Swift J1644+57: Chandra observations
ATel #4610; A. J. Levan (University of Warwick), N. R. Tanvir, (University of Leicester) report for a larger collaboration
on 28 Nov 2012; 12:05 UT
Credential Certification: Klaas Wiersema (kw113@star.le.ac.uk)
Subjects: X-ray, Transient
We observed the X-ray counterpart to the candidate relativistic tidal disruption event Swift J1644+57 (Levan et al. 2011 Science, 333 199; Bloom et al. 2011 Science 333 202; Burrows et al. 2011 Nature 476 421; Zauderer et al. 2011 Nature 476 425) with the Chandra X-ray Observatory, beginning on 26 November 2012 at 10:25 UT. A total integration of 24.7 ks was obtained, and the object was placed at the default position on the ACIS S3 chip.
At the location of the X-ray counterpart we clearly detect a source with a total of ~8 counts. Assuming a constant spectral shape from the earlier observations this corresponds to a 0.2-10 keV flux of F_X~3.5e-15 ergs/s/cm^2. This confirms the rapid decay first observed by the Swift XRT in August (Sbarufatti, Burrows, Gehrels & Kennea 2012 ATEL 4398), but implies that it is not so rapid that the source has entirely switched off.
We thank Harvey Tananbaum and the staff of the CXC for their help in scheduling these observations.
