The intriguing GRB980425 and the Supernova Connection

Another GRB which impacted significantly on the evolution of GRB science was the GRB980425. Not peculiar in any particular feature from the point of view of Gamma/X-ray emission it had no outstanding afterglow source associated. A very faint source, not unlikely a field object was marginally detected only during the first 12 hours. This could be compared with the fading behavior of the well established X-ray afterglows and is the best "X-ray selected" candidate as the afterglow source. But the optical search following the X-ray position found a really unusual object. A Supernova (SN1998bw) with a very bright radio emission (5 times brighter of any radio SN previously known). The extrapolation to time 0 of the radio curve is coincident ($\pm$ 1 day) with the GRB. This could open the way to an entirely new perspective. Is this the first finding of a separate class of GRBs or is it a different phenomenology of GRBs observed from a peculiar sight angle?

  

Figure 5.10: Error boxes of the two X-ray sources detected by BeppoSAX NFI in the error box of GRB980425 superimposed to the Palomar Digital Sky Survey