Stirring the embers: High-sensitivity VLBI observations of GRB 030329

Y. M. Pihlström, G. B. Taylor, J. Granot, S. Doeleman

Research output: Contribution to journalArticlepeer-review


We present high-sensitivity Very Long Baseline Interferometry (VLBI) observations 806 days after the 7-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-2 windlike 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 nonrelativistic transition time of tNR ∼ 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.

Original languageEnglish
Pages (from-to)411-415
Number of pages5
JournalAstrophysical Journal
Issue number1 I
StatePublished - 20 Jul 2007
Externally publishedYes


  • Gamma rays: bursts


Dive into the research topics of 'Stirring the embers: High-sensitivity VLBI observations of GRB 030329'. Together they form a unique fingerprint.

Cite this