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Chandra Observations of the X-ray Environs of SN 1998bw/GRB 980425We report X-ray studies of the environs of SN 1998bw and GRB 980425 using the Chandra X-Ray Observatory 1281 days after the gamma-ray burst (GRB). Eight X-ray point sources were localized, three and five each in the original error boxes, S1 and S2, assigned for variable X-ray counteparts to the GRB by BeppoSAX. The sum of the discrete X-ray sources plus continuous emission in S2 observed by Chandra on day 1281 is within a factor of 1.5 of the maximum and the upper limits seen by BeppoSAX. We conclude that S2 is the sum of several variable sources that have not disappeared and therefore is not associated with the GRB. Within S1, clear evidence is seen for a decline of approximately a factor of 12 between day 200 and day 1281. One of the sources in S 1, S 1 a, is coincident with the well-determined radio location of SN 1998bw and is certainly the remnant of that explosion. The nature of the other sources is also discussed. Combining our observation of the supernova with others of the GRB afterglow, a smooth X-ray light curve, spanning approx. 1400 days, is obtained by assuming that the burst and supernova were coincident at 35.6 Mpc. When this X-ray light curve is compared with those of the X-ray af "erglows" of ordinary GRBs, X-ray flashes, and ordinary supernovae, evidence emerges for at least two classes of light curves, perhaps bounding a continuum. By 3-10 yr, all these phenomena seem to converge on a common X-ray luminosity, possibly indicative of the supernova underlying them all. This convergence strengthens the conclusion that SN 1998 bw aid GRB 980425 took place in the same object.One possible explanation for the two classes is that a (nearly) standard GRB was observed at different angles, in which case X-ray afterglows with intermediate luminosities should eventually be discovered. Finally, we comment on the contribution of GRB afterglows to the ultraluminous X-ray source population.
Document ID
20040082401
Acquisition Source
Marshall Space Flight Center
Document Type
Reprint (Version printed in journal)
Authors
Kouveliotou, C.
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Woosley, S. E.
(California Univ. Santa Cruz, CA, United States)
Patel, S. K.
(Universities Space Research Association Huntsville, AL, United States)
Levan, A.
(Leicester Univ. United Kingdom)
Blandford, R.
(Kavli Inst. for Particle Astrophysics and Cosmology Stanford, CA, United States)
Ramirez-Ruiz, E.
(Institute for Advanced Study Princeton, NJ, United States)
Wijers, R. A. M. J.
(Amsterdam Univ. Netherlands)
Weisskopf, M. C.
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Tennant, A.
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Pian, E.
(Osservatorio Astronomico Trieste, Italy)
Date Acquired
August 21, 2013
Publication Date
June 20, 2004
Publication Information
Publication: The Astrophysical Journal
Publisher: American Astronomical Society
Volume: 608
Subject Category
Astrophysics
Funding Number(s)
CONTRACT_GRANT: NAG5-12036
CONTRACT_GRANT: EEC-HPRN-CT-2002-00294
CONTRACT_GRANT: SAO-GO1-2055X
CONTRACT_GRANT: DE-FC02-01ER-41176
Distribution Limits
Public
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