A Comparison and Joint Analysis of Sunyaev-Zel'dovich Effect Measurements from Planck and Bolocam for a set of 47 Massive Galaxy Clusters

We measure the SZ signal toward a set of 47 clusters with a median mass of $9.5 \times 10^{14}$ M$_{\odot}$ and a median redshift of 0.40 using data from Planck and the ground-based Bolocam receiver. When Planck XMM-like masses are used to set the scale radius $\theta_{\textrm{s}}$, we find consistency between the integrated SZ signal, $Y_{\textrm{5R500}}$, derived from Bolocam and Planck based on gNFW model fits using A10 shape parameters, with an average ratio of $1.069 \pm 0.030$ (allowing for the $\simeq 5$% Bolocam flux calibration uncertainty). We also perform a joint fit to the Bolocam and Planck data using a modified A10 model with the outer logarithmic slope $\beta$ allowed to vary, finding $\beta = 6.13 \pm 0.16 \pm 0.76$ (measurement error followed by intrinsic scatter). In addition, we find that the value of $\beta$ scales with mass and redshift according to $\beta \propto M^{0.077 \pm 0.026} \times (1+z)^{-0.06 \pm 0.09}$. This mass scaling is in good agreement with recent simulations. We do not observe the strong trend of $\beta$ with redshift seen in simulations, though we conclude that this is most likely due to our sample selection. Finally, we use Bolocam measurements of $Y_{500}$ to test the accuracy of the Planck completeness estimate. We find consistency, with the actual number of Planck detections falling approximately $1 \sigma$ below the expectation from Bolocam. We translate this small difference into a constraint on the the effective mass bias for the Planck cluster cosmology results, with $(1-b) = 0.93 \pm 0.06$.Comment: Updated to include one additional co-author. Also some minor changes to the text based on initial feedbac

Thermodynamic Profiles of Galaxy Clusters from a Joint X-ray/SZ Analysis

We jointly analyze Bolocam Sunyaev-Zeldovich (SZ) effect and Chandra X-ray data for a set of 45 clusters to derive gas density and temperature profiles without using spectroscopic information. The sample spans the mass and redshift range $3 \times 10^{14} M_{\odot} \le M_{500} \le 25 \times 10^{14} M_{\odot}$ and $0.15\le z \le 0.89$. We define cool-core (CC) and non-cool core (NCC) subsamples based on the central X-ray luminosity, and 17/45 clusters are classified as CC. In general, the profiles derived from our analysis are found to be in good agreement with previous analyses, and profile constraints beyond $r_{500}$ are obtained for 34/45 clusters. In approximately 30% of the CC clusters our analysis shows a central temperature drop with a statistical significance of $>3\sigma$; this modest detection fraction is due mainly to a combination of coarse angular resolution and modest S/N in the SZ data. Most clusters are consistent with an isothermal profile at the largest radii near $r_{500}$, although 9/45 show a significant temperature decrease with increasing radius. The sample mean density profile is in good agreement with previous studies, and shows a minimum intrinsic scatter of approximately 10% near $0.5 \times r_{500}$. The sample mean temperature profile is consistent with isothermal, and has an intrinsic scatter of approximately 50% independent of radius. This scatter is significantly higher compared to earlier X-ray-only studies, which find intrinsic scatters near 10%, likely due to a combination of unaccounted for non-idealities in the SZ noise, projection effects, and sample selection.Comment: 42 pages, 52 figure

The Status of MUSIC: The Multiwavelength Sub/millimeter Inductance Camera

The Multiwavelength Sub/millimeter Inductance Camera (MUSIC) is a four-band photometric imaging camera operating from the Caltech Submillimeter Observatory (CSO). MUSIC is designed to utilize 2304 microwave kinetic inductance detectors (MKIDs), with 576 MKIDs for each observing band centered on 150, 230, 290, and 350 GHz. MUSIC’s field of view (FOV) is 14′ square, and the point-spread functions (PSFs) in the four observing bands have 45′′, 31′′, 25′′, and 22′′ full-widths at half maximum (FWHM). The camera was installed in April 2012 with 25% of its nominal detector count in each band, and has subsequently completed three short sets of engineering observations and one longer duration set of early science observations. Recent results from on-sky characterization of the instrument during these observing runs are presented, including achieved map- based sensitivities from deep integrations, along with results from lab-based measurements made during the same period. In addition, recent upgrades to MUSIC, which are expected to significantly improve the sensitivity of the camera, are described

The cryomechanical design of MUSIC: a novel imaging instrument for millimeter-wave astrophysics at the Caltech Submillimeter Observatory

MUSIC (Multicolor Submillimeter kinetic Inductance Camera) is a new facility instrument for the Caltech Submillimeter Observatory (Mauna Kea, Hawaii) developed as a collaborative effect of Caltech, JPL, the University of Colorado at Boulder and UC Santa Barbara, and is due for initial commissioning in early 2011. MUSIC utilizes a new class of superconducting photon detectors known as microwave kinetic inductance detectors (MKIDs), an emergent technology that offers considerable advantages over current types of detectors for submillimeter and millimeter direct detection. MUSIC will operate a focal plane of 576 spatial pixels, where each pixel is a slot line antenna coupled to multiple detectors through on-chip, lumped-element filters, allowing simultaneously imaging in four bands at 0.86, 1.02, 1.33 and 2.00 mm. The MUSIC instrument is designed for closed-cycle operation, combining a pulse tube cooler with a two-stage Helium-3 adsorption refrigerator, providing a focal plane temperature of 0.25 K with intermediate temperature stages at approximately 50, 4 and 0.4 K for buffering heat loads and heat sinking of optical filters. Detector readout is achieved using semi-rigid coaxial cables from room temperature to the focal plane, with cryogenic HEMT amplifiers operating at 4 K. Several hundred detectors may be multiplexed in frequency space through one signal line and amplifier. This paper discusses the design of the instrument cryogenic hardware, including a number of features unique to the implementation of superconducting detectors. Predicted performance data for the instrument system will also be presented and discussed

A GMBCG Galaxy Cluster Catalog of 55,424 Rich Clusters from SDSS DR7

We present a large catalog of optically selected galaxy clusters from the application of a new Gaussian Mixture Brightest Cluster Galaxy (GMBCG) algorithm to SDSS Data Release 7 data. The algorithm detects clusters by identifying the red sequence plus Brightest Cluster Galaxy (BCG) feature, which is unique for galaxy clusters and does not exist among field galaxies. Red sequence clustering in color space is detected using an Error Corrected Gaussian Mixture Model. We run GMBCG on 8240 square degrees of photometric data from SDSS DR7 to assemble the largest ever optical galaxy cluster catalog, consisting of over 55,000 rich clusters across the redshift range from 0.1 < z < 0.55. We present Monte Carlo tests of completeness and purity and perform cross-matching with X-ray clusters and with the maxBCG sample at low redshift. These tests indicate high completeness and purity across the full redshift range for clusters with 15 or more members.Comment: Updated to match the published version. The catalog can be accessed from: http://home.fnal.gov/~jghao/gmbcg_sdss_catalog.htm

The Panchromatic Hubble Andromeda Treasury II. Tracing the Inner M31 Halo with Blue Horizontal Branch Stars

We attempt to constrain the shape of M31's inner stellar halo by tracing the surface density of blue horizontal branch (BHB) stars at galactocentric distances ranging from 2 kpc to 35 kpc. Our measurements make use of resolved stellar photometry from a section of the Panchromatic Hubble Andromeda Treasury (PHAT) survey, supplemented by several archival Hubble Space Telescope observations. We find that the ratio of BHB to red giant stars is relatively constant outside of 10 kpc, suggesting that the BHB is as reliable a tracer of the halo population as the red giant branch. In the inner halo, we do not expect BHB stars to be produced by the high metallicity bulge and disk, making BHB stars a good candidate to be a reliable tracer of the stellar halo to much smaller galactocentric distances. If we assume a power-law profile r^(-\alpha) for the 2-D projected surface density BHB distribution, we obtain a high-quality fit with a 2-D power-law index of \alpha=2.6^{+0.3}_{-0.2} outside of 3 kpc, which flattens to \alpha<1.2 inside of 3 kpc. This slope is consistent with previous measurements but is anchored to a radial baseline that extends much farther inward. Finally, assuming azimuthal symmetry and a constant mass-to-light ratio, the best-fitting profile yields a total halo stellar mass of 2.1^{+1.7}_{-0.4} x 10^9 M_sun. These properties are comparable with both simulations of stellar halo formation formed by satellite disruption alone, and with simulations that include some in situ formation of halo stars.Comment: 15 pages, 1 table, 5 figures, accepted for publication in Ap

A Comparison and Joint Analysis of Sunyaev-Zel'dovich Effect Measurements from Planck and Bolocam for a set of 47 Massive Galaxy Clusters

We measure the Sunyaev–Zel'dovich (SZ) signal toward a set of 47 clusters with a median mass of 9.5 × 10^(14) M_☉ and a median redshift of 0.40 using data from Planck and the ground-based Bolocam receiver. When Planck XMM-like masses are used to set the scale radius θ_s, we find consistency between the integrated SZ signal, Y_(5R500), derived from Bolocam and Planck based on generalized Navarro, Frenk, and White model fits using A10 shape parameters, with an average ratio of 1.069 ± 0.030 (allowing for the ≃ 5% Bolocam flux calibration uncertainty). We also perform a joint fit to the Bolocam and Planck data using a modified A10 model with the outer logarithmic slope β allowed to vary, finding β = 6.13 ± 0.16 ± 0.76 (measurement error followed by intrinsic scatter). In addition, we find that the value of β scales with mass and redshift according to β ∝ M^(0.077 ± 0.026) x (1 + z))^(-0.06 ± 0.09). This mass scaling is in good agreement with recent simulations. We do not observe the strong trend of β with redshift seen in simulations, though we conclude that this is most likely due to our sample selection. Finally, we use Bolocam measurements of Y 500 to test the accuracy of the Planck completeness estimate. We find consistency, with the actual number of Planck detections falling approximately 1σ below the expectation from Bolocam. We translate this small difference into a constraint on the effective mass bias for the Planck cluster cosmology results, with (1 - b)=0.93 ± 0.06