The eROSITA Final Equatorial-Depth Survey (eFEDS): The variability catalogue and multi-epoch comparison

Abstract

The 140 square degree Final Equatorial-Depth Survey (eFEDS) field, observed with the extended ROentgen Survey with an Imaging Telescope Array (eROSITA) aboard the Spectrum-Roentgen-Gamma (SRG) mission, provides a first look at the variable eROSITA sky. We analyze the intrinsic X-ray variability of the eFEDS sources, provide X-ray light curves and tables with variability test results in the 0.2-2.3 keV (soft) and 2.3-5.0 keV (hard) bands. respectively. We perform variability tests using the normalized excess variance and maximum amplitude variability methods as performed for the 2RXS catalogue and add results from the Bayesian excess variance and the Bayesian block methods. In total 65 sources have been identified as being significantly variable in the soft band. In the hard band only one source is found to vary significantly. For the most variable sources fits to stellar flare events reveal extreme flare properties. A few highly variable AGN have also been detected. About half of the variable eFEDS sources have been detected at X-rays with eROSITA for the first time. Comparison with 2RXS and XMM observations provide variability information on timescales of years to decades.

To appear on A&A, Special Issue: The Early Data Release of eROSITA and Mikhail Pavlinsky ART-XC on the SRG Mission; 13 pages, 10 figures, accepted June 21, 2021

References in corpus (11)

• Second ROSAT all-sky survey (2RXS) source catalogue
• The eROSITA Final Equatorial Depth Survey (eFEDS): The X-ray catalog
• A new method for determining the sensitivity of X-ray imaging observations and the X-ray number counts
• The eROSITA Final Equatorial-Depth Survey (eFEDS): Identification and characterization of the counterparts to the point-like sources
• The eROSITA Final Equatorial-Depth Survey (eFEDS): The AGN Catalogue and its X-ray Spectral Properties
• First eROSITA study of nearby M dwarfs and the rotation-activity relation in combination with TESS
• The RapidXMM Upper Limit Server: X-ray aperture photometry of the XMM-Newton archival observations
• Multi-scale time- and frequency-domain likelihood analysis with photon weights
• The XMM-Newton survey in the H-ATLAS field
• Systematic evaluation of variability detection methods for eROSITA
• Simultaneous eROSITA and TESS observations of the ultra-active star AB~Doradus

Cited by in corpus (14)

• The eROSITA Final Equatorial Depth Survey (eFEDS): The X-ray catalog
• The eROSITA Final Equatorial-Depth Survey (eFEDS): Identification and characterization of the counterparts to the point-like sources
• Gaia Data Release 3: Cross-match of Gaia sources with variable objects from the literature
• First eROSITA study of nearby M dwarfs and the rotation-activity relation in combination with TESS
• Cosmic hide and seek: the volumetric rate of X-ray quasi-periodic eruptions
• The eROSITA Final Equatorial-Depth Survey (eFEDS). The stellar counterparts of eROSITA sources identified by machine learning and Bayesian algorithms
• Compact white-dwarf binaries in the combined SRG/eROSITA/SDSS eFEDS survey
• Discovery of late-time X-ray flare and anomalous emission line enhancement after the nuclear optical outburst in a narrow-line Seyfert 1 Galaxy
• Systematic evaluation of variability detection methods for eROSITA
• The first look at Narrow-Line Seyfert 1 Galaxies with eROSITA
• eRO-ExTra: eROSITA extragalactic non-AGN X-ray transients and variables in eRASS1 and eRASS2
• Characterising X-ray variability in light curves with complex sampling patterns: application to the eROSITA south ecliptic pole survey
• The eROSITA DR1 variability catalogue
• The SRG/eROSITA all-sky survey: Hard X-ray selected Active Galactic Nuclei