The eROSITA Final Equatorial Depth Survey (eFEDS)

Abstract

Context. The eROSITA X-ray telescope on board the Spectrum-Poentgen-Gamma (SPG) observatory combines a large field of view and a large collecting area in the energy range between ~0.2 and ~8.0 keV. This gives the telescope the capability to perform uniform scanning observations of large sky areas. Aims. SRG/eROSITA performed scanning observations of the ~140 square degree eROSITA Final Equatorial Depth Survey field (the eFEDS field) as part of its performance verification phase ahead of the planned four year of all-sky scanning operations. The observing time of eFEDS was chosen to slightly exceed the depth expected in an equatorial field after the completion of the all-sky survey. While verifying the capability of eROSITA to perform large-area uniform surveys and saving as a test and training dataset to establish calibration and data analysis procedures, the eFEDS survey also constitutes the largest contiguous soft X-ray survey at this depth to date, supporting a range of early eROSITA survey science investigations. Here we (i) present a catalogue of detected X-ray sources in the eFEDS field providing information about source positions and extent, as well as fluxes in multiple energy bands, and (ii) document the suite of tools and procedures developed for eROSITA data processing and analysis, which were validated and optimised by the eFEDS work. Methods. The data were fed through a standard data processing pipeline, which appltes X-ray event calibration and provides a set of standard calibrated data products. A mutiti-stage source detection procedure, building in part on experience from XMM-Newton, was optimised and calibrated by performing realistic simulations of the eROSITA eFEDS observations. Source fluxes were computed in multiple standard energy bands by forced point source fitting and aperture photometry. We cross-matched the eROSITA eFEDS source catalogue with previous XMM-ATLAS observations, which confirmed the excellentt agreement of the eROSITA and XMM-ATLAS source fluxes. Astrometric corrections were performed by cross-matching the eROSITA source positions with an optical reference catalogue of quasars. Results. We present a primary catalogue of 27 910 X-ray sources (542 of which are significantly spatially extended) detected in the 0.2–2.3 keV energy range with detection likelihoods ≥6, corresponding to a (point source) flux limit of 6.5 × 10–15 erg cm–2 s–1 in the 0.5–2.0 keV energy band (80% completeness). A supplementary catalogue contains 4774 low-significance source candidates with detection likelihoods between 5 and 6. In addition, a hard-band sample of 246 sources detected in the energy range 22.3–5.0 keV above a detection likelihood of 10 is provided. In an appendix, we finally describe the dedicated data analysis software package, the eROSITA calibration database, and the standard calibrated data products.

The Circumgalactic Medium from the CAMELS Simulations: Forecasting Constraints on Feedback Processes from Future Sunyaev–Zeldovich Observations

“…X-ray observations will be useful in constraining the inner regions because they are more sensitive to the higher-density gas and they have higher angular resolution than SZ observations. Current data sets such as the eROSITA Final Equatorial-Depth Survey (eFEDS; Predehl et al 2021;Brunner et al 2022) have the potential to further constrain these astrophysical models. Additionally, combining density and pressure information with other types of tracers such as metallicity profiles from line measurements could also potentially help in assessing the validity of different feedback models.…”

BASS. XXI. The Data Release 2 Overview

“…We limit our comparison to X-ray sources with confirmed counterparts with spectroscopic redshifts. For eFEDS, unlike the other surveys, the soft-band flux (0.2-2.3 keV) was used to estimate the hard X-ray 2-10 keV emission assuming a power-law spectral model with Γ = 1.7 since only a small number of sources were detected above 2.3 keV (<1% Brunner et al 2022). For these higher-redshift X-ray surveys we assumed a power-law spectral model with Γ = 1.7, to bring each X-ray luminosity to the rest frame by K-correcting the apparent luminosities based on the observed redshifts into the 2-10 keV rest frame.…”

Cosmological Constraints from Galaxy Clusters and Groups in the eROSITA Final Equatorial Depth Survey

“…The imaging depth is expected to match the final depth of the eROSITA All-Sky Survey in the equatorial region, by design, and is uniform with an average exposure time of ≈ 2.2 𝑘s and ≈ 1.2 𝑘s before and after the correction for vignetting, respectively. The data were processed by the pipeline eSASSusers_201009, which is described in detail in Brunner et al (2022). In what follows, we provide a brief summary.…”