{
  "bibcode": "2004GCN..2612....1D",
  "body": "S. Dado [Technion], A. Dar [Technion] and A. De Rujula [CERN] report:\n\nTaylor, Frail, Berger and Kulkarni [1] reported the discovery of a second\ncompact radio source in the afterglow of GRB 030329 at an angular distance\nof 0.28 +\\- 0.05 mas from the main source on day 51.3 after burst, which\nwas not resolved in their VLBI observations at other epochs. This\nseparation is \"hyperluminal\": the relative mean sky-projected-velocity is\n> 19c. A transient strong rebrightening of the second radio source is\nconsistent with the reported \"jitter\"  first seen in observations of the\noptical afterglow that began on day 51.75 (GCN 2224 [2], GCN 2259 [3]).\nAt that late time, the optical afterglow of GRB 030329/SN 2003dh is\nexpected to be dominated by the supernova. The spectroscopic resolution of\nthe afterglow into the individual contributions of the SN and GRB [2]\nindicates that the GRB contribution rebrightened by a factor 2 or more.\nAn analogous rebrightening of the second radio source may explain why\nit was resolved only on day 51.3.\n\nThe discovery [1] of a hyperluminal compact source may pin down the origin\nof GRBs [5]. We encourage prompt and follow-up VLBI observations of XRFs.\nIn the cannonball model the source separation observed by Taylor et al. is\nthe expected one [5], and both GRBs and XRFs are produced by hyperluminal\nplasmoids ejected in SN explosions. Relative to GRBs, XRFs are selectively\nviewed at closer distances, and at viewing angles typically 3 times larger\n[6]. This makes them very attractive targets for radio searches of the\nexpected hyperluminal motions, in particular promptly after the burst.\n\n[1] astro-ph/0405300:  G.B. Taylor, D.A. Frail, E. Berger, S. Kulkarni\n[2] GCN 2224: K.Z. Stanek, D.W. Latham, M.E. Everett\n[3] GCN 2259: K.Z. Stanek, D. Bersier, M. Calkins, D.L. Freedman, T. Spahr\n[4] astro-ph/0307435: T. Matheson et al.\n[5] astro-ph/0406325: Dado, A. Dar, A. De Rujula\n[6] astro-ph/0309294: S. Dado, A. Dar, A. De Rujula",
  "circularId": 2612,
  "createdOn": 1087538983000,
  "email": "arnon@physics.technion.ac.il",
  "subject": "GRB 030329: Rebrightening of hyperluminal ejecta.",
  "submitter": "Arnon Dar at Technion-Israel Inst. of Tech  <arnon@physics.technion.ac.il>",
  "eventId": "GRB 030329"
}