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Swift XRT Non-detection of TDE Candidate AT2018dyb in X-rays

ATel #11876; J. M. Miller (Univ. of Michigan), B. Cenko (NASA/GSFC)
on 20 Jul 2018; 16:16 UT
Credential Certification: Jon Miller (jonmm@umich.edu)

Subjects: X-ray, Transient, Tidal Disruption Event

The Neil Gehrels Swift Observatory made an XRT photon counting mode exposure of the candidate tidal disruption event (TDE) AT2018dyb (Pan et al. 2018, ATEL #11865) starting on 2018 July 18 at 14:04:51 UT, for a net exposure of 2.98 ks.

No source is detected at the location of AT2018dyb. A standard extraction circle with a radius of 20 pixels finds 10 events; background regions of equivalent size find a similar number of events.

Assuming a kT = 0.2 keV blackbody spectrum as typical of TDEs, Galactic absorption of 2.0 E+21 cm^-2, 10 total photons in 2.98 ks equates to a flux of F < 7 E-14 erg/cm^2/s in the 0.3-10 keV band. This might be regarded as a conservative upper limit. The corresponding luminosity limit for a redshift of z = 0.018 is L < 5 E+40 erg/s.