Late-time observations of the relativistic tidal disruption flare candidate Swift J1112.2-8238
Cenko, S. B.; Krühler, T.; Levan, A. J.; Tanvir, N. R.; Metzger, B. D.; Davies, L. J. M.; Stanway, E. R.; Fruchter, A.; Brown, G. C.
United Kingdom, Germany, Australia, United States
Abstract
We present late-time follow-up of the relativistic tidal disruption flare (rTDF) candidate Swift J1112.2-8238. We confirm the previously determined redshift of z = 0.8900 ± 0.0005 based on multiple emission line detections. Hubble Space Telescope imaging of the host galaxy indicates a complex and distorted morphology with at least two spatially distinct components. These are offset in velocity space by less than 350 km s-1 in VLT/X-Shooter observations, suggesting that the host is undergoing interaction with another galaxy. The transient position is consistent to 2.2σ with the centre of a bulge-like component at a distance of 1.1 ± 0.5 kpc from its centre. Luminous, likely variable radio emission has also been observed, strengthening the similarities between Swift J1112.2-8238 and other previously identified rTDFs. While the transient location is ∼ 2σ from the host centroid, the disrupted nature of the host may provide an explanation for this. The tidal disruption model remains a good description for these events.