Establishing the X-ray Source Detection Strategy for eROSITA with Simulations

Abstract

The eROSITA X-ray telescope on board the Spectrum-Roentgen-Gamma (SRG) satellite has started to detect new X-ray sources over the full sky at an unprecedented rate. Understanding the performance and selection function of the source detection is important for the subsequent scientific analysis of the eROSITA catalogs. Through simulations, we test and optimize the eROSITA source detection procedures, and we characterize the detected catalog quantitatively. Taking the eROSITA Final Equatorial-Depth Survey (eFEDS) as an example, we ran extensive photon-event simulations based on our best knowledge of the instrument characteristics, the background spectrum, and the population of astronomical X-ray sources. We introduce a method of analyzing source detection completeness, purity, and efficiency based on the origin of each photon. According to the source detection efficiency measured in the simulation, we chose a two-pronged strategy to build eROSITA X-ray catalogs, creating a main catalog using only the most sensitive band (0.2-2.3 keV) and an independent hard-band-selected catalog using multiband detection in a range up to 5 keV. Because our mock data are highly representative of the real eFEDS data, we used the mock catalogs to measure the completeness and purity of the eFEDS catalogs as a function of multiple parameters, such as detection likelihood, flux, and luminosity. These measurements provide a basis for choosing the eFEDS catalog selection thresholds. The mock catalogs (available with this paper) can be used to construct the selection function of active galactic nuclei and galaxy clusters. A direct comparison of the output and input mock catalogs also gives rise to a correction curve that converts the raw point-source flux distribution into the intrinsic number counts distribution.

Accepted by A&A for the Special Issue: The Early Data Release of eROSITA and Mikhail Pavlinsky ART-XC on the SRG Mission

References in corpus (9)

• eROSITA Science Book: Mapping the Structure of the Energetic Universe
• The eROSITA Final Equatorial Depth Survey (eFEDS): The X-ray catalog
• Cosmic X-ray Surveys of Distant Active Galaxies: The Demographics, Physics, and Ecology of Growing Supermassive Black Holes
• Unifying X-ray Scaling Relations from Galaxies to Clusters
• 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): Catalog of galaxy clusters and groups
• The eROSITA Final Equatorial-Depth Survey (eFEDS): The AGN Catalogue and its X-ray Spectral Properties
• Active Galactic Nuclei and their Large-scale Structure: an eROSITA mock catalogue
• EXSdetect: an end-to-end software for extended source detection in X-ray images: application to Swift-XRT data

Cited by in corpus (27)

• 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
• The SRG/eROSITA all-sky survey: Cosmology constraints from cluster abundances in the western Galactic hemisphere
• The eROSITA Final Equatorial-Depth Survey (eFEDS): The AGN Catalogue and its X-ray Spectral Properties
• The eROSITA Final Equatorial-Depth Survey (eFEDS): X-ray Observable-to-Mass-and-Redshift Relations of Galaxy Clusters and Groups with Weak-Lensing Mass Calibration from the Hyper Suprime-Cam Subaru Strategic Program Survey
• Cosmological Constraints from Galaxy Clusters and Groups in the eROSITA Final Equatorial Depth Survey
• The eROSITA Final Equatorial Depth Survey (eFEDS): X-ray emission around star-forming and quiescent galaxies at $0.05<z<0.3$
• The eROSITA Final Equatorial-Depth Survey (eFEDS): Galaxy Clusters and Groups in Disguise
• The eROSITA Final Equatorial-Depth Survey (eFEDS): X-ray Properties and Scaling Relations of Galaxy Clusters and Groups
• Detecting clusters of galaxies and active galactic nuclei in an eROSITA all-sky survey digital twin
• The eROSITA Final Equatorial-Depth Survey (eFEDS): Characterization of Morphological Properties of Galaxy Groups and Clusters
• The cosmic web of X-ray active galactic nuclei seen through the eROSITA Final Equatorial Depth Survey (eFEDS)
• Compact white-dwarf binaries in the combined SRG/eROSITA/SDSS eFEDS survey
• The eROSITA Final Equatorial-Depth Survey (eFEDS): Presenting The Demographics of X-ray Emission From Normal Galaxies
• Detecting Galaxy Groups and AGNs populating the local Universe in the eROSITA era
• Effects of Multiphase Gas and Projection on X-ray Observables in Simulated Galaxy Clusters as Seen by eROSITA
• The LOFAR-eFEDS survey: The incidence of radio and X-ray AGN and the disk-jet connection
• X-ray emission from a rapidly accreting narrow-line Seyfert 1 galaxy at z=6.56
• Phase-resolved X-ray spectroscopy of PSR B0656+14 with SRG/eROSITA and XMM-Newton
• The SRG/eROSITA All-Sky Survey: X-ray beacons at late cosmic dawn
• The impact of assembly history on the X-ray detectability of halos. From galaxy groups to galaxy clusters
• The eROSITA Final Equatorial Depth Survey (eFEDS): the hard X-ray selected sample
• Characterising X-ray variability in light curves with complex sampling patterns: application to the eROSITA south ecliptic pole survey
• The eROSITA extragalactic CalPV serendipitous catalog
• Characterisation of the X-ray point source variability in the eROSITA south ecliptic pole field
• Modelling the selection of galaxy groups with end to end simulations
• Bayesian Multi-wavelength Imaging of the LMC SN1987A with SRG/eROSITA