An IllustrisTNG View of the Caustic Technique for Galaxy Cluster Mass Estimation
Abstract
The TNG3001 run of the IllustrisTNG simulations includes 1697 clusters of galaxies with $M_{200c}>10^{14}$M$_\odot$ covering the redshift range $0.011.04$. We build mock spectroscopic redshift catalogues of simulated galaxies within these clusters and apply the caustic technique to estimate the cumulative cluster mass profiles. We compute the total true cumulative mass profile from the 3D simulation data and calculate the ratio of caustic mass to total 3D mass, $\mathcal{F}_\beta$, as a function of clustercentric distance and identify the radial range where $\mathcal{F}_\beta$ is roughly constant. The filling factor, $\mathcal{F}_\beta=0.41\pm 0.08$, is constant on a plateau that covers a wide clustercentric distance range, $(0.64.2)R_{200c}$. This calibration is insensitive to redshift. The calibrated caustic mass profiles are unbiased, with an average uncertainty of $23\%$. At $R_{200c}$, the average $M^C/M^{3D}=1.03\pm 0.22$; at $2R_{200c}$, the average $M^C/M^{3D}=1.02\pm 0.23$. Simulated galaxies are unbiased tracers of the mass distribution. IllustrisTNG is a broad statistical platform for application of the caustic technique to large samples of clusters with spectroscopic redshifts for $\gtrsim 200$ members in each system. These observations will allow extensive comparisons with weak lensing masses and will complement other techniques for measuring the growth rate of structure in the universe.
 Publication:

arXiv eprints
 Pub Date:
 March 2023
 DOI:
 10.48550/arXiv.2303.18147
 arXiv:
 arXiv:2303.18147
 Bibcode:
 2023arXiv230318147P
 Keywords:

 Astrophysics  Cosmology and Nongalactic Astrophysics
 EPrint:
 11 pages, 9 figures, 2 tables