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6,100 | Spectral States of XTE J1701-462: Link between Z and Atoll Sources | astro-ph.HE | We have analyzed 866 RXTE observations of the 2006-2007 outburst of the
accreting neutron star XTE J1701-462, during which the source evolves from
super-Eddington luminosities to quiescence. The X-ray color evolution first
resembles the Cyg X-2 subgroup of Z sources, with frequent excursions on the
horizontal and norma... | physics |
6,101 | Gamma-ray Bursts: Light on the distant Universe | astro-ph.HE | Observations of a long-lasting Gamma-ray burst, one that has the brightest
optical counterpart yet discovered, challenge theoretical understanding of
these bursts but may enhance their usefulness as cosmic probes. | physics |
6,102 | GRB physics with Fermi | astro-ph.HE | Radiation from GRBs in the prompt phase, flares and an afterglow is thought
to be produced by accelerated electrons in magnetic fields. Such emission may
be produced at collisionless shocks of baryonic outflows or at reconnection
sites (at least for the prompt and flares) of the magnetically dominated
(Poynting flux dr... | physics |
6,103 | Dark Matter Annihilation Induced Gamma Ray Emission from Galaxy Cluster 1E0657-56 | astro-ph.HE | Based on minimal supersymmetric standard model, neutralino dark matter
annihilation induced gamma ray emission from galaxy cluster 1E0657-56 is
calculated. The merge of bullet-like subcluster with the main cluster is also
investigated. | physics |
6,104 | Different satellites - different GRB redshift distributions? | astro-ph.HE | The measured redshifts of gamma-ray bursts (GRBs), which were first detected
by the Swift satellite, seem to be bigger on average than the redshifts of GRBs
detected by other satellites. We analyzed the redshift distribution of GRBs
triggered and observed by different satellites (Swift[1], HETE2[2], BeppoSax,
Ulyssses)... | physics |
6,105 | The First X-Ray Proper-Motion Measurements of the Forward Shock in the Northeastern Limb of SN 1006 | astro-ph.HE | We report on the first X-ray proper-motion measurements of the
nonthermally-dominated forward shock in the northeastern limb of SN 1006, based
on two Chandra observations taken in 2000 and 2008. We find that the proper
motion of the forward shock is about 0.48 arcsec/yr and does not vary around
the rim within the ~10% ... | physics |
6,106 | Blazar nuclei in radio-loud narrow-line Seyfert 1? | astro-ph.HE | It has been suggested that some radio-loud narrow-line Seyfert 1 contain
relativistic jets, on the basis of their flat-spectrum radio nuclei and studies
on variability. We present preliminary results of an ongoing investigation of
the X-ray and multiwavelength properties of 5 radio-loud NLS1 based on archival
data from... | physics |
6,107 | Ultra High Energy Cosmic Ray Protons: Signatures and Observations | astro-ph.HE | The status of the Greisen-Zatsepin-Kuzmin (GZK) cutoff and pair-production
dip in Ultra High Energy Cosmic Rays (UHECR) is discussed.They are the features
in the spectrum of protons propagating through CMB radiation in extragalactic
space, and discovery of these features implies that primary particles are
mostly extrag... | physics |
6,108 | Evidence for an anticorrelation between the duration of the shallow decay phase of GRB X-ray afterglows and redshift | astro-ph.HE | One of the most intriguing features discovered by Swift is a plateau phase in
the X-ray flux decay of about 70% of the afterglows of gamma-ray bursts (GRBs).
The physical origin of this feature is still being debated. We constrain the
proposed interpretations, based on the intrinsic temporal properties of the
plateau p... | physics |
6,109 | The new intermediate long bursting source XTE J1701-407 | astro-ph.HE | XTE J1701-407 is a newly discovered X-ray transient source. In this work we
investigate its flux variability and study the intermediate long and short
bursts discovered by Swift on July 17, and 27, 2008, respectively. So far, only
one intermediate long burst, with a duration of ~18 minutes and ten days later
a short bu... | physics |
6,110 | TeV Gamma-rays from accreting magnetars in massive binaries | astro-ph.HE | We consider the neutron star (NS) of the magnetar type inside the massive
binary system. We determine the conditions under which the matter from the
stellar wind can penetrate the inner magnetosphere of the magnetar. At some
distance from the NS surface, the magnetic pressure can balance the
gravitational pressure of t... | physics |
6,111 | Toward explanation of the X-ray - radio correlation in the Vela pulsar | astro-ph.HE | Recent observations of the Vela pulsar have revealed a peculiar connection of
its emission in the soft X-ray and radio ranges. We suggest the model of the
radio pulse formation in the Vela pulsar, develop the theory of the radio
photon reprocessing to high energies and on this basis interpret the observed
X-ray - radio... | physics |
6,112 | The Dependence of Spectral State Transition and Disk Truncation on Viscosity Parameter $α | astro-ph.HE | A wealth of Galactic accreting X-ray binaries have been observed both in
low/hard state and high/soft state. The transition between these two states was
often detected. Observation shows that the transition luminosity between these
two states is different for different sources, ranging from 1% to 4% of the
Eddington lu... | physics |
6,113 | Swift GRBs and the blast wave model | astro-ph.HE | The complex structure of the light curves of Swift GRBs has made their
interpretation and that of the blast wave caused by the burst, more difficult
than in the pre-Swift era. We aim to constrain the blast wave parameters:
electron energy distribution, p, density profile of the circumburst medium, k,
and the continued ... | physics |
6,114 | Is the Rapid Decay Phase from High Latitude Emission? | astro-ph.HE | There is good observationnal evidence that the Steep Decay Phase (SDP) that
is observed in most Swift GRBs is the tail of the prompt emission. The most
popular model to explain the SDP is Hight Latitude Emission (HLE). Many models
for the prompt emission give rise to HLE, like the popular internal shocks (IS)
model, bu... | physics |
6,115 | An Intermediate Luminosity Transient in NGC300: The Eruption of a Dust-Enshrouded Massive Star | astro-ph.HE | [abridged] We present multi-epoch high-resolution optical spectroscopy,
UV/radio/X-ray imaging, and archival Hubble and Spitzer observations of an
intermediate luminosity optical transient recently discovered in the nearby
galaxy NGC300. We find that the transient (NGC300 OT2008-1) has a peak absolute
magnitude of M_bo... | physics |
6,116 | The early phase of a H1743-322 outburst observed by INTEGRAL, RXTE, Swift, and XMM/Newton | astro-ph.HE | We investigate the early phase of the first state change during the 2008
September-November outburst of H1743-322, first detected by the INTEGRAL
satellite. We analyse INTEGRAL, RXTE, Swift, and XMM/Newton observations, which
provide coverage of the quiescence to outburst evolution in the 3-200 keV range
every few days... | physics |
6,117 | Hypernova and Gamma-Ray Burst Remnants as TeV Unidentified Sources | astro-ph.HE | We investigate hypernova (hyper-energetic supernova) and gamma-ray burst
(GRB) remnants in our Galaxy as TeV gamma-ray sources, particularly in the role
of potential TeV unidentified sources, which have no clear counterpart at other
wavelengths. We show that the observed bright sources in the TeV sky could be
dominated... | physics |
6,118 | 3D modelling of the colliding winds in Eta Carinae - evidence for radiative inhibition | astro-ph.HE | The X-ray emission from the super-massive star Eta Carinae is simulated using
a three dimensional model of the wind-wind collision. In the model the
intrinsic X-ray emission is spatially extended and energy dependent. Absorption
due to the unshocked stellar winds and the cooled postshock material from the
primary LBV s... | physics |
6,119 | Study of low energy hadronic interaction models based on BESS observed cosmic ray proton and antiproton spectra at medium high altitude | astro-ph.HE | We study low energy hadronic interaction models based on BESS observed cosmic
ray proton and antiproton spectra at medium high altitude. Among the three
popular low energy interaction models, we find that FLUKA reproduces results of
BESS observations on secondary proton spectrum reasonably well over the whole
observed ... | physics |
6,120 | A Determination of the Spin of the Black Hole Primary in LMC X-1 | astro-ph.HE | The first extragalactic X-ray binary, LMC X-1, was discovered in 1969. In the
1980s, its compact primary was established as the fourth dynamical black-hole
candidate. Recently, we published accurate values for the mass of the black
hole and the orbital inclination angle of the binary system. Building on these
results, ... | physics |
6,121 | Spectral trends in the Very High Energy blazar sample due to EBL absorption | astro-ph.HE | The absorption of gamma-rays in the intergalactic medium due to the EBL
(Extragalactic Background Light) causes the observed blazar spectrum to be
fainter and softer than their intrinsic state. It could thus be expected to see
an effective spectral-softening trend with redshift. No such trend is evident
in the sample o... | physics |
6,122 | On the nature of the AGILE galactic transient sources | astro-ph.HE | The Italian gamma-ray satellite AGILE has recently reported the detection of
some variable high-energy sources likely of galactic origin. These sources do
not have any obvious counterpart at lower energies. We propose that these
sources are produced in proton-dominated jets of galactic microquasars. We
develop a model ... | physics |
6,123 | Narrow Radiative Recombination Continua: A Signature of Ions Crossing the Contact Discontinuity of Astrophysical Shocks | astro-ph.HE | X-rays from planetary nebulae (PNs) are believed to originate from a shock
driven into the fast stellar wind (v ~ 1000 km/s) as it collides with an
earlier circumstellar slow wind (v ~ 10 km/s). In theory, the shocked fast wind
(hot bubble) and the ambient cold nebula can remain separated by magnetic
fields along a sur... | physics |
6,124 | GRB Light Curves in the Relativistic Turbulence Model | astro-ph.HE | Randomly oriented relativistic emitters in a relativistically expanding shell
provides an alternative to internal shocks as a mechanism for producing GRBs'
variable light curves with efficient conversion of energy to radiation. In this
model the relativistic outflow is broken into small emitters moving
relativistically... | physics |
6,125 | The Implications of a High Cosmic-Ray Ionization Rate in Diffuse Interstellar Clouds | astro-ph.HE | Diffuse interstellar clouds show large abundances of H_3^+ which can be
maintained only by a high ionization rate of H_2. Cosmic rays are the dominant
ionization mechanism in this environment, so the large ionization rate implies
a high cosmic-ray flux, and a large amount of energy residing in cosmic rays.
In this pape... | physics |
6,126 | Multiwavelength Observations of Markarian 421 in 2005 - 2006 | astro-ph.HE | Since September 2005, the Whipple 10m Gamma-ray Telescope has been operated
primarily as a blazar monitor. The five Northern Hemisphere blazars that have
already been detected at the Whipple Observatory, Markarian 421, H1426+428,
Markarian 501, 1ES 1959+650 and 1ES 2344+514, are monitored routinely each
night that they... | physics |
6,127 | Is very high energy emission from the BL Lac 1ES 0806+524 centrifugally driven? | astro-ph.HE | We investigate the role of centrifugal acceleration of electrons in producing
the very high energy (VHE) radiation from the BL Lac object 1ES 0806+524,
recently detected by VERITAS. The efficiency of the inverse Compton scattering
(ICS) of the accretion disk thermal photons against rotationally accelerated
electrons is... | physics |
6,128 | Swift observations of IBL and LBL objects | astro-ph.HE | BL Lacs are an enigmatic class of active galactic nuclei (AGNs),
characterized by the non-thermal continuum typically attributed to synchrotron
and inverse Compton emission. Depending on the frequency location of the maxima
of these components, they are subdivided into three subclasses LBLs, IBLs, and
HBLs. We present ... | physics |
6,129 | Extended X-ray emission in radio galaxies: the peculiar case of 3C 305 | astro-ph.HE | Extended X-ray structures are common in Active Galactic Nuclei (AGNs). Here
we present the first case of a Compact Steep Spectrum (CSS) radio galaxy, 3C
305, in which the X-ray radiation appears to be associated with the optical
emission line region, dominated by the [O III]5007. On the basis of a
morphological study, ... | physics |
6,130 | RXTE and BeppoSAX Observations of the Transient X-ray Pulsar XTE J1859+083 | astro-ph.HE | We present observations of the 9.8 s X-ray pulsar XTE J1859+083 made with the
ASM and PCA on board RXTE, and the WFC on board BeppoSAX. The ASM data cover a
12 year time interval and show that an extended outburst occurred between
approximately MJD 50,250 and 50,460 (1996 June 16 to 1997 January 12). The ASM
data exclu... | physics |
6,131 | X-ray emission from GPS and CSS sources | astro-ph.HE | Many X-ray observations of GigaHertz Peaked Spectrum and Compact Steep
Spectrum sources have been made with Chandra X-ray Observatory and XMM-Newton
Observatory over the last few years. The X-ray spectra contribute the important
information to the total energy distribution of the compact radio sources. In
addition the ... | physics |
6,132 | High-energy particle acceleration at the radio-lobe shock of Centaurus A | astro-ph.HE | We present new results on the shock around the southwest radio lobe of
Centaurus A using data from the Chandra Very Large Programme observations. The
X-ray spectrum of the emission around the outer southwestern edge of the lobe
is well described by a single power-law model with Galactic absorption --
thermal models are... | physics |
6,133 | Highly Accelerated Diamagnetic Plasmoids: A New X-ray Production Mechanism for OB Stellar Winds | astro-ph.HE | The observed X-ray source temperature distributions in OB stellar winds, as
determined from high energy resolution Chandra observations, show that the
highest temperatures occur near the star, and then steadily decrease outward
through the wind. To explain this unexpected behavior, we propose a shock model
concept that... | physics |
6,134 | High energy emission from galaxy clusters and particle acceleration due to MHD turbulence | astro-ph.HE | In the next years the FERMI gamma ray telescope and the Cherenkov telescopes
will put very stringent constraints to models of gamma ray emission from galaxy
clusters providing crucial information on relativistic particles in the
inter-galactic-medium. We derive the broad band non-thermal spectrum of galaxy
clusters in ... | physics |
6,135 | GRB Observed by IBIS/PICsIT in the MeV Energy Range | astro-ph.HE | We present the preliminary results of a systematic search for GRB and other
transients in the publicly available data for the IBIS/PICsIT (0.2-10 MeV)
detector on board INTEGRAL. Lightcurves in 2-8 energy bands with time
resolution from 1 to 62.5 ms have been collected and an analysis of spectral
and temporal character... | physics |
6,136 | The canonical Gamma-Ray Bursts and their "precursors" | astro-ph.HE | The fireshell model for Gamma-Ray Bursts (GRBs) naturally leads to a
canonical GRB composed of a proper-GRB (P-GRB) and an afterglow. P-GRBs,
introduced by us in 2001, are sometimes considered "precursors" of the main GRB
event in the current literature. We show in this paper how the fireshell model
leads to the unders... | physics |
6,137 | The canonical Gamma-Ray Bursts: long, "fake"-"disguised" and "genuine" short bursts | astro-ph.HE | The Gamma-Ray Bursts (GRBs) offer the unprecedented opportunity to observe
for the first time the blackholic energy extracted by the vacuum polarization
during the process of gravitational collapse to a black hole leading to the
formation of an electron-positron plasma. The uniqueness of the Kerr-Newman
black hole impl... | physics |
6,138 | Optical pulsations from the anomalous X-ray pulsar 1E 1048.1-5937 | astro-ph.HE | We present high-speed optical photometry of the anomalous X-ray pulsar 1E
1048.1-5937 obtained with ULTRACAM on the 8.2-m Very Large Telescope in June
2007. We detect 1E 1048.1-5937 at a magnitude of i'=25.3+/-0.2, consistent with
the values found by Wang et al. (2008) and hence confirming their conclusion
that the sou... | physics |
6,139 | Gamma-ray burst observations with new generation imaging atmospheric Cerenkov Telescopes in the FERMI era | astro-ph.HE | After the launch and successful beginning of operations of the FERMI
satellite, the topics related to high-energy observations of gamma-ray bursts
have obtained a considerable attention by the scientific community.
Undoubtedly, the diagnostic power of high-energy observations in constraining
the emission processes and ... | physics |
6,140 | Non-thermal transient sources from rotating black holes | astro-ph.HE | Rotating black holes can power the most extreme non-thermal transient
sources. They have a long-duration viscous time-scale of spin-down and produce
non-thermal emissions along their spin-axis, powered by a relativistic
capillary effect. We report on the discovery of exponential decay in BATSE
light curves of long GRBs... | physics |
6,141 | Self-Similar Evolution of Cosmic-Ray Modified Shocks: The Cosmic-Ray Spectrum | astro-ph.HE | We use kinetic simulations of diffusive shock acceleration (DSA) to study the
time-dependent evolution of plane, quasi-parallel, cosmic-ray (CR) modified
shocks. Thermal leakage injection of low energy CRs and finite Alfv\'en wave
propagation and dissipation are included. Bohm diffusion as well as the
diffusion with th... | physics |
6,142 | Cosmic Rays VI - Starburst galaxies at multiwavelengths | astro-ph.HE | We propose an explanation for the far-infrared/radio correlation of galaxies
in terms of the energy balance of the interstellar medium and determine the
flux from high-energy photons and neutrinos from starburst galaxies. We present
a catalog of the 127 brightest starburst galaxies with redshifts of z<0.03. In
order to... | physics |
6,143 | Gamma ray burst triggers at daytime and night-time interface | astro-ph.HE | There is a difference between the solar ionization concentration in the
ionosphere in the daytime and at night-time. At night the E-region ion
concentration peak is dramatically reduced due to chemical losses and the rapid
change in the vertical polarization electric field at the time around sunset,
which is due to the... | physics |
6,144 | Fast TeV variability in blazars: jets in a jet | astro-ph.HE | The fast TeV variability of the blazars Mrk 501 and PKS 2155--304 implies a
compact emitting region that moves with a bulk Lorentz factor of Gamma_{em}~100
toward the observer. The Lorentz factor is clearly in excess of the jet Lorentz
factors Gamma_j\simless 10 measured on sub-pc scales in these sources. We
propose th... | physics |
6,145 | XMM-Newton and Suzaku analysis of the Fe K complex in the Seyfert 1 galaxy Mrk 509 | astro-ph.HE | We report on partially overlapping XMM-Newton (~260 ks) and Suzaku (~100 ks)
observations of the iron K band in the nearby, bright Seyfert 1 galaxy Mrk 509.
The source shows a resolved neutral Fe K line, most probably produced in the
outer part of the accretion disc. Moreover, the source shows further emission
blue-war... | physics |
6,146 | GRS 1915+105 in "Soft State": Nature of Accretion Disk Wind and Origin of X-Ray Emission | astro-ph.HE | We present the results from simultaneous Chandra HETGS and RXTE observations
of the microquasar GRS 1915+105 in its quasi-stable "soft state" (or State A)
performed on 2007 August 14, several days after the state transition from "hard
state" (State C). The X-ray flux increased with spectral hardening around the
middle ... | physics |
6,147 | Spatio-Kinematic Structure at the Base of the [Fe II] Jets From L1551 IRS 5 | astro-ph.HE | We present observational results of the [Fe II] 1.644 um emission from the
jets of L1551 IRS 5. The data sets were obtained through 13 fully sampled slits
aimed at the base of the jets. These sets are used to construct a
three-dimensional cube. The field of view was 5."8 X 4."2. We confirmed that
the position of the kn... | physics |
6,148 | Naked-eye optical flash from GRB 080319B: Tracing the decaying neutrons in the outflow | astro-ph.HE | For an unsteady baryonic gamma-ray burst (GRB) outflow, the fast and slow
proton shells collide with each other and produce energetic soft gamma-ray
emission. If the outflow has a significant neutron component, the
ultra-relativistic neutrons initially expand freely until decaying at a larger
radius. The late time prot... | physics |
6,149 | 3D numerical model of the Omega Nebula (M17): simulated thermal X-ray emission | astro-ph.HE | We present 3D hydrodynamical simulations of the superbubble M17, also known
as the Omega nebula, carried out with the adaptive grid code yguazu'-a, which
includes radiative cooling. The superbubble is modelled considering the winds
of 11 individual stars from the open cluster inside the nebula (NGC 6618), for
which the... | physics |
6,150 | A spectacular giant arc in the massive cluster lens MACSJ1206.2-0847 | astro-ph.HE | We discuss the X-ray and optical properties of the massive galaxy cluster
MACSJ1206.2-0847 (z=0.4385), discovered in the Massive Cluster Survey (MACS).
Our Chandra observation of the system yields a total X-ray luminosity of 2.4 x
10^45 erg/s (0.1-2.4 keV) and a global gas temperature of (11.6 +/- 0.7) keV,
very high v... | physics |
6,151 | The XMM-Newton X-ray emission of the SNR N120 in the LMC | astro-ph.HE | We present new XMM-Newton observations of the supernova remnant N120 in the
LMC, and numerical simulations on the evolution of this supernova remnant which
we compare with the X-ray observations. The supernova remnant N120, together
with several HII regions, forms a large nebular complex5D (also called N120)
whose shap... | physics |
6,152 | Monte-Carlo studies of the angular resolution of a future Cherenkov gamma-ray telescope | astro-ph.HE | The current generation of Imaging Atmospheric telescopes (IACTs) has
demonstrated the power of this observational technique, providing high
sensitivity and an angular resolution of $\sim0.1^{\circ}$ per event above an
energy threshold of $\sim$100 GeV. Planned future arrays of IACTs such as AGIS
or CTA are aiming at si... | physics |
6,153 | Simulation studies of the high-energy component of a future imaging Cherenkov telescope array | astro-ph.HE | The current generation of Imaging Atmospheric telescopes (IACTs) has
demonstrated the power of the technique in an energy range between ~100 GeV up
to several tens of TeV. At the high-energy end, these instruments are limited
by photon statistics. Future arrays of IACTs such as CTA or AGIS are planned to
push into the ... | physics |
6,154 | H.E.S.S. observations of gamma-ray bursts in 2003-2007 | astro-ph.HE | Very-high-energy (VHE; >~100 GeV) gamma-rays are expected from gamma-ray
bursts (GRBs) in some scenarios. Exploring this photon energy regime is
necessary for understanding the energetics and properties of GRBs. GRBs have
been one of the prime targets for the H.E.S.S. experiment, which makes use of
four Imaging Atmosph... | physics |
6,155 | The unusual X-ray light-curve of GRB 080307: the onset of the afterglow? | astro-ph.HE | Swift-detected GRB 080307 showed an unusual smooth rise in its X-ray
light-curve around 100 seconds after the burst, at the start of which the
emission briefly softened. This `hump' has a longer duration than is normal for
a flare at early times and does not demonstrate a typical flare profile. Using
a two component po... | physics |
6,156 | From outburst to quiescence: the decay of the transient Anomalous X-ray Pulsar XTE J1810-197 | astro-ph.HE | XTE J1810-197 is the first transient Anomalous X-ray Pulsar ever discovered.
Its highly variable X-ray flux allowed us to study the timing and spectral
emission properties of a magnetar candidate over a flux range of about two
orders of magnitude. We analyzed nine XMM-Newton observations of XTE J1810-197
collected over... | physics |
6,157 | Discovery of a broad iron line in the black-hole candidate Swift J1753.5-0127, and the disk emission in the low/hard state revisited | astro-ph.HE | We analyzed simultaneous archival XMM-Newton and RXTE observations of the
X-ray binary and black hole candidate Swift J1753.5-0127. In a previous
analysis of the same data a soft thermal component was found in the X-ray
spectrum, and the presence of an accretion disk extending close to the
innermost stable circular orb... | physics |
6,158 | X-ray and optical study of the new SMC X-ray binary pulsar system SXP7.92 and its probable optical counterpart, AzV285 | astro-ph.HE | Optical and X-ray observations are presented here of a newly reported X-ray
transient system in the Small Magellanic Cloud - SXP7.92. A detailed analysis
of the X-ray data reveal a coherent period of 7.9s. A search through earlier
X-ray observations of the SMC reveal a previously unknown earlier detection of
this syste... | physics |
6,159 | The XMM-Newton wide-field survey in the COSMOS field. The point-like X-ray source catalogue | astro-ph.HE | The COSMOS survey is a multiwavelength survey aimed to study the evolution of
galaxies, AGN and the large scale structure. The XMM-COSMOS is a deep X-ray
survey over the full 2 deg2 of the COSMOS area. It consists of 55 XMM-Newton
pointings for a total exposure of ~1.5 Ms with an average vignetting corrected
depth of 4... | physics |
6,160 | Monte-Carlo simulations of the broadband X-ray continuum of SS433 | astro-ph.HE | We develop a Monte-Carlo technique based on L.B. Lucy's indivisible photon
packets method to calculate X-ray continuum spectra of comptonized thermal
plasma in arbitrary geometry and apply it to describe the broadband X-ray
continuum of the galactic superaccreting microquasar SS433 observed by
INTEGRAL. A physical mode... | physics |
6,161 | Search for photons at the Pierre Auger Observatory | astro-ph.HE | The Pierre Auger Observatory has a unique potential to search for ultra-high
energy photons (above ~1 EeV). First experimental limits on photons were
obtained during construction of the southern part of the Observatory.
Remarkably, already these limits have proven useful to falsify proposals about
the origin of cosmic ... | physics |
6,162 | Probes of Diffusive Shock Acceleration using Gamma-Ray Burst Prompt Emission | astro-ph.HE | The principal paradigm for gamma-ray bursts (GRBs) suggests that the prompt
transient gamma-ray signal arises from multiple shocks internal to the
relativistic expansion. This paper explores how GRB prompt emission spectra can
constrain electron (or ion) acceleration properties at the relativistic shocks
that pertain t... | physics |
6,163 | Particle Acceleration in Relativistic Magnetized Collisionless Pair Shocks: Dependence of Shock Acceleration on Magnetic Obliquity | astro-ph.HE | We investigate shock structure and particle acceleration in relativistic
magnetized collisionless pair shocks by means of 2.5D and 3D particle-in-cell
simulations. We explore a range of inclination angles between the pre-shock
magnetic field and the shock normal. We find that only magnetic inclinations
corresponding to... | physics |
6,164 | The GeV to TeV view of SNR IC443: predictions for Fermi | astro-ph.HE | We present a theoretical model that explains the high energy phenomenology of
the neighborhood of SNR IC 443, as observed with the Major Atmospheric Gamma
Imaging Cherenkov (MAGIC) telescope and the Energetic Gamma-Ray Experiment
Telescope (EGRET). We also discuss how the model can be tested with
observations by the Fe... | physics |
6,165 | Evolution of the cosmic ray anisotropy above 10^{14} eV | astro-ph.HE | The amplitude and phase of the cosmic ray anisotropy are well established
experimentally between 10^{11} eV and 10^{14} eV. The study of their evolution
into the energy region 10^{14}-10^{16} eV can provide a significant tool for
the understanding of the steepening ("knee") of the primary spectrum. In this
letter we ex... | physics |
6,166 | QPOs from Random X-ray Bursts around Rotating Black Holes | astro-ph.HE | We continue our earlier studies of quasi-periodic oscillations (QPOs) in the
power spectra of accreting, rapidly-rotating black holes that originate from
the geometric "light echoes" of X-ray flares occurring within the black hole
ergosphere. Our present work extends our previous treatment to
three-dimensional photon e... | physics |
6,167 | Investigating the Possibility of Screening High-z GRBs based on BAT Prompt Emission Properties | astro-ph.HE | Being able to quickly select among gamma-ray bursts (GRBs) seen by the Swift
satellite those which are high-z candidates would give ground-based observers a
better chance to determine a redshift for such distant GRBs. Information about
these high-z GRBs is important in helping to resolve questions about the early
unive... | physics |
6,168 | Determining the Distance of Cyg X-3 with its X-ray Dust Scattering Halo | astro-ph.HE | Using a cross-correlation method, we study the X-ray halo of Cyg X-3. Two
components of dust distributions are needed to explain the time lags derived by
the cross-correlation method. Assuming the distance as 1.7 kpc for Cygnus OB2
association (a richest OB association in the local Galaxy) and another uniform
dust dist... | physics |
6,169 | A Model of Magnetically Induced Disc-Corona for Black Hole Binaries | astro-ph.HE | We propose a model of magnetic connection (MC) of a black hole with its
surrounding accretion disc based on large-scale magnetic field. The MC gives
rise to transport of energy and angular momentum between the black hole and the
disc, and the closed field lines pipe the hot matter evaporated from the disc,
and shape it... | physics |
6,170 | Physical properties of amorphous solid interstellar material from X-ray absorption spectroscopy of Sco X-1 | astro-ph.HE | High quality, high resolution X-ray spectra were obtained of Sco X-1 with the
Reflection Grating Spectrometer (RGS) on board the XMM-Newton satellite. The
spectrum around the Oxygen K-edge is searched for signatures indicative for
EXAFS. Analysis shows a clear indication for the existence of EXAFS with
photo-electron s... | physics |
6,171 | The angular resolution of the Pierre Auger Observatory | astro-ph.HE | We discuss the angular resolution obtained for events registered with the
surface detector alone and for hybrid events, i.e., those observed
simultaneously by both the surface and fluorescence detectors. The angular
accuracy of the surface detector is directly extracted from the data itself and
on an event by event bas... | physics |
6,172 | Broad relativistic iron emission line observed in SAX J1808.4-3658 | astro-ph.HE | During the September-October 2008 outburst of the accreting millisecond
pulsar SAX J1808.4-3658, the source was observed by both Suzaku and XMM-Newton
approximately 1 day apart. Spectral analysis reveals a broad relativistic Fe
K-alpha emission line which is present in both data-sets, as has recently been
reported for ... | physics |
6,173 | 3C 33: another case of photoionized soft X-ray emission in radio galaxies | astro-ph.HE | All the observations available in the Chandra and XMM-Newton archives have
been used to investigate the X-ray spectral properties of 3C 33. In this paper
is presented a complete X-ray analysis of the nuclear emission of this narrow
line radio galaxy. The broad band spectrum of 3C 33 is complex. The hard part
resembles ... | physics |
6,174 | Mass Composition Studies of the Highest Energy Cosmic Rays | astro-ph.HE | The determination of the mass composition of the highest energy cosmic rays
is one of the greatest challenges in cosmic ray experiments. The highest energy
cosmic rays are only detected indirectly because of their very low flux. Using
the atmosphere as a large target, Air Fluorescence Detectors are capable of
tracing t... | physics |
6,175 | The Synchrotron Emission Mechanism in the Recently Detected Very High Energy Radiation from the Crab Pulsar | astro-ph.HE | Interpretation of the recently discovered very high energy (VHE) pulsed
emission from the Crab pulsar is presented. By taking into account the fact
that Crab pulsar's radiation for the optical and VHE spectrum peak at the same
phases, we argue that the source of this broad band emission is spatially
localized. It is sh... | physics |
6,176 | A Multi-Wavelength Study of the High Surface Brightness Hotspot in PKS1421-490 | astro-ph.HE | Long Baseline Array imaging of the z=0.663 broad line radio galaxy
PKS1421-490 reveals a 400 pc diameter high surface brightness hotspot at a
projected distance of approximately 40kpc from the active galactic nucleus. The
isotropic X-ray luminosity of the hotspot, L_{2-10 keV} = 3 10^{44} ergs/s, is
comparable to the i... | physics |
6,177 | A New Paradigm for Gamma Ray Bursts: Long Term Accretion Rate Modulation by an External Accretion Disk | astro-ph.HE | We present a new way of looking at the very long term evolution of GRBs in
which the disk of material surrounding the putative black hole powering the GRB
jet modulates the mass flow, and hence the efficacy of the process that
extracts rotational energy from the black hole and inner accretion disk. The
pre-Swift paradi... | physics |
6,178 | VLT/NACO near-infrared observations of the transient radio magnetar 1E 1547.0-5408 | astro-ph.HE | Despite about a decade of observations, very little is known about the
optical and infrared (IR) emission properties of the Soft Gamma-ray Repeaters
(SGRs) and of the Anomalous X-ray Pulsars (AXPs), the magnetar candidates, and
about the physical processes which drive their emission at these wavelengths.
This is mainly... | physics |
6,179 | A statistical study of gamma-ray burst afterglows measured by the Swift Ultra-violet Optical Telescope | astro-ph.HE | We present the first statistical analysis of 27 UVOT optical/ultra-violet
lightcurves of GRB afterglows. We have found, through analysis of the
lightcurves in the observer's frame, that a significant fraction rise in the
first 500s after the GRB trigger, that all lightcurves decay after 500s,
typically as a power-law w... | physics |
6,180 | A Search for Three and Four Point Correlation in HiRes Stereo Data | astro-ph.HE | In this paper we investigate the possible existence of multi-point
correlation in the arrival direction of the UHECR events detected by the High
Resolution Fly's Eye (HiRes) stereo detector. Multi-point correlations could
result from the deflection of UHECRs by galactic and intergalactic magnetic
fields, and the subseq... | physics |
6,181 | The XMM-Newton long look of NGC 1365: lack of a high/soft state in its ultraluminous X-ray sources | astro-ph.HE | Based on our long (~ 300 ks) 2007 XMM-Newton observation of the Seyfert
galaxy NGC 1365, we report here on the spectral and timing behaviour of two
ultraluminous X-ray sources, which had previously reached isotropic X-ray
luminosities L_X ~ 4 x 10^{40} erg/s (0.3-10 keV band). In 2007, they were in a
lower state (L_X ~... | physics |
6,182 | Magnetized Relativistic Jets and Long-Duration GRBs from Magnetar Spindown during Core-Collapse Supernovae | astro-ph.HE | We use ideal axisymmetric relativistic magnetohydrodynamic simulations to
calculate the spindown of a newly formed millisecond, B ~ 10^{15} G, magnetar
and its interaction with the surrounding stellar envelope during a
core-collapse supernova (SN) explosion. The mass, angular momentum, and
rotational energy lost by the... | physics |
6,183 | Strange Quarks Nuggets in Space: Charges in Seven Settings | astro-ph.HE | We have computed the charge that develops on an SQN in space as a result of
balance between the rates of ionization by ambient gammas and capture of
ambient electrons. We have also computed the times for achieving that
equilibrium and binding energy of the least bound SQN electrons. We have done
this for seven differen... | physics |
6,184 | Optical spectroscopy and photometry of SAX J1808.4-3658 in outburst | astro-ph.HE | We present phase resolved optical spectroscopy and photometry of V4580
Sagittarii, the optical counterpart to the accretion powered millisecond pulsar
SAX J1808.4-3658, obtained during the 2008 September/October outburst. Doppler
tomography of the N III 4640.64 Bowen blend emission line reveals a focused
spot of emissi... | physics |
6,185 | The Standing Accretion Shock Instability in the Disk around the Kerr Black Hole | astro-ph.HE | This paper is a sequel to our previous work for accretion onto a
Schwarzschild black hole and the so-called standing accretion shock instability
(SASI), in this paper we investigate non-axisymmetric perturbations for a Kerr
black hole. The linear and non-linear phases for the shock evolution are
analyzed in detail by b... | physics |
6,186 | Radiation from relativistic jets in turbulent magnetic fields | astro-ph.HE | Using our new 3-D relativistic electromagnetic particle (REMP) code
parallelized with MPI, we have investigated long-term particle acceleration
associated with an relativistic electron-positron jet propagating in an
unmagnetized ambient electron-positron plasma. The simulations have been
performed using a much longer s... | physics |
6,187 | Some properties of synchrotron radio and inverse-Compton gamma-ray images of supernova remnants | astro-ph.HE | The synchrotron radio maps of supernova remnants (SNRs) in uniform
interstellar medium and interstellar magnetic field (ISMF) are analyzed,
allowing different `sensitivity' of injection efficiency to the shock
obliquity. The very-high energy gamma-ray maps due to inverse Compton process
are also synthesized. The proper... | physics |
6,188 | The cannonball model of long GRBs - overview | astro-ph.HE | During the past ten years, the predictions of the cannonball (CB) model of
gamma ray bursts (GRBs) were repeatedly confronted with the mounting data from
space- and ground-based observations of GRBs and their afterglows (AGs). The
two underlying radiation mechanisms of the model, inverse Compton scattering
(ICS) and sy... | physics |
6,189 | Different types of ultraluminous X-ray sources in NGC 4631 | astro-ph.HE | We have re-examined the most luminous X-ray sources in the starburst galaxy
NGC 4631, using XMM-Newton, Chandra and ROSAT data. The most interesting source
is a highly variable supersoft ULX. We suggest that its bolometric luminosity ~
a few 10^{39} erg/s in the high/supersoft state: this is an order of magnitude
lower... | physics |
6,190 | Geomagnetic origin of the radio emission from cosmic ray induced air showers observed by CODALEMA | astro-ph.HE | The new setup of the CODALEMA experiment installed at the Radio Observatory
in Nancay, France, is described. It includes broadband active dipole antennas
and an extended and upgraded particle detector array. The latter gives access
to the air shower energy, allowing us to compute the efficiency of the radio
array as a ... | physics |
6,191 | Broad-band nonthermal emission from molecular clouds illuminated by cosmic rays from nearby supernova remnants | astro-ph.HE | Molecular clouds are expected to emit non-thermal radiation due to cosmic ray
interactions in the dense magnetized gas. Such emission is amplified if a cloud
is located close to an accelerator of cosmic rays and if energetic particles
can leave the accelerator site and diffusively reach the cloud. We consider
here the ... | physics |
6,192 | Test of the hadronic interaction model EPOS with air shower data | astro-ph.HE | Predictions of the hadronic interaction model EPOS~1.61 as implemented in the
air shower simulation program CORSIKA are compared to observations with the
KASCADE experiment. The investigations reveal that the predictions of EPOS are
not compatible with KASCADE measurements. The discrepancies seen are most
likely due to... | physics |
6,193 | Search for clustering of ultra high energy cosmic rays from the Pierre Auger Observatory | astro-ph.HE | We present the results of a search for clustering among the highest energy
events detected by the surface detector of the Pierre Auger Observatory between
1 January 2004 and 31 August 2007. We analyse the autocorrelation function, in
which the number of pairs with angular separation within a given angle is
compared wit... | physics |
6,194 | MRI channel flows and their parasites | astro-ph.HE | Local simulations of the magnetorotational instability (MRI) in accretion
disks can exhibit recurrent coherent structures called channel flows. The
formation and destruction of these structures may play a role in the
development and saturation of MRI-induced turbulence, and consequently help us
understand the time-depe... | physics |
6,195 | IceCube Science | astro-ph.HE | We discuss the status of the kilometer-scale neutrino detector IceCube and
its low energy upgrade Deep Core and review its scientific potential for
particle physics. We subsequently appraise IceCube's potential for revealing
the enigmatic sources of cosmic rays. After all, this aspiration set the scale
of the instrumen... | physics |
6,196 | Stability of Relativistic Force-Free Jets | astro-ph.HE | We consider a two-parameter family of cylindrical force-free equilibria,
modeled to match numerical simulations of relativistic force-free jets. We
study the linear stability of these equilibria, assuming a rigid impenetrable
wall at the outer cylindrical radius R_j. We find that equilibria in which the
Lorentz factor ... | physics |
6,197 | Efficiency of Magnetic to Kinetic Energy Conversion in a Monopole Magnetosphere | astro-ph.HE | Unconfined relativistic outflows from rotating, magnetized compact objects
are often well-modeled by assuming the field geometry is approximately a
split-monopole at large radii. Earlier work has indicated that such an
unconfined flow has an inefficient conversion of magnetic energy to kinetic
energy. This has led to t... | physics |
6,198 | Thermalization of the mildly relativistic plasma | astro-ph.HE | In the recent Letter [1] we considered the approach of nonequilibrium pair
plasma towards thermal equilibrium state adopting a kinetic treatment and
solving numerically the relativistic Boltzmann equations. It was shown that
plasma in the energy range 0.1-10 MeV first reaches kinetic equilibrium, on a
timescale t_{k}<1... | physics |
6,199 | Indication of Two Classes in the Swift Short Gamma-Ray Bursts from the XRT X-Ray Afterglow Light Curves | astro-ph.HE | We present the discovery of two distinct classes in the Swift short duration
gamma-ray bursts (S-GRBs) from the X-Ray Telescope (XRT) X-ray afterglow light
curve. We find that about 40% of the Swift S-GRBs have an X-ray afterglow light
curves which only lasts less than 10000 seconds after the burst trigger
(hereafter s... | physics |
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