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arXiv · 2506.08925

Splashback radius and the mass accretion rate of RASS MCMF galaxy clusters

Jitendra Joshi·Divya Rana·Surhud More·Matthias Klein
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Abstract

We present measurements of the radial profile of mass and galaxy number density around X-ray selected ROSAT All Sky Survey-Multi-Component Matched Filter galaxy clusters using Year 3 data from the Dark Energy Survey. We measure the projected cross-correlation signal of the RedMaGiC "high density" galaxies around an approximately volume-limited sample of 255 galaxy clusters at a median redshift of $z=0.4$ and an X-ray luminosity $L_X > 10^{44} \,\text{ergs} \, \text{s}^{-1} \, \text{h}^{-2}$. This cross-correlation signal measured with a signal-to-noise ratio of 16.41 allows us to infer a 3D number density profile which shows a significant steepening at the edges of these galaxy clusters, namely the splashback radius of $r_{sp}$ /$h^{-1} \mathrm{M_{\odot}} = 2.19^{+0.50}_{-0.43}$. We present the dependence of the splashback radius value over a range of absolute galaxy magnitude cuts to look for any evidence of dynamical friction affecting these results. The weak lensing signal around our galaxy clusters measured with a signal-to-noise ratio of 32.19 allows us to infer a halo mass $\text{log} (M_{\rm 200m} / h^{-1} \text{Mpc}) = 14.68_{-0.04}^{+0.04}$. Comparison of the location of the splashback radius with the spherical overdensity boundary $r_{\rm 200m}$ shows consistency with the $\mathrm{ΛCDM}$ predictions. We present the first inference of the average mass accretion rate of galaxy clusters using our measurements of the splashback radius.

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Jitendra Joshi, Divya Rana, Surhud More, Matthias Klein. 2025-06-10. Splashback radius and the mass accretion rate of RASS MCMF galaxy clusters. https://doi.org/10.1103/7d62-3gnp

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