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Swift Detection of an X-Ray Source at the Position of the Type Ia SN 2011by

ATel #3410; S. Immler (NASA/CRESST/GSFC) and B. R. Russell (UMCP), on behalf of the Swift satellite team
on 7 Jun 2011; 21:10 UT
Credential Certification: Stefan Immler (immler@milkyway.gsfc.nasa.gov)

Subjects: X-ray, Supernovae

Referred to by ATel #: 3456

Using 42 epochs of Swift X-Ray Telescope (XRT) observations of SN 2011by (CBET 2708) obtained between 2011-04-27 and 2011-06-05 (80.8 ks exposure time), an X-ray point-source is detected consistent with the position of the SN, with a 3.9-sigma significance of source detection. The PSF, dead-time, and vignetting corrected XRT net count rate is (3.9+/-1.0)E-04 cts/s, corresponding to an unabsorbed (0.2-10 keV band) X-ray flux of (1.7+/-0.4)E-14 erg/cm/cm/s and a luminosity of (7.1+/-1.8)E38 erg/s for an adopted thermal plasma spectrum with a temperature of kT = 10 keV, a Galactic foreground column density of N_H = 1.2E+20 (Dickey & Lockman, 1990, ARAA 28) and a distance of 18.6 Mpc (NED).

Binning of the XRT data into two time periods does not give a high enough photon statistics to check whether the source is fading. No archival X-ray data are available that cover the SN field. It is therefore inconclusive at this point whether the X-ray source is caused by the outgoing SN shock running into dense circumstellar material, or from an unrelated and spatially unresolved X-ray source in the host galaxy.

Additional Swift observations are scheduled and observations at other wavelengths are encouraged.

Swift XRT/UVOT image of SN 2011by