Galli 2008 X射线耀发和余辉阶段的高能辐射

主要内容:
以及MAGIC的探测率

精彩摘抄:


文章信息:

arXiv:0805.2884 [ps, pdf, other]

Title: Prospects for detection of very high energy emission from GRB in the context of the External Shock model

Authors: A. Galli, L. Piro (INAF/Isaf-Roma)

Comments: 5 pages, 2 color figures, submitted to A&A letters

Subjects: Astrophysics (astro-ph)

The detection of the 100 GeV-TeV emission by a Gamma-Ray Burst (GRB) will provide an unprecedented opportunity to enlighten the nature of the central engine and the interaction between the relativistic flow and the environment of the burst progenitor. In this paper we show that there are exciting prospects of detecting by MAGIC high energy (HE) emission from the burst during the "early" X-ray flaring activity and, later, during the "normal" afterglow phase. We also identify the best observational strategy (trigger conditions and time period of observation). We determine the expected HE emission from the flaring and afterglow phases of GRBs in the context of the External Shock scenario and compare them with the MAGIC threshold. We find that a X-ray flare with the average properties of the class, can be detected in the 100 GeV range by MAGIC provided that z<1.> a few cm^{-3}. In this case the MAGIC observation shall extend to about 10-20 ksec. We provide recipes to tailor this prediction to the observational properties of each burst, in particular the fluence in the prompt emission and the redshift, thus allowing an almost "real time" decision procedure to decide whether to continue the follow up observation of a burst at late times.

McGlynn 2008 短暴GRB070707的观测

主要内容:
是第一个被INTEGRAL观测到的短暴。

精彩摘抄:


文章信息:

arXiv:0805.2880 [ps, pdf, other]

Title: GRB 070707: the first short gamma-ray burst observed by INTEGRAL

Authors: S. McGlynn (1,2), S. Foley (1), S. McBreen (3), L. Hanlon (1), R. O'Connor (1), A. Martin Carrillo (1), B. McBreen (1) ((1) University College Dublin, (2) Royal Institute of Technology (KTH), Stockholm (3) MPE Garching)

Comments: 7 pages, 3 figures, accepted for publication in A&A

Subjects: Astrophysics (astro-ph)

INTEGRAL has observed 47 long-duration GRBs (T_90 > 2s) and 1 short-duration GRB (T_90 < alpha =" -1.19">~ 25 for GRB 070707, assuming the typical redshift for short GRBs of z=0.35. This limit is consistent with previous estimates for short GRBs and is smaller than the lower limits of Gamma >~ 100 calculated for long GRBs. If GRB 070707 is a member of the recently postulated class of short GRBs at z ~ 1, the lower limit on Gamma increases to Gamma >~ 35.

Kruhler 2008 GRB070802的余辉观测

主要内容:
说可能有dust的信号

精彩摘抄:


文章信息:

arXiv:0805.2824 [ps, pdf, other]

Title: The 2175 A dust feature in a Gamma Ray Burst afterglow at redshift 2.45

Authors: T. Krühler, A. Küpcü Yoldaş, J. Greiner, C. Clemens, S. McBreen, N. Primak, S. Savaglio, A. Yoldaş, G. P. Szokoly

Comments: 21 pages, 3 figures, accepted for publication by ApJ

Subjects: Astrophysics (astro-ph)

We present optical and near-infrared photometry of the afterglow of the long Gamma-Ray Burst GRB 070802 at redshift 2.45 obtained with the ESO/MPI 2.2 m telescope equipped with the multi-channel imager GROND. Follow-up observations in g'r'i'z' and JHK_S bands started ~17 min and extended up to 28 h post burst. We find an increase in brightness of the afterglow at early times, which can be explained by the superposition of reverse and forward shock (FS) emission or the onset of the afterglow FS. Additionally, we detect a strong broad-band absorption feature in the i' band, which we interpret as extinction from the redshifted 2175 A bump in the GRB host galaxy. This is one of the first and clearest detections of the 2175 A feature at high redshift. It is strong evidence for a carbon rich environment, indicating that Milky Way or Large Magellanic Cloud like dust was already formed in substantial amounts in a galaxy at z=2.45.

Sonabas 2008 GRB060218/SN2006aj的超新星阶段的观测

主要内容:
可以看到星风包层的信号。

精彩摘抄:


文章信息:

arXiv:0805.2657 [ps, pdf, other]

Title: The stellar-wind envelope around the supernova XRF/GRB060218/SN2006aj massive progenitor star

Authors: E. Sonbas, A.S. Moskvitin, T.A. Fatkhullin, V.V. Sokolov, A. Castro-Tirado, A. de Ugarte Postigo, J. Gorosabel, S. Guziy, M. Jelinek, T.N. Sokolova, V.N. Chernenkov

Comments: 26 pages, 7 figures, 3 tables, Accepted for publication in Astrophysical Bulletin, 2008, v. 63, No 3

Subjects: Astrophysics (astro-ph)

In BTA spectra of the supernova SN2006aj, identified with the X-ray flash (XRF) and gamma-ray burst XRF/GRB060218/SN2006aj, we detected details interpreted as hydrogen lines, which is a sign of stellar-wind envelope around a massive progenitor star of the gamma-ray burst. Results of modeling two early spectra obtained with the BTA in 2.55 and 3.55 days after the explosion of Type Ic supernova SN2006aj (z=0.0331) are presented. The spectra were modeled in the Sobolev approximation with the SYNOW code (Branch et al. 2001; Elmhamdi et al. 2006). In the spectra of the optical afterglow of the X-ray flash XRF/GRB060218 we detected spectral features interpreted as (1) the H_alpha PCyg profile for the velocity 33000 km s$^{-1}$ -- a wide and almost unnoticeable deformation of continuum in the range of $\simeq5600 - 6600\AA$ for the first epoch (2.55 days) and (2) a part (``remnant'') of the H_alpha PCyg profile in absorption blueshifted by 24000 km s$^{-1}$ -- a wide spectral feature with a minimum at $\simeq6100\AA$ (the rest wavelength) for the second epoch (3.55 days). Taking into consideration early BTA observations and spectra obtained with other telescopes (ESO Lick, ESO VLT, NOT) before 2006 Feb. 23 UT, it can be said that we observe evolution of optical spectra of Type Ic core-collapse supernova SN 2006aj during {\it transition} from the short phase related to the shock breakout to outer layers of the stellar-wind envelope to spectra of the phase of increasing brightness corresponding to radioactive heating. Signs of hydrogen in spectra of the gamma-ray burst afterglow were detected for the first time.

Perley 2008 GRB 071003的观测

主要内容:


精彩摘抄:


文章信息:

· arXiv e-print (arXiv:0805.2394)

· References in the Article

·

· Translate This Page

Title:		GRB 071003: Broadband Follow-up Observations of a Very Bright Gamma-Ray Burst in a Galactic Halo
Authors:		Perley, D. A.; Li, W.; Chornock, R.; Prochaska, J. X.; Butler, N. R.; Chandra, P.; Pollack, L. K.; Bloom, J. S.; Filippenko, A. V.; Akerlof, C.; Auger, M. W.; Cenko, S. B.; Chen, H. -W.; Fassnacht, C. D.; Fox, D.; Frail, D.; Johansson, E. M.; Le Mignant, D.; Modjaz, M.; Skinner, M. A.; Smith, G. H.; Swan, H.; van Dam, M. A.; Yuan, F.
Publication:		eprint arXiv:0805.2394
Publication Date:		05/2008
Origin:		ARXIV
Keywords:		Astrophysics
Comment:		Submitted to astro-ph
Bibliographic Code:		2008arXiv0805.2394P

Abstract

The optical afterglow of long-duration gamma-ray burst (GRB) 071003 is among the brightest yet to be detected from any GRB, with R ~ 12 mag in Katzman Automatic Imaging Telescope observations starting 42 s after the GRB trigger, including filtered detections during prompt emission. However, our high signal-to-noise ratio afterglow spectrum displays only extremely weak absorption lines at what we argue is the host redshift of z=1.60435 - in contrast to the three other, much stronger Mg II absorption systems observed at lower redshifts. Together with Keck Adaptive Optics observations which fail to reveal a host galaxy coincident with the burst position, our observations suggest a halo progenitor and offer a cautionary tale about the use of Mg II for GRB redshift determination. We present early through late-time observations spanning the electromagnetic spectrum, constrain the connection between the prompt emission and early variations in the light curve (we observe no correlation), and discuss possible origins for an unusual, marked rebrightening that occurs a few hours after the burst: likely either a late-time refreshed shock or a wide-angle secondary jet. Analysis of the late-time afterglow is most consistent with a wind environment, suggesting a massive star progenitor. Together with GRB 070125, this may indicate that a small but significant portion of star formation in the early universe occurred far outside what we consider a normal galactic disk.

---

Bibtex entry for this abstract Preferred format for this abstract (see Preferences)

Koers 2008 伽玛暴中的中微子产生

主要内容:


精彩摘抄:


文章信息:

· arXiv e-print (arXiv:0805.2514)

· References in the Article

·

· Translate This Page

Title:		Neutrino production in nucleonic interactions in gamma-ray bursters
Authors:		Koers, Hylke B. J.
Publication:		eprint arXiv:0805.2514
Publication Date:		05/2008
Origin:		ARXIV
Keywords:		Astrophysics
Comment:		6 pages, no figures. Contribution to the Rencontres de Moriond 2008 (Electroweak session), La Thuile, Italy, 1-8 March 2008
Bibliographic Code:		2008arXiv0805.2514K

Abstract

Neutrinos produced in gamma-ray bursters (GRBers) may provide a unique probe for the physics of these extreme astrophysical systems. Here we discuss neutrino production in inelastic neutron-proton collisions within the relativistic outflows associated with GRBers. We consider both the widely used fireball model and a recently proposed magneto-hydrodynamic (MHD) model for the GRB outflow.

---

Bibtex entry for this abstract Preferred format for this abstract

Mirabel 2008 微类星体综述

主要内容:
微类星体小综述。

精彩摘抄:


文章信息:
arXiv e-print (arXiv:0805.2378)
· References in the Article
·
· Translate This Page
Title:
Microquasars: summary and outlook
Authors:
Mirabel, I. F.
Publication:
eprint arXiv:0805.2378
Publication Date:
05/2008
Origin:
ARXIV
Keywords:
Astrophysics
Comment:
Review based on courses given at international schools for graduate students and post-docs; 13 pages, 7 color figures
Bibliographic Code:
2008arXiv0805.2378M
AbstractMicroquasars are compact objects (stellar-mass black holes and neutron stars) that mimic, on a smaller scale, many of the phenomena seen in quasars. Their discovery provided new insights into the physics of relativistic jets observed elsewhere in the universe, and in particular, the accretion-jet coupling in black holes. Microquasars are opening new horizons for the understanding of ultraluminous X-ray sources observed in external galaxies, gamma-ray bursts of long duration, and the origin of stellar black holes and neutron stars. Microquasars are one of the best laboratories to probe General Relativity in the limit of the strongest gravitational fields, and as such, have become an area of topical interest for both high energy physics and astrophysics. At present, back hole astrophysics exhibits historical and epistemological similarities with the origins of stellar astrophysics in the last century.
Bibtex entry for this abstract Preferred format for this abstract (see Preferences)

Fan 2008 伽玛暴的高能辐射

主要内容:
综述了伽玛暴的高能辐射的产生机制。

精彩摘抄:


文章信息:
· arXiv e-print (arXiv:0805.2221)
· References in the Article
·
· Translate This Page
Title:
High energy gamma-ray emission from Gamma-Ray Bursts -- before GLAST
Authors:
Fan, Yi-Zhong; Piran, Tsvi
Publication:
eprint arXiv:0805.2221
Publication Date:
05/2008
Origin:
ARXIV
Keywords:
Astrophysics
Comment:
An invited review article for Front. Phys. China. (Possible prompt and very early GeV-TeV emission from GRB 080319B are discussed in Sec. V)
Bibliographic Code:
2008arXiv0805.2221F
AbstractGamma-ray bursts (GRBs) are short and intense emission of soft gamma-rays, which have fascinated astronomers and astrophysicists since their unexpected discovery in 1960s. The X-ray/optical/radio afterglow observations confirm the cosmological origin of GRBs, support the fireball model, and imply a long-activity of the central engine. The high energy gamma-ray emission (>20 MeV) from GRBs is particularly important because they shed some lights on the radiation mechanisms and can help us to constrain the physical processes giving rise to the early afterglows. In this work, we review observational and theoretical studies of the high energy emission from GRBs. Special attention is given to the expected high energy emission signatures accompanying the canonical early-time X-ray afterglow that was observed by the Swift X-ray Telescope. We also discuss the detection prospect of the upcoming GLAST satellite and the current ground-based Cerenkov detectors.
Bibtex entry for this abstract Preferred format for this abstract

Racusin 2008 GRB 080319B的观测

主要内容:
Swift组的文章

精彩摘抄:


文章信息:

· arXiv e-print (arXiv:0805.1557)

· References in the Article

·

· Translate This Page

Title:		GRB 080319B: A Naked-Eye Stellar Blast from the Distant Universe
Authors:		Racusin, J. L.; Karpov, S. V.; Sokolowski, M.; Granot, J.; Wu, X. F.; Pal'shin, V.; Covino, S.; van der Horst, A. J.; Oates, S. R.; Schady, P.; Smith, R. J.; Cummings, J.; Starling, R. L. C.; Piotrowski, L. W.; Zhang, B.; Evans, P. A.; Holland, S. T.; Malek, K.; Page, M. T.; Vetere, L.; Margutti, R.; Guidorzi, C.; Kamble, A.; Curran, P. A.; Beardmore, A.; Kouveliotou, C.; Mankiewicz, L.; Melandri, A.; O'Brien, P. T.; Page, K. L.; Piran, T.; Tanvir, N. R.; Wrochna, G.; Aptekar, R. L.; Bartolini, C.; Barthelmy, S.; Beskin, G. M.; Bondar, S.; Campana, S.; Cucchiara, A.; Cwiok, M.; D'Avanzo, P.; D'Elia, V.; Della Valle, M.; Dominik, W.; Falcone, A.; Fiore, F.; Fox, D. B.; Frederiks, D. D.; Fruchter, A. S.; Fugazza, D.; Garrett, M.; Gehrels, N.; Golenetskii, S.; Gomboc, A.; Greco, G.; Guarnieri, A.; Immler, S.; Kasprowicz, G.; Levan, A. J.; Mazets, E. P.; Molinari, E.; Moretti, A.; Nawrocki, K.; Oleynik, P. P.; Osborne, J. P.; Pagani, C.; Paragi, Z.; Perri, M.; Piccioni, A.; Ramirez-Ruiz, E.; Roming, P. W. A.; Steele, I. A.; Strom, R. G.; Testa, V.; Tosti, G.; Ulanov, M. V.; Wiersema, K.; Wijers, R. A. M. J.; Zarnecki, A. F.; Zerbi, F.; Meszaros, P.; Chincarini, G.; Burrows, D. N.
Publication:		eprint arXiv:0805.1557
Publication Date:		05/2008
Origin:		ARXIV
Keywords:		Astrophysics
Comment:		43 pages, 18 figures, 3 tables, submitted to Nature May 11, 2008
Bibliographic Code:		2008arXiv0805.1557R

Abstract

Long duration gamma-ray bursts (GRBs) release copious amounts of energy across the entire electromagnetic spectrum, and so provide a window into the process of black hole formation from the collapse of a massive star. Over the last forty years, our understanding of the GRB phenomenon has progressed dramatically; nevertheless, fortuitous circumstances occasionally arise that provide access to a regime not yet probed. GRB 080319B presented such an opportunity, with extraordinarily bright prompt optical emission that peaked at a visual magnitude of 5.3, making it briefly visible with the naked eye. It was captured in exquisite detail by wide-field telescopes, imaging the burst location from before the time of the explosion. The combination of these unique optical data with simultaneous gamma-ray observations provides powerful diagnostics of the detailed physics of this explosion within seconds of its formation. Here we show that the prompt optical and gamma-ray emissions from this event likely arise from different spectral components within the same physical region located at a large distance from the source, implying an extremely relativistic outflow. The chromatic behaviour of the broadband afterglow is consistent with viewing the GRB down the very narrow inner core of a two-component jet that is expanding into a wind-like environment consistent with the massive star origin of long GRBs. These circumstances can explain the extreme properties of this GRB.

---

Bibtex entry for this abstract Preferred format for this abstract (see Preferences)

Morgan 2008 Optimal Coaddition技术观测快速变暗的余辉

主要内容:


精彩摘抄:


文章信息:

· arXiv e-print (arXiv:0805.1426)

· References in the Article

·

· Translate This Page

Title:		Optimal Coaddition of Imaging Data for Rapidly Fading Gamma-Ray Burst Afterglows
Authors:		Morgan, A. N.; Vanden Berk, D. E.; Roming, P. W. A.; Nousek, J. A.; Koch, T. S.; Breeveld, A. A.; de Pasquale, M.; Holland, S. T.; Kuin, N. P. M.; Page, M. J.; Still, M.
Publication:		eprint arXiv:0805.1426
Publication Date:		05/2008
Origin:		ARXIV
Keywords:		Astrophysics
Comment:		17 pages, accepted for publication in ApJ
Bibliographic Code:		2008arXiv0805.1426M

Abstract

We present a technique for optimal coaddition of image data for rapidly varying sources, with specific application to gamma-ray burst (GRB) afterglows. Unweighted coaddition of rapidly fading afterglow lightcurve data becomes counterproductive relatively quickly. It is better to stop coaddition of the data once noise dominates late exposures. A better alternative is to optimally weight each exposure to maximize the signal-to-noise ratio (S/N) of the final coadded image data. By using information about GRB lightcurves and image noise characteristics, optimal image coaddition increases the probability of afterglow detection and places the most stringent upper limits on non-detections. For a temporal power law flux decay typical of GRB afterglows, optimal coaddition has the greatest potential to improve the S/N of afterglow imaging data (relative to unweighted coaddition), when the decay rate is high, the source count rate is low, and the background rate is high. The optimal coaddition technique is demonstrated with applications to Swift Ultraviolet/Optical Telescope (UVOT) data of several GRBs, with and without detected afterglows.

---

Bibtex entry for this abstract Preferred format for this abstract (see Preferences)