SZE observables, pressure profiles and centre offsets in Magneticum simulation galaxy clusters

Abstract

We present a detailed study of the galaxy cluster thermal Sunyaev-Zel'dovich effect (SZE) signal Y and pressure profiles using Magneticum Pathfinder hydrodynamical simulations. With a sample of 50,000 galaxy clusters (M 500c > 1.4 × 10 14 M ) out to z = 2, we find significant variations in the shape of the pressure profile with mass and redshift and present a new generalized NFW model that follows these trends. We show that the thermal pressure at R 500c accounts for only 80 percent of the pressure required to maintain hydrostatic equilibrium, and therefore even idealized hydrostatic mass estimates would be biased at the 20 percent level. We compare the cluster SZE signal extracted from a sphere with different virial-like radii, a virial cylinder within a narrow redshift slice and the full light cone, confirming small scatter (σ ln Y 0.087) in the sphere and showing that structure immediately surrounding clusters increases the scatter and strengthens non self-similar redshift evolution in the cylinder. Uncorrelated large scale structure along the line of sight leads to an increase in the SZE signal and scatter that is more pronounced for low mass clusters, resulting in non self-similar trends in both mass and redshift and a mass dependent scatter that is ∼ 0.16 at low masses. The scatter distribution is consistent with log-normal in all cases. We present a model of the offsets between the center of the gravitational potential and the SZE center that follows the variations with cluster mass and redshift.

Cosmological constraints from Planck galaxy clusters with CMB lensing mass bias calibration

“…This offset is difficult to estimate, but we expect it to be smaller than the offset due to the beam. Indeed, using hydrodynamical simulations, Gupta et al (2017) find that for about 80 % of the clusters the typical value of this offset is of about 0.04R 500 . For a typical cluster in our sample, this translates into an offset of about 0.25 arcmin, which, added in quadrature to the offset due to the beam, does not increase it significantly.…”

Cluster mass calibration at high redshift: HST weak lensing analysis of 13 distant galaxy clusters from the South Pole Telescope Sunyaev–Zel'dovich Survey

“…To mimic this effect in the BK11 and MXXL N-body simulations, where we have neither mock SZ nor mock X-ray observations, we employ offset distributions derived from the Magneticum Pathfinder Simulation (Dolag, Komatsu & Sunyaev 2016; see also Bocquet et al 2016), which is a large volume, high-resolution cosmological hydrodynamical simulation. It includes simulated SZ and X-ray observations, where we make use of SPT mock catalogues (Saro et al 2014;Gupta et al 2017) that include the full SPT cluster detection procedure. We find that the most relevant parameter regarding the centring uncertainty when using the SZ centres is the smoothing scale θ c used for the cluster detection (see Bleem et al 2015).…”

Cosmology with the pairwise kinematic SZ effect: calibration and validation using hydrodynamical simulations

“…As these offsets are already included in the calibration of our scaling relation, using the full miscentring model in our estimate is a conservative choice. Also, while Saro et al (2015) calibrate the model using mostly more massive clusters, Gupta et al (2017) obtain comparable results and no strong trend in mass down to M 500c 10 14 h −1 M . If, on the other hand, the observational centring properties are significantly worse for low-mass clusters or groups, miscentring would have a larger effect.…”

“…Here we only describe the simulations briefly; for a more detailed description we refer to previous work using these simulations (e.g. Dolag et al 2016;Bocquet et al 2016;Gupta et al 2017). The Magneticum simulations are a set of state-of-the-art, cosmological hydrodynamical simulations of different cosmological volumes with different resolutions performed with an improved version of GADGET3 (Springel 2005;Beck et al 2016).…”

“…By measuring the signal from the map (and not from the simulation particle data) we automatically take both of these contributions into account. As a test for our pipeline, we first measure the integrated cylindrical tSZ signal within θ 500 including the lightcone contribution, and compare to the results that Gupta et al (2017) obtained from a smaller (L = 896 h −1 Mpc) box of the Magneticum suite and for clusters with M 500 > 10 14 M . For this purpose, we apply the average filter from eq.…”