Oates, SR;
Kuin, NPM;
Nicholl, M;
Marshall, F;
Ridley, E;
Boutsia, K;
Breeveld, AA;
... Xu, D; + view all
(2024)
Swift/UVOT discovery of Swift J221951−484240: a UV luminous ambiguous nuclear transient.
Monthly Notices of the Royal Astronomical Society
, 530
(2)
pp. 1688-1710.
10.1093/mnras/stae795.
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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 Ultraviolet/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 blackbody with an approximately constant temperature of T ∼ 2.5 × 104 K. At a redshift z = 0.5205, J221951 had a peak absolute magnitude of Mu,AB = −23 mag, peak bolometric luminosity Lmax = 1.1 × 1045 erg s−1 and a total radiated energy of E > 2.6 × 1052 erg. The archival Wide-field Infrared Survey Explorer 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 towards an outflow at coronal temperatures. The lack of emission in the higher H α 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 cannot be determined with certainty but has properties consistent with a tidal disruption event and the turn-on of an active galactic nucleus.
| Type: | Article |
|---|---|
| Title: | Swift/UVOT discovery of Swift J221951−484240: a UV luminous ambiguous nuclear transient |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1093/mnras/stae795 |
| Publisher version: | http://dx.doi.org/10.1093/mnras/stae795 |
| Language: | English |
| Additional information: | This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third-party material in this article are included in the Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/ |
| Keywords: | Black hole physics, gravitational waves, galaxies: nuclei, ultraviolet: general, transients: tidal disruption events |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Space and Climate Physics |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/10192060 |
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