eRO-ExTra: eROSITA extragalactic non-AGN X-ray transients and variables in eRASS1 and eRASS2

Abstract

(Abridged) While previous X-ray studies showed the dominance of regular active galactic nuclei (AGN) variability, a small fraction of sources arise from more exotic phenomena such as tidal disruption events (TDEs), quasi-periodic eruptions, or other short-lived events associated with supermassive black hole accretion. This paper describes the systematic selection of X-ray extragalactic transients found in the first two eROSITA all-sky surveys (eRASS) that are not associated with known AGN prior to eROSITA observations. We generated a variability sample from eRASS1 and eRASS2 (Dec. 2019-Dec. 2020), which includes sources with a variability significance and a fractional amplitude larger than four, located in the Legacy Survey DR10 (LS10) footprint. The properties of LS10 counterparts were used to exclude stars and known AGN. The sample was additionally cleaned using pre-eROSITA classifications, archival optical spectra, and archival X-ray data. The final catalog eRO-ExTra includes 304 extragalactic eROSITA transients and variables not associated with known AGN. More than 90% of sources have reliable LS10 optical counterparts. For each source, we provide archival X-ray data from Swift, ROSAT, and XMM-Newton; the eROSITA long-term light curve (2-2.5 years) with a light curve classification; as well as the best power law fit spectral results at the peak eROSITA epoch. Reliable spectroscopic and photometric redshifts are provided for more than 80% of the sample. Several sources in the catalog are known TDE candidates discovered by eROSITA. In addition, 31 sources are radio detected. The eRO-ExTra transients constitute a relatively clean parent sample of non-AGN variability phenomena associated with massive black holes. More than 95% of eRO-ExTra sources were discovered in X-rays with eROSITA for the first time, which makes it a valuable resource for studying unique nuclear transients.

arXiv comment18 pages, 15 figures, published in A&A. To download the eRO-ExTra catalog, see https://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/693/A62

References in corpus (60)

• Planck 2015 results. XIII. Cosmological parameters
• The Gaia mission
• Gaia Data Release 3: Summary of the content and survey properties
• The Swift X-ray Telescope
• The SIMBAD astronomical database
• Overview of the DESI Legacy Imaging Surveys
• X-ray spectral modelling of the AGN obscuring region in the CDFS: Bayesian model selection and catalogue
• HI4PI: A full-sky HI survey based on EBHIS and GASS
• The eROSITA X-ray telescope on SRG
• Calibrating Extinction-Free Star Formation Rate Diagnostics with 33GHz Free-Free Emission in NGC6946
• Mid-Infrared Selection of AGN with the Wide-Field Infrared Survey Explorer. I. Characterizing WISE-Selected AGN in COSMOS
• Automated data reduction workflows for astronomy
• Discovery of the Onset of Rapid Accretion by a Dormant Massive Black Hole
• Tidal Disruption Events
• Swift J2058.4+0516: Discovery of a Possible Second Relativistic Tidal Disruption Flare?
• The SRG X-ray orbital observatory, its telescopes and first scientific results
• The SRG/eROSITA all-sky survey: First X-ray catalogues and data release of the western Galactic hemisphere
• The eROSITA Final Equatorial Depth Survey (eFEDS): The X-ray catalog
• Ubiquitous variability of X-ray absorbing column densities in Seyfert 2 Galaxies
• The 5th edition of the Roma-BZCAT. A short presentation
• The CatWISE2020 Catalog
• The first XMM-Newton slew survey catalogue: XMMSL1
• Nine-hour X-ray quasi-periodic eruptions from a low-mass black hole galactic nucleus
• The Rapid ASKAP Continuum Survey I: Design and First Results
• Changing look: from Compton-thick to Compton-thin, or the re-birth of fossil AGN
• Explaining changing-look AGN with state transition triggered by rapid mass accretion rate drop
• The Wide Field Spectrograph (WiFeS): Performance and Data Reduction
• X-ray Quasi-Periodic Eruptions from two previously quiescent galaxies
• X-ray quasi-periodic eruptions from the galactic nucleus of RX J1301.9+2747
• Finding counterparts for All-sky X-ray surveys with Nway: a Bayesian algorithm for cross-matching multiple catalogues
• The destruction and recreation of the X-ray corona in a changing-look Active Galactic Nucleus
• Magnetic reconnection: flares and coronal heating in Active Galactic Nuclei
• PyWiFeS: A Rapid Data Reduction Pipeline for the Wide Field Spectrograph (WiFeS)
• Driving extreme variability: The evolving corona and evidence for jet launching in Markarian 335
• Variability in active galactic nuclei: confrontation of models with observations
• The eROSITA Final Equatorial-Depth Survey (eFEDS): Identification and characterization of the counterparts to the point-like sources
• The 3HSP catalogue of Extreme & High Synchrotron Peaked Blazars
• Repeating tidal disruptions in GSN 069: Long-term evolution and constraints on quasi-periodic eruptions' models
• The eROSITA Final Equatorial-Depth Survey (eFEDS): The AGN Catalogue and its X-ray Spectral Properties
• Two new catalogs of blazar candidates in the WISE infrared sky
• Tormund's return: Hints of quasi-periodic eruption features from a recent optical tidal disruption event
• Deciphering the extreme X-ray variability of the nuclear transient eRASSt J045650.3-203750: A likely repeating partial tidal disruption event
• AGN X-ray variability in the XMM-COSMOS survey
• A Systematic Study Of X-Ray Variability In The ROSAT All-Sky Survey
• Tracing the accretion history of supermassive Black Holes through X-ray variability: results from the Chandra Deep Field-South
• Long-term X-ray variability of Swift J1644+57
• Monthly quasi-periodic eruptions from repeated stellar disruption by a massive black hole
• X-ray detection of a nova in the fireball phase
• Detecting clusters of galaxies and active galactic nuclei in an eROSITA all-sky survey digital twin
• The rebrightening of a ROSAT-selected tidal disruption event: repeated weak partial disruption flares from a quiescent galaxy?
• A radio-emitting outflow produced by the tidal disruption event AT2020vwl
• AT 2019avd: A novel addition to the diverse population of nuclear transients
• XZ: Deriving redshifts from X-ray spectra of obscured AGN
• The RapidXMM Upper Limit Server: X-ray aperture photometry of the XMM-Newton archival observations
• Discovery of the luminous X-ray ignition eRASSt J234402.9$-$352640; I. Tidal disruption event or a rapid increase in accretion in an active galactic nucleus?
• eRASSt J074426.3+291606: prompt accretion disc formation in a 'faint and slow' tidal disruption event
• Gamma-Ray Bursts
• The eROSITA Final Equatorial-Depth Survey (eFEDS): The variability catalogue and multi-epoch comparison
• A New Multi-Wavelength Census of Blazars
• Characterising X-ray variability in light curves with complex sampling patterns: application to the eROSITA south ecliptic pole survey

Cited by in corpus (5)

• The population of tidal disruption events discovered with eROSITA
• eROSITA-RU Tidal Disruption Events with Keck-I/LRIS: Sample Selection, Optical Properties, and Host Galaxy Demographics
• A new Bowen Fluorescence Flare and Extreme Coronal Line Emitter discovered by SRG/eROSITA
• Searching for supermassive black holes binaries within SRG/eROSITA-De I: Properties of the X-ray selected candidates
• Wind-mediated Eddington-limited emission in a $10^4{M}_{\odot }$ Black Hole Tidal Disruption Event