Showing papers by "W. L. Holzapfel published in 2010"
McGill University1, University of Chicago2, Yale University3, Cardiff University4, University of California, Berkeley5, Harvard University6, University of Illinois at Urbana–Champaign7, University of California, Davis8, University of Colorado Boulder9, Marshall Space Flight Center10, Lawrence Berkeley National Laboratory11, University of Michigan12, Max Planck Society13, Case Western Reserve University14, National Central University15, Ludwig Maximilian University of Munich16
TL;DR: A detection-significance-limited catalog of 21 Sunyaev-Zel'dovich-selected galaxy clusters is presented in this paper. But it is not a complete catalog.
Abstract: We present a detection-significance-limited catalog of 21 Sunyaev-Zel'dovich-selected galaxy clusters. These clusters, along with one unconfirmed candidate, were identified in 178 deg2 of sky surveyed in 2008 by the South Pole Telescope (SPT) to a depth of 18 μK arcmin at 150 GHz. Optical imaging from the Blanco Cosmology Survey (BCS) and Magellan telescopes provided photometric (and in some cases spectroscopic) redshift estimates, with catalog redshifts ranging from z = 0.15 to z>1, with a median z = 0.74. Of the 21 confirmed galaxy clusters, 3 were previously identified as Abell clusters, 3 were presented as SPT discoveries in Staniszewski et al., and 3 were first identified in a recent analysis of BCS data by Menanteau et al.; the remaining 12 clusters are presented for the first time in this work. Simulated observations of the SPT fields predict the sample to be nearly 100% complete above a mass threshold of M 200 5 × 1014 M ☉ h –1 at z = 0.6. This completeness threshold pushes to lower mass with increasing redshift, dropping to ~4 × 1014 M ☉ h –1 at z = 1. The size and redshift distribution of this catalog are in good agreement with expectations based on our current understanding of galaxy clusters and cosmology. In combination with other cosmological probes, we use this cluster catalog to improve estimates of cosmological parameters. Assuming a standard spatially flat wCDM cosmological model, the addition of our catalog to the WMAP seven-year results yields σ8 = 0.81 ± 0.09 and w = –1.07 ± 0.29, a ~50% improvement in precision on both parameters over WMAP7 alone.
358 citations
University of Chicago1, Cardiff University2, Harvard University3, University of California, Berkeley4, McGill University5, University of California, Davis6, University of Colorado Boulder7, Marshall Space Flight Center8, Lawrence Berkeley National Laboratory9, Commonwealth Scientific and Industrial Research Organisation10, University of Michigan11, Max Planck Society12, Case Western Reserve University13, Yale University14, University of Illinois at Urbana–Champaign15
TL;DR: In this article, the authors report the results of an 87 deg(2) point-source survey centered at R.A. 5(h)30(m), decl. −55° taken with the South Pole Telescope at 1.4 and 2.0 mm wavelengths with arcminute resolution and milli-Jansky depth.
Abstract: We report the results of an 87 deg(2) point-source survey centered at R.A. 5(h)30(m), decl. –55° taken with the South Pole Telescope at 1.4 and 2.0 mm wavelengths with arcminute resolution and milli-Jansky depth. Based on the ratio of flux in the two bands, we separate the detected sources into two populations, one consistent with synchrotron emission from active galactic nuclei and the other consistent with thermal emission from dust. We present source counts for each population from 11 to 640 mJy at 1.4 mm and from 4.4 to 800 mJy at 2.0 mm. The 2.0 mm counts are dominated by synchrotron-dominated sources across our reported flux range; the 1.4 mm counts are dominated by synchrotron-dominated sources above ~15 mJy and by dust-dominated sources below that flux level. We detect 141 synchrotron-dominated sources and 47 dust-dominated sources at signal-to-noise ratio S/N >4.5 in at least one band. All of the most significantly detected members of the synchrotron-dominated population are associated with sources in previously published radio catalogs. Some of the dust-dominated sources are associated with nearby (z 1) galaxies whose dust emission is also detected by the Infrared Astronomy Satellite. However, most of the bright, dust-dominated sources have no counterparts in any existing catalogs. We argue that these sources represent the rarest and brightest members of the population commonly referred to as submillimeter galaxies (SMGs). Because these sources are selected at longer wavelengths than in typical SMG surveys, they are expected to have a higher mean redshift distribution and may provide a new window on galaxy formation in the early universe.
325 citations
California Institute of Technology1, Princeton University2, University of Wales3, National Radio Astronomy Observatory4, University of California, San Diego5, Jet Propulsion Laboratory6, French Alternative Energies and Atomic Energy Commission7, Institut d'Astrophysique de Paris8, University of California, Berkeley9, Stanford University10, University of Chicago11, University of Paris-Sud12, National Institute of Standards and Technology13
TL;DR: In this article, the E-mode angular power spectrum was measured with high precision at 21 ≤ l ≤ 335, detecting for the first time the peak expected at l ~ 140.
Abstract: Background Imaging of Cosmic Extragalactic Polarization (BICEP) is a bolometric polarimeter designed to measure the inflationary B-mode polarization of the cosmic microwave background (CMB) at degree angular scales. During three seasons of observing at the South Pole (2006 through 2008), BICEP mapped ~2% of the sky chosen to be uniquely clean of polarized foreground emission. Here, we present initial results derived from a subset of the data acquired during the first two years. We present maps of temperature, Stokes Q and U, E and B modes, and associated angular power spectra. We demonstrate that the polarization data are self-consistent by performing a series of jackknife tests. We study potential systematic errors in detail and show that they are sub-dominant to the statistical errors. We measure the E-mode angular power spectrum with high precision at 21 ≤ l ≤ 335, detecting for the first time the peak expected at l ~ 140. The measured E-mode spectrum is consistent with expectations from a ΛCDM model, and the B-mode spectrum is consistent with zero. The tensor-to-scalar ratio derived from the B-mode spectrum is r = 0.02^(+0.31)_(–0.26), or r < 0.72 at 95% confidence, the first meaningful constraint on the inflationary gravitational wave background to come directly from CMB B-mode polarization.
258 citations
TL;DR: In this paper, the authors present results of X-ray observations of a sample of 15 clusters selected via their imprint on the cosmic microwave background (CMB) from the thermal Sunyaev-Zel'dovich (SZ) effect.
Abstract: We present results of X-ray observations of a sample of 15 clusters selected via their imprint on the cosmic microwave background (CMB) from the thermal Sunyaev-Zel'dovich (SZ) effect. These clusters are a subset of the first SZ-selected cluster catalog, obtained from observations of 178 deg^2 of sky surveyed by the South Pole Telescope. Using X-ray observations with Chandra and XMM-Newton, we estimate the temperature, T_X, and mass, M_g, of the intracluster medium (ICM) within r_500 for each cluster. From these, we calculate Y_X=M_g T_X and estimate the total cluster mass using a M_500-Y_X scaling relation measured from previous X-ray studies. The integrated Comptonization, Y_SZ, is derived from the SZ measurements, using additional information from the X-ray measured gas density profiles and a universal temperature profile. We calculate scaling relations between the X-ray and SZ observables, and find results generally consistent with other measurements and the expectations from simple self-similar behavior. Specifically, we fit a Y_SZ-Y_X relation and find a normalization of 0.82 +- 0.07, marginally consistent with the predicted ratio of Y_SZ/Y_X=0.91+-0.01 that would be expected from the density and temperature models used in this work. Using the Y_X derived mass estimates, we fit a Y_SZ-M_500 relation and find a slope consistent with the self-similar expectation of Y_SZ ~ M^5/3 with a normalization consistent with predictions from other X-ray studies. We compare the X-ray mass estimates to previously published SZ mass estimates derived from cosmological simulations of the SPT survey. We find that the SZ mass estimates are lower by a factor of 0.89+-0.06, which is within the ~15% systematic uncertainty quoted for the simulation-based SZ masses.
171 citations
University of California, Berkeley1, University of Chicago2, Lawrence Berkeley National Laboratory3, Cardiff University4, McGill University5, University of California, Davis6, University of Colorado Boulder7, Marshall Space Flight Center8, University of Michigan9, Max Planck Society10, Case Western Reserve University11, Yale University12, Harvard University13
TL;DR: In this paper, the authors reported the first 100?deg2 field observed by the South Pole Telescope (SPT) at 150 and 220?GHz at both frequencies and showed strong evidence for a point source contribution, consistent with a population of dusty, star-forming galaxies.
Abstract: We report cosmic microwave background (CMB) power-spectrum measurements from the first 100?deg2 field observed by the South Pole Telescope (SPT) at 150 and 220?GHz. On angular scales where the primary CMB anisotropy is dominant, ? 3000, the SPT power spectrum is consistent with the standard ?CDM cosmology. On smaller scales, we see strong evidence for a point-source contribution, consistent with a population of dusty, star-forming galaxies. After we mask bright point sources, anisotropy power on angular scales of 3000 < ? < 9500 is detected with a signal-to-noise ratio 50 at both frequencies. We combine the 150 and 220?GHz data to remove the majority of the point-source power and use the point-source-subtracted spectrum to detect Sunyaev-Zel'dovich (SZ) power at 2.6?. At ? = 3000, the SZ power in the subtracted bandpowers is 4.2 ? 1.5 ?K2, which is significantly lower than the power predicted by a fiducial model using WMAP5 cosmological parameters. This discrepancy may suggest that contemporary galaxy cluster models overestimate the thermal pressure of intracluster gas. Alternatively, this result can be interpreted as evidence for lower values of ?8. When combined with an estimate of the kinetic SZ contribution, the measured SZ amplitude shifts ?8 from the primary CMB anisotropy derived constraint of 0.794 ? 0.028 down to 0.773 ? 0.025. The uncertainty in the constraint on ?8 from this analysis is dominated by uncertainties in the theoretical modeling required to predict the amplitude of the SZ power spectrum for a given set of cosmological parameters.
170 citations
University of California, Berkeley1, University of Chicago2, Cardiff University3, McGill University4, University of California, Davis5, University of Colorado Boulder6, Marshall Space Flight Center7, Lawrence Berkeley National Laboratory8, National Radio Astronomy Observatory9, University of Michigan10, Max Planck Society11, Case Western Reserve University12, Harvard University13
TL;DR: In this paper, Sunyaev-Zel'dovich (SZ) measurements of 15 massive X-ray-selected galaxy clusters obtained with the South Pole Telescope (SPT) are presented.
Abstract: We present Sunyaev-Zel'dovich (SZ) measurements of 15 massive X-ray-selected galaxy clusters obtained with the South Pole Telescope (SPT). The SZ cluster signals are measured at 150 GHz, and concurrent 220 GHz data are used to reduce astrophysical contamination. Radial profiles are computed using a technique that takes into account the effects of the beams and filtering. In several clusters, significant SZ decrements are detected out to a substantial fraction of the virial radius. The profiles are fit to the {beta}-model and to a generalized Navarro-Frenk-White (NFW) pressure profile, and are scaled and stacked to probe their average behavior. We find model parameters that are consistent with previous studies: {beta} = 0.86 and r{sub core}/r{sub 500} = 0.20 for the {beta}-model, and ({alpha}{sub n}, {beta}{sub n}, {gamma}{sub n}, c{sub 500}) = (1.0, 5.5, 0.5, 1.0) for the generalized NFW model. Both models fit the SPT data comparably well, and both are consistent with the average SZ profile out to beyond r{sub 500}. The integrated Compton-y parameter Y{sub SZ} is computed for each cluster using both model-dependent and model-independent techniques, and the results are compared to X-ray estimates of cluster parameters. We find that Y{sub SZ} scales with Y{sub X} and gasmore » mass with low scatter. Since these observables have been found to scale with total mass, our results point to a tight mass-observable relation for the SPT cluster survey.« less
164 citations
University of California, Davis1, University of Chicago2, University of California, Berkeley3, Cardiff University4, McGill University5, University of Colorado Boulder6, Marshall Space Flight Center7, Lawrence Berkeley National Laboratory8, Max Planck Society9, Case Western Reserve University10, Harvard University11
TL;DR: In this paper, the authors used data from the first 100 deg2 field observed by the South Pole Telescope (SPT) in 2008 to measure the angular power spectrum of temperature anisotropies contributed by the background of dusty star-forming galaxies (DSFGs) at millimeter wavelengths.
Abstract: We use data from the first 100 deg2 field observed by the South Pole Telescope (SPT) in 2008 to measure the angular power spectrum of temperature anisotropies contributed by the background of dusty star-forming galaxies (DSFGs) at millimeter wavelengths. From the auto- and cross-correlation of 150 and 220 GHz SPT maps, we significantly detect both Poisson distributed and, for the first time at millimeter wavelengths, clustered components of power from a background of DSFGs. The spectral indices of the Poisson and clustered components are found to be and α C 150–220 = 3.8 ± 1.3, implying a steep scaling of the dust emissivity index β ~ 2. The Poisson and clustered power detected in SPT, BLAST (at 600, 860, and 1200 GHz), and Spitzer (1900 GHz) data can be understood in the context of a simple model in which all galaxies have the same graybody spectrum with dust emissivity index of β = 2 and dust temperature Td = 34 K. In this model, half of the 150 GHz background light comes from redshifts greater than 3.2. We also use the SPT data to place an upper limit on the amplitude of the kinetic Sunyaev-Zel'dovich power spectrum at l = 3000 of 13 μK2 at 95% confidence.
149 citations
Harvard University1, Cardiff University2, University of Chicago3, Massachusetts Institute of Technology4, Ludwig Maximilian University of Munich5, McGill University6, University of Illinois at Urbana–Champaign7, Pennsylvania State University8, University of California, Berkeley9, University of Florida10, University of Colorado Boulder11, Marshall Space Flight Center12, University of California, Davis13, Lawrence Berkeley National Laboratory14, Max Planck Society15, Case Western Reserve University16, Yale University17
TL;DR: In this article, the authors reported the spectroscopic confirmation of SPT-CL J0546-5345 at z = 1.067, which is the first z>1 cluster discovered by the Sunyaev-Zel'dovich Effect (SZE).
Abstract: We report the spectroscopic confirmation of SPT-CL J0546-5345 at z = 1.067. To date this is the most distant cluster to be spectroscopically confirmed from the 2008 South Pole Telescope (SPT) catalog, and indeed the first z>1 cluster discovered by the Sunyaev-Zel'dovich Effect (SZE). We identify 21 secure spectroscopic members within 0.9 Mpc of the SPT cluster position, 18 of which are quiescent, early-type galaxies. From these quiescent galaxies we obtain a velocity dispersion of 1179(+232)( –167) km s(–1), ranking SPT-CL J0546-5345 as the most dynamically massive cluster yet discovered at z>1. Assuming that SPT-CL J0546-5345 is virialized, this implies a dynamical mass of M (200) = 1.0(+0.6) (–0.4) × 10(15) M ☉, in agreement with the X-ray and SZE mass measurements. Combining masses from several independent measures leads to a best-estimate mass of M (200) = (7.95 ± 0.92) × 10(14 )M ☉. The spectroscopic confirmation of SPT-CL J0546-5345, discovered in the wide-angle, mass-selected SPT cluster survey, marks the onset of the high-redshift SZE-selected galaxy cluster era.
137 citations
University of California, Berkeley1, University of Wales2, California Institute of Technology3, National Radio Astronomy Observatory4, University of California, San Diego5, Jet Propulsion Laboratory6, Princeton University7, French Alternative Energies and Atomic Energy Commission8, Institut d'Astrophysique de Paris9, Stanford University10, University of Chicago11, University of Paris-Sud12, National Institute of Standards and Technology13
TL;DR: In this paper, the authors describe the characterization of potential systematic errors for the BICEP experiment, supplementing a companion paper on the initial cosmological results, using the analysis pipelines for the experiment, have simulated the impact of systematic errors on the B-mode polarization measurement, and established benchmarks for the critical instrumental properties including bolometer relative gains, beam mismatch, polarization orientation, telescope pointing, sidelobes, thermal stability and timestream noise model.
Abstract: The Background Imaging of Cosmic Extragalactic Polarization (BICEP) experiment was designed specifically to search for the signature of inflationary gravitational waves in the polarization of the cosmic microwave background (CMB). Using a novel small-aperture refractor and 49 pairs of polarization-sensitive bolometers, BICEP has completed three years of successful observations at the South Pole beginning in 2006 February. To constrain the amplitude of the inflationary B-mode polarization, which is expected to be at least 7 orders of magnitude fainter than the 3 K CMB intensity, precise control of systematic effects is essential. This paper describes the characterization of potential systematic errors for the BICEP experiment, supplementing a companion paper on the initial cosmological results. Using the analysis pipelines for the experiment, we have simulated the impact of systematic errors on the B-mode polarization measurement. Guided by these simulations, we have established benchmarks for the characterization of critical instrumental properties including bolometer relative gains, beam mismatch, polarization orientation, telescope pointing, sidelobes, thermal stability, and timestream noise model. A comparison of the benchmarks with the measured values shows that we have characterized the instrument adequately to ensure that systematic errors do not limit BICEP's two-year results, and identifies which future refinements are likely necessary to probe inflationary B-mode polarization down to levels below a tensor-to-scalar ratio r = 0.1.
95 citations
Harvard University1, University of Illinois at Urbana–Champaign2, Cardiff University3, University of Chicago4, Fermilab5, National Center for Supercomputing Applications6, University of North Dakota7, University of California, Berkeley8, Los Alamos National Laboratory9, McGill University10, University of Colorado Boulder11, University of Chile12, University of California, Santa Cruz13, Marshall Space Flight Center14, Lawrence Berkeley National Laboratory15, University of Tokyo16, University of Michigan17, Max Planck Society18, Case Western Reserve University19, Yale University20, University of Pittsburgh21, Ludwig Maximilian University of Munich22
TL;DR: In this article, the authors presented redshifts and optical richness properties of 21 galaxy clusters uniformly selected by their Sunyaev-Zel'dovich (SZ) signature.
Abstract: We present redshifts and optical richness properties of 21 galaxy clusters uniformly selected by their Sunyaev-Zel'dovich (SZ) signature. These clusters, plus an additional, unconfirmed candidate, were detected in a 178 deg(2) area surveyed by the South Pole Telescope (SPT) in 2008. Using griz imaging from the Blanco Cosmology Survey and from pointed Magellan telescope observations, as well as spectroscopy using Magellan facilities, we confirm the existence of clustered red-sequence galaxies, report red-sequence photometric redshifts, present spectroscopic redshifts for a subsample, and derive R (200) radii and M (200) masses from optical richness. The clusters span redshifts from 0.15 to greater than 1, with a median redshift of 0.74; three clusters are estimated to be at z>1. Redshifts inferred from mean red-sequence colors exhibit 2% rms scatter in σ (z) /(1 + z) with respect to the spectroscopic subsample for z < 1. We show that the M (200) cluster masses derived from optical richness correlate with masses derived from SPT data and agree with previously derived scaling relations to within the uncertainties. Optical and infrared imaging is an efficient means of cluster identification and redshift estimation in large SZ surveys, and exploiting the same data for richness measurements, as we have done, will be useful for constraining cluster masses and radii for large samples in cosmological analysis.
85 citations
TL;DR: In this article, a non-parametric de-projection method was proposed to study the physical properties of the intra-cluster gas by using a nonparametric method that is, aside from the assumption of spherical symmetry, free from modeling bias.
Abstract: Aims. We aim to demonstrate the usability of mm-wavelength imaging data obtained from the APEX-SZ bolometer array to derive the radial temperature profile of the hot intra-cluster gas out to radius r(500) and beyond. The goal is to study the physical properties of the intra-cluster gas by using a non-parametric de-projection method that is, aside from the assumption of spherical symmetry, free from modeling bias. Methods. We use publicly available X-ray spectroscopic-imaging data in the 0.7-2 keV energy band from the XMM-Newton observatory and our Sunyaev-Zel'dovich Effect (SZE) imaging data from the APEX-SZ experiment at 150 GHz to de-project the density and temperature profiles for a well-studied relaxed cluster, Abell 2204. We derive the gas density, temperature and entropy profiles assuming spherical symmetry, and obtain the total mass profile under the assumption of hydrostatic equilibrium. For comparison with X-ray spectroscopic temperature models, a re-analysis of recent Chandra observation is done with the latest calibration updates. We compare the results with that from an unrelaxed cluster, Abell 2163, to illustrate some differences between relaxed and merging systems. Results. Using the non-parametric modeling, we demonstrate a decrease of gas temperature in the cluster outskirts, and also measure gas entropy profiles, both of which are done for the first time independently of X-ray spectroscopy using the SZE and X-ray imaging data. The gas entropy measurement in the central 100 kpc shows the usability of APEX-SZ data for inferring cluster dynamical states with this method. The contribution of the SZE systematic uncertainties in measuring T-e at large radii is shown to be small compared to XMM-Newton and Chandra systematic spectroscopic errors. The total mass profile obtained using the hydrostatic equilibrium assumption is in agreement with the published X-ray and weak lensing results; the upper limit on M-200 derived from the non-parametric method is consistent with the NFW model prediction from weak lensing analysis.
TL;DR: The polarbear experiment as discussed by the authors is a CMB polarization experiment that will search for evidence of inflationary gravitational waves and gravitational lensing in the polarization of the CMB, and it has been successfully used for the detection of the first time.
Abstract: POLARBEAR is a Cosmic Microwave Background (CMB) polarization experiment that will search for evidence of inflationary gravitational waves and gravitational lensing in the polarization of the CMB. This proceeding presents an overview of the design of the instrument and the architecture of the focal plane, and shows some of the recent tests of detector performance and early data from the ongoing engineering run.
02 Nov 2010
TL;DR: The Polarbear experiment as mentioned in this paper used the Huan Tran Telescope equipped with a powerful 1,200-bolometer array receiver to map the CMB polarization with unprecedented accuracy, achieving state-of-the-art results.
Abstract: We describe the Cosmic Microwave Background (CMB) polarization experiment called Polarbear. This experiment will use the dedicated Huan Tran Telescope equipped with a powerful 1,200-bolometer array receiver to map the CMB polarization with unprecedented accuracy. We summarize the experiment, its goals, and current status.
McGill University1, University of Chicago2, Yale University3, Cardiff University4, University of California, Berkeley5, Harvard University6, University of Illinois at Urbana–Champaign7, University of California, Davis8, University of Colorado Boulder9, Marshall Space Flight Center10, Lawrence Berkeley National Laboratory11, University of Michigan12, Max Planck Society13, Case Western Reserve University14, National Central University15, Ludwig Maximilian University of Munich16
TL;DR: In this article, a detection-significance-limited catalog of 21 Sunyaev-Zel'dovich selected galaxy clusters is presented, along with 1 unconfirmed candidate.
Abstract: We present a detection-significance-limited catalog of 21 Sunyaev-Zel'dovich selected galaxy clusters. These clusters, along with 1 unconfirmed candidate, were identified in 178 deg^2 of sky surveyed in 2008 by the South Pole Telescope to a depth of 18 uK-arcmin at 150 GHz. Optical imaging from the Blanco Cosmology Survey (BCS) and Magellan telescopes provided photometric (and in some cases spectroscopic) redshift estimates, with catalog redshifts ranging from z=0.15 to z>1, with a median z = 0.74. Of the 21 confirmed galaxy clusters, three were previously identified as Abell clusters, three were presented as SPT discoveries in Staniszewski et al, 2009, and three were first identified in a recent analysis of BCS data by Menanteau et al, 2010; the remaining 12 clusters are presented for the first time in this work. Simulated observations of the SPT fields predict the sample to be nearly 100% complete above a mass threshold of M_200 ~ 5x10^14 M_sun/h at z = 0.6. This completeness threshold pushes to lower mass with increasing redshift, dropping to ~4x10^14 M_sun/h at z=1. The size and redshift distribution of this catalog are in good agreement with expectations based on our current understanding of galaxy clusters and cosmology. In combination with other cosmological probes, we use the cluster catalog to improve estimates of cosmological parameters. Assuming a standard spatially flat wCDM cosmological model, the addition of our catalog to the WMAP 7-year analysis yields sigma_8 = 0.81 +- 0.09 and w = -1.07 +- 0.29, a ~50% improvement in precision on both parameters over WMAP7 alone.
TL;DR: The Atacama pathfinder experiment Sunyaev-Zel'dovich (APEX-SZ) instrument as discussed by the authors is a millimeter-wave cryogenic receiver designed to observe galaxy clusters via the SZ effect.
Abstract: The Atacama pathfinder experiment Sunyaev-Zel'dovich (APEX-SZ) instrument is a millimeter-wave cryogenic receiver designed to observe galaxy clusters via the Sunyaev-Zel'dovich effect from the 12 m APEX telescope on the Atacama plateau in Chile. The receiver contains a focal plane of 280 superconducting transition-edge sensor (TES) bolometers instrumented with a frequency-domain multiplexed readout system. The bolometers are cooled to 280 mK via a three-stage helium sorption refrigerator and a mechanical pulse-tube cooler. Three warm mirrors, two 4 K lenses, and a horn array couple the TES bolometers to the telescope. APEX-SZ observes in a single frequency band at 150 GHz with 1' angular resolution and a 22' field-of-view, all well suited for cluster mapping. The APEX-SZ receiver has played a key role in the introduction of several new technologies including TES bolometers, the frequency-domain multiplexed readout, and the use of a pulse-tube cooler with bolometers. As a result of these new technologies, the instrument has a higher instantaneous sensitivity and covers a larger field-of-view than earlier generations of Sunyaev-Zel'dovich instruments. The TES bolometers have a median sensitivity of 890 uKcmb-sqrt(s) (NEy of 3.5e-4 sqrt(s)). We have also demonstrated upgraded detectors with improved sensitivity of 530 uKcmb-sqrt(s) (NEy of 2.2e-4 sqrt(s)). Since its commissioning in April 2007, APEX-SZ has been used to map 48 clusters. We describe the design of the receiver and its performance when installed on the APEX telescope.
TL;DR: In this article, the authors present a method of reliable extraction of the flux of individual sources from sky maps in the presence of noise and a source population in which number counts are a steeply falling function of flux.
Abstract: We present a method of reliable extraction of the flux of individual sources from sky maps in the presence of noise and a source population in which number counts are a steeply falling function of flux. The method is an extension of a standard Bayesian procedure in the millimeter/submillimeter literature. As in the standard method, the prior applied to source flux measurements is derived from an estimate of the source counts as a function of flux, dN/dS. The key feature of the new method is that it enables reliable extraction of properties of individual sources, which previous methods in the literature do not. We first present the method for extracting individual source fluxes from data in a single observing band, then we extend the method to multiple bands, including prior information about the spectral behavior of the source population(s). The multi-band estimation technique is particularly relevant for classifying individual sources into populations according to their spectral behavior. We find that proper treatment of the correlated prior information between observing bands is key to avoiding significant biases in estimations of multi-band fluxes and spectral behavior, biases which lead to significant numbers of misclassified sources. We test the single- and multi-band versionsmore » of the method using simulated observations with observing parameters similar to that of the South Pole Telescope data used in Vieira et al.« less
Posted Content•
TL;DR: The Polarbear experiment as discussed by the authors used the Huan Tran Telescope equipped with a powerful 1,200-bolometer array receiver to map the CMB polarization with unprecedented accuracy, achieving state-of-the-art results.
Abstract: We describe the Cosmic Microwave Background (CMB) polarization experiment called Polarbear. This experiment will use the dedicated Huan Tran Telescope equipped with a powerful 1,200-bolometer array receiver to map the CMB polarization with unprecedented accuracy. We summarize the experiment, its goals, and current status.
TL;DR: In this article, a dual-polarized multi-channel antenna-coupled transition edge sensor (TES) bolometer was developed for CMB polarimetry in terrestrial experiments.
Abstract: We are developing dual-polarized multi-channel antenna-coupled Transition Edge Sensor (TES) Bolometers for Cosmic Microwave Background (CMB) Polarimetry in terrestrial experiments. Each pixel of the array couples incident power into the lithographed microstrip circuits with a dual-polarized broadband planar sinuous antenna who's gain is increased with a contacting extended hemispherical lens. Microstrip filter manifolds partition the two-octave bandwidth into narrow channels before terminating at separate TES bolometers. We describe the design methodology and fabrication methods used, and also the results of optical tests that show high optical throughput in properly located bands, as well as high cross-polarization rejection. We have explored two antenna feeding schemes that result in different quality beams and we comment on the relative merits of each. Finally, we quantify the increases in mapping speed that an array of our multichroic pixels might realize over traditional monochromatic pixels
Harvard University1, University of Illinois at Urbana–Champaign2, Cardiff University3, University of Chicago4, Fermilab5, National Center for Supercomputing Applications6, University of North Dakota7, University of California, Berkeley8, Los Alamos National Laboratory9, McGill University10, University of Colorado Boulder11, University of Chile12, University of California, Santa Cruz13, Marshall Space Flight Center14, Lawrence Berkeley National Laboratory15, University of Tokyo16, University of Michigan17, Max Planck Society18, Case Western Reserve University19, Yale University20, University of Pittsburgh21, Ludwig Maximilian University of Munich22
TL;DR: In this article, the authors used griz imaging from the Blanco Cosmology Survey and from pointed Magellan telescope observations, as well as spectroscopy using Magellan facilities, to confirm the existence of clustered red-sequence galaxies.
Abstract: We present redshifts and optical richness properties of 21 galaxy clusters uniformly selected by their Sunyaev-Zel'dovich signature. These clusters, plus an additional, unconfirmed candidate, were detected in a 178 square-degree area surveyed by the South Pole Telescope in 2008. Using griz imaging from the Blanco Cosmology Survey and from pointed Magellan telescope observations, as well as spectroscopy using Magellan facilities, we confirm the existence of clustered red-sequence galaxies, report red-sequence photometric redshifts, present spectroscopic redshifts for a subsample, and derive R_200 radii and M_200 masses from optical richness. The clusters span redshifts from 0.15 to greater than 1, with a median redshift of 0.74; three clusters are estimated to be at z > 1. Redshifts inferred from mean red-sequence colors exhibit 2% RMS scatter in sigma_z/(1+z) with respect to the spectroscopic subsample for z < 1. We show that M_200 cluster masses derived from optical richness correlate with masses derived from South Pole Telescope data and agree with previously derived scaling relations to within the uncertainties. Optical and infrared imaging is an efficient means of cluster identification and redshift estimation in large Sunyaev-Zel'dovich surveys, and exploiting the same data for richness measurements, as we have done, will be useful for constraining cluster masses and radii for large samples in cosmological analysis.
Posted Content•
02 Aug 2010
TL;DR: The Atacama pathfinder experiment Sunyaev-Zel'dovich (APEX-SZ) instrument as discussed by the authors is a millimeter-wave cryogenic receiver designed to observe galaxy clusters via the SZ effect.
Abstract: The Atacama pathfinder experiment Sunyaev-Zel'dovich (APEX-SZ) instrument is a millimeter-wave cryogenic receiver designed to observe galaxy clusters via the Sunyaev-Zel'dovich effect from the 12 m APEX telescope on the Atacama plateau in Chile. The receiver contains a focal plane of 280 superconducting transition-edge sensor (TES) bolometers instrumented with a frequency-domain multiplexed readout system. The bolometers are cooled to 280 mK via a three-stage helium sorption refrigerator and a mechanical pulse-tube cooler. Three warm mirrors, two 4 K lenses, and a horn array couple the TES bolometers to the telescope. APEX-SZ observes in a single frequency band at 150 GHz with 1' angular resolution and a 22' field-of-view, all well suited for cluster mapping. The APEX-SZ receiver has played a key role in the introduction of several new technologies including TES bolometers, the frequency-domain multiplexed readout, and the use of a pulse-tube cooler with bolometers. As a result of these new technologies, the instrument has a higher instantaneous sensitivity and covers a larger field-of-view than earlier generations of Sunyaev-Zel'dovich instruments. The TES bolometers have a median sensitivity of 890 uKcmb-sqrt(s) (NEy of 3.5e-4 sqrt(s)). We have also demonstrated upgraded detectors with improved sensitivity of 530 uKcmb-sqrt(s) (NEy of 2.2e-4 sqrt(s)). Since its commissioning in April 2007, APEX-SZ has been used to map 48 clusters. We describe the design of the receiver and its performance when installed on the APEX telescope.
TL;DR: In this article, a monolithic array of orthomode transducer (OMT) coupled transition edge sensor (TES) polarimeters for operation at 150 GHz is presented.
Abstract: The next generation of Cosmic Microwave Background (CMB) experiments probing for signals of inflation and
small angular scale polarization anisotropies require higher sensitivity and better control of systematics. We are
developing monolithic arrays of orthomode transducer (OMT) coupled transition edge sensor (TES) polarimeters
designed for operation at 150 GHz to address these requirements. OMT coupling allows for simultaneous and
independent detection of two orthogonal linear polarization states incident on a single pixel. We present measurements
of optical efficiencies η op of single pixels with on-chip band-defining filters, with η op = 57±4 stat±9 sys %.
We also provide evidence for an out-of-band blue leak and address possible sources as well as mitigation techniques.
Additionally, we discuss methods for increasing efficiency being implemented in the next generation of
pixels, currently in fabrication. Still under development, these pixels are produced as monolithic polarimeter arrays
and are slated for use in the Atacama Cosmology Telescope Polarization (ACTpol) and South Pole Telescope
Polarization (SPTpol) experiments, while single-pixel polarimeters are to be deployed in the Atacama B-mode
Search (ABS) experiment.
California Institute of Technology1, University of Wales2, University of California, San Diego3, Princeton University4, French Alternative Energies and Atomic Energy Commission5, Institut d'Astrophysique de Paris6, University of California, Berkeley7, Harvard University8, Stanford University9, University of Chicago10, National Institute of Standards and Technology11
TL;DR: In this paper, a method of cross-calibrating the polarization angle of a polarimeter using Bicep Galactic observations is presented, which is based on a ground-based experiment using an array of 49 pairs of polarization sensitive bolometers observing from the geographic South Pole at 100 and 150 GHz.
Abstract: We present a method of cross-calibrating the polarization angle of a polarimeter using Bicep Galactic observations. Bicep was a ground based experiment using an array of 49 pairs of polarization sensitive bolometers observing from the geographic South Pole at 100 and 150 GHz. The Bicep polarimeter is calibrated to ±0.01 in cross-polarization and less than ±0.7° in absolute polarization orientation. Bicep observed the temperature and polarization of the Galactic plane (R.A = 100° ~ 270° and Dec. = -67° ~ -48°). We show that the statistical error in the 100 GHz Bicep Galaxy map can constrain the polarization angle offset of Wmap W band to 0.6° ± 1.4°. The expected 1σ errors on the polarization angle cross-calibration for Planck or EPIC are 1.3° and 0.3° at 100 and 150 GHz, respectively. We also discuss the expected improvement of the Bicep Galactic field observations with forthcoming Bicep2 and Keck observations.
Harvard University1, Cardiff University2, University of Chicago3, Massachusetts Institute of Technology4, Ludwig Maximilian University of Munich5, McGill University6, University of Illinois at Urbana–Champaign7, Pennsylvania State University8, University of California, Berkeley9, University of Florida10, University of Colorado Boulder11, Marshall Space Flight Center12, University of California, Davis13, Lawrence Berkeley National Laboratory14, Max Planck Society15, Case Western Reserve University16, Yale University17
TL;DR: In this article, the authors reported the spectroscopic confirmation of SPT-CL J0546-5345 at = 1.067, the first z > 1 cluster discovered by the Sunyaev-Zel'dovich Effect.
Abstract: We report the spectroscopic confirmation of SPT-CL J0546-5345 at = 1.067. To date this is the most distant cluster to be spectroscopically confirmed from the 2008 South Pole Telescope (SPT) catalog, and indeed the first z > 1 cluster discovered by the Sunyaev-Zel'dovich Effect (SZE). We identify 21 secure spectroscopic members within 0.9 Mpc of the SPT cluster position, 18 of which are quiescent, early-type galaxies. From these quiescent galaxies we obtain a velocity dispersion of 1179^{+232}_{-167} km/s, ranking SPT-CL J0546-5345 as the most dynamically massive cluster yet discovered at z > 1. Assuming that SPT-CL J0546-5345 is virialized, this implies a dynamical mass of M_200 = 1.0^{+0.6}_{-0.4} x 10^{15} Msun, in agreement with the X-ray and SZE mass measurements. Combining masses from several independent measures leads to a best-estimate mass of M_200 = (7.95 +/- 0.92) x 10^{14} Msun. The spectroscopic confirmation of SPT-CL J0546-5345, discovered in the wide-angle, mass-selected SPT cluster survey, marks the onset of the high redshift SZE-selected galaxy cluster era.
University of California, Berkeley1, Yale University2, University of California, Davis3, Cardiff University4, University of Chicago5, National Institute of Standards and Technology6, McGill University7, University of Colorado Boulder8, Marshall Space Flight Center9, Lawrence Berkeley National Laboratory10, California Institute of Technology11, University of Michigan12, Max Planck Society13, Case Western Reserve University14, School of the Art Institute of Chicago15, Harvard University16
TL;DR: In this article, an improved cosmological parameter estimator was used to fit multi-frequency models to the SPT 150 and 220 GHz bandpowers. But the results of the analysis were limited by the fact that the power spectrum of dusty galaxies at high signal-to-noise (SNO) was not available.
Abstract: We report measurements of the cosmic microwave background (CMB) power spectrum from the complete 2008 South Pole Telescope (SPT) data set. We analyze twice as much data as the first SPT power spectrum analysis, using an improved cosmological parameter estimator which fits multi-frequency models to the SPT 150 and $220\,$GHz bandpowers. We find an excellent fit to the measured bandpowers with a model that includes lensed primary CMB anisotropy, secondary thermal (tSZ) and kinetic (kSZ) Sunyaev-Zel'dovich anisotropies, unclustered synchrotron point sources, and clustered dusty point sources. In addition to measuring the power spectrum of dusty galaxies at high signal-to-noise, the data primarily constrain a linear combination of the kSZ and tSZ anisotropy contributions at $150\,$GHz and $\ell=3000$: $D^{tSZ}_{3000} + 0.5\,D^{kSZ}_{3000} = 4.5\pm 1.0 \,\mu{\rm K}^2$. The 95% confidence upper limits on secondary anisotropy power are $D^{tSZ}_{3000} < 5.3\,\mu{\rm K}^2$ and $D^{kSZ}_{3000} < 6.5\,\mu{\rm K}^2$. We also consider the potential correlation of dusty and tSZ sources, and find it incapable of relaxing the tSZ upper limit. These results increase the significance of the lower than expected tSZ amplitude previously determined from SPT power spectrum measurements. We find that models including non-thermal pressure support in groups and clusters predict tSZ power in better agreement with the SPT data. Combining the tSZ power measurement with primary CMB data halves the statistical uncertainty on $\sigma_8$. However, the preferred value of $\sigma_8$ varies significantly between tSZ models. Improved constraints on cosmological parameters from tSZ power spectrum measurements require continued progress in the modeling of the tSZ power.
California Institute of Technology1, University of Wales2, University of California, San Diego3, Princeton University4, French Alternative Energies and Atomic Energy Commission5, Institut d'Astrophysique de Paris6, University of California, Berkeley7, Harvard University8, Stanford University9, University of Chicago10, National Institute of Standards and Technology11
TL;DR: In this article, a method of cross-calibrating the polarization angle of a polarimeter using BICEP Galactic observations was presented, where the predicted 1 sigma errors on the predicted cross-polarization for Planck or EPIC were 1.3 degrees and 0.4 degrees, respectively.
Abstract: We present a method of cross-calibrating the polarization angle of a polarimeter using BICEP Galactic observations. \bicep\ was a ground based experiment using an array of 49 pairs of polarization sensitive bolometers observing from the geographic South Pole at 100 and 150 GHz. The BICEP polarimeter is calibrated to +/-0.01 in cross-polarization and less than +/-0.7 degrees in absolute polarization orientation. BICEP observed the temperature and polarization of the Galactic plane (R.A= 100 degrees ~ 270 degrees and Dec. = -67 degrees ~ -48 degrees). We show that the statistical error in the 100 GHz BICEP Galaxy map can constrain the polarization angle offset of WMAP Wband to 0.6 degrees +\- 1.4 degrees. The expected 1 sigma errors on the polarization angle cross-calibration for Planck or EPIC are 1.3 degrees and 0.3 degrees at 100 and 150 GHz, respectively. We also discuss the expected improvement of the BICEP Galactic field observations with forthcoming BICEP2 and Keck observations.