GCN Circular 2612

S. Dado [Technion], A. Dar [Technion] and A. De Rujula [CERN] report:

Taylor, Frail, Berger and Kulkarni [1] reported the discovery of a second
compact radio source in the afterglow of GRB 030329 at an angular distance
of 0.28 +\- 0.05 mas from the main source on day 51.3 after burst, which
was not resolved in their VLBI observations at other epochs. This
separation is "hyperluminal": the relative mean sky-projected-velocity is
> 19c. A transient strong rebrightening of the second radio source is
consistent with the reported "jitter"  first seen in observations of the
optical afterglow that began on day 51.75 (GCN 2224
Not found
 
 
 [2], GCN 2259
Not found
 
 
 [3]).
At that late time, the optical afterglow of GRB 030329/SN 2003dh is
expected to be dominated by the supernova. The spectroscopic resolution of
the afterglow into the individual contributions of the SN and GRB [2]
indicates that the GRB contribution rebrightened by a factor 2 or more.
An analogous rebrightening of the second radio source may explain why
it was resolved only on day 51.3.

The discovery [1] of a hyperluminal compact source may pin down the origin
of GRBs [5]. We encourage prompt and follow-up VLBI observations of XRFs.
In the cannonball model the source separation observed by Taylor et al. is
the expected one [5], and both GRBs and XRFs are produced by hyperluminal
plasmoids ejected in SN explosions. Relative to GRBs, XRFs are selectively
viewed at closer distances, and at viewing angles typically 3 times larger
[6]. This makes them very attractive targets for radio searches of the
expected hyperluminal motions, in particular promptly after the burst.

[1] astro-ph/0405300:  G.B. Taylor, D.A. Frail, E. Berger, S. Kulkarni
[2] GCN 2224
Not found
 
 
: K.Z. Stanek, D.W. Latham, M.E. Everett
[3] GCN 2259
Not found
 
 
: K.Z. Stanek, D. Bersier, M. Calkins, D.L. Freedman, T. Spahr
[4] astro-ph/0307435: T. Matheson et al.
[5] astro-ph/0406325: Dado, A. Dar, A. De Rujula
[6] astro-ph/0309294: S. Dado, A. Dar, A. De Rujula