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Swift/XRT monitoring observations of SN2011dh

ATel #3414; S. Campana (OA Brera), D. N. Burrows (PSU)
on 8 Jun 2011; 16:58 UT
Credential Certification: Sergio Campana (campana@merate.mi.astro.it)

Subjects: X-ray, Supernovae

Referred to by ATel #: 3420, 3432, 3456, 3641

SN 2011dh (Silverman et al. 2001, Atel #3398; Reiland et al. 2011, CBET #2736) has been monitored by Swift with 14 observations up to now. Here we report on the first 6 observations, spanning the June 3-6, 2011 interval, with 21.2 ks effective exposure time. An X-ray source was positively detected at the location of SN 2011dh with a high signal-to-noise ratio (S/N~8). This source was not present in deep observations taken in 2007, and we tentatively associate it with SN 2001dh, in agreement with Margutti & Soderberg (2011, ATel #3400) results. The X-ray light curve is consistent with a constant rate of (6.44+/-0.67)E-03 c/s. An indication of flux decay is present in the data but it is not statistically significant. The relatively low number of photons (110 counts) precludes a thorough spectral analysis. Assuming only Galactic absorption (N_H=1.8E20 cm-2), a fit with a power law provides a relatively good fit (chi^2_red=1.3 with 19 degrees of freedom). The power law photon index is hard, with Gamma=0.7+/-0.3 (90% confidence level). The mean unabsorbed 0.3-10 keV flux is 4.4E-13 erg/cm2/s.