Swift XRT Detection of Supernova 2012aw in X-Rays
ATel #3995; S. Immler (NASA/CRESST/GSFC) and P. J. Brown (Texas A&M)
on 22 Mar 2012; 16:57 UT
Credential Certification: Stefan Immler (stefan.immler@nasa.gov)
Subjects: X-ray, Supernovae
Using 14.7 ks of Swift X-Ray Telescope (XRT) observations of the Type IIP SN 2012aw in M95 (CBET #3054, ATel #3979), obtained between 2012-03-19.7 and 2012-03-22.2, an X-ray point-source is detected, consistent with the optical position of the SN, with a 3.8-sigma significance of source detection. The PSF, dead-time, and vignetting corrected XRT net count rate is (1.7+/-0.4)E-03 cts/s, corresponding to an unabsorbed (0.2-10 keV band) X-ray flux of (7.8+/-2.1)E-14 erg/cm/cm/s and a luminosity of (9.2+/-2.5)E38 erg/s for an adopted thermal plasma spectrum with a temperature of kT = 10 keV, a Galactic foreground column density of N_H = 2.88E+20 (Dickey & Lockman, 1990, ARAA 28) and a distance of 10 Mpc (NED).
The centroid position of the XRT source is consistent with the position of the SN, and 5 arcsec offset from a catalogued Chandra X-ray source (source s08 in Swartz et al. 2006, ApJ 647, 1030). No X-ray source is detected at this position in pre-explosion XRT data obtained on 2008-01-16 (9.3 ks exposure time) down to a 3-sigma upper limit of <7.0E38 erg/s (0.2-10 keV). The new XRT X-ray source is around a factor of 40 more luminous than the Chandra X-ray source from 2005 (2.4E37 erg/s, 0.3-8 keV). The much higher luminosity and offset from the Chandra position indicate that the two X-ray sources are likely unrelated and that the X-ray emission observed by Swift XRT is due to the SN.
Additional Swift observations are scheduled to monitor the evolution and observations at other wavelengths are encouraged.
