Unifying Sunyaev-Zel'dovich and X-ray predictions from clusters to galaxy groups: the impact of X-ray mass estimates on the $Y-M$ scaling relation

Abstract

One of the main limitations in precision cluster cosmology arises from systematic errors and uncertainties in estimating cluster masses. Using the Mock-X pipeline, we produce synthetic X-ray images and derive cluster and galaxy group X-ray properties for a sample of over 30,000 simulated galaxy groups and clusters with $M_{500crit}$ between $10^{12}$ and $2\times 10^{15}$ M${}_{\odot }$ in IllustrisTNG. We explore the similarities and differences between IllustrisTNG predictions of the Sunyaev-Zel'dovich and X-ray scaling relations with mass. We find a median hydrostatic mass bias $b=0.125\pm 0.003$ for $M_{500crit}$ $>10^{13}$ M${}_{\odot }$. The bias increases to $b=0.17\pm 0.004$ when masses are derived from synthetic X-ray observations. We model how different underlying assumptions about the dependence of $Y_{\mathrm{X}}$ on halo mass can generate biases in the observed $Y_{\mathrm{SZ}}-M_{Y_{\mathrm{X}}}$ scaling relation. In particular, the simplifying assumption that $Y_{\mathrm{X}}-M_{\mathrm{tot}}$ is self-similar at all mass scales largely hides the break in $Y_{\mathrm{SZ}}-M_{\mathrm{tot}}$ and overestimates $Y_{\mathrm{SZ}}$ at galaxy and groups scales. We show that calibrating the $Y_{\mathrm{X}}-$mass proxy using a new model for a smoothly broken power law reproduces the true underlying $Y_{\mathrm{SZ}}-M_{\mathrm{tot}}$ scaling relation with high accuracy. Moreover, $M_{Y_{\mathrm{X}}}$ estimates calibrated with this method lead to $Y_{\mathrm{SZ}}-M_{Y_{\mathrm{X}}}$ predictions that are not biased by the presence of lower mass clusters or galaxy groups in the sample. Finally, we show that our smoothly broken power law model provides a robust way to derive the $Y_{\mathrm{X}}-$mass proxy, significantly reducing the level of mass bias for clusters, groups, and galaxies.

12 pages, 5 figures; submitted to MNRAS. This is a companion paper to Pop et al. 2022: "Sunyaev-Zel'dovich effect and X-ray scaling relations of galaxies, groups and clusters in the IllustrisTNG simulations"

Cited by in corpus (2)

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