ar X iv : a st ro - p h / 99 03 43 8 v 1 2 9 M ar 1 99 9 GRB 990123 : The Case for Saturated Comptonization

ar X iv : a st ro - p h / 99 12 40 2 v 1 1 8 D ec 1 99 9 LOTIS Upper Limits and the Prompt OT from GRB 990123

GRB 990123 established the existence of prompt optical emission from gamma-ray bursts (GRBs). The Livermore Optical Transient Imaging System (LOTIS) has been conducting a fully automated search for this kind of simultaneous low energy emission from GRBs since October 1996. Although LOTIS has obtained simultaneous, or near simultaneous, coverage of the error boxes obtained with BATSE, IPN, XTE, ...

ar X iv : a st ro - p h / 99 11 43 8 v 1 2 3 N ov 1 99 9 H 2 molecules and cold clouds in cooling flow clusters †

ar X iv : a st ro - p h / 99 04 02 5 v 1 2 A pr 1 99 9 The Afterglow of GRB 990123 and a Dense Medium

Recent observations show that the temporal decay of the R-band afterglow from GRB 990123 steepened about 2.5 days after the burst. We here propose a possible explanation for such a steepening: a shock expanding in a dense medium has undergone the transition from a relativistic phase to a nonrelativistic phase. We find that this model is consistent with the observations if the medium density is ...

ar X iv : a st ro - p h / 99 03 44 1 v 2 1 8 Ju l 1 99 9 Discovery of a Radio Flare from GRB 990123

We report the discovery of a radio counterpart to GRB 990123. In contrast to previous well-studied radio afterglows which rise to peak flux on a timescale of a week and then decay over several weeks to months, the radio emission from this GRB was clearly detected one day after the burst, after which it rapidly faded away. The simplest interpretation of this " radio flare " is that it arises fro...

ar X iv : a st ro - p h / 99 03 09 0 v 1 5 M ar 1 99 9 Origin of GRB Afterglows in the Model of Galactic Neutron Stars

The launch of the Beppo-Sax satellite gave a unique opportunity to investigate gamma ray bursts (GRB) in different spectral regions. The large diversity of the afterglow behavior creates additional problems for the cosmological model with a fireball. Formation of the afterglow giving the observed diversity of properties is suggested in the Galactic neutron star model of GRBs. It is based on the...