ABSTRACT
Large area surveys continue to increase the samples of galaxy clusters that can be used to constrain cosmological parameters, provided that the masses of the clusters are measured robustly. ...To improve the calibration of cluster masses using weak gravitational lensing we present new results for 48 clusters at 0.05 < z < 0.15, observed as part of the Multi Epoch Nearby Cluster Survey, and re-evaluate the mass estimates for 52 clusters from the Canadian Cluster Comparison Project. Updated high-fidelity photometric redshift catalogues of reference deep fields are used in combination with advances in shape measurements and state-of-the-art cluster simulations, yielding an average systematic uncertainty in the lensing signal below 5 per cent, similar to the statistical uncertainty for our cluster sample. We derive a scaling relation with Planck measurements for the full sample and find a bias in the Planck masses of 1 − b = 0.84 ± 0.04 (stat) ±0.05 (syst). We find no statistically significant trend of the mass bias with redshift or cluster mass, but find that different selections could change the bias by up to 0.07. We find a gas fraction of 0.139 ± 0.014 (stat) for eight relaxed clusters in our sample, which can also be used to infer cosmological parameters.
We present a method for measuring the masses of galaxy clusters using the imprint of their gravitational lensing signal on the cosmic microwave background (CMB) temperature anisotropies. The method ...first reconstructs the projected gravitational potential with a quadratic estimator and then applies a matched filter to extract cluster mass. The approach is well-suited for statistical analyses that bin clusters according to other mass proxies. We find that current experiments, such as Planck, the South Pole Telescope and the Atacama Cosmology Telescope, can practically implement such a statistical methodology, and that future experiments will reach sensitivities sufficient for individual measurements of massive systems. As illustration, we use simulations of Planck observations to demonstrate that it is possible to constrain the mass scale of a set of 62 massive clusters with prior information from X-ray observations, similar to the published Planck ESZ-XMM sample. We examine the effect of the thermal (tSZ) and kinetic (kSZ) Sunyaev-Zeldovich (SZ) signals, finding that the impact of the kSZ remains small in this context. The stronger tSZ signal, however, must be actively removed from the CMB maps by component separation techniques prior to reconstruction of the gravitational potential. Our study of two such methods highlights the importance of broad frequency coverage for this purpose. A companion paper presents application to the Planck data on the ESZ-XMM sample.
The halo mass function (HMF) is a critical element in cosmological analyses of galaxy cluster catalogs. We quantify the impact of uncertainties in HMF parameters on cosmological constraints from ...cluster catalogs similar to those from
Planck
, those expected from the
Euclid
, Roman, and
Rubin
surveys, and from a hypothetical larger future survey. We analyze simulated catalogs in each case, gradually loosening priors on HMF parameters to evaluate the degradation in cosmological constraints. While current uncertainties on HMF parameters do not substantially impact
Planck
-like surveys, we find that they can significantly degrade the cosmological constraints for a
Euclid
-like survey. Consequently, the current precision on the HMF is not sufficient for
Euclid
, Roman,
Rubin
or possible larger surveys. Future experiments will have to properly account for uncertainties in HMF parameters, and it will be necessary to improve the precision of HMF fits to avoid weakening constraints on cosmological parameters.
ABSTRACT
We present weak lensing mass estimates for a sample of 458 galaxy clusters from the redMaPPer Sloan Digital Sky Survey DR8 catalogue using Hyper Suprime-Cam weak lensing data. We develop a ...method to quickly estimate cluster masses from weak lensing shear and use this method to estimate weak lensing masses for each of the galaxy clusters in our sample. Subsequently, we constrain the mass–richness relation as well as the intrinsic scatter between the cluster richness and the measured weak lensing masses. When calculating the mass–richness relation for all clusters with a richness λ > 20, we find a tension in the slope of the mass–richness relation with the Dark Energy Survey Year 1 stacked weak lensing analysis. For a reduced sample of clusters with a richness λ > 40, our results are consistent with the Dark Energy Survey Year 1 analysis.
We compare the Planck Sunyaev–Zeldovich (SZ) cluster sample (PSZ1) to the Sloan Digital Sky Survey (SDSS) redMaPPer catalogue, finding that all Planck clusters within the redMaPPer mask and within ...the redshift range probed by redMaPPer are contained in the redMaPPer cluster catalogue. These common clusters define a tight scaling relation in the richness-SZ mass (λ–M
SZ) plane, with an intrinsic scatter in richness of
$\sigma _{\lambda |M_{{\rm SZ}}} = 0.266 \pm 0.017$
. The corresponding intrinsic scatter in true cluster halo mass at fixed richness is ≈21 per cent. The regularity of this scaling relation is used to identify failures in both catalogues. The failure rates for redMaPPer and PSZ1 1.2 per cent and 14.7 per cent, respectively. The PSZ1 failure rates decreases to 9.8 per cent after removing incorrect redshifts that were drawn from the literature. We note the failure rates in the PSZ1 from this analysis are specific to the SDSS overlap region, and may not be indicative of failure rates over the full Planck survey. We have further identified five PSZ1 sources that suffer from projection effects (multiple rich systems along the line of sight of the SZ detection) and 17 new high-redshift (z ≳ 0.6) cluster candidates of varying degrees of confidence.
The thermal Sunyaev–Zel'dovich (tSZ) effect offers a means of probing the hot gas in and around massive galaxies and galaxy groups and clusters, which is thought to constitute a large fraction of the ...baryon content of the Universe. The Planck collaboration recently performed a stacking analysis of a large sample of ‘locally brightest galaxies’ (LBGs) and, surprisingly, inferred an approximately self-similar relation between the tSZ flux and halo mass. At face value, this implies that the hot gas mass fraction is independent of halo mass, a result which is in apparent conflict with resolved X-ray observations. We test the robustness of the inferred trend using synthetic tSZ maps generated from cosmological hydrodynamical simulations and using the same tools and assumptions applied in the Planck study. We show that, while the detection and the estimate of the ‘total’ flux (within 5r
500) is reasonably robust, the inferred flux originating from within r
500 (i.e. the limiting radius to which X-ray observations typically probe) is highly sensitive to the assumed pressure distribution of the gas. Using our most realistic simulations with AGN feedback, that reproduce a wide variety of X-ray and optical properties of groups and clusters, we estimate that the derived tSZ flux within r
500 is biased high by up to an order of magnitude for haloes with masses M
500 ∼ 1013 M⊙. Moreover, we show that the AGN simulations are consistent with the total tSZ flux–mass relation observed with Planck, whereas a self-similar model is ruled out.
Abstract
Using Chandra observations, we derive the
Y
X
proxy and associated total mass measurement,
, for 147 clusters with
z
< 0.35 from the Planck early Sunyaev–Zeldovich catalog, and for 80 ...clusters with
z
< 0.22 from an X-ray flux-limited sample. We reextract the Planck
Y
SZ
measurements and obtain the corresponding mass proxy,
, from the full Planck mission maps, minimizing Malmquist bias due to observational scatter. The masses reextracted using the more precise X-ray position and characteristic size agree with the published PSZ2 values, but yield a significant reduction in the scatter (by a factor of two) in the
–
relation. The slope is 0.93 ± 0.03, and the median ratio,
, is within the expectations from known X-ray calibration systematics.
Y
SZ
/
Y
X
is 0.88 ± 0.02, in good agreement with predictions from cluster structure, and implying a low level of clumpiness. In agreement with the findings of the Planck Collaboration, the slope of the
Y
SZ
–
flux relation is significantly less than unity (0.89 ± 0.01). Using extensive simulations, we show that this result is not due to selection effects, intrinsic scatter, or covariance between quantities. We demonstrate analytically that changing the
Y
SZ
–
Y
X
relation from apparent flux to intrinsic properties results in a best-fit slope that is closer to unity and increases the dispersion about the relation. The redistribution resulting from this transformation implies that the best-fit parameters of the
–
relation will be sample-dependent.
Abstract
Mergers between galaxy clusters often drive shocks into the intracluster medium, the effects of which are sometimes visible via temperature and density jumps in the X-ray and via radio ...emission from relativistic particles energized by the shock’s passage. A2108 was selected as a likely merger system through comparing the X-ray luminosity to the Planck Sunyaev–Zeldovich signal, where this cluster appeared highly X-ray underluminous. Follow-up observations confirmed it to be a merging low-mass cluster featuring two distinct subclusters, both with a highly disturbed X-ray morphology. Giant Metrewave Radio Telescope (GMRT) data in bands 2, 3, & 4 (covering 120–750 MHz) show an extended radio feature resembling a radio relic near the location of a temperature discontinuity in the X-rays. We measure a Mach number from the X-ray temperature jump (
X
=
1.6
±
0.2
). Several characteristics of radio relics (location and morphology of extended radio emission) are found in A2108, making this cluster one of the few low-mass mergers (
M
L−M
= 1.8 ± 0.4 × 10
14
M
⊙
) likely hosting a radio relic. The radio spectrum is exceptionally steep (
α
= −2 at the lowest frequencies), and the radio power is very weak (
P
1.4 GHz
= 1 × 10
22
W Hz
−1
). To account for the shock/relic offset, we propose a scenario in which the shock created the relic by re-accelerating a cloud of pre-existing relativistic electrons and then moved away, leaving behind a
fading
relic. The electron-aging timescale derived from the high-frequency steepening in the relic spectrum is consistent with the shock travel time to the observed X-ray discontinuity. However, the lower flux in GMRT band 4 data causing the steepening could be due to instrumental limitations and deeper radio data are needed to constrain the spectral slope of the relic at high frequencies. A background cluster, 4′ from the merger, may have contributed to the ROSAT and Planck signals, but SZ modeling shows that the merger system is still X-ray underluminous, supporting the use of this approach to identifying merger-disrupted clusters.
We measure the far-infrared emission of the general quasar (QSO) population using Planck observations of the Baryon Oscillation Spectroscopic Survey QSO sample. By applying multi-component matched ...multi-filters to the seven highest Planck frequencies, we extract the amplitudes of dust, synchrotron, and thermal Sunyaev-Zeldovich (SZ) signals for nearly 300 000 QSOs over the redshift range 0.1 <z< 5. We bin these individual low signal-to-noise measurements to obtain the mean emission properties of the QSO population as a function of redshift. The emission is dominated by dust at all redshifts, with a peak at z ~ 2, the same location as the peak in the general cosmic star formation rate. Restricting analysis to radio-loud QSOs, we find synchrotron emission with a monochromatic luminosity at 100 GHz (rest-frame) rising from \hbox{$\overline{L_{\rm synch}}=0$}Lsynch=0 to 0.2 L⊙ Hz-1 between z = 0 and 3. The radio-quiet subsample does not show any synchrotron emission, but we detect thermal SZ between z = 2.5 and 4; no significant SZ emission is seen at lower redshifts. Depending on the supposed mass for the halos hosting the QSOs, this may or may not leave room for heating of the halo gas by feedback from the QSO.
We used an unbiased cosmic microwave background (CMB) lensing mass estimator on 468 SPT-SZ clusters from the SPT-SZ and the public data. We measured the average ratio between CMB lensing and the SZ ...masses to be $ CMBlens /M_ SZ (stat.) (syst.) $. The average CMB lensing mass from the combination of the two datasets is measured at 4.8sigma , which is a significant gain with respect to the measurement performed on the SPT-SZ-only (3.9sigma ) or the (3.7sigma ) dataset. We showed that the combination not only takes advantage of the two different ranges of spatial scales (i.e. Fourier modes) observed but also exploits the lensing-induced correlation between scales observed by one experiment and the other. This result demonstrates the importance of measuring a large range of spatial scales for CMB lensing mass estimation, from arcmins to degrees. This large range of scales will most probably be provided by the combination of various datasets, such as from the large- and small-aperture telescopes of the upcoming Observatory and future CMB-S4 experiment, and In this context, the temperature data will remain a key element of CMB lensing cluster studies in the years to come.
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