학술논문
Swift/UVOT discovery of Swift J221951-484240: a UV luminous ambiguous nuclear transient
Document Type
Working Paper
Author
Oates, S. R.; Kuin, N. P. M.; Nicholl, M.; Marshall, F.; Ridley, E.; Boutsia, K.; Breeveld, A. A.; Buckley, D. A. H.; Cenko, S. B.; De Pasquale, M.; Edwards, P. G.; Gromadzki, M.; Gupta, R.; Laha, S.; Morrell, N.; Orio, M.; Pandey, S. B.; Page, M. J.; Page, K. L.; Parsotan, T.; Rau, A.; Schady, P.; Stevens, J.; Brown, P. J.; Evans, P. A.; Gronwall, C.; Kennea, J. A.; Klingler, N. J.; Siegel, M. H.; Tohuvavohu, A.; Ambrosi, E.; Barthelmy, S. D.; Beardmore, A. P.; Bernardini, M. G.; Bonnerot, C.; Campana, S.; Caputo, R.; Ciroi, S.; Cusumano, G.; D'Ai, A.; D'Avanzo, P.; D'Elia, V.; Giommi, P.; Hartmann, D. H.; Krimm, H. A.; Malesani, D. B.; Melandri, A.; Nousek, J. A.; O'Brien, P. T.; Osborne, J. P.; Pagani, C.; Palmer, D. M.; Perri, M.; Racusin, J. L.; Sakamoto, T.; Sbarufatti, B.; Schlieder, J. E.; Tagliaferri, G.; Troja, E.; Xu, D.
Source
Subject
Language
Abstract
We report the discovery of Swift J221951-484240 (hereafter: J221951), a luminous slow-evolving blue transient that was detected by the Neil Gehrels Swift Observatory Ultra-violet/Optical Telescope (Swift/UVOT) during the follow-up of Gravitational Wave alert S190930t, to which it is unrelated. Swift/UVOT photometry shows the UV spectral energy distribution of the transient to be well modelled by a slowly shrinking black body with an approximately constant temperature of T~2.5x10^4 K. At a redshift z=0.5205, J221951 had a peak absolute magnitude of M_u,AB = -23 mag, peak bolometric luminosity L_max=1.1x10^45 erg s^-1 and a total radiated energy of E>2.6x10^52 erg. The archival WISE IR photometry shows a slow rise prior to a peak near the discovery date. Spectroscopic UV observations display broad absorption lines in N V and O VI, pointing toward an outflow at coronal temperatures. The lack of emission in the higher H~Lyman lines, N I and other neutral lines is consistent with a viewing angle close to the plane of the accretion or debris disc. The origin of J221951 can not be determined with certainty but has properties consistent with a tidal disruption event and the turn-on of an active galactic nucleus.
Comment: 37 pages (25 main + 12 supplementary), submitted to MNRAS
Comment: 37 pages (25 main + 12 supplementary), submitted to MNRAS