The eROSITA Final Equatorial-Depth Survey (eFEDS): Presenting The Demographics of X-ray Emission From Normal Galaxies

Abstract

The $eROSITA$ Final Equatorial Depth Survey (eFEDS), completed during the calibration and performance verification phase of the $eROSITA$ instrument on $SpectrumRoentgenGamma$, delivers data at and beyond the final depth of the four-year $eROSITA$ all-sky survey (eRASS:8), $f_{0.5-2\text{ keV}}$ = $1.1\times 10^{-14}$ erg s${}^{-1}$ cm${}^2$, over 140 deg${}^2$. It provides the first view of normal galaxy X-ray emission from X-ray binaries (XRBs) and the hot interstellar medium at the full depth of eRASS:8. We use the Heraklion Extragalactic Catalogue (HECATE) of galaxies to correlate with eFEDS X-ray sources and identify 94 X-ray detected normal galaxies. We classify galaxies as star-forming, early-type, composite, and AGN using SDSS and 6dF optical spectroscopy. The eFEDS field harbours 37 normal galaxies: 36 late-type (star-forming) galaxies and 1 early-type galaxy. There are 1.9 times as many normal galaxies as predicted by scaling relations via SIXTE simulations, with an overabundance of late-type galaxies and a dearth of early-type galaxies. Dwarf galaxies with high specific star formation rate (SFR) have elevated L${}_{\text{X}}$/SFR when compared with specific SFR and metallicity, indicating an increase in XRB emission due to low-metallicity. We expect that eRASS:8 will detect 12,500 normal galaxies, the majority of which will be star-forming, with the caveat that there are unclassified sources in eFEDS and galaxy catalogue incompleteness issues that could increase the actual number of detected galaxies over these current estimates. eFEDS observations detected a rare population of galaxies -- the metal-poor dwarf starbursts -- that do not follow known scaling relations. eRASS is expected to discover significant numbers of these high-redshift analogues, which are important for studying the heating of the intergalactic medium at high-redshift.

17 pages, 10 figures, 3 tables. Submitted to A&A for the Special Issue: The Early Data Release of eROSITA and Mikhail Pavlinsky ART-XC on the SRG Mission

References in corpus (20)

• HyperLEDA. III. The catalogue of extragalactic distances
• The Chandra Deep Field-South Survey: 7 Ms Source Catalogs
• The XMM-Newton serendipitous survey IX. The fourth XMM-Newton serendipitous source catalogue
• The eROSITA Final Equatorial Depth Survey (eFEDS): The X-ray catalog
• The XMM-Newton wide-field survey in the COSMOS field. The point-like X-ray source catalogue
• Observational evidence for intermediate-mass black holes
• The Chandra COSMOS-Legacy survey: Source X-ray spectral properties
• The eROSITA Final Equatorial-Depth Survey (eFEDS): Identification and characterization of the counterparts to the point-like sources
• A census of ultraluminous X-ray sources in the local Universe
• The Metallicity Dependence of the High-Mass X-ray Binary Luminosity Function
• X-ray binary formation in low-metallicity blue compact dwarf galaxies
• Metallicity dependence of HMXB populations
• The Circum-Galactic Medium of MASsive Spirals II: Probing the Nature of Hot Gaseous Halo around the Most Massive Isolated Spiral Galaxies
• NuSTAR, XMM-Newton and Suzaku Observations of the Ultraluminous X-ray Source Holmberg II X-1
• The Heraklion Extragalactic Catalogue (HECATE): a value-added galaxy catalogue for multi-messenger astrophysics
• SDSS-IV eBOSS Spectroscopy of X-ray and WISE AGN in Stripe 82X: Overview of the Demographics of X-ray and Mid-Infrared Selected Active Galactic Nuclei
• On the Spatially Resolved Star-Formation History in M51 II: X-ray Binary Population Evolution
• Establishing the X-ray Source Detection Strategy for eROSITA with Simulations
• Sub-galactic scaling relations between X-ray luminosity, star-formation rate, and stellar mass
• The Next Generation X-ray Galaxy Survey with eROSITA

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• The eROSITA Final Equatorial-Depth Survey (eFEDS). The stellar counterparts of eROSITA sources identified by machine learning and Bayesian algorithms
• Decomposition of galactic X-ray emission with Phox: Contributions from hot gas and XRBs
• The hot circumgalactic medium in the eROSITA All-Sky Survey III. Star-forming and quiescent galaxies
• X-ray luminosity-star formation rate scaling relation: Constraints from the eROSITA Final Equatorial Depth Survey (eFEDS)
• The first all-sky survey of star-forming galaxies with eROSITA: Scaling relations and a population of X-ray luminous starbursts
• The eROSITA Final Equatorial Depth Survey (eFEDS): the hard X-ray selected sample
• The hot gas mass fraction in halos. From Milky Way-like groups to massive clusters
• Average X-ray properties of galaxy groups. From Milky Way-like halos to massive clusters
• The eROSITA Final Equatorial Depth Survey (eFEDS): SDSS spectroscopic observations of X-ray sources
• Gas excitation in galaxies and active galactic nuclei with He IIλ4686 and X-ray emission