To TDE or not to TDE: the luminous transient ASASSN-18jd with TDE-like and AGN-like qualities

Neustadt, Jack M. M.; Holoien, T. W. S.; Kochanek, C. S.; Auchettl, Katie; Brown, J. S.; Shappee, B. J.; Pogge, Richard W.; Dong, Subo; Stanek, K. Z.; Tucker, M. A.; Bose, S.; Chen, Ping; Ricci, Cláudio; Vallely, P.; Prieto, J. L.; Thompson, Todd A.; Coulter, D. A.; Drout, M. R.; Foley, R. J.; Kilpatrick, C. D.; Piro, Anthony L.; Rojas-Bravo, C.; Buckley, D.; Gromadzki, M.; Dimitriadis, G.; Siebert, M. R.; Do, A.; Huber, M. E.; Payne, A. V.

doi:10.1093/mnras/staa859

Cited by 45 publications

(42 citation statements)

References 129 publications

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“…TDEs are typically characterized by smoothly declining optical light curves, and the handful of discrepant examples such as PS18kh (Holoien et al 2019) and 2018fyk/ASASSN-18ul (Wevers et al 2019) tend to display atypical features like rebrightenings and plateaus only in their ultraviolet (UV) light curves, thought to be connected with processes in the accretion disk. The fluctuations in optical light curves shown by 2020nov and 2021ehb in our sample are perhaps similar to those seen in ASASSN-18jd, whose nature as either a TDE or a new class of nuclear transient is still unclear (Neustadt et al 2020). The rebrightening episode of 2020acka, though classified as a TDE by Hammerstein et al (2021b), resembles that of ZTF19abvgxrq/2019pev (also included in our sample; see below), which has been proposed as a member of the Trakhtenbrot AGN (Trakhtenbrot et al 2019) by Frederick et al (2021).…”

Section: Bumpy Extragalactic Transient Categoriessupporting

confidence: 73%

Optical Rebrightening of Extragalactic Transients from the Zwicky Transient Facility

Soraisam,

Matheson,

Lee

et al. 2022

Preprint

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Ongoing large-scale optical time-domain surveys, such as the Zwicky Transient Facility (ZTF), are producing alerts at unprecedented rates. Analysis of transient sources has so far followed two distinct paths: archival analysis of data on transient sources at a time when they are no longer observable and real-time analysis at the time when the sources are first detected. The latter is the realm of alert brokers such as the Arizona-NOIRLab Temporal Analysis and Response to Events System (ANTARES). In this paper, we synthesize the two analysis paths and present a first systematic study of archival alert-broker data, focusing on extragalactic transients with multipeaked light curves identified in the ANTARES archive of ZTF alerts. Our analysis yields a sample of 37 such sources, including corecollapse supernovae (with two analogs of iPTF14hls), thermonuclear supernovae interacting with their surrounding circumstellar medium, tidal disruption events, luminous blue variables, and as yet unclassified objects. A large fraction of the identified sources is currently active, warranting allocation of follow-up resources in the immediate future to further constrain their nature and the physical processes at work.

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Section: Bumpy Extragalactic Transient Categoriessupporting

confidence: 73%

Optical Rebrightening of Extragalactic Transients from the Zwicky Transient Facility

Soraisam,

Matheson,

Lee

et al. 2022

Preprint

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“…Ne V λ3426, when observable, is typically associated with AGN, and is present in the spectra of these sources. Strong He II profiles, although somewhat rare in association with normal stochastic AGN variability (Neustadt et al 2020), have been observed before and interpreted as the signature of a sudden enhancement of accretion (e.g. Trakhtenbrot et al 2019a;Frederick et al 2019).…”

Section: Association Of the Transients With Agnmentioning

confidence: 78%

A Family Tree of Optical Transients from Narrow-line Seyfert 1 Galaxies

Frederick

Gezari

Graham

et al. 2021

ApJ

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The Zwicky Transient Facility (ZTF) has discovered five new events belonging to an emerging class of AGN undergoing smooth flares with large amplitudes and rapid rise times. This sample consists of several transients that were initially classified as supernovae with narrow spectral lines. However, upon closer inspection, all of the host galaxies display resolved Balmer lines characteristic of a narrow-line Seyfert 1 (NLSy1) galaxy. The transient events are long-lived, over 400 days on average. We report UV and X-ray follow-up of the flares and observe persistent UV-bright emission, with two of the five transients detected with luminous X-ray emission, ruling out a supernova interpretation. We compare the properties of this sample to previously reported flaring NLSy1 galaxies, and find that they fall into three spectroscopic categories: Transients with 1) Balmer line profiles and Fe II complexes typical of NLSy1s, 2) strong He II profiles, and 3) He II profiles including Bowen fluorescence features. The latter are members of the growing class of AGN flares attributed to enhanced accretion reported by Trakhtenbrot et al. (2019). We consider physical interpretations in the context of related transients from the literature. For example, two of the sources show high amplitude rebrightening in the optical, ruling out a simple tidal disruption event scenario for those transients. We conclude that three of the sample belong to the Trakhtenbrot et al. ( 2019) class, and two are TDEs in NLSy1s. We also aim to understand why NLSy1s are preferentially the sites of such rapid enhanced flaring activity.

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“…The host-subtracted UV/optical SEDs of TDEs (e.g., Holoien et al 2014Holoien et al , 2016a and some AGN flares (e.g., Neustadt et al 2020) are well-fit as blackbodies. While in AGN the geometry of the emitting region is likely nonspherical and the emission is at least partly non-thermal, a simple blackbody fit should provide a reasonable estimate of the size and luminosity of the optically thick, Note-Synthetic host photometry computed from the Monte Carlo sampling of host galaxy SED fits with FAST.…”

Section: Blackbody Fitsmentioning

confidence: 85%

A Swift Fix for Nuclear Outbursts

Hinkle

Holoien

Shappee

et al. 2021

ApJ

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In November 2020, the Swift team announced an update to the UltraViolet and Optical Telescope calibration to correct for the loss of sensitivity over time. This correction affects observations in the three near-ultraviolet (UV) filters, by up to 0.3 mag in some cases. As UV photometry is critical to characterizing tidal disruption events (TDEs) and other peculiar nuclear outbursts, we recomputed published Swift data for TDEs and other singular nuclear outbursts with Swift photometry in 2015 or later as a service to the community. Using archival UV, optical, and infrared photometry, we ran host SED fits for each host galaxy. From these, we computed synthetic host magnitudes and host-galaxy properties. We calculated host-subtracted magnitudes for each transient and computed blackbody fits. In addition to the nuclear outbursts, we include the ambiguous transient ATLAS18qqn (AT2018cow), which has been classified as a potential TDE on an intermediate-mass black hole. Finally, with updated bolometric light curves, we recover the relationship of Hinkle et al., where more-luminous TDEs decay more slowly than less-luminous TDEs, with decreased scatter compared to the original relationship.

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To TDE or not to TDE: the luminous transient ASASSN-18jd with TDE-like and AGN-like qualities

Cited by 45 publications

References 129 publications

Optical Rebrightening of Extragalactic Transients from the Zwicky Transient Facility

Optical Rebrightening of Extragalactic Transients from the Zwicky Transient Facility

A Family Tree of Optical Transients from Narrow-line Seyfert 1 Galaxies

A Swift Fix for Nuclear Outbursts

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