Optical Flash of GRB 990123: Constraints on the Physical Parameters of the Reverse Shock

The optical flash accompanying GRB 990123 is believed to be powered by the reverse shock of a thin shell. With the best-fit physical parameters for GRB 990123 and the assumption that the parameters in the optical flash are the same as in the afterglow, we show that: 1) the shell is thick rather than thin, and we have provided the light curve for the thick shell case which coincides with the observation; 2) the theoretical peak flux of the optical flash accounts for only 3◊10 4 of the observed. In order to remove this discrepancy, the physical parameters, the electron energy and magnetic ratios, e and B, should be 0.61 and 0.39, which are very dierent from their values for the late afterglow.

[1]  M. Feroci,et al.  Discovery of a Radio Flare from GRB 990123 , 1999, astro-ph/9903441.

[2]  Z. G. Dai,et al.  The afterglow of GRB 990123 and a dense medium , 1999 .

[3]  E. Ramirez-Ruiz,et al.  Was GRB 990123 a unique optical flash , 2001, astro-ph/0110519.

[4]  et,et al.  Decay of the GRB 990123 optical afterglow: implications for the fireball model , 1999, Science.

[5]  S. Djorgovski,et al.  The afterglow, the redshift, and the extreme energetics of the gamma-ray burst 990123 , 1999, astro-ph/9902272.

[6]  E. Guinan,et al.  The Best Brown Dwarf Yet? A Companion to the Hyades Eclipsing Binary V471 Tauri , 2000, astro-ph/0010487.

[7]  M. Boettcher,et al.  GRB 990123: The Case for Saturated Comptonization , 1999, astro-ph/9903438.

[8]  Z. Dai,et al.  Intrinsic parameters of GRB 990123 from its prompt optical flash and afterglow , 1999, astro-ph/9906062.

[9]  Jets in GRBs , 1999, astro-ph/9903339.

[10]  E. Ramirez-Ruiz,et al.  GRB 990123: Evidence that the Gamma Rays Come from a Central Engine , 1999, astro-ph/9902007.

[11]  Dai Zi-gao,et al.  Afterglows from jetted gamma-ray-burst remnant: Does the light curve break? , 2000 .

[12]  S. Djorgovski,et al.  The afterglow, redshift and extreme energetics of the γ-ray burst of 23 January 1999 , 1999, Nature.

[13]  Shiho Kobayashi,et al.  Light Curves of Gamma-Ray Burst Optical Flashes , 2000, astro-ph/0009319.

[14]  J. Rhoads.  The Dynamics and Light Curves of Beamed Gamma-Ray Burst Afterglows , 1999, astro-ph/9903399.

[15]  Wijers,et al.  UvA-DARE ( Digital Academic Repository ) Physical parametres of GRB 970508 and GRB 971214 from their afterglow synchroton emission , 1999 .

[16]  G. Gisler,et al.  Observation of contemporaneous optical radiation from a γ-ray burst , 1999, Nature.

[17]  Duccio Macchetto,et al.  Hubble Space Telescope and Palomar imaging of GRB 990123: Implications for the nature of gamma-ray bursts and their hosts , 1999 .

[18]  Tsvi Piran,et al.  Predictions for the Very Early Afterglow and the Optical Flash , 1999, astro-ph/9901338.

[19]  Z. Dai,et al.  Environment and Energy Injection Effects in Gamma-Ray Burst Afterglows , 1999, astro-ph/9906109.

[20]  Li-Lian Wang,et al.  A family of interesting exact solutions of the sine-Gordon equation , 2000 .

[21]  R. Blandford,et al.  Fluid dynamics of relativistic blast waves , 1976 .

[22]  Tsvi Piran,et al.  Jets in Gamma-Ray Bursts , 1999 .

[23]  O. Williams,et al.  Observations of GRB 990123 by the Compton Gamma Ray Observatory , 1999, astro-ph/9903247.

[24]  Z. Dai,et al.  Overall Evolution of Jetted Gamma-Ray Burst Ejecta , 1999, astro-ph/9910493.

[25]  Z. Dai,et al.  Gamma-Ray Burst Afterglows from Realistic Fireballs , 1998, astro-ph/9806334.

[26]  Z. Dai,et al.  On the Optical Light Curves of Afterglows from Jetted Gamma-ray Burst Ejecta: Effects of Parameters , 2000, astro-ph/0005549.

[27]  Z. Dai,et al.  The Inverse Compton Emission Spectra in the Very Early Afterglows of Gamma-Ray Bursts , 2001, astro-ph/0104128.

[28]  T. Piran,et al.  Spectra and Light Curves of Gamma-Ray Burst Afterglows , 1997, astro-ph/9712005.

[29]  A. Panaitescu,et al.  Fundamental Physical Parameters of Collimated Gamma-Ray Burst Afterglows , 2001 .

[30]  Stuart Marshall,et al.  A Search for Early Optical Emission from Short- and Long-Duration Gamma-Ray Bursts , 2001 .

[31]  M. Rees,et al.  GRB 990123: reverse and internal shock flashes and late afterglow behaviour , 1999 .

[32]  Martin J. Rees,et al.  Refreshed Shocks and Afterglow Longevity in Gamma-Ray Bursts , 1998 .