Relativistic SZ temperatures and hydrostatic mass bias for massive clusters in the FLAMINGO simulations
Scott T. Kay, Joey Braspenning, Jens Chluba, John C. Helly, Roi Kugel, Matthieu Schaller, Joop Schaye
arXiv:2404.08539v1 Announce Type: new
Abstract: The relativistic Sunyaev-Zel’dovich (SZ) effect can be used to measure intracluster gas temperatures independently of X-ray spectroscopy. Here, we use the large-volume FLAMINGO simulation suite to determine whether SZ $y$-weighted temperatures lead to more accurate hydrostatic mass estimates in massive ($M_{rm 500c} > 7.5times 10^{14},{rm M}_{odot}$) clusters than when using X-ray spectroscopic-like temperatures. We find this to be the case, on average. The median bias in the SZ mass at redshift zero is $left equiv 1-left = -0.05 pm 0.01$, over 4 times smaller in magnitude than the X-ray spectroscopic-like case, $left = 0.22 pm 0.01$. However, the scatter in the SZ bias, $sigma_{b} approx 0.2$, is around 40 per cent larger than for the X-ray case. We show that this difference is strongly affected by clusters with large pressure fluctuations, as expected from shocks in ongoing mergers. Selecting the clusters with the best-fitting generalized NFW pressure profiles, the median SZ bias almost vanishes, $left = -0.009 pm 0.005$, and the scatter is halved to $sigma_{b} approx 0.1$. We study the origin of the SZ/X-ray difference and find that, at $R_{rm 500c}$ and in the outskirts, SZ weighted gas better reflects the hot, hydrostatic atmosphere than the X-ray weighted gas. The SZ/X-ray temperature ratio increases with radius, a result we find to be insensitive to variations in baryonic physics, cosmology and numerical resolution.arXiv:2404.08539v1 Announce Type: new
Abstract: The relativistic Sunyaev-Zel’dovich (SZ) effect can be used to measure intracluster gas temperatures independently of X-ray spectroscopy. Here, we use the large-volume FLAMINGO simulation suite to determine whether SZ $y$-weighted temperatures lead to more accurate hydrostatic mass estimates in massive ($M_{rm 500c} > 7.5times 10^{14},{rm M}_{odot}$) clusters than when using X-ray spectroscopic-like temperatures. We find this to be the case, on average. The median bias in the SZ mass at redshift zero is $left equiv 1-left = -0.05 pm 0.01$, over 4 times smaller in magnitude than the X-ray spectroscopic-like case, $left = 0.22 pm 0.01$. However, the scatter in the SZ bias, $sigma_{b} approx 0.2$, is around 40 per cent larger than for the X-ray case. We show that this difference is strongly affected by clusters with large pressure fluctuations, as expected from shocks in ongoing mergers. Selecting the clusters with the best-fitting generalized NFW pressure profiles, the median SZ bias almost vanishes, $left = -0.009 pm 0.005$, and the scatter is halved to $sigma_{b} approx 0.1$. We study the origin of the SZ/X-ray difference and find that, at $R_{rm 500c}$ and in the outskirts, SZ weighted gas better reflects the hot, hydrostatic atmosphere than the X-ray weighted gas. The SZ/X-ray temperature ratio increases with radius, a result we find to be insensitive to variations in baryonic physics, cosmology and numerical resolution.