arXiv subjects

I-Non Chiu

Publications and source records attributed to I-Non Chiu.

35 records · Page 2Linked to original sources

arXiv2021

Angular clustering and host halo properties of [OII] emitters at $z >1$ in the Subaru HSC survey

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) SSP survey. We use [OII] 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 deg^2 and 16.9 deg^2. Our sample contains 8302 and 9578 [OII] emitters at z=1.19 (NB816) and z=1.47 (NB921), respectively. We detect a strong clustering signal over a wide angular range, 0.001 < θ< 1 [deg], with the 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 a 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 [OII] emitters is derived to be $\log{M_{eff}/(h^{-1}M_\odot)}=12.70^{+0.09}_{-0.07}$ and $12.61^{+0.09}_{-0.05}$ at z=1.19 and 1.47, respectively, which will become halos with the present-day mass, $M\sim 1.5 \times 10^{13}h^{-1}M_\odot$. The satellite fraction of the [OII] emitter sample is found to be $f_{sat}\sim 0.15$. All these values are consistent with the 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 [OII] 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 PFS survey.

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arXiv2020

A clustering-based self-calibration of the richness-to-mass relation of CAMIRA galaxy clusters out to $z\approx1.1$ in the Hyper Suprime-Cam survey

We perform a self-calibration of the richness-to-mass ($N$-$M$) relation of CAMIRA galaxy clusters with richness $N\geq15$ at redshift $0.2\leq z<1.1$ by modeling redshift-space two-point correlation functions. These correlation functions are $ξ_{\mathrm{cc}}$ of CAMIRA clusters, the auto-correlation function $ξ_{\mathrm{gg}}$ of the CMASS galaxies spectroscopically observed in the BOSS survey, and the cross-correlation function $ξ_{\mathrm{cg}}$ between these two samples. We focus on constraining the normalization $A_{\mathrm{N}}$ of the $N$-$M$ relation in a forward-modeling approach, carefully accounting for the redshift-space distortion, the Finger-of-God effect, and the uncertainty in photometric redshifts of CAMIRA clusters. The modeling also takes into account the projection effect on the halo bias of CAMIRA clusters. The parameter constraints are shown to be unbiased according to validation tests using a large set of mock catalogs constructed from N-body simulations. At the pivotal mass $M_{500}=10^{14}h^{-1}M_{\odot}$ and the pivotal redshift $z_{\mathrm{piv}} = 0.6$, the resulting normalization $A_{\mathrm{N}}$ is constrained as $13.8^{+5.8}_{-4.2}$, $13.2^{+3.4}_{-2.7}$, and $11.9^{+3.0}_{-1.9}$ by modeling $ξ_{\mathrm{cc}}$, $ξ_{\mathrm{cc}}+ξ_{\mathrm{cg}}$, and $ξ_{\mathrm{cc}} + ξ_{\mathrm{cg}} + ξ_{\mathrm{gg}}$, with average uncertainties at levels of $36\%$, $23\%$, and $21\%$, respectively. We find that the resulting $A_{\mathrm{N}}$ is statistically consistent with those independently obtained from weak-lensing magnification and from a joint analysis of shear and cluster abundance, with a preference for a lower value at a level of $\lesssim1.9σ$. This implies that the absolute mass scale of CAMIRA clusters inferred from clustering is mildly higher than those from the independent methods. [abridged]

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arXiv2020

Active gas features in three HSC-SSP CAMIRA clusters revealed by high angular resolution analysis of MUSTANG-2 SZE and XXL X-ray observations

We present results from simultaneous modeling 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 multi-component 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 $\sim20-30$ keV in contrast to the cool core component of $\sim2$ 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 $S_X$ 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.

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arXiv2020

The Radial Acceleration Relation in CLASH Galaxy Clusters

The radial acceleration relation (RAR) in galaxies describes a tight empirical scaling law between the total acceleration $g_\mathrm{tot}(r)=GM_\mathrm{tot}(<r)/r^2$ observed in galaxies and that expected from their baryonic mass $g_\mathrm{bar}(r)=GM_\mathrm{bar}(<r)/r^2$, with a characteristic acceleration scale of $g_\dagger\simeq 1.2\times 10^{-10}$ms$^{-2}$. 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 CLASH survey. 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, $g_\mathrm{tot}\propto g_\mathrm{bar}^{0.51^{+0.04}_{-0.05}}$, with lognormal intrinsic scatter of $14.7^{+2.9}_{-2.8}\%$. The slope is consistent with the low acceleration limit of the RAR in galaxies, $g_\mathrm{tot}=\sqrt{g_\dagger\,g_\mathrm{bar}}$, whereas the intercept implies a much higher acceleration scale of $g_\ddagger = (2.02\pm0.11)\times 10^{-9}$ms$^{-2}$, 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 semi-analytical model developed in the standard $Λ$CDM framework. Our results also predict the presence of a baryonic Faber--Jackson relation ($σ_v^4\propto M_\mathrm{bar}$) on cluster scales.

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arXiv2020

The Richness-to-Mass Relation of CAMIRA Galaxy Clusters from Weak-lensing Magnification in the Subaru Hyper Suprime-Cam Survey

We present a statistical weak-lensing magnification analysis on an optically selected sample of 3029 \texttt{CAMIRA} galaxy clusters with richness $N>15$ at redshift $0.2\leq z <1.1$ in the Subaru Hyper Suprime-Cam (HSC) survey. We use two distinct populations of color-selected, flux-limited background galaxies, namely the low-$z$ and high-$z$ samples at mean redshifts of $\approx1.1$ and $\approx1.4$, 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 \texttt{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 \texttt{CAMIRA} sample with informative priors on other parameters. The resulting scaling relation is $N\propto {M_{500}}^{0.92\pm0.13} (1 + z)^{-0.48\pm0.69}$, with a characteristic richness of $N=\left(17.72\pm2.60\right)$ and intrinsic log-normal scatter of $0.15\pm0.07$ at $M_{500} = 10^{14}h^{-1}M_{\odot}$. With the derived $N$--$M$ relation, we provide magnification-calibrated mass estimates of individual \texttt{CAMIRA} clusters, with the typical uncertainty of $\approx39\%$ and $\approx32\%$ at richness$\approx20$ and $\approx40$, respectively. We further compare our magnification-inferred $N$--$M$ relation with those from the shear-based results in the literature, finding good agreement.

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arXiv2020

Weak lensing Analysis of X-Ray-selected XXL Galaxy Groups and Clusters with Subaru HSC Data

We present a weak-lensing analysis of X-ray galaxy groups and clusters selected from the XMM-XXL survey using the first-year data from the Hyper Suprime-Cam (HSC) Subaru Strategic Program. Our joint weak-lensing and X-ray analysis focuses on 136 spectroscopically confirmed X-ray-selected systems at 0.031 < z < 1.033 detected in the 25sqdeg XXL-N region. We characterize the mass distributions of individual clusters and establish the concentration-mass (c-M) relation for the XXL sample, by accounting for selection bias and statistical effects, and marginalizing over the remaining mass calibration uncertainty. We find the mass-trend parameter of the c-M relation to be β= -0.07 \pm 0.28 and the normalization to be c200 = 4.8 \pm 1.0 (stat) \pm 0.8 (syst) at M200=10^{14}Msun/h and z = 0.3. We find no statistical evidence for redshift evolution. Our weak-lensing results are in excellent agreement with dark-matter-only c-M relations calibrated for recent LCDM cosmologies. The level of intrinsic scatter in c200 is constrained as σ(\ln[c200]) < 24% (99.7% CL), which is smaller than predicted for the full population of LCDM halos. This is likely caused in part by the X-ray selection bias in terms of the relaxation state. We determine the temperature-mass (Tx-M500) relation for a subset of 105 XXL clusters that have both measured HSC lensing masses and X-ray temperatures. The resulting Tx-M500 relation is consistent with the self-similar prediction. Our Tx-M500 relation agrees with the XXL DR1 results at group scales, but has a slightly steeper mass trend, implying a smaller mass scale in the cluster regime. The overall offset in the Tx-M500 relation is at the $1.5σ$ level, corresponding to a mean mass offset of (34\pm 20)%. We also provide bias-corrected, weak-lensing-calibrated M200 and M500 mass estimates of individual XXL clusters based on their measured X-ray temperatures.

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arXiv2019

XXL Survey groups and clusters in the Hyper Suprime-Cam Survey. Scaling relations between X-ray properties and weak lensing mass

Scaling relations trace the formation and evolution of galaxy clusters. We exploited multi-wavelength surveys -- the XXL survey at \emph{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 AGN feedback in groups. From the multi-variate analysis, we found some evidence for steeper than self-similar slopes for gas mass ($β_{m_\text{g}|m}=1.73 \pm0.80$) and luminosity ($β_{l|m}=1.91\pm0.94$) and a nearly self-similar slope for the temperature ($β_{t|m}=0.78\pm0.43$). Intrinsic scatters of X-ray properties appear to be positively correlated at a fixed mass (median correlation factor $ρ_{X_1X_2|m}\sim0.34$) due to dynamical state and merger history of the halos. Positive correlations with the weak lensing mass (median correlation factor $ρ_{m_\text{wl}X|m}\sim0.35$) can be connected to triaxiality and orientation. Comparison of weak lensing and hydrostatic masses suggests a small role played by non-thermal pressure support ($9\pm17\%$).

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arXiv2018

X-ray Properties of SPT Selected Galaxy Clusters at 0.2<z<1.5 Observed with XMM-Newton

We present measurements of the X-ray observables of the intra-cluster medium (ICM), including luminosity $L_X$, ICM mass $M_{ICM}$, emission-weighted mean temperature $T_X$, and integrated pressure $Y_X$, that are derived from XMM-Newton X-ray observations of a Sunyaev-Zel'dovich Effect (SZE) selected sample of 59 galaxy clusters from the South Pole Telescope SPT-SZ survey that span the redshift range of $0.20 < z < 1.5$. We constrain the best-fit power law scaling relations between X-ray observables, redshift, and halo mass. The halo masses are estimated based on previously published SZE observable to mass scaling relations, calibrated using information that includes the halo mass function. Employing SZE-based masses in this sample enables us to constrain these scaling relations for massive galaxy clusters ($M_{500}\geq 3 \times10^{14}$ $M_\odot$) to the highest redshifts where these clusters exist without concern for X-ray selection biases. We find that the mass trends are steeper than self-similarity in all cases, and with $\geq 2.5σ$ significance in the case of $L_X$ and $M_{ICM}$. The redshift trends are consistent with the self-similar expectation, but the uncertainties remain large. Core-included scaling relations tend to have steeper mass trends for $L_X$. There is no convincing evidence for a redshift-dependent mass trend in any observable. The constraints on the amplitudes of the fitted scaling relations are currently limited by the systematic uncertainties on the SZE-based halo masses, however the redshift and mass trends are limited by the X-ray sample size and the measurement uncertainties of the X-ray observables.

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arXiv2018

The Projected Dark and Baryonic Ellipsoidal Structure of 20 CLASH Galaxy Clusters

We reconstruct the two-dimensional (2D) matter distributions in 20 high-mass galaxy clusters selected from the CLASH survey by using the new approach of performing a joint weak lensing analysis of 2D shear and azimuthally averaged magnification measurements. This combination allows for a complete analysis of the field, effectively breaking the mass-sheet degeneracy. In a Bayesian framework, we simultaneously constrain the mass profile and morphology of each individual cluster assuming an elliptical Navarro-Frenk-White halo characterized by the mass, concentration, projected axis ratio, and position angle of the projected major axis.. We find that spherical mass estimates of the clusters from azimuthally averaged weak-lensing measurements in previous work are in excellent agreement with our results from a full 2D analysis. Combining all 20 clusters in our sample, we detect the elliptical shape of weak-lensing halos at the $5σ$ significance level within a scale of 2Mpc$/h$. The median projected axis ratio is $0.67\pm 0.07$ at a virial mass of $M_\mathrm{vir}=(15.2\pm 2.8) \times 10^{14} M_\odot$, which is in agreement with theoretical predictions of the standard collisionless cold dark matter model. We also study misalignment statistics of the brightest cluster galaxy, X-ray, thermal Sunyaev-Zel'dovich effect, and strong-lensing morphologies with respect to the weak-lensing signal. Among the three baryonic tracers studied here, we find that the X-ray morphology is best aligned with the weak-lensing mass distribution, with a median misalignment angle of $21\pm 7$ degrees. We also conduct a stacked quadrupole shear analysis assuming that the X-ray major axis is aligned with that of the projected mass distribution. This yields a consistent axis ratio of $0.67\pm 0.10$, suggesting again a tight alignment between the intracluster gas and dark matter.

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arXiv2018

CLUMP-3D. Testing $Λ$CDM with galaxy cluster shapes

The $Λ$CDM model of structure formation makes strong predictions on concentration and shape of DM (dark matter) halos, which are determined by mass accretion processes. Comparison between predicted shapes and observations provides a geometric test of the $Λ$CDM model. Accurate and precise measurements needs a full three-dimensional analysis of the cluster mass distribution. We accomplish this with a multi-probe 3D analysis of the X-ray regular CLASH (Cluster Lensing And Supernova survey with Hubble) clusters combining strong and weak lensing, X-ray photometry and spectroscopy, and the Sunyaev-Zel'dovich effect. The cluster shapes and concentrations are consistent with $Λ$CDM predictions. The CLASH clusters are randomly oriented, as expected given the sample selection criteria. Shapes agree with numerical results for DM-only halos, which hints at baryonic physics being not so effective in making halos rounder.

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arXiv2018

CLUMP-3D: Three-dimensional Shape and Structure of 20 CLASH Galaxy Clusters from Combined Weak and Strong Lensing

We perform a three-dimensional triaxial analysis of 16 X-ray regular and 4 high-magnification galaxy clusters selected from the CLASH survey by combining two-dimensional weak-lensing and central strong-lensing constraints. In a Bayesian framework, we constrain the intrinsic structure and geometry of each individual cluster assuming a triaxial Navarro-Frenk-White halo with arbitrary orientations, characterized by the mass $M_{200\mathrm{c}}$, halo concentration $C_{200\mathrm{c}}$, and triaxial axis ratios ($q_{\mathrm{a}} \le q_{\mathrm{b}}$), and investigate scaling relations between these halo structural parameters. From triaxial modeling of the X-ray-selected subsample, we find that the halo concentration decreases with increasing cluster mass, with a mean concentration of $C_{200\mathrm{c}} = 4.82\pm0.30$ at the pivot mass $M_{200\mathrm{c}}=10^{15}M_{\odot}h^{-1}$. This is consistent with the result from spherical modeling, $C_{200\mathrm{c}}=4.51\pm 0.14$. Independently of the priors, the minor-to-major axis ratio $q_{\mathrm{a}}$ of our full sample exhibits a clear deviation from the spherical configuration ($q_{\mathrm{a}}=0.52 \pm 0.04$ at $10^{15}M_{\odot}h^{-1}$ with uniform priors), with a weak dependence on the cluster mass. Combining all 20 clusters, we obtain a joint ensemble constraint on the minor-to-major axis ratio of $q_{\mathrm{a}}=0.652^{+0.162}_{-0.078}$ and a lower bound on the intermediate-to-major axis ratio of $q_{\mathrm{b}}>0.63$ at the $2σ$ level from an analysis with uniform priors. Assuming priors on the axis ratios derived from numerical simulations, we constrain the degree of triaxiality for the full sample to be $\mathcal{T}=0.79 \pm 0.03$ at $10^{15}M_{\odot}h^{-1}$, indicating a preference for a prolate geometry of cluster halos. We find no statistical evidence for an orientation bias ($f_{\mathrm{geo}}=0.93 \pm 0.07$) (abridged)

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arXiv2018

Planck Sunyaev-Zel'dovich Cluster Mass Calibration using Hyper Suprime-Cam Weak Lensing

Using $\sim$140 deg$^2$ Subaru Hyper Suprime-Cam (HSC) survey data, we stack the weak lensing (WL) signal around five Planck clusters found within the footprint. This yields a 15$σ$ detection of the mean Planck cluster mass density profile. The five Planck clusters span a relatively wide mass range, $M_{\rm WL,500c} = (2-30)\times10^{14}\,M_\odot/h$ with a mean mass of $M_{\rm WL,500c} = (4.15\pm0.61)\times10^{14}\,M_\odot/h$. The ratio of the stacked Planck Sunyaev-Zel'dovich (SZ) mass to the stacked WL mass is $ \langle M_{\rm SZ}\rangle/\langle M_{\rm WL}\rangle = 1-b = 0.80\pm0.14$. This mass bias is consistent with previous WL mass calibrations of Planck clusters within the errors. We discuss the implications of our findings for the calibration of SZ cluster counts and the much discussed tension between Planck SZ cluster counts and Planck $Λ$CDM cosmology.

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arXiv2017

First results on the cluster galaxy population from the Subaru Hyper Suprime-Cam survey. III. Brightest cluster galaxies, stellar mass distribution, and active galaxies

The unprecedented depth and area surveyed by the Subaru Strategic Program with the Hyper Suprime-Cam (HSC-SSP) have enabled us to construct and publish the largest distant cluster sample out to $z\sim 1$ to date. In this exploratory study of cluster galaxy evolution from $z=1$ to $z=0.3$, we investigate the stellar mass assembly history of brightest cluster galaxies (BCGs), evolution of stellar mass and luminosity distributions, stellar mass surface density profile, as well as the population of radio galaxies. Our analysis is the first high redshift application of the top N richest cluster selection, which is shown to allow us to trace the cluster galaxy evolution faithfully. Over the 230 deg$^2$ area of the current HSC-SSP footprint, selecting the top 100 clusters in each of the 4 redshift bins allows us to observe the buildup of galaxy population in descendants of clusters whose $z\approx 1$ mass is about $2\times 10^{14}\,M_\odot$. Our stellar mass is derived from a machine-learning algorithm, which is found to be unbiased and accurate with respect to the COSMOS data. We find very mild stellar mass growth in BCGs (about 35% between $z=1$ and 0.3), and no evidence for evolution in both the total stellar mass-cluster mass correlation and the shape of the stellar mass surface density profile. We also present the first measurement of the radio luminosity distribution in clusters out to $z\sim 1$, and show hints of changes in the dominant accretion mode powering the cluster radio galaxies at $z\sim 0.8$.

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arXiv2017

Multiwavelength study of X-ray Luminous Clusters in the Hyper Suprime-Cam Subaru Strategic Program S16A field

We present a joint X-ray, optical and weak-lensing analysis for X-ray luminous galaxy clusters selected from the MCXC (Meta-Catalog of X-Ray Detected Clusters of Galaxies) cluster catalog in the Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) survey field with S16A data, As a pilot study of our planned series papers, we measure hydrostatic equilibrium (H.E.) masses using XMM-Newton data for four clusters in the current coverage area out of a sample of 22 MCXC clusters. We additionally analyze a non-MCXC cluster associated with one MCXC cluster. We show that H.E. masses for the MCXC clusters are correlated with cluster richness from the CAMIRA catalog (Oguri et al. 2017), while that for the non-MCXC cluster deviates from the scaling relation. The mass normalization of the relationship between the cluster richness and H.E. mass is compatible with one inferred by matching CAMIRA cluster abundance with a theoretical halo mass function. The mean gas mass fraction based on H.E. masses for the MCXC clusters is $\langle f_{\rm gas} \rangle = 0.125\pm0.012$ at spherical overdensity $Δ=500$, which is $\sim80-90$ percent of the cosmic mean baryon fraction, $Ω_b/Ω_m$, measured by cosmic microwave background experiments. We find that the mean baryon fraction estimated from X-ray and HSC-SSP optical data is comparable to $Ω_b/Ω_m$. A weak-lensing shear catalog of background galaxies, combined with photometric redshifts, is currently available only for three clusters in our sample. Hydrostatic equilibrium masses roughly agree with weak-lensing masses, albeit with large uncertainty. This study demonstrates that further multiwavelength study for a large sample of clusters using X-ray, HSC-SSP optical and weak lensing data will enable us to understand cluster physics and utilize cluster-based cosmology.

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arXiv2017

An optically-selected cluster catalog at redshift 0.1<z<1.1 from the Hyper Suprime-Cam Subaru Strategic Program S16A data

We present an optically-selected cluster catalog from the Hyper Suprime-Cam (HSC) Subaru Strategic Program. The HSC images are sufficiently deep to detect cluster member galaxies down to $M_*\sim 10^{10.2}M_\odot$ even at $z\sim 1$, allowing a reliable cluster detection at such high redshifts. We apply the CAMIRA algorithm to the HSC Wide S16A dataset covering $\sim 232$ deg$^2$ to construct a catalog of 1921 clusters at redshift $0.1 15$ that roughly corresponds to $M_{\rm 200m}\gtrsim 10^{14}h^{-1}M_\odot$. We confirm good cluster photometric redshift performance, with the bias and scatter in $Δz/(1+z)$ being better than 0.005 and 0.01 over most of the redshift range, respectively. We compare our cluster catalog with large X-ray cluster catalogs from XXL and XMM-LSS surveys and find good correlation between richness and X-ray properties. We also study the miscentering effect from the distribution of offsets between optical and X-ray cluster centers. We confirm the high ($>0.9$) completeness and purity for high mass clusters by analyzing mock galaxy catalogs.

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arXiv2017

CLUMP-3D. Three dimensional lensing and multi-probe analysis of MACS J1206.2-0847, a remarkably regular cluster

Multi-wavelength techniques can probe the distribution and the physical properties of baryons and dark matter in galaxy clusters from the inner regions out to the peripheries. We present a full three-dimensional analysis combining strong and weak lensing, X-ray surface brightness and temperature, and the Sunyaev-Zel'dovich effect. The method is applied to MACS J1206.2-0847, a remarkably regular, face-on, massive, M_{200}=(1.1+-0.2)*10^{15}M_Sun/h, cluster at z=0.44. The measured concentration, c_{200}=6.3+-1.2, and the triaxial shape are common to halos formed in a LCDM scenario. The gas has settled in and follows the shape of the gravitational potential, which is evidence of pressure equilibrium via the shape theorem. There is no evidence for significant non-thermal pressure and the equilibrium is hydrostatic.

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arXiv2016

$\mathtt{ComEst}$: a Completeness Estimator of Source Extraction on Astronomical Imaging

The completeness of source detection is critical for analyzing the photometric and spatial properties of the population of interest observed by astronomical imaging. We present a software package $\mathtt{ComEst}$, which calculates the completeness of source detection on charge-coupled device (CCD) images of astronomical observations, especially for the optical and near-infrared (NIR) imaging of galaxies and point sources. The completeness estimator $\mathtt{ComEst}$ is designed for the source finder $\mathtt{SExtractor}$ used on the CCD images saved in the Flexible Image Transport System (FITS) format. Specifically, $\mathtt{ComEst}$ estimates the completeness of the source detection by deriving the detection rate of synthetic point sources and galaxies simulated on the observed CCD images. In order to capture any observational artifacts or noise properties while deriving the completeness, $\mathtt{ComEst}$ directly carries out the detection of simulated sources on the observed images. Given an observed CCD image saved in FITS format, $\mathtt{ComEst}$ derives the completeness of the source detection from end to end as a function of source flux (or magnitude) and CCD position. In addition, $\mathtt{ComEst}$ can also estimate the purity of the source detection by comparing the catalog of the detected sources to the input catalogs of the simulated sources. We run ComEst on the images from Blanco Cosmology Survey (BCS) and compare the derived completeness as a function of magnitude to the limiting magnitudes derived by using the Signal-to-Noise ratio (SNR) and number count histogram of the detected sources. $\mathtt{ComEst}$ is released as a Python package with an easy-to-use syntax and is publicly available at https://github.com/inonchiu/ComEst

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