The X-ray Angular Power Spectrum of Extended Sources in the eROSITA Final Equatorial Depth Survey

TL;DR

This paper measures the X-ray angular power spectrum of galaxy clusters in the eROSITA eFEDS survey, confirming consistency with previous data and models, and predicts future constraints on cosmological parameters from upcoming survey data.

Contribution

It provides the first measurement of the X-ray angular power spectrum in the eFEDS field and compares it with models and past observations, setting the stage for future cosmological constraints.

Findings

Measured power spectrum consistent with past observations

Cluster gas halo model aligns with eFEDS data

Future eROSITA data expected to constrain cosmological parameters

Abstract

The eROSITA Final Equatorial Depth Survey (eFEDS), with a sky area of 140 square degrees with depth equivalent to the equatorial patch of the final eROSITA all-sky survey, represents the largest continuous non-full-sky X-ray fields to-date, making it the premier data set for measuring the angular power spectrum. In this work, we measure the X-ray angular power spectrum of galaxy clusters and groups in the eFEDS field. We show that the measured power spectrum is consistent with past observations, including the ROSAT All Sky Survey, and the Chandra COSMOS and Bootes fields. The predictions of cluster gas halo model that is calibrated from Chandra observations is also consistent with the eFEDS power spectrum. While the eFEDS does not have large enough sky coverage to provide meaningful cosmological constraints, we predict that the X-ray power spectrum from the cycle 4 of the eROSITA All-Sky Survey (eRASS4) will provide constraints on $\Omega_M$ and $\sigma_8$ at the 10% level.