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Register a new userA Measurement of the Galaxy Group-Thermal Sunyaev-Zeldovich Effect Cross-Correlation Function
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Stacking cosmic microwave background (CMB) maps around known galaxy clusters and groups provides a powerful probe of the distribution of hot gas in these systems via the Sunyaev-Zeldovich (SZ) effect. A stacking analysis allows one to detect the average SZ signal around low mass halos, and to extend measurements out to large scales, which are too faint to detect individually in the SZ or in X-ray emission. In addition, cross correlations between SZ maps and other tracers of large-scale structure (with known redshifts) can be used to extract the redshift-dependence of the SZ background. Motivated by these exciting prospects, we measure the two-point cross-correlation function between a catalog of $sim 380,000$ galaxy groups (with redshifts spanning $z=0.01-0.2$) from the Sloan Digital Sky Survey (SDSS) and Compton-y parameter maps constructed by the Planck collaboration. We find statistically significant correlations between the group catalog and Compton-y maps in each of six separate mass bins, with estimated halo masses in the range $10^{11.5-15.5} M_odot/h$. We compare these measurements with halo models of the SZ signal, which describe the stacked measurement in terms of one-halo and two-halo terms. The one-halo term quantifies the average pressure profile around the groups in a mass bin, while the two-halo term describes the contribution of correlated neighboring halos. For the more massive groups we find clear evidence for the one- and two-halo regimes, while groups with mass below $10^{13} M_odot/h$ are dominated by the two-halo term given the resolution of Planck data. We use the signal in the two-halo regime to determine the bias-weighted electron pressure of the universe: $langle b P_e rangle= 1.50 pm 0.226 times 10^{-7}$ keV cm$^{-3}$ (1-$sigma$) at $zapprox 0.15$.
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We confront the universal pressure profile (UPP) proposed by~citet{Arnaud10} with the recent measurement of the cross-correlation function of the thermal Sunyaev-Zeldovich (tSZ) effect from Planck and weak gravitational lensing measurement from the Red Cluster Sequence lensing survey (RCSLenS). By using the halo model, we calculate the prediction of $xi^{y-kappa}$ (lensing convergence and Compton-$y$ parameter) and $xi^{y-gamma_{rm t}}$ (lensing shear and Compton-$y$ parameter) and fit the UPP parameters by using the observational data. We find consistent UPP parameters when fixing the cosmology to either WMAP 9-year or Planck 2018 best-fitting values. The best constrained parameter is the pressure profile concentration $c_{500}=r_{500}/r_{rm s}$, for which we find $c_{500} = 2.68^{+1.46}_{-0.96}$ (WMAP-9) and $c_{500} = 1.91^{+1.07}_{-0.65}$ (Planck-2018) for the $xi^{y-gamma_t}$ estimator. The shape index for the intermediate radius region $alpha$ parameter is constrained to $alpha=1.75^{+1.29}_{-0.77}$ and $alpha = 1.65^{+0.74}_{-0.5}$ for WMAP-9 and Planck-2018 cosmologies, respectively. Propagating the uncertainties of the UPP parameters to pressure profiles results in a factor of $3$ uncertainty in the shape and magnitude. Further investigation shows that most of the signal of the cross-correlation comes from the low-redshift, inner halo profile ($r leqslant r_{rm vir}/2$) with halo mass in the range of $10^{14}$--$10^{15},{rm M}_{odot}$, suggesting that this is the major regime that constitutes the cross-correlation signal between weak lensing and tSZ.
We use the cosmo-OWLS suite of cosmological hydrodynamical simulations, which includes different galactic feedback models, to predict the cross-correlation signal between weak gravitational lensing and the thermal Sunyaev-Zeldovich (tSZ) $y$-parameter. The predictions are compared to the recent detection reported by van Waerbeke and collaborators. The simulations reproduce the weak lensing-tSZ cross-correlation, $xi_{ykappa}(theta)$, well. The uncertainty arising from different possible feedback models appears to be important on small scales only ($theta lesssim 10$ arcmin), while the amplitude of the correlation on all scales is sensitive to cosmological parameters that control the growth rate of structure (such as $sigma_8$, $Omega_m$ and $Omega_b$). This study confirms our previous claim (in Ma et al.) that a significant proportion of the signal originates from the diffuse gas component in low-mass ($M_{rm{halo}} lesssim 10^{14} M_{odot}$) clusters as well as from the region beyond the virial radius. We estimate that approximately 20$%$ of the detected signal comes from low-mass clusters, which corresponds to about 30$%$ of the baryon density of the Universe. The simulations also suggest that more than half of the baryons in the Universe are in the form of diffuse gas outside halos ($gtrsim 5$ times the virial radius) which is not hot or dense enough to produce a significant tSZ signal or be observed by X-ray experiments. Finally, we show that future high-resolution tSZ-lensing cross-correlation observations will serve as a powerful tool for discriminating between different galactic feedback models.
We present a group-galaxy cross-correlation analysis using a group catalog produced from the 16,500 spectra from the optical zCOSMOS galaxy survey. Our aim is to perform a consistency test in the redshift range 0.2 < z < 0.8 between the clustering strength of the groups and mass estimates that are based on the richness of the groups. We measure the linear bias of the groups by means of a group-galaxy cross-correlation analysis and convert it into mass using the bias-mass relation for a given cosmology, checking the systematic errors using realistic group and galaxy mock catalogs. The measured bias for the zCOSMOS groups increases with group richness as expected by the theory of cosmic structure formation and yields masses that are reasonably consistent with the masses estimated from the richness directly, considering the scatter that is obtained from the 24 mock catalogs. An exception are the richest groups at high redshift (estimated to be more massive than 10^13.5 M_sun), for which the measured bias is significantly larger than for any of the 24 mock catalogs (corresponding to a 3-sigma effect), which is attributed to the extremely large structure that is present in the COSMOS field at z ~ 0.7. Our results are in general agreement with previous studies that reported unusually strong clustering in the COSMOS field.
A recent stacking analysis of Planck HFI data of galaxy clusters (Hurier 2016) allowed to derive the cluster temperatures by using the relativistic corrections to the Sunyaev-Zeldovich effect (SZE). However, the temperatures of high-temperature clusters, as derived from this analysis, resulted to be basically higher than the temperatures derived from X-ray measurements, at a moderate statistical significance of $1.5sigma$. This discrepancy has been attributed by Hurier (2016) to calibration issues. In this paper we discuss an alternative explanation for this discrepancy in terms of a non-thermal SZE astrophysical component. We find that this explanation can work if non-thermal electrons in galaxy clusters have a low value of their minimum momentum ($p_1sim0.5-1$), and if their pressure is of the order of $20-30%$ of the thermal gas pressure. Both these conditions are hard to obtain if the non-thermal electrons are mixed with the hot gas in the intra cluster medium, but can be possibly obtained if the non-thermal electrons are mainly confined in bubbles with high content of non-thermal plasma and low content of thermal plasma, or in giant radio lobes/relics located in the outskirts of clusters. In order to derive more precise results on the properties of non-thermal electrons in clusters, and in view of more solid detections of a discrepancy between X-rays and SZE derived clusters temperatures that cannot be explained in other ways, it would be necessary to reproduce the full analysis done by Hurier (2016) by adding systematically the non-thermal component of the SZE.
We use Planck data to detect the cross-correlation between the thermal Sunyaev-Zeldovich (tSZ) effect and the infrared emission from the galaxies that make up the the cosmic infrared background (CIB). We first perform a stacking analysis towards Planck-confirmed galaxy clusters. We detect infrared emission produced by dusty galaxies inside these clusters and demonstrate that the infrared emission is about 50% more extended than the tSZ effect. Modelling the emission with a Navarro--Frenk--White profile, we find that the radial profile concentration parameter is $c_{500} = 1.00^{+0.18}_{-0.15}$. This indicates that infrared galaxies in the outskirts of clusters have higher infrared flux than cluster-core galaxies. We also study the cross-correlation between tSZ and CIB anisotropies, following three alternative approaches based on power spectrum analyses: (i) using a catalogue of confirmed clusters detected in Planck data; (ii) using an all-sky tSZ map built from Planck frequency maps; and (iii) using cross-spectra between Planck frequency maps. With the three different methods, we detect the tSZ-CIB cross-power spectrum at significance levels of (i) 6 $sigma$, (ii) 3 $sigma$, and (iii) 4 $sigma$. We model the tSZ-CIB cross-correlation signature and compare predictions with the measurements. The amplitude of the cross-correlation relative to the fiducial model is $A_{rm tSZ-CIB}= 1.2pm0.3$. This result is consistent with predictions for the tSZ-CIB cross-correlation assuming the best-fit cosmological model from Planck 2015 results along with the tSZ and CIB scaling relations.
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