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

Abstract

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.

Submitted to ApJ, 27 pages, 11 figures

References in corpus (35)

• The Zwicky Transient Facility: System Overview, Performance, and First Results
• A Catalog of Quasar Properties from SDSS DR7
• The Zwicky Transient Facility: Data Processing, Products, and Archive
• The eROSITA X-ray telescope on SRG
• The Zwicky Transient Facility: Science Objectives
• The Discovery of the First "Changing Look" Quasar: New Insights into the Physics & Phenomenology of AGN
• Seventeen Tidal Disruption Events from the First Half of ZTF Survey Observations: Entering a New Era of Population Studies
• The Zwicky Transient Facility: Surveys and Scheduler
• A Comprehensive Study of 2 000 Narrow Line Seyfert 1 Galaxies from the Sloan Digital Sky Survey: I. The Sample
• The first XMM-Newton slew survey catalogue: XMMSL1
• The effect of radiation pressure on virial black hole mass estimates and the case of Narrow Line Seyfert 1 galaxies
• A tidal disruption event coincident with a high-energy neutrino
• Fully-Automated Reduction of Longslit Spectroscopy with the Low Resolution Imaging Spectrometer at Keck Observatory
• Optical-Ultraviolet Tidal Disruption Events
• A large fraction of hydrogen-rich supernova progenitors experience elevated mass loss shortly prior to explosion
• The GROWTH Marshal: A Dynamic Science Portal for Time-Domain Astronomy
• A Fully Automated Integral Field Spectrograph Pipeline for the SEDMachine: pysedm
• The Zwicky Transient Facility Alert Distribution System
• Investigating the nature of narrow-line Seyfert 1 galaxies with high-energy spectral complexity
• Understanding extreme quasar optical variability with CRTS: I. Major AGN flares
• ASASSN-14ko is a Periodic Nuclear Transient in ESO 253-G003
• A new class of flares from accreting supermassive black holes
• TDE Hosts are Green and Centrally Concentrated: Signatures of a Post-Merger System
• On the geometry of broad emission region in quasars
• A population of highly energetic transient events in the centres of active galaxies
• Minidisks in Binary Black Hole Accretion
• To TDE or not to TDE: The luminous transient ASASSN-18jd with TDE-like and AGN-like qualities
• NLS1 galaxies and estimation of their central black hole masses from the X-ray excess variance method
• Rapid "Turn-on" of type 1 AGN in a quiescent early type galaxy SDSS1115+0544
• AT 2019avd: A novel addition to the diverse population of nuclear transients
• Two stripped envelope supernovae with circumstellar interaction -- but only one really shows it
• A Tidal Disruption Event Candidate Discovered in the Active Galactic Nucleus SDSS J022700.77-042020.6
• Discovery and Follow-up of the Unusual Nuclear Transient OGLE17aaj
• Four (Super)luminous Supernovae from the First Months of the ZTF Survey
• Helium-rich Superluminous Supernovae From the Zwicky Transient Facility

Cited by in corpus (15)

• Candidate Tidal Disruption Event AT2019fdr Coincident with a High-Energy Neutrino
• The Curious Case of ASASSN-20hx: A Slowly-Evolving, UV and X-ray Luminous, Ambiguous Nuclear Transient
• Establishing accretion flares from massive black holes as a source of high-energy neutrinos
• AT 2019avd: A novel addition to the diverse population of nuclear transients
• AT2019 avd: A tidal disruption event with a two-phase evolution
• The Rapid X-ray and UV Evolution of ASASSN-14ko
• Energetic nuclear transients in luminous and ultraluminous infrared galaxies
• Investigating the Nature of the Luminous Ambiguous Nuclear Transient ASASSN-17jz
• Micro Tidal Disruption Events in Active Galactic Nuclei
• Is the high-energy neutrino event IceCube-200530A associated with a hydrogen-rich superluminous supernova?
• Light Curves of Partial Tidal Disruption Events
• The nascent milliquasar VT J154843.06+220812.6: tidal disruption event or extreme accretion-state change?
• TESS Shines Light on the Origin of the Ambiguous Nuclear Transient ASASSN-18el
• An X-ray View of the Ambiguous Nuclear Transient AT2019pev
• Search for neutrinos from the tidal disruption events AT2019dsg and AT2019fdr with the ANTARES telescope