منابع مشابه
The Redshift of Grb 970508
GRB 970508 is the second gamma-ray burst (GRB) for which an optical afterglow has been detected. It is the first GRB for which a distance scale has been determined: absorption and emission features in spectra of the optical afterglow place GRB 970508 at a redshift of z ≥ 0.835 (Metzger et al. 1997a, 1997b). The lack of a Lyman-α forest in these spectra further constrains this redshift to be les...
متن کاملThe Host Galaxy of Grb 970508
We present late-time imaging and spectroscopic observations of the optical transient (OT) of gammaray burst (GRB) 970508. Imaging observations roughly 200 and 300 days after the burst provide unambiguous evidence for the flattening of the light-curve. The spectroscopic observations reveal two persistent features which we identify with [O II] 3727 Å and [Ne III] 3869 Å at a redshift of z = 0.835...
متن کاملDid GRB 970228 and GRB 970508 present similar optical properties ?
The analysis of the light curves of the optical counterparts of GRB 970228 and GRB 970508 points out remarkable similarities. The spectral distribution obtained from the color indices shows that both the transients became bluer during the increasing stage, and redder after the maximum. A main difference concerns the behaviour of the optical fading which is well fitted by a single power law in t...
متن کاملOptical observations of GRB afterglows : GRB 970508 and GRB 980326 revisited ⋆ , ⋆ ⋆
Since January 1997, we have monitored 15 GRB fields, detecting 6 optical/IR afterglows. We have revisited GRB 970508 and GRB 980326. For GRB 970508, we derive a power-law decay exponent α =-1.19 (R-band). The luminosity of the host galaxy L relative to the characteristic luminosity L ⋆ is in the range 0.06–0.15, i.e. a dwarf galaxy. For GRB 980326, we derive a power-law decay exponent α =-1.7, ...
متن کاملOn the anomalous X – ray afterglows of GRB 970508 and GRB 970828
Recently, BeppoSAX and ASCA have reported an unusual resurgence of soft X–ray emission during the afterglows of GRB 970508 and GRB 970828, together with marginal evidence for the existence of Fe–lines in both objects. We consider the implications of the existence of a torus of iron–rich material surrounding the sites of gamma ray bursts as would be expected in the Supra-Nova model; in particula...
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ژورنال
عنوان ژورنال: The Astrophysical Journal
سال: 1998
ISSN: 0004-637X
DOI: 10.1086/311307