X-Ray Flashes from Off-Axis Gamma-Ray Bursts

K. Ioka and T. Nakamura proposed a simple jet model that is compatible with the peak luminosity-spectral lag relation, the peak luminosity-variability relation, and various other relations in the gamma-ray bursts. If the viewing angle is much larger than the collimation angle of the jet in the model by Ioka and Nakamura, for appropriate model parameters we obtain the observational characteristics of the X-ray flashes, such as the peak flux ratio and the fluence ratio between the ?-ray (50-300 keV) and the X-ray (2-10 keV) band, the X-ray photon index, the typical duration, and the event rate, ~100 yr-1. In our model, if the distance to the X-ray flashes is much larger than ~1 Gpc (or z 0.2) they are too dim to be observed, so the spatial distribution of the X-ray flashes should be homogeneous and isotropic.

[1]  F. Frontera.  Gamma Ray Bursts in the Afterglow Era , 2003 .

[2]  Usra,et al.  X-ray flashes and X-ray rich Gamma Ray Bursts , 2001, astro-ph/0111246.

[3]  W. S. Paciesas,et al.  The BATSE Gamma-Ray Burst Spectral Catalog. I. High Time Resolution Spectroscopy of Bright Bursts Using High Energy Resolution Data , 2000 .

[4]  Sergei Nayakshin,et al.  Expanding relativistic shells and gamma-ray burst temporal structure , 1996 .

[5]  Jonathan Granot,et al.  Images and spectra from the interior of a relativistic fireball , 1999 .

[6]  Jay D. Salmonson,et al.  Discovery of a Tight Correlation between Pulse Lag/Luminosity and Jet-Break Times: A Connection between Gamma-Ray Bursts and Afterglow Properties , 2001, astro-ph/0112298.

[7]  Nakamura.  Multiple Sub-Jet Model of Gamma-Ray Bursts and Possible Origin of X-Ray Precursors and Postcursors. , 2000, The Astrophysical journal.

[8]  Cambridge,et al.  Cooling Timescales and Temporal Structure of Gamma-Ray Bursts , 1996, astro-ph/9605005.

[9]  D. J. Helfand,et al.  The Einstein Observatory Detection of Faint X-Ray Flashes , 1996 .

[10]  Takashi S. Nakamura,et al.  Peak Luminosity-Spectral Lag Relation Caused by the Viewing Angle of the Collimated Gamma-Ray Bursts , 2001, astro-ph/0105321.

[11]  Gamma-ray bursts and the fireball model , 1998, astro-ph/9810256.

[12]  S. R. Kulkarni,et al.  BEAMING IN GAMMA-RAY BURSTS: EVIDENCE FOR A STANDARD ENERGY RESERVOIR , 2001 .

[13]  D. Palmer,et al.  BATSE observations of gamma-ray burst spectra. I: Spectral diversity , 1993 .

[14]  J. I. Katz.  Yet Another Model of Gamma-Ray Bursts , 1997 .

[15]  G. J. Hueter,et al.  Application of the V/V(max) test to gamma-ray bursts , 1988 .

[16]  T. Piran,et al.  Can Internal Shocks Produce the Variability in Gamma-Ray Bursts? , 1997, astro-ph/9705013.

[17]  J. Chiang,et al.  Fireball Loading and the Blast-Wave Model of Gamma-Ray Bursts , 1998, astro-ph/9804174.

[18]  Z. Dai,et al.  Failed gamma-ray bursts and orphan afterglows , 2001, astro-ph/0112469.

[19]  Universities Space Research Association,et al.  BATSE Observations of Fast X-ray Transients Detected by BeppoSAX-WFC , 2001, astro-ph/0102277.