Halo Scaling Relations and Hydrostatic Mass Bias in the Simba Simulation From Realistic Mock X-ray Catalogues

Fred Jennings; Romeel Davé

doi:10.1093/mnras/stad2666

paper

Halo Scaling Relations and Hydrostatic Mass Bias in the Simba Simulation From Realistic Mock X-ray Catalogues

arXiv:2306.01397 · doi:10.1093/mnras/stad2666

Abstract

We present a new end-to-end pipeline for Mock Observations of X-ray Halos and Analysis (MOXHA) for hydrodynamic simulations of massive halos, and use it to investigate X-ray scaling relations and hydrostatic mass bias in the Simba cosmological hydrodynamic simulation for halos with $M_{500} \sim 1 0^{13 - 15} M_{⊙}$ . MOXHA ties together existing yT-based software packages and adds new functionality to provide an end-to-end pipeline for generating mock X-ray halo data from large-scale or zoom simulation boxes. We compare MOXHA-derived halo properties in Simba to their emission-weighted counterparts, and forecast the systematic mass bias in mock Athena observations. Overall, we find inferred hydrostatic masses are biased low compared to true Simba values. For simple mass-weighting, we find $b_{MW} = 0.1 5_{- 0.14}^{+ 0.15}$ ( $16 - 84%$ range), while emission-weighting increases this to $b_{LW} = 0.3 0_{- 0.10}^{+ 0.19}$ . The larger bias versus mass-weighted values we attribute to the spectroscopic and emission-weighted temperatures being biased systematically lower than mass-weighted temperatures. The full MOXHA pipeline recovers the emission-weighted hydrostatic masses at $R_{500}$ reasonably well, yielding $b_{X} = 0.3 3_{- 0.34}^{+ 0.28}$ . MOXHA-derived halo X-ray scalings are in very good agreement with observed scaling relations, with the inclusion of lower-mass groups significantly steepening the $L_{X} - M_{500}$ , $M_{500} - T_{X}$ , and $L_{X} - T_{X}$ relations. This indicates the strong effect the Simba feedback model has on low-mass halos, which strongly evacuates poor groups but still retains enough gas to reproduce observations. We find similar trends for analogous scaling relations measured at $R_{500}$ , as expected for halo-wide gas evacuation.

arXiv commentAccepted for publication in MNRAS

Halo Scaling Relations and Hydrostatic Mass Bias in the Simba Simulation From Realistic Mock X-ray Catalogues

Abstract

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