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X-ray flashes (XRFs) are a new type of fast transient source observed with the BeppoSAX Wide Field Cameras (WFC) at a rate of about four per year. Apart from their large fraction of 2-26 keV X-rays, the bulk properties of these events are…

Astrophysics · Physics 2009-11-07 R. M. Kippen , P. M. Woods , J. Heise , J. J. M. in 't Zand , M. S. Briggs , R. D. Preece

We have detected significant X-ray emission from the direction of the young radio pulsar PSR J1105-6107 using the ASCA Observatory. The 11 sigma detection includes 460 background-subtracted source counts derived using data from all four…

Astrophysics · Physics 2009-10-30 E. V. Gotthelf , V. M. Kaspi

Context: In April 2013, the nearby (z=0.031) TeV blazar, Mkn 421, showed one of the largest flares in X-rays since the past decade. Aim: To study all multiwavelength data available during MJD 56392 to 56403, with special emphasis on X-ray…

Astrophysics of Galaxies · Physics 2015-08-12 Atreyee Sinha , Amit Shukla , Ranjeev Misra , Varsha R. Chitnis , A. R. Rao , B. S. Acharya

We performed time-resolved spectroscopy on a sample of 38 single pulses from 37 gamma-ray bursts detected by the Fermi/Gamma-ray Burst Monitor during its first 9 years of mission. For the first time a fully Bayesian approach is applied. A…

High Energy Astrophysical Phenomena · Physics 2020-01-08 Hoi-Fung Yu , Hüsne Dereli-Bégué , Felix Ryde

Detection of prompt emission by Swift-XRT provides a unique tool to study how the prompt spectrum of gamma-ray bursts (GRBs) extends down to the soft X-ray band. This energy band is particularly important for prompt emission studies, since…

High Energy Astrophysical Phenomena · Physics 2018-09-05 Gor Oganesyan , Lara Nava , Giancarlo Ghirlanda , Annalisa Celotti

NASA's Fermi space telescope has provided us with a bountiful new population of gamma-ray sources following its discovery of 150 new gamma-ray pulsars. One common feature exhibited by all of these pulsars is the form of their spectral…

High Energy Astrophysical Phenomena · Physics 2015-03-06 Andrew McCann

We present a detailed analysis of all archival INTEGRAL data of the accreting X-ray pulsar Vela X-1. We extracted lightcurves in several energy bands from 20 keV up to 60 keV. The lightcurves show that the source was found in very active as…

High Energy Astrophysical Phenomena · Physics 2010-04-30 Felix Fürst , Ingo Kreykenbohm , Jörn Wilms , Peter Kretschmar , Dmitry Klochkov , Andrea Santangelo , Rüdiger Staubert

The emission process responsible for the so-called "prompt" emission of gamma-ray bursts is still unknown. A number of empirical models fitting the typical spectrum still lack a satisfactory interpretation. A few GRB spectral catalogues…

High Energy Astrophysical Phenomena · Physics 2011-05-03 C. Guidorzi , M. Lacapra , F. Frontera , E. Montanari , L. Amati , F. Calura , L. Nicastro , M. Orlandini

We present statistical analysis of a fluence limited sample of over 1100 giant pulses from the Crab pulsar, with fluence > 130 Jy ms at ~1330 MHz. These were detected in ~260 hours of observation with the National Centre for Radio…

High Energy Astrophysical Phenomena · Physics 2019-10-01 Apurba Bera , Jayaram N. Chengalur

ROSAT observations indicate that approximately half of all nearby groups of galaxies contain spatially extended X-ray emission. The radial extent of the X-ray emission is typically 50-500 kpc or approximately 10-50% of the virial radius of…

Astrophysics · Physics 2009-10-31 John S. Mulchaey

Until now X-radiation from nine millisecond pulsars has been detected. In the present paper we summarize the observations and show the results of a re-analysis of archival ROSAT data. In addition we present the results of recent…

Astrophysics · Physics 2007-05-23 W. Becker , J. Trümper

Fast Radio Bursts (FRBs) are energetic radio bursts that typically last for milliseconds. They are mostly of extragalactic origin, but the progenitors, trigger mechanisms and radiation processes are still largely unknown. Here we present a…

High Energy Astrophysical Phenomena · Physics 2025-12-03 Nurimangul Nurmamat , Yong-Feng Huang , Xiao-Fei Dong , Chen-Ran Hu , Orkash Amat , Ze-Cheng Zou , Abdusattar Kurban , Jin-Jun Geng , Chen Deng

An intense, short laser pulse incident on a transparent dielectric can excite electrons from valence to the conduction band. As these electrons undergo scattering, both from phonons and ions, they emit bremsstrahlung radiation. Here we…

Plasma Physics · Physics 2017-05-31 G. M. Petrov , J. P. Palastro , J. Peñano

We investigate accelerated electron energy spectra for different sources in a large flare using simultaneous observations obtained with two instruments, the Nobeyama Radio Heliograph (NoRH) at 17 and 34 GHz, and the Reuven Ramaty High…

Solar and Stellar Astrophysics · Physics 2015-05-13 M. R. Kundu , V. V. Grechnev , S. M. White , E. J. Schmahl , N. S. Meshalkina , L. K. Kashapova

The GOES X1.5 class flare that occurred on August 30,2002 at 1327:30 UT is one of the few events detected so far at submillimeter wavelengths. We present a detailed analysis of this flare combining radio observations from 1.5 to 212 GHz (an…

Solar and Stellar Astrophysics · Physics 2015-05-13 C. G. Gimenez de Castro , G. Trottet , A. Silva-Valio , S. Krucker , J. E. R. Costa , P. Kaufmann , E. Correia , H. Levato

This paper presents measurements of the energy radiated by the lower solar atmosphere, at optical, UV, and EUV wavelengths, during an X-class solar flare (SOL2011-02-15T01:56) in response to an injection of energy assumed to be in the form…

Significant improvements in our understanding of nuclear $\gamma$-ray line production and instrument performance allow us to better characterize the continuum emission from electrons at energies $\gtrsim$ 300 keV during solar flares. We…

Solar and Stellar Astrophysics · Physics 2025-02-25 Gerald H. Share , Ronald J. Murphy , Brian R. Dennis , Justin D. Finke

Gamma ray bursts (GRBs) are known to have short-time variability and power-law behavior with the index -1.67 in the power spectrum density. Reanalyzing the expanded data, we have found a) the power-law comes from the global profile of the…

Astrophysics · Physics 2009-11-06 Motoko Suzuki , Masahiro Morikawa , Izumi Joichi

Unsteady activity of gamma-ray burst sources leads to internal shocks in their emergent relativistic wind. We study the emission spectra from such shocks, assuming that they produce a power-law distribution of relativistic electrons and…

Astrophysics · Physics 2009-10-30 Ravi Pilla , Abraham Loeb

Using the HEAO1 A2 full sky, 2-10 keV X-ray map evidence is found for the presence of diffuse X-ray emission in the plane of the local supercluster. Fitting this diffuse component with a simple ``pillbox'' model implies a volume X-ray…

Astrophysics · Physics 2007-05-23 Stephen P. Boughn