Abstract

We discuss an algorithm whereby the massive galaxy clusters detected in the SRG/eROSITA all-sky survey are identified and their photometric redshifts are estimated. For this purpose, we use photometric redshift estimates for galaxies and WISE forced photometry. To estimate the algorithm operation quality, we used a sample of 634 massive galaxy clusters from the Planck survey with known spectroscopic redshifts in the range \(0.1<z_{\textrm{spec}}<0.6\). The accuracy of the photometric redshift estimates for this sample is \(\delta z_{\textrm{phot}}/(1+z_{\textrm{phot}})\approx 0.5{\%}\), the fraction of large deviations is 1.3\({\%}\). We show that these large deviations arise mainly from the projections of galaxy clusters or other large-scale structures at different redshifts in the X-ray source field. Measuring the infrared (IR) luminosities of galaxy clusters allows one to estimate the reliability of the optical identification of the clusters detected in the SRG/eROSITA survey and to obtain an additional independent measurement of their total gravitational masses, \(M_{500}\). We show that the masses \(M_{500}\) of the galaxy clusters estimated from their IR luminosity measurements have an accuracy \(\sigma_{\log M_{500}}=0.124\), comparable to the accuracy of the mass estimation for the galaxy clusters from their X-ray luminosities.

中文翻译：

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基于星系光度红移估计的 SRG/eROSITA X 射线源中星系团的光学识别

摘要

我们讨论了一种算法，通过该算法可以识别 SRG/eROSITA 全天巡天中检测到的大质量星系团，并估计它们的光度红移。为此，我们使用星系光度红移估计和 WISE 强制光度测量。为了估计算法的运行质量，我们使用了普朗克巡天中 634 个巨大星系团的样本，已知光谱红移范围为\(0.1<z_{\textrm{spec}}<0.6\)。该样本的光度红移估计的精度为\(\delta z_{\textrm{phot}}/(1+z_{\textrm{phot}})\approx 0.5{\%}\)，即大的分数偏差为 1.3 \({\%}\)。我们表明，这些大的偏差主要来自星系团或其他大尺度结构在 X 射线源场中不同红移的投影。通过测量星系团的红外 (IR) 光度，人们可以估计 SRG/eROSITA 巡天中检测到的星系团光学识别的可靠性，并获得对其总引力质量的额外独立测量，\( M_{500}\ ）。我们表明，根据红外光度测量估计的星系团质量\(M_{500}\)的精度为\(\sigma_{\log M_{500}}=0.124\)，与质量的精度相当根据 X 射线光度估计星系团。