Multiwavelength Study of an X-Ray Tidal Disruption Event Candidate in NGC 5092

Abstract

We present multiwavelength studies of a transient X-ray source, XMMSL1 J131952.3+225958, associated with the galaxy NGC 5092 at z = 0.023 detected in the XMM-Newton SLew survey (XMMSL). The source brightened in the 0.2-2 keV band by a factor of > 20 in 2005 as compared with previous flux limits and then faded by a factor of > 200 as observed with XMM-Newton in 2013 and with Swift in 2018. At the flaring state, the X-ray spectrum can be modeled with a blackbody at a temperature of ∼ 60 eV and an overall luminosity of ∼ 1.5 × 10 43 erg s −1 . A UV flare and optical flare were also detected with the Galaxy Evolution Explorer and the Sloan Digital Sky Survey, respectively, within several months of the X-ray flare, whose nonstellar UVoptical spectrum can be described with a blackbody at a temperature of ∼ (1 − 2) × 10 4 K and a luminosity of ∼ (2 − 6) × 10 43 erg s −1 . Interestingly, mid-infrared monitoring observations of NGC 5092 with the Wide-field Infrared Survey Explorer 5-13 yr later show a continuous flux decline. These dramatic variability properties, from the X-ray through UV and optical to infrared, appear to be orderly, suggestive of a stellar tidal disruption event (TDE) by a massive black hole, confirming the postulation by Kanner et al. (2013). This TDE candidate belongs to a rare sample with contemporaneous bright emission detected in the X-ray, UV, and optical, which are later echoed by dust-reprocessed light in the mid-infrared. The black hole has a mass of ∼ 5 × 10 7 M , residing in a galaxy that is dominated by a middle-aged stellar population of 2.5 Gyr.

Partial, zombie, and full tidal disruption of stars by supermassive black holes

“…These events produce luminous, multiwavelength flares that form and evolve on timescales of days to years, which allows one to explore (for example) dormant black holes in galaxy centres, nuclear galactic dynamics, stel-lar structure, accretion and jet physics. Observations of TDEs across different wavelengths and at various epochs have now been made (e.g., Bade et al 1996;Komossa & Greiner 1999;Esquej et al 2007;Gezari et al 2009Gezari et al , 2012Holoien et al 2014;Miller et al 2015;Vinkó et al 2015;Alexander et al 2016;Cenko et al 2016;Holoien et al 2016;Kara et al 2016;van Velzen et al 2016;Alexander et al 2017;Blanchard et al 2017;Brown et al 2017;Gezari et al 2017;Hung et al 2017;Saxton et al 2017;Brown et al 2018;Pasham & van Velzen 2018;Blagorodnova et al 2019;Hung et al 2019;Holoien et al 2019;Leloudas et al 2019;Nicholl et al 2019;Pasham et al 2019;Saxton et al 2019;Hung et al 2020a,b;Holoien et al 2020;Jonker et al 2020;Kajava et al 2020;Li et al 2020;Hinkle et al 2021;Payne et al 2021;van Velzen et al 2021); see also the recent reviews by Alexander et al (2020); van Velzen et ...…”

A new X-ray tidal disruption event candidate with fast variability

“…In the X-ray band, several new TDEs were identified with Chandra and XMM-Newton with peak luminosities up to a few times 10 44 erg/s and very soft X-ray spectra, located in quiescent host galaxies (e.g., Maksym et al 2010;Esquej et al 2008;Saxton et al 2012b;Maksym et al 2013;Donato et al 2014;Lin et al 2015Lin et al , 2017Li et al 2020;Lin et al 2021). Since TDEs are rare events, and their properties like light curve and spectral evolution can vary, identification of each single new event is of great interest.…”

Populations of highly variable X-ray sources in the XMM$-$Newton slew survey

“…A comparison of source fluxes in the XMMSL data with previous measurements has allowed the detection of individual variable sources and transients, such as novae (e.g., Read et al 2008Read et al , 2009, tidal disruption events (e.g., Esquej et al 2008;Saxton et al 2012Saxton et al , 2014Li et al 2020) and AGN activity (e.g., Miniutti et al 2013;Strotjohann et al 2016). Kanner et al (2013) performed a search for low-redshift extragalactic soft X-ray transients in XMMSL2 and gave the first estimate of the event rate within the LIGO/Virgo horizon.…”