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We present the splashback radius measurements around the SRG/eROSITA eFEDS X-ray selected galaxy clusters by cross-correlating them with HSC S19A photometric galaxies. The X-ray selection is expected to be less affected by systematics related to projection that affects optical cluster finder algorithms. We use a nearly volume-limited sample of 109 galaxy clusters selected in 0.5–2.0 keV band having luminosity |$L_X \gt 10^{43.5}\, {\rm erg \, s}^{-1}\, h^{-2}$| within the redshift z < 0.75 and obtain measurements of the projected cross-correlation with a signal to noise of 17.43. We model our measurements to infer a 3D profile and find that the steepest slope is sharper than −3 and associate the location with the splashback radius. We infer the value of the 3D splashback radius |$r_{\rm sp} = 1.45^{+0.30}_{-0.26}\, h^{-1}\, {\rm Mpc}$|. We also measure the weak-lensing signal of the galaxy clusters and obtain halo mass |$\log [M_{\rm 200m}/ h^{-1}\, {\rm M_\odot }] = 14.52 \pm 0.06$| using the HSC-S16A shape catalogue data at the median redshift z  = 0.46 of our cluster sample. We compare our r sp values with the spherical overdensity boundary |$r_{\rm 200m} = 1.75 \pm 0.08\, h^{-1} \, {\rm Mpc}$| based on the halo mass, which is consistent within 1.2σ with the ΛCDM predictions. Our constraints on the splashback radius, although broad, are the best measurements thus far obtained for an X-ray selected galaxy cluster sample. [ABSTRACT FROM AUTHOR]

We present the first cosmological study of a sample of eROSITA clusters, which were identified in the eROSITA Final Equatorial Depth Survey (eFEDS). In a joint selection on X-ray and optical observables, the sample contains 455 clusters within a redshift range of 0.1 < z < 1.2, of which 177 systems are covered by the public data from the Hyper Suprime-Cam (HSC) survey that enables uniform weak-lensing cluster mass constraints. With minimal assumptions, at each cluster redshift we empirically model (1) the scaling relations between the cluster halo mass and the observables, which include the X-ray count rate, the optical richness, and the weak-lensing mass, and (2) the X-ray selection in terms of the completeness function |$\mathcal {C}$|⁠. Using the richness distribution of the clusters, we directly measure the X-ray completeness and adopt those measurements as informative priors for the parameters of |$\mathcal {C}$|⁠. In a blinded analysis, we obtain the cosmological constraints |$\Omega _{\mathrm{m}}= 0.245^{+0.048}_{-0.058}$|⁠ , |$\sigma _{8}= 0.833^{+0.075}_{-0.063}$|⁠ , and |$S_{8}\equiv \sigma _{8}\left(\Omega _{\mathrm{m}}/0.3\right)^{0.3}= 0.791^{+0.028}_{-0.031}$| in a flat ΛCDM cosmology. Extending to a flat w CDM cosmology leads to the constraint on the equation of state parameter of the dark energy of w  = −1.25 ± 0.47. The eFEDS constraints are in good agreement with the results from the Planck mission, the galaxy–galaxy lensing and clustering analysis of the Dark Energy Survey, and the cluster abundance analysis of the SPT-SZ survey at a level of ≲ 1σ. With the empirical modelling, this work presents the first fully self-consistent cosmological constraints based on a synergy between wide-field X-ray and weak lensing surveys. [ABSTRACT FROM AUTHOR]

Using the extended halo-based group finder developed by Yang et al., which is able to deal with galaxies via spectroscopic and photometric redshifts simultaneously, we construct galaxy group and candidate protocluster catalogs in a wide redshift range (0 < z < 6) from the joint CFHT Large Area U -band Deep Survey and Hyper Suprime-Cam Subaru Strategic Program deep data set. Based on a selection of 5,607,052 galaxies with i -band magnitude m i < 26 and a sky coverage of 34.41 deg2, we identify a total of 2,232,134 groups, of which 402,947 groups have at least three member galaxies. We have visually checked and discussed the general properties of these richest groups at redshift z > 2.0. By checking the galaxy number distributions within a 5â€"7 h âˆ'1Mpc projected separation and a redshift difference Î" z ≤ 0.1 around those richest groups at redshift z > 2, we identify lists of 761, 343, and 43 protocluster candidates in the redshift bins 2 ≤ z < 3, 3 ≤ z < 4, and z ≥ 4, respectively. In general, these catalogs of galaxy groups and protocluster candidates will provide useful environmental information in probing galaxy evolution along cosmic time. [ABSTRACT FROM AUTHOR]

We present our determination of the baryon budget for an X-ray-selected XXL sample of 136 galaxy groups and clusters spanning nearly two orders of magnitude in mass (M 500 ∼ 1013–1015  M ⊙) and the redshift range 0 ≲ z ≲ 1. Our joint analysis is based on the combination of Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) weak-lensing mass measurements, XXL X-ray gas mass measurements, and HSC and Sloan Digital Sky Survey multiband photometry. We carry out a Bayesian analysis of multivariate mass-scaling relations of gas mass, galaxy stellar mass, stellar mass of brightest cluster galaxies (BCGs), and soft-band X-ray luminosity, by taking into account the intrinsic covariance between cluster properties, selection effect, weak-lensing mass calibration, and observational error covariance matrix. The mass-dependent slope of the gas mass–total mass (M 500) relation is found to be |$1.29_{-0.10}^{+0.16}$|⁠ , which is steeper than the self-similar prediction of unity, whereas the slope of the stellar mass–total mass relation is shallower than unity; |$0.85_{-0.09}^{+0.12}$|⁠. The BCG stellar mass weakly depends on cluster mass with a slope of |$0.49_{-0.10}^{+0.11}$|⁠. The baryon, gas mass, and stellar mass fractions as a function of M 500 agree with the results from numerical simulations and previous observations. We successfully constrain the full intrinsic covariance of the baryonic contents. The BCG stellar mass shows the larger intrinsic scatter at a given halo total mass, followed in order by stellar mass and gas mass. We find a significant positive intrinsic correlation coefficient between total (and satellite) stellar mass and BCG stellar mass and no evidence for intrinsic correlation between gas mass and stellar mass. All the baryonic components show no redshift evolution. [ABSTRACT FROM AUTHOR]

We study the angular correlation function of star-forming galaxies and properties of their host dark matter halos at z > 1 using the Hyper-Suprime Cam (HSC) Subaru Stragetic Program (SSP) survey. We use [O  ii ] emitters identified using two narrow-band (NB) filters, NB816 and NB921 , in the Deep/UltraDeep layers, which respectively cover large angular areas of 16.3 deg2 and 16.9 deg2. Our sample contains 8302 and 9578 [O  ii ] emitters at z = 1.19 (NB816) and z = 1.47 (NB921), respectively. We detect a strong clustering signal over a wide angular range, |$0{_{.}^{\circ}} 001$| < θ < 1 °, with bias |$b=1.61^{+0.13}_{-0.11}$| (z = 1.19) and |$b=2.09^{+0.17}_{-0.15}$| (z = 1.47). We also find a clear deviation of the correlation from a simple power-law form. To interpret the measured clustering signal, we adopt a halo occupation distribution (HOD) model that is constructed to explain the spatial distribution of galaxies selected by star formation rate. The observed correlation function and number density are simultaneously explained by the best-fitting HOD model. From the constrained HOD model, the average mass of halos hosting the [O  ii ] emitters is derived to be |$\log {M_{\rm eff}/(h^{-1}\, {M}_{\odot })}=12.70^{+0.09}_{-0.07}$| and |$12.61^{+0.09}_{-0.05}$| at z = 1.19 and 1.47, respectively, which will become halos with the present-day mass M ∼ 1.5 × 1013  h −1  M ⊙. The satellite fraction of the [O  ii ] emitter sample is found to be f sat ∼ 0.15. All these values are consistent with previous studies of similar samples, but we obtain tighter constraints even in a larger parameter space due to the larger sample size from the HSC. The results obtained for host halos of [O  ii ] emitters in this paper enable the construction of mock galaxy catalogs and the systematic forecast study of cosmological constraints from upcoming emission line galaxy surveys such as the Subaru Prime Focus Spectrograph survey. [ABSTRACT FROM AUTHOR]

We present results from simultaneous modelling of high angular resolution GBT/MUSTANG-2 90 GHz Sunyaev–Zel'dovich effect (SZE) measurements and XMM-XXL X-ray images of three rich galaxy clusters selected from the HSC-SSP Survey. The combination of high angular resolution SZE and X-ray imaging enables a spatially resolved multicomponent analysis, which is crucial to understand complex distributions of cluster gas properties. The targeted clusters have similar optical richnesses and redshifts, but exhibit different dynamical states in their member galaxy distributions: a single-peaked cluster, a double-peaked cluster, and a cluster belonging to a supercluster. A large-scale residual pattern in both regular Compton-parameter y and X-ray surface brightness distributions is found in the single-peaked cluster, indicating a sloshing mode. The double-peaked cluster shows an X-ray remnant cool core between two SZE peaks associated with galaxy concentrations. The temperatures of the two peaks reach ∼20–30 keV in contrast to the cool core component of ∼2 keV, indicating a violent merger. The main SZE signal for the supercluster is elongated along a direction perpendicular to the major axis of the X-ray core, suggesting a minor merger before core passage. The SX and y distributions are thus perturbed at some level, regardless of the optical properties. We find that the integrated Compton y parameter and the temperature for the major merger are boosted from those expected by the weak-lensing mass and those for the other two clusters show no significant deviations, which is consistent with predictions of numerical simulations. [ABSTRACT FROM AUTHOR]

We present a statistical weak-lensing magnification analysis on an optically selected sample of 3029 CAMIRA (Cluster finding Algorithm based on Multiband Identification of Red-sequence gAlaxies) galaxy clusters with richness N > 15 at redshift 0.2 ≤ z < 1.1 in the Subaru Hyper Suprime-Cam survey. We use two distinct populations of colour-selected, flux-limited background galaxies, namely the low- z and high- z samples at mean redshifts of ≈1.1 and ≈1.4, respectively, from which to measure the weak-lensing magnification signal by accounting for cluster contamination as well as masking effects. Our magnification bias measurements are found to be uncontaminated according to validation tests against the 'null-test' samples for which the net magnification bias is expected to vanish. The magnification bias for the full CAMIRA sample is detected at a significance level of 9.51σ, which is dominated by the high- z background. We forward-model the observed magnification data to constrain the normalization of the richness-to-mass (N – M) relation for the CAMIRA sample with informative priors on other parameters. The resulting scaling relation is N ∝ (M 500)0.92 ± 0.13(1 + z)−0.48 ± 0.69, with a characteristic richness of N = 17.72 ± 2.60 and intrinsic lognormal scatter of 0.15 ± 0.07 at M 500 = 1014  h −1 M⊙. With the derived N – M relation, we provide magnification-calibrated mass estimates of individual CAMIRA clusters, with the typical uncertainty of ≈39 and ≈32  per cent at richness of ≈20 and ≈40, respectively. We further compare our magnification-inferred N – M relation with those from the shear-based results in the literature, finding good agreement. [ABSTRACT FROM AUTHOR]

The radial acceleration relation (RAR) in galaxies describes a tight empirical scaling law between the total acceleration observed in galaxies and that expected from their baryonic mass , with a characteristic acceleration scale of m s−2. Here, we examine if such a correlation exists in galaxy clusters using weak-lensing, strong-lensing, and X-ray data sets available for 20 high-mass clusters targeted by the Cluster Lensing And Supernova survey with Hubble (CLASH). By combining our CLASH data with stellar mass estimates for the brightest cluster galaxies (BCGs) and accounting for the stellar baryonic component in clusters, we determine, for the first time, an RAR on BCG–cluster scales. The resulting RAR is well described by a tight power-law relation, , with lognormal intrinsic scatter of. The slope is consistent with the low acceleration limit of the RAR in galaxies, , whereas the intercept implies a much higher acceleration scale of m s−2, indicating that there is no universal RAR that holds on all scales from galaxies to clusters. We find that the observed RAR in CLASH clusters is consistent with predictions from a semianalytical model developed in the standard ΛCDM framework. Our results also predict the presence of a baryonic Faber–Jackson relation () on cluster scales. [ABSTRACT FROM AUTHOR]

Scaling relations trace the formation and evolution of galaxy clusters. We exploited multi-wavelength surveys – the XXL survey at XMM-Newton in the X-ray band, and the Hyper Suprime-Cam Subaru Strategic Program for optical weak lensing – to study an X-ray selected, complete sample of clusters and groups. The scalings of gas mass, temperature, and soft-band X-ray luminosity with the weak lensing mass show imprints of radiative cooling and active galactic nucleus feedback in groups. From the multi-variate analysis, we found some evidence for steeper than self-similar slopes for gas mass (⁠|$\beta _{m_\text{g}|m}=1.73 \pm 0.80$|⁠) and luminosity (β l | m  = 1.91 ± 0.94) and a nearly self-similar slope for the temperature (β t | m  = 0.78 ± 0.43). Intrinsic scatters of X-ray properties appear to be positively correlated at a fixed mass (median correlation factor |$\rho _{X_1X_2|m}\sim 0.34$|⁠) due to dynamical state and merger history of the haloes. Positive correlations with the weak lensing mass (median correlation factor |$\rho _{m_\text{wl}X|m}\sim 0.35$|⁠) can be connected to triaxiality and orientation. Comparison of weak lensing and hydrostatic masses suggests a small role played by non-thermal pressure support (⁠|$9\pm 17{{\ \rm per\ cent}}$|⁠). [ABSTRACT FROM AUTHOR]

Since the discovery of the “Bullet Cluster,” several similar cases have been uncovered that suggest relative velocities well beyond the tail of high speed collisions predicted by the concordance ΛCDM model. However, quantifying such post-merger events with hydrodynamical models requires a wide coverage of possible initial conditions. Here, we show that it is simpler to interpret pre-merger cases, such as A1750, where the gas between the colliding clusters is modestly affected, so that the initial conditions are clear. We analyze publicly available Chandra data confirming a significant increase in the projected X-ray temperature between the two cluster centers in A1750 consistent with our expectations for a merging cluster. We model this system with a self-consistent hydrodynamical simulation of dark matter and gas using the FLASH code. Our simulations reproduce well the X-ray data and the measured redshift difference between the two clusters in the phase before the first core passage viewed at an intermediate projection angle. The deprojected initial relative velocity derived using our model is 1460 km s–1, which is considerably higher than the predicted mean impact velocity for simulated massive haloes derived by recent ΛCDM cosmological simulations, but is within the allowed range. Our simulations demonstrate that such systems can be identified using a multi-wavelength approach and numerical simulations, for which the statistical distribution of relative impact velocities may provide a definitive examination of a broad range of dark matter scenarios. [ABSTRACT FROM AUTHOR]