic magnetic field. we find that the cr escape time τesc(e) exhibits a knee-like structure aroun... | the escape model for galactic cosmic rays |
during the formation of galaxy clusters by accretion of matter and mergers, turbulence is driven on large ~mpc scales in the intracluster medium (icm). the turbulence then cascades from driving scales to dissipative scales and heats the plasma, (re-)accelerates cosmic-ray particles and amplifies magnetic field. in this... | agn near and far - clues to galaxy evolution from small to large scales |
recurrent novae (rne) undergo episodic eruptions in the form of thermonuclear explosions, due to the accumulation of material accreted by a white dwarf from a binary companion star. the well known rn rs ophiuchi (rs oph) underwent its latest eruption in 2021, triggering numerous follow-up observations, including with t... | efficient cosmic-ray acceleration in the recurrent nova rs ophuichi revealed by h.e.s.s. |
compact binary millisecond pulsars (msps) are providing new insights into sub-luminous accretion flows and pulsar winds near the light cylinder, as well as new constraints on the maximum mass that a neutron star can support. a small sub-set of these known as "transitional msps" have shown *both* accretion- and rotation... | pulsar winds and accretion flows in compact binary msps |
the identification of galactic pevatrons (objects capable of accelerating particles up to the pev = 1015 ev range) is one of the main goals of the cherenkov telescope array consortium. this task is in tight connection with the problem of the origin of cosmic rays, since the sources of galactic cosmic rays must accelera... | the identification of cosmic-ray pevatrons with the cherenkov telescope array |
the radio luminosities at 1.4 ghz is tightly correlated with the far-infrared luminosities for various galaxy types (e.g. [16, 6, 2]) over a wide range of redshift (see e.g. [5, 1, 15, 8, 7]). the relationship is widely believed to be driven by the internal star formation activity. radio emission from these galaxies ar... | far-infrared-radio relation in cluster galaxies at intermediate redshift |
high-velocity clouds moving towards the disc will reach the galactic plane and will inevitably collide with the disc, producing shocks. these shocks having velocities of hundreds of kilometres per second can reaccelerate and compress galactic cosmic rays from the background. in this work, we investigate the interaction... | shocked high-velocity clouds as gamma-ray emitters |
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