http://www.kocevski.com/astro-grb an index of new GRB papers on astro-ph Tue, 07 Sep 2010 07:38:59 +0000 http://backend.userland.com/rss092 en Lixin Xu, Yuting WangIn this paper, a parameterization describing the kinematical state of the universe in cosmographic approach is considered, where the minimum input is the assumption of the cosmological principle, i.e. the Friedmann-Robertson-Walker metric. A distinguished feature is that the result does not depend on any gravity theory. As a result, a series ... http://www.kocevski.com/astro-grb/?p=1536 Szymon Kozlowski, C. S. Kochanek, D. Stern, J. L. Prieto, K. Z. Stanek, T. A. Thompson, R. J. Assef, A. J. Drake, D. M. Szczygiel, P. R. Wozniak, P. Nugent, M. L. N. Ashby, E. Beshore, M. J. I. Brown, Arjun Dey, R. Griffith, F. Harrison, B. T. Jannuzi, S. ... http://www.kocevski.com/astro-grb/?p=1535 Daniel A. Perley, A. N. Morgan, A. Updike, F. Yuan, C. W. Akerlof, A. A. Miller, J. S. Bloom, S. B. Cenko, W. Li, A. V. Filippenko, J. X. Prochaska, D. A. Kann, N. R. Butler, P. Christian, D. H. Hartmann, P. Milne, E. S. Rykoff, W. Rujopakarn, J. C. ... http://www.kocevski.com/astro-grb/?p=1534 R. Margutti, G. Bernardini, R. Barniol Duran, C. Guidorzi, R. F. Shen, G. ChincariniGamma-ray burst X-ray flares are believed to mark the late time activity of the central engine. We compute the temporal evolution of the average flare luminosity $< L >$ in the common rest frame energy band of 44 GRBs ... http://www.kocevski.com/astro-grb/?p=1533 Junichi Aoi, Kohta Murase, Keitaro Takahashi, Kunihito Ioka, Shigehiro NagatakiWe revisit the high-energy spectral cutoff originating from the electron-positron pair creation in the prompt phase of gamma-ray bursts (GRBs) with numerical and analytical calculations. We show that the conventional exponential and/or broken power law cutoff should be drastically modified to a shallower broken power-law ... http://www.kocevski.com/astro-grb/?p=1532 J. M. Castro Cerón (1,2), M. J. Michałowski (1,3), J. Hjorth (1), D. Malesani (1), J. Gorosabel (4), D. Watson (1), J. P. U. Fynbo (1), M. Morales Calderón (5); ((1) Dark Cosmology Centre (NBI) Copenhagen; (2) Herschel Science Centre (ESA/ESAC) Madrid; (3) Institute for Astronomy (ROE) Edinburgh; (4) Instituto ... http://www.kocevski.com/astro-grb/?p=1531 The Fermi LAT, the GBM Collaboration: A. A. Abdo, et al.The Extragalactic Background Light (EBL) includes photons with wavelengths from ultraviolet to infrared, which are effective at attenuating gamma rays with energy above ~10 GeV during propagation from sources at cosmological distances. This results in a redshift- and energy-dependent attenuation of the gamma-ray flux ... http://www.kocevski.com/astro-grb/?p=1530 Z. Mao, Yun-Wei Yu, Z. G. Dai, C. M. Pi, X. P. ZhengContext: Swift observations suggest that the X-ray afterglow emission of some gamma-ray bursts (GRB) may have internal origins, and the conventional external shock (ES) cannot be the exclusive source of the afterglow emission. Aims: If the central compact objects of some ... http://www.kocevski.com/astro-grb/?p=1529 Men-Quan LiuThe steady equilibrium conditions for a mixed gas of neutrons, protons, electrons, positrons and radiation field (abbreviated as $npe^{\pm}$ gas) with/without external neutrino flux are investigated, and a general chemical potential equilibrium equation $\mu_n=\mu_p+C\mu_e$ is obtained to describe the steady equilibrium at high temperatures ($T>10^9$K). An analytic fitting formula of coefficient $C$ is presented ... http://www.kocevski.com/astro-grb/?p=1528 Todd A. Thompson, Brian D. Metzger, Niccolò BucciantiniThe millisecond proto-magnetar model for the central engine of long-duration gamma-ray bursts is briefly reviewed. Limitations and uncertainties in the model are highlighted. A short discussion of the maximum energy, maximum duration, radiative efficiency, jet formation mechanism, late-time energy injection, and (non-)association with supernovae of millisecond magnetar-powered GRBs ... http://www.kocevski.com/astro-grb/?p=1527