To TDE or not to TDE: the luminous transient ASASSN-18jd with TDE-like and AGN-like qualities. Issue 2 (4th April 2020)

• Record Type: Journal Article
• Authors: Neustadt, J M M; Holoien, T W-S; Kochanek, C S; Auchettl, K; Brown, J S; Shappee, B J; Pogge, R W; Dong, Subo; Stanek, K Z; Tucker, M A; Bose, S; Chen, Ping; Ricci, C; Vallely, P J; Prieto, J L; Thompson, T A; Coulter, D A; Drout, M R; Foley, R J; Kilpatrick, C D; Piro, A L; Rojas-Bravo, C; Buckley, D A H; Gromadzki, M; Dimitriadis, G; Siebert, M R; Do, A; Huber, M E; Payne, A V
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 494:Issue 2(2020)
• Page Start: 2538
• Page End: 2560
• Publication Date: 2020-04-04
• Subjects: accretion, accretion discs -- black hole physics -- galaxies: nuclei; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/staa859
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: We present the discovery of ASASSN-18jd (AT 2018bcb), a luminous optical/ultraviolet(UV)/X-ray transient located in the nucleus of the galaxy 2MASX J22434289–1659083 at z = 0.1192. Over the year after discovery, Swift UltraViolet and Optical Telescope (UVOT) photometry shows the UV spectral energy distribution of the transient to be well modelled by a slowly shrinking blackbody with temperature $T \sim 2.5 \times 10^{4} \, {\rm K}$, a maximum observed luminosity of $L_{\rm max} = 4.5^{+0.6}_{-0.3}\times 10^{44} \, {\rm erg \, s}^{-1}$, and a radiated energy of $E = 9.6^{+1.1}_{-0.6} \times 10^{51} \, {\rm erg}$ . X-ray data from Swift X-Ray Telescope (XRT) and XMM–Newton show a transient, variable X-ray flux with blackbody and power-law components that fade by nearly an order of magnitude over the following year. Optical spectra show strong, roughly constant broad Balmer emission and transient features attributable to He ii, N iii–v, O iii, and coronal Fe. While ASASSN-18jd shares similarities with tidal disruption events (TDEs), it is also similar to the newly discovered nuclear transients seen in quiescent galaxies and faint active galactic nuclei (AGNs).