SN1998bw

While not especially noteworthy as an X-ray supernova, the importance of SN 1998bw comes from its possible association with the gamma ray burst GRB 980425. This was a highly unusual gamma ray burst, with a luminosity four orders of magnitude lower than a typical one, and an X-ray afterglow with a substantially slower rate of decline. BeppoSAX observations revealed two possible counterparts to the GRB in the host galaxy ESO 184-G82, but a Chandra observation showed that only one of these had shown a steady luminosity decline. This source is spatially coincident with the radio position of SN 1998bw [88]. The X-ray light curve shows a gentle decline over the first 200 days, followed by an order of magnitude decline over the next 1000 days. This later behavior is typical of other X-ray SN light curves, suggesting that while the supernova explosion itself may have been unusual, the subsequent interaction with the interstellar medium is not. SN 1998bw has been classified as a supernova Type Ib/c. Its late time X-ray luminosity is somewhat higher than other Ib/c or Ic SNe, suggesting a higher pre-supernova mass loss rate.

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