伽玛暴(Gamma-Ray Burst)笔记。记录有关伽玛暴的新文章,另外也包括看的老文章、自己的想法、以及跟天文相关的一些东西。 Feel free to leave me a message by comments or by email.

星期二, 五月 08, 2007

Pihlström 2007 GRB030329的晚期几年的射电余辉观测

主要内容:
用VLBI给出了GRB030329直到806天以后的射电观测。测得了流量,速度和尺度等。

精彩摘抄:
射电光变1000天。

文章信息:
Stirring the Embers: High Sensitivity VLBI Observations of GRB030329

Authors: Y.M. Pihlström (1), G.B. Taylor (1), J. Granot (2), S. Doeleman (3) ((1) University of New Mexico, (2) Kavli Institute of Particle Astrophysics and Cosmology, (3) MIT Haystack Observatory)
Abstract: We present high sensitivity Very Long Baseline Interferometry (VLBI) observations 806 days after the gamma-ray burst of 2003 March 29 (GRB030329). The angular diameter of the radio afterglow is measured to be 0.347 +- 0.09 mas, corresponding to 0.99 +- 0.26 pc at the redshift of GRB030329 (z = 0.1685). The evolution of the image size favors a uniform external density over an R^-2 wind-like density profile (at distances of R >~10^18 cm from the source), although the latter cannot be ruled out yet. The current apparent expansion velocity of the image size is only mildly relativistic, suggesting a non-relativistic transition time of t_NR ~ 1 yr. A rebrightening, or at least a significant flattening in the flux decay, is expected within the next several years as the counter-jet becomes visible (this has not yet been observed). An upper limit of <1.9c>
Comments:
16 pages, 5 figures, accepted for publication in Astrophysical Journal
Subjects:
Astrophysics (astro-ph)
Cite as:

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