论文标题
伽马射线爆发grb191221b的早期余辉的光谱法和光度法
Spectropolarimetry and photometry of the early afterglow of the gamma-ray burst GRB191221B
论文作者
论文摘要
我们报告了用盐/RSS和VLT/fors2获得的长伽马射线爆发GRB 191221b的余波结果的结果，以及来自Master Global Robotic Network的两个望远镜的光度计，在Master-Saao（South Africa）（南非）和Master-Saaao（Master-oafa）和Argentina（Argentina）（Argentina）（Argentina）。警报后38 s的主 - saao检测到迅速的光发射，在〜10 ks期间，幅度（白色轻）降低了约10至16.2 mag，然后在80 ks后持续约10 ks的高原阶段持续〜10 ks，然后下降到〜18 mag。光曲线显示出复杂的结构，在幂律下降率中有四个或五个不同的断裂。余辉的盐/RSS线性光谱法在爆发后〜2.9 h开始，在光曲线的高原阶段的早期。在〜6010Å处看到的吸收线和5490Å在Z = 1.15时的MG II2799Å线鉴定出，并在z = 0.96处识别。在3400-8000Å以上测得的平均线性极化为〜1.5％，平均赤道位置角theta〜65度。在燃烧后〜10 h，在缓慢下降的时期（alpha = -0.44）获得了VLT/FORS2光谱法，并且测量极化为p = 1.2％，theta = 60度。 GRB触发后30和444天，对Meerkat射电望远镜进行了两次观察，仅检测到宿主星系的无线电发射。我们用缓慢冷的前震来解释该长GRB的光曲线和极化。
We report on results of spectropolarimetry of the afterglow of the long gamma-ray burst GRB 191221B, obtained with SALT/RSS and VLT/FORS2, as well as photometry from two telescopes in the MASTER Global Robotic Network, at the MASTER-SAAO (South Africa) and MASTER-OAFA (Argentina) stations. Prompt optical emission was detected by MASTER-SAAO 38 s after the alert, which dimmed from a magnitude (white-light) of ~10 to 16.2 mag over a period of ~10 ks, followed by a plateau phase lasting ~10 ks and then a decline to ~18 mag after 80 ks. The light curve shows complex structure, with four or five distinct breaks in the power-law decline rate. SALT/RSS linear spectropolarimetry of the afterglow began ~2.9 h after the burst, during the early part of the plateau phase of the light curve. Absorption lines seen at ~6010 Å and 5490 Å are identified with the Mg II 2799 Å line from the host galaxy at z=1.15 and an intervening system located at z=0.96. The mean linear polarisation measured over 3400-8000 Å was ~1.5% and the mean equatorial position angle theta ~65 degrees. VLT/FORS2 spectropolarimetry was obtained ~10 h post-burst, during a period of slow decline (alpha = -0.44), and the polarisation was measured to be p = 1.2% and theta = 60 degrees. Two observations with the MeerKAT radio telescope, taken 30 and 444 days after the GRB trigger, detected radio emission from the host galaxy only. We interpret the light curve and polarisation of this long GRB in terms of a slow-cooling forward-shock.
