Stirring the Embers: High-Sensitivity VLBI Observations of GRB 030329

Journal Article · Mon Sep 24 00:00:00 EDT 2007 · Astrophys.J.664:411,2007

DOI:https://doi.org/10.1086/518955· OSTI ID:916983

Pihlstrom, Y M; Taylor, G B; Granot, J; Doeleman, S

We present high-sensitivity Very Long Baseline Interferometry (VLBI) observations 806 days after the {gamma}-ray burst of 2003 March 29 (GRB 030329). 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 GRB 030329 (z = 0:1685). The evolution of the image size favors a uniform external density over an R{sup -2} windlike density profile (at distances of R {approx}> 10{sup 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 nonrelativistic transition time of tNR {approx} 1 yr. A rebrightening, or at least a significant flattening in the flux decay, is expected within the next several years as the counterjet becomes visible (this has not yet been observed). An upper limit of <1.9c is set on the proper motion of the flux centroid.

• Research Organization: Stanford Linear Accelerator Center (SLAC)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC02-76SF00515
• OSTI ID: 916983
• Report Number(s): SLAC-PUB-12828
• Journal Information: Astrophys.J.664:411,2007, Journal Name: Astrophys.J.664:411,2007 Vol. 664
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
Astrophysics
ASTRO
COSMIC GAMMA BURSTS
INTERFEROMETRY
RED SHIFT
SENSITIVITY