| タイトル | Low-resolution VLT Spectroscopy of GRBs 991216, 011211, 021211 and 030328 |
| 著者（英） | Palazzi, E.; Pian, E.; Smette, A.; Wijers, R. A. M. J.; Vreeswijk, P. M.; Masetti, N.; Rol, E.; Kouveliotou, C.; Kaper, L.; Fruchter, A. S. |
| 著者所属（英） | NASA Marshall Space Flight Center |
| 発行日 | 2005-01-01 |
| 言語 | eng |
| 内容記述 | We present low-resolution VLT spectroscopy of the aftergiow position of the gamma ray bursts 991216, 011211, 021211 and 030328. The spectmm of GRB 991216 shows two probable absorption systems at z = 0.80 and z = 1.02, where the highest redshift most likely reflects the distance to the host galaxy. A third, more uncertain, system may be detected at z = 0.77. HST imaging of the field obtained 4 months later, show two amorphous regions of emission, one at the projected OT position, the presumed host galaxy at z = 1.02, and the other 0"6 away. All significant lines in the spectrum of GRB 011211 are identified with lines originating in a single absorption system at z = 2.142 plus or minus 0.002, the redshift of the GRB 011211 host galaxy. We also detect Lya in the host, for which we fit a neutral hydrogen column density of log N(HI)=20.4 plus or minus 0.2, which indicates that it is a damped Lya system. For GRB021211, we detect a single emission line in a spectrum tens of days after the burst, which we identify as [OII] at z = 1.006. The galaxy l"5 away from the afterglow location has z = 0.800, and is therefore unrelated to the GRB. Finally, for GRB030328 at least two absorption systems are required to explain all significant lines: one at z = 1.522, the likely redshift of the GRB, and the other at z = 1.295. For the latter system we only detect two lines, and we consider the reality of this system to be uncertain. |
| NASA分類 | Astronomy |
| 権利 | Copyright |
|
