A search for faint blue starlike objects in the central part of the error region of the June 13, 1979, gamma-ray burst
Abstract
Single compact objects of a neutron-star type in the solar neighborhood with a finite, nonzero surface temperature are potential sources of gamma-ray bursts (GRBs). Within the framework of this hypothesis, a method of searching for an appropriate optical candidate in the error region of an energetic GRB is considered. A 120" x 80" area of the sky that includes the central part of the gamma-ray error box of GRB790613 is studied in the B, V and R bands. The B-V and V-R colors were measured for 263 sources with a signal-to-noise ratio (S/N) > 4 up to magnitudes B <~ 26.2^m^, V <~ 25.7^m^, and R <~ 25.2^m^. There are no blue (in the two color indices) objects up to B ~ 25^m^ near the center of the gamma-ray error box, which can be interpreted as the absence of a compact object with a temperature in the range (0.5-1.5) x 10^5^ K in this direction to distances as large as 20-40 Pc. Optical and X-ray data are used to place a possible general upper limit, T_lim_ < 1.8 x 10^5^ K, on the temperature of the putative compact objects in the vicinity of the Sun. The study of blue (B-V < 0) objects in the gamma-ray error box of GRB790613, the smallest in the northern sky, using the results of searches for point sources in the soft X-ray band in the error regions of bright GRBs, does not rule out the existence of such "cool" (T <~ 10^5^ K) objects. These objects could contribute significantly to the observed density of hidden mass not far from the Sun, and some of them could be associated with the nearest GRB sources.
- Publication:
-
Astronomy Letters
- Pub Date:
- July 1996
- Bibcode:
- 1996AstL...22..502S