The Impact of Galaxy Formation on the Sunyaev‐Zel'dovich Effect of Galaxy Clusters

Abstract

We study the effects of galaxy formation on the Sunyaev-Zel'dovich effect (SZE) observable-mass relations using high-resolution cosmological simulations. The simulations of eleven individual clusters spanning a decade in mass are performed with the shock-capturing Eulerian adaptive mesh refinement N-body+gasdynamics ART code. To assess the impact of galaxy formation, we compare two sets of simulations performed in an adiabatic regime (without galaxy formation) and those with several physical processes critical to various aspects of galaxy formation: radiative cooling, star formation, stellar feedback and metal enrichment. We show that a SZE signal integrated to a sufficiently large fraction of cluster volume correlates strongly with its enclosed mass, independent of details of gas physics and dynamical state of the cluster. The slope and redshift evolution of the SZE flux-mass relation are also insensitive to processes of galaxy formation and are well characterized by a simple self-similar cluster model. Its normalization, on the other hand, is significantly affected by gas cooling and associated star formation. Our simulations show that inclusion of these processes suppresses the normalization by ≈ 30 − 40%. The effect is due to a decrease in gas mass fraction, which is offset slightly by an increase in gas mass-weighted temperature. Gas cooling and star formation also cause an increase in total mass and modify the normalization by a few percent. Finally, we compare the results of our simulations to recent observations of the SZE scaling relations obtained using 36 OVRO/BIMA SZE+Chandra X-ray observations. The comparison highlights the importance of galaxy formation in theoretical modelling of clusters and shows that current generation of simulations produce clusters with gross properties quite similar to their observed counterparts.

Cosmological simulations of galaxy clusters with feedback from active galactic nuclei: profiles and scaling relations

“…Unlike X-ray luminosity, it should be relatively insensitive to non-gravitational physics, a result confirmed with previous simulations (e.g. da Silva et al 2004;Nagai 2006;Battaglia et al 2012;Kay et al 2012). …”

Covariance in the thermal SZ–weak lensing mass scaling relation of galaxy clusters

“…The simulation volume has a comoving box length of 500 h −1 Mpc, resolved using a uniform 512 3 root grid and 8 levels of mesh refinement, implying a maximum comoving spatial resolution of 3.8 h −1 kpc. While the effects of baryonic physics, such as radiative gas cooling, star formation and energy feedback from supernovae and active galactic nuclei are important in the cluster core regions (r < ∼ 0.15R500c), these additional physics are shown to have negligible ( 2%) impact on the scatter in the tSZ-mass scaling relation (Nagai 2006;Battaglia et al 2012;Kay et al 2012). In Section 5, we assess the impact of baryonic physics with the Omega500 simulation that includes radiative cooling, star formation, and supernova feedback.…”

“…Following the analyses in Section 3, we first measure the Y − M relation and its intrinsic scatter in the CSF run. We find that the best-fit scaling relation between log Y3D and log M3D is log Y3D (h −1 Mpc) 2 = 1.88 log M3D 10 14 h −1 M⊙ − 5.84, (31) where the best-fit slope of 1.88 ± 0.030 (1σ error; see the best-fit relation shown as the hatched region in Figure 10) is different from the self-similar prediction of 5/3 because of the increasingly larger reduction in the gas mass fraction at the low-mass clusters (e.g., Nagai 2006). The intrinsic scatter in the CSF run is σ log Y,3D = 0.050, suggesting that gas cooling and star formation can increase the intrinsic scatter of the Y3D − M3D relation by up to 70%.…”

“…Numerical simulations predict that the tSZ effect signal is a robust proxy of cluster mass with intrinsic scatter of 10% as it directly probes the thermal energy content of the virialized ICM (e.g., Motl et al 2005;Nagai 2006;Kay et al 2012;Sembolini et al 2013;Yu, Nelson & Nagai 2015).…”

A comparison of algorithms for the construction of SZ cluster catalogues

“…Surveying the entire sky in 9 millimeter/submillimeter bands with ∼5-10 arcmin resolution over the channels most sensitive to the cosmic microwave background (CMB) anisotropies, the Planck satellite will find large numbers of clusters through the Sunyaev-Zel'dovich (SZ) effect (Sunyaev & Zeldovich 1970, 1972Birkinshaw 1999;Carlstrom et al 2002). The advantages of this, much anticipated, technique include efficient detection of distant clusters and selection based on an observable expected to correlate tightly with cluster mass (Bartlett 2002;da Silva et al 2004;Motl et al 2005;Nagai 2006;Bonaldi et al 2007;Shaw et al 2008). An official mission deliverable, the Planck SZ catalogue will be the first A&A 548, A51 (2012) all-sky cluster catalogue since the workhorse catalogues from the ROSAT All-Sky Survey (RASS, Truemper 1992), in other words, Planck will be the first all-sky cluster survey since the early 1990s!…”