arXiv subjects

A. A. Stark

Publications and source records attributed to A. A. Stark.

At least 109 records · Page 6Linked to original sources

arXiv2015

Constraints on the Richness-Mass Relation and the Optical-SZE Positional Offset Distribution for SZE-Selected Clusters

We cross-match galaxy cluster candidates selected via their Sunyaev-Zel'dovich effect (SZE) signatures in 129.1 deg$^2$ of the South Pole Telescope 2500d SPT-SZ survey with optically identified clusters selected from the Dark Energy Survey (DES) science verification data. We identify 25 clusters between $0.1\lesssim z\lesssim 0.8$ in the union of the SPT-SZ and redMaPPer (RM) samples. RM is an optical cluster finding algorithm that also returns a richness estimate for each cluster. We model the richness $λ$-mass relation with the following function $\langle\lnλ|M_{500}\rangle\propto B_λ\ln M_{500}+C_λ\ln E(z)$ and use SPT-SZ cluster masses and RM richnesses $λ$ to constrain the parameters. We find $B_λ= 1.14^{+0.21}_{-0.18}$ and $C_λ=0.73^{+0.77}_{-0.75}$. The associated scatter in mass at fixed richness is $σ_{\ln M|λ} = 0.18^{+0.08}_{-0.05}$ at a characteristic richness $λ=70$. We demonstrate that our model provides an adequate description of the matched sample, showing that the fraction of SPT-SZ selected clusters with RM counterparts is consistent with expectations and that the fraction of RM selected clusters with SPT-SZ counterparts is in mild tension with expectation. We model the optical-SZE cluster positional offset distribution with the sum of two Gaussians, showing that it is consistent with a dominant, centrally peaked population and a sub-dominant population characterized by larger offsets. We also cross-match the RM catalog with SPT-SZ candidates below the official catalog threshold significance $ξ=4.5$, using the RM catalog to provide optical confirmation and redshifts for additional low-$ξ$ SPT-SZ candidates.In this way, we identify 15 additional clusters with $ξ\in [4,4.5]$ over the redshift regime explored by RM in the overlapping region between DES science verification data and the SPT-SZ survey.

astro-ph.CO↗

arXiv2015

A Measurement of Gravitational Lensing of the Cosmic Microwave Background by Galaxy Clusters Using Data from the South Pole Telescope

Clusters of galaxies are expected to gravitationally lens the cosmic microwave background (CMB) and thereby generate a distinct signal in the CMB on arcminute scales. Measurements of this effect can be used to constrain the masses of galaxy clusters with CMB data alone. Here we present a measurement of lensing of the CMB by galaxy clusters using data from the South Pole Telescope (SPT). We develop a maximum likelihood approach to extract the CMB cluster lensing signal and validate the method on mock data. We quantify the effects on our analysis of several potential sources of systematic error and find that they generally act to reduce the best-fit cluster mass. It is estimated that this bias to lower cluster mass is roughly $0.85σ$ in units of the statistical error bar, although this estimate should be viewed as an upper limit. We apply our maximum likelihood technique to 513 clusters selected via their SZ signatures in SPT data, and rule out the null hypothesis of no lensing at $3.1σ$. The lensing-derived mass estimate for the full cluster sample is consistent with that inferred from the SZ flux: $M_{200,\mathrm{lens}} = 0.83_{-0.37}^{+0.38}\, M_{200,\mathrm{SZ}}$ (68% C.L., statistical error only).

astro-ph.CO↗

arXiv2015

Analysis of Sunyaev-Zel'dovich Effect Mass-Observable Relations using South Pole Telescope Observations of an X-ray Selected Sample of Low Mass Galaxy Clusters and Groups

(Abridged) We use 95, 150, and 220GHz observations from the SPT to examine the SZE signatures of a sample of 46 X-ray selected groups and clusters drawn from ~6 deg^2 of the XMM-BCS. These systems extend to redshift z=1.02, have characteristic masses ~3x lower than clusters detected directly in the SPT data and probe the SZE signal to the lowest X-ray luminosities (>10^42 erg s^-1) yet. We develop an analysis tool that combines the SZE information for the full ensemble of X-ray-selected clusters. Using X-ray luminosity as a mass proxy, we extract selection-bias corrected constraints on the SZE significance- and Y_500-mass relations. The SZE significance- mass relation is in good agreement with an extrapolation of the relation obtained from high mass clusters. However, the fit to the Y_500-mass relation at low masses, while in good agreement with the extrapolation from high mass SPT clusters, is in tension at 2.8 sigma with the constraints from the Planck sample. We examine the tension with the Planck relation, discussing sample differences and biases that could contribute. We also present an analysis of the radio galaxy point source population in this ensemble of X-ray selected systems. We find 18 of our systems have 843 MHz SUMSS sources within 2 arcmin of the X-ray centre, and three of these are also detected at significance >4 by SPT. Of these three, two are associated with the group brightest cluster galaxies, and the third is likely an unassociated quasar candidate. We examine the impact of these point sources on our SZE scaling relation analyses and find no evidence of biases. We also examine the impact of dusty galaxies using constraints from the 220 GHz data. The stacked sample provides 2.8$σ$ significant evidence of dusty galaxy flux, which would correspond to an average underestimate of the SPT Y_500 signal that is (17+-9) per cent in this sample of low mass systems.

astro-ph.CO↗

arXiv2015

Measurements of Sub-degree B-mode Polarization in the Cosmic Microwave Background from 100 Square Degrees of SPTpol Data

We present a measurement of the $B$-mode polarization power spectrum (the $BB$ spectrum) from 100 $\mathrm{deg}^2$ of sky observed with SPTpol, a polarization-sensitive receiver currently installed on the South Pole Telescope. The observations used in this work were taken during 2012 and early 2013 and include data in spectral bands centered at 95 and 150 GHz. We report the $BB$ spectrum in five bins in multipole space, spanning the range $300 \le \ell \le 2300$, and for three spectral combinations: 95 GHz $\times$ 95 GHz, 95 GHz $\times$ 150 GHz, and 150 GHz $\times$ 150 GHz. We subtract small ($< 0.5 σ$ in units of statistical uncertainty) biases from these spectra and account for the uncertainty in those biases. The resulting power spectra are inconsistent with zero power but consistent with predictions for the $BB$ spectrum arising from the gravitational lensing of $E$-mode polarization. If we assume no other source of $BB$ power besides lensed $B$ modes, we determine a preference for lensed $B$ modes of $4.9 σ$. After marginalizing over tensor power and foregrounds, namely polarized emission from galactic dust and extragalactic sources, this significance is $4.3 σ$. Fitting for a single parameter, $A_\mathrm{lens}$, that multiplies the predicted lensed $B$-mode spectrum, and marginalizing over tensor power and foregrounds, we find $A_\mathrm{lens} = 1.08 \pm 0.26$, indicating that our measured spectra are consistent with the signal expected from gravitational lensing. The data presented here provide the best measurement to date of the $B$-mode power spectrum on these angular scales.

astro-ph.CO↗

arXiv2015

Galaxy Clusters Discovered via the Sunyaev-Zel'dovich Effect in the 2500-square-degree SPT-SZ survey

We present a catalog of galaxy clusters selected via their Sunyaev-Zel'dovich (SZ) effect signature from 2500 deg$^2$ of South Pole Telescope (SPT) data. This work represents the complete sample of clusters detected at high significance in the 2500-square-degree SPT-SZ survey, which was completed in 2011. A total of 677 (409) cluster candidates are identified above a signal-to-noise threshold of $ξ$ =4.5 (5.0). Ground- and space-based optical and near-infrared (NIR) imaging confirms overdensities of similarly colored galaxies in the direction of 516 (or 76%) of the $ξ$>4.5 candidates and 387 (or 95%) of the $ξ$>5 candidates; the measured purity is consistent with expectations from simulations. Of these confirmed clusters, 415 were first identified in SPT data, including 251 new discoveries reported in this work. We estimate photometric redshifts for all candidates with identified optical and/or NIR counterparts; we additionally report redshifts derived from spectroscopic observations for 141 of these systems. The mass threshold of the catalog is roughly independent of redshift above $z$~0.25 leading to a sample of massive clusters that extends to high redshift. The median mass of the sample is $M_{\scriptsize 500c}(ρ_\mathrm{crit})$ ~ 3.5 x 10$^{14} M_\odot h^{-1}$, the median redshift is $z_{med}$ =0.55, and the highest-redshift systems are at $z$>1.4. The combination of large redshift extent, clean selection, and high typical mass makes this cluster sample of particular interest for cosmological analyses and studies of cluster formation and evolution.

astro-ph.CO↗

arXiv2014

Mass Calibration and Cosmological Analysis of the SPT-SZ Galaxy Cluster Sample Using Velocity Dispersion $σ_v$ and X-ray $Y_\textrm{X}$ Measurements

We present a velocity dispersion-based mass calibration of the South Pole Telescope Sunyaev-Zel'dovich effect survey (SPT-SZ) galaxy cluster sample. Using a homogeneously selected sample of 100 cluster candidates from 720 deg2 of the survey along with 63 velocity dispersion ($σ_v$) and 16 X-ray Yx measurements of sample clusters, we simultaneously calibrate the mass-observable relation and constrain cosmological parameters. The calibrations using $σ_v$ and Yx are consistent at the $0.6σ$ level, with the $σ_v$ calibration preferring ~16% higher masses. We use the full cluster dataset to measure $σ_8(Ω_ m/0.27)^{0.3}=0.809\pm0.036$. The SPT cluster abundance is lower than preferred by either the WMAP9 or Planck+WMAP9 polarization (WP) data, but assuming the sum of the neutrino masses is $\sum m_ν=0.06$ eV, we find the datasets to be consistent at the 1.0$σ$ level for WMAP9 and 1.5$σ$ for Planck+WP. Allowing for larger $\sum m_ν$ further reconciles the results. When we combine the cluster and Planck+WP datasets with BAO and SNIa, the preferred cluster masses are $1.9σ$ higher than the Yx calibration and $0.8σ$ higher than the $σ_v$ calibration. Given the scale of these shifts (~44% and ~23% in mass, respectively), we execute a goodness of fit test; it reveals no tension, indicating that the best-fit model provides an adequate description of the data. Using the multi-probe dataset, we measure $Ω_ m=0.299\pm0.009$ and $σ_8=0.829\pm0.011$. Within a $ν$CDM model we find $\sum m_ν= 0.148\pm0.081$ eV. We present a consistency test of the cosmic growth rate. Allowing both the growth index $γ$ and the dark energy equation of state parameter $w$ to vary, we find $γ=0.73\pm0.28$ and $w=-1.007\pm0.065$, demonstrating that the expansion and the growth histories are consistent with a LCDM model ($γ=0.55; \,w=-1$).

astro-ph.CO↗

arXiv2014

A measurement of secondary cosmic microwave background anisotropies from the 2500-square-degree SPT-SZ survey

We present measurements of secondary cosmic microwave background (CMB) anisotropies and cosmic infrared background (CIB) fluctuations using data from the South Pole Telescope (SPT) covering the complete 2540 sq.deg. SPT-SZ survey area. Data in the three SPT-SZ frequency bands centered at 95, 150, and 220 GHz, are used to produce six angular power spectra (three single-frequency auto-spectra and three cross-spectra) covering the multipole range 2000 < ell < 11000 (angular scales 5' > θ> 1'). These are the most precise measurements of the angular power spectra at ell > 2500 at these frequencies. The main contributors to the power spectra at these angular scales and frequencies are the primary CMB, CIB, thermal and kinematic Sunyaev-Zel'dovich effects (tSZ and kSZ), and radio galaxies. We include a constraint on the tSZ power from a measurement of the tSZ bispectrum from 800 sq.deg. of the SPT-SZ survey. We measure the tSZ power at 143 GHz to be DtSZ = 4.08 +0.58 -0.67 μK^2 and the kSZ power to be DkSZ = 2.9 +- 1.3 μK^2. The data prefer positive kSZ power at 98.1% CL. We measure a correlation coefficient of ξ= 0.113 +0.057 -0.054 between sources of tSZ and CIB power, with ξ< 0 disfavored at a confidence level of 99.0%. The constraint on kSZ power can be interpreted as an upper limit on the duration of reionization. When the post-reionization homogeneous kSZ signal is accounted for, we find an upper limit on the duration Δz < 5.4 at 95% CL.

astro-ph.CO↗

arXiv2014

Measurements of E-Mode Polarization and Temperature-E-Mode Correlation in the Cosmic Microwave Background from 100 Square Degrees of SPTpol Data

We present measurements of $E$-mode polarization and temperature-$E$-mode correlation in the cosmic microwave background (CMB) using data from the first season of observations with SPTpol, the polarization-sensitive receiver currently installed on the South Pole Telescope (SPT). The observations used in this work cover 100~\sqdeg\ of sky with arcminute resolution at $150\,$GHz. We report the $E$-mode angular auto-power spectrum ($EE$) and the temperature-$E$-mode angular cross-power spectrum ($TE$) over the multipole range $500 < \ell \leq5000$. These power spectra improve on previous measurements in the high-$\ell$ (small-scale) regime. We fit the combination of the SPTpol power spectra, data from \planck\, and previous SPT measurements with a six-parameter \LCDM cosmological model. We find that the best-fit parameters are consistent with previous results. The improvement in high-$\ell$ sensitivity over previous measurements leads to a significant improvement in the limit on polarized point-source power: after masking sources brighter than 50\,mJy in unpolarized flux at 150\,GHz, we find a 95\% confidence upper limit on unclustered point-source power in the $EE$ spectrum of $D_\ell = \ell (\ell+1) C_\ell / 2 π< 0.40 \ μ{\mbox{K}}^2$ at $\ell=3000$, indicating that future $EE$ measurements will not be limited by power from unclustered point sources in the multipole range $\ell < 3600$, and possibly much higher in $\ell.$

astro-ph.CO↗

arXiv2014

SPT-CLJ2040-4451: An SZ-Selected Galaxy Cluster at z = 1.478 With Significant Ongoing Star Formation

SPT-CLJ2040-4451 -- spectroscopically confirmed at z = 1.478 -- is the highest redshift galaxy cluster yet discovered via the Sunyaev-Zel'dovich effect. SPT-CLJ2040-4451 was a candidate galaxy cluster identified in the first 720 deg^2 of the South Pole Telescope Sunyaev-Zel'dovich (SPT-SZ) survey, and confirmed in follow-up imaging and spectroscopy. From multi-object spectroscopy with Magellan-I/Baade+IMACS we measure spectroscopic redshifts for 15 cluster member galaxies, all of which have strong [O II] 3727 emission. SPT-CLJ2040-4451 has an SZ-measured mass of M_500,SZ = 3.2 +/- 0.8 X 10^14 M_Sun/h_70, corresponding to M_200,SZ = 5.8 +/- 1.4 X 10^14 M_Sun/h_70. The velocity dispersion measured entirely from blue star forming members is sigma_v = 1500 +/- 520 km/s. The prevalence of star forming cluster members (galaxies with > 1.5 M_Sun/yr) implies that this massive, high-redshift cluster is experiencing a phase of active star formation, and supports recent results showing a marked increase in star formation occurring in galaxy clusters at z >1.4. We also compute the probability of finding a cluster as rare as this in the SPT-SZ survey to be >99%, indicating that its discovery is not in tension with the concordance Lambda-CDM cosmological model.

astro-ph.CO↗

arXiv2014

Optical Spectroscopy and Velocity Dispersions of Galaxy Clusters from the SPT-SZ Survey

We present optical spectroscopy of galaxies in clusters detected through the Sunyaev-Zel'dovich (SZ) effect with the South Pole Telescope (SPT). We report our own measurements of $61$ spectroscopic cluster redshifts, and $48$ velocity dispersions each calculated with more than $15$ member galaxies. This catalog also includes $19$ dispersions of SPT-observed clusters previously reported in the literature. The majority of the clusters in this paper are SPT-discovered; of these, most have been previously reported in other SPT cluster catalogs, and five are reported here as SPT discoveries for the first time. By performing a resampling analysis of galaxy velocities, we find that unbiased velocity dispersions can be obtained from a relatively small number of member galaxies ($\lesssim 30$), but with increased systematic scatter. We use this analysis to determine statistical confidence intervals that include the effect of membership selection. We fit scaling relations between the observed cluster velocity dispersions and mass estimates from SZ and X-ray observables. In both cases, the results are consistent with the scaling relation between velocity dispersion and mass expected from dark-matter simulations. We measure a $\sim$30% log-normal scatter in dispersion at fixed mass, and a $\sim$10% offset in the normalization of the dispersion-mass relation when compared to the expectation from simulations, which is within the expected level of systematic uncertainty.

astro-ph.CO↗

arXiv2014

SPT-3G: A Next-Generation Cosmic Microwave Background Polarization Experiment on the South Pole Telescope

We describe the design of a new polarization sensitive receiver, SPT-3G, for the 10-meter South Pole Telescope (SPT). The SPT-3G receiver will deliver a factor of ~20 improvement in mapping speed over the current receiver, SPTpol. The sensitivity of the SPT-3G receiver will enable the advance from statistical detection of B-mode polarization anisotropy power to high signal-to-noise measurements of the individual modes, i.e., maps. This will lead to precise (~0.06 eV) constraints on the sum of neutrino masses with the potential to directly address the neutrino mass hierarchy. It will allow a separation of the lensing and inflationary B-mode power spectra, improving constraints on the amplitude and shape of the primordial signal, either through SPT-3G data alone or in combination with BICEP-2/KECK, which is observing the same area of sky. The measurement of small-scale temperature anisotropy will provide new constraints on the epoch of reionization. Additional science from the SPT-3G survey will be significantly enhanced by the synergy with the ongoing optical Dark Energy Survey (DES), including: a 1% constraint on the bias of optical tracers of large-scale structure, a measurement of the differential Doppler signal from pairs of galaxy clusters that will test General Relativity on ~200 Mpc scales, and improved cosmological constraints from the abundance of clusters of galaxies.

astro-ph.IM↗

arXiv2014

The Redshift Evolution of the Mean Temperature, Pressure, and Entropy Profiles in 80 SPT-Selected Galaxy Clusters

(Abridged) We present the results of an X-ray analysis of 80 galaxy clusters selected in the 2500 deg^2 South Pole Telescope survey and observed with the Chandra X-ray Observatory. We divide the full sample into subsamples of ~20 clusters based on redshift and central density, performing an X-ray fit to all clusters in a subsample simultaneously, assuming self-similarity of the temperature profile. This approach allows us to constrain the shape of the temperature profile over 0 R500) regions than their low-z (0.3 R500 in our high-z subsample. This flattening is consistent with a temperature bias due to the enhanced (~3x) rate at which group-mass (~2 keV) halos, which would go undetected at our survey depth, are accreting onto the cluster at z~1. This work demonstrates a powerful method for inferring spatially-resolved cluster properties in the case where individual cluster signal-to-noise is low, but the number of observed clusters is high.

astro-ph.HE↗

arXiv2014

A measurement of the secondary-CMB and millimeter-wave-foreground bispectrum using 800 square degrees of South Pole Telescope data

We present a measurement of the angular bispectrum of the millimeter-wave sky in observing bands centered at roughly 95, 150, and 220 GHz, on angular scales of $1^\prime \lesssim θ\lesssim 10^\prime$ (multipole number $1000 \lesssim l \lesssim 10000$). At these frequencies and angular scales, the main contributions to the bispectrum are expected to be the thermal Sunyaev-Zel'dovich (tSZ) effect and emission from extragalactic sources, predominantly dusty, star-forming galaxies (DSFGs) and active galactic nuclei. We measure the bispectrum in 800 $\mathrm{deg}^2$ of three-band South Pole Telescope data, and we use a multi-frequency fitting procedure to separate the bispectrum of the tSZ effect from the extragalactic source contribution. We simultaneously detect the bispectrum of the tSZ effect at $>$10$σ$, the unclustered component of the extragalactic source bispectrum at $>$5$σ$ in each frequency band, and the bispectrum due to the clustering of DSFGs---i.e., the clustered cosmic infrared background (CIB) bispectrum---at $>$5$σ$. This is the first reported detection of the clustered CIB bispectrum. We use the measured tSZ bispectrum amplitude, compared to model predictions, to constrain the normalization of the matter power spectrum to be $σ_8 = 0.787 \pm 0.031$ and to predict the amplitude of the tSZ power spectrum at $l = 3000$. This prediction improves our ability to separate the thermal and kinematic contributions to the total SZ power spectrum. The addition of bispectrum data improves our constraint on the tSZ power spectrum amplitude by a factor of two compared to power spectrum measurements alone and demonstrates a preference for a nonzero kinematic SZ (kSZ) power spectrum, with a derived constraint on the kSZ amplitude at $l=3000$ of A_kSZ $ = 2.9 \pm 1.6 \ μ$K$^2$, or A_kSZ $ = 2.6 \pm 1.8 \ μ$K$^2$ if the default A_kSZ > 0 prior is removed.

astro-ph.CO↗

arXiv2014

The Rest-Frame Submillimeter Spectrum of High-Redshift, Dusty, Star-Forming Galaxies

We present the average rest-frame spectrum of high-redshift dusty, star-forming galaxies from 250-770GHz. This spectrum was constructed by stacking ALMA 3mm spectra of 22 such sources discovered by the South Pole Telescope and spanning z=2.0-5.7. In addition to multiple bright spectral features of 12CO, [CI], and H2O, we also detect several faint transitions of 13CO, HCN, HNC, HCO+, and CN, and use the observed line strengths to characterize the typical properties of the interstellar medium of these high-redshift starburst galaxies. We find that the 13CO brightness in these objects is comparable to that of the only other z>2 star-forming galaxy in which 13CO has been observed. We show that the emission from the high-critical density molecules HCN, HNC, HCO+, and CN is consistent with a warm, dense medium with T_kin ~ 55K and n_H2 >~ 10^5.5 cm^-3. High molecular hydrogen densities are required to reproduce the observed line ratios, and we demonstrate that alternatives to purely collisional excitation are unlikely to be significant for the bulk of these systems. We quantify the average emission from several species with no individually detected transitions, and find emission from the hydride CH and the linear molecule CCH for the first time at high redshift, indicating that these molecules may be powerful probes of interstellar chemistry in high-redshift systems. These observations represent the first constraints on many molecular species with rest-frame transitions from 0.4-1.2mm in star-forming systems at high redshift, and will be invaluable in making effective use of ALMA in full science operations.

astro-ph.GA↗

arXiv2014

Constraints on Cosmology from the Cosmic Microwave Background Power Spectrum of the 2500 ${\rm deg}^2$ SPT-SZ Survey

We explore extensions to the $Λ$CDM cosmology using measurements of the cosmic microwave background (CMB) from the recent SPT-SZ survey, along with data from WMAP7 and measurements of $H_0$ and BAO. We check for consistency within $Λ$CDM between these datasets, and find some tension. The CMB alone gives weak support to physics beyond $Λ$CDM, due to a slight trend relative to $Λ$CDM of decreasing power towards smaller angular scales. While it may be due to statistical fluctuation, this trend could also be explained by several extensions. We consider running index (nrun), as well as two extensions that modify the damping tail power (the primordial helium abundance $Y_p$ and the effective number of neutrino species $N_{\rm eff}$) and one that modifies the large-scale power due to the ISW effect (the sum of neutrino masses $\sum m_ν$). These extensions have similar observational consequences and are partially degenerate when considered simultaneously. Of the 6 one-parameter extensions considered, we find CMB to have the largest preference for nrun with -0.046 0 from CMB+BAO+$H_0$+$\rm{SPT_{CL}}$. The median value is $(0.32\pm0.11)$ eV, a factor of six above the lower bound set by neutrino oscillation observations. ... [abridged]

astro-ph.CO↗

arXiv2013

Measurement of Galaxy Cluster Integrated Comptonization and Mass Scaling Relations with the South Pole Telescope

We describe a method for measuring the integrated Comptonization (YSZ) of clusters of galaxies from measurements of the Sunyaev-Zel'dovich (SZ) effect in multiple frequency bands and use this method to characterize a sample of galaxy clusters detected in South Pole Telescope (SPT) data. We test this method on simulated cluster observations and verify that it can accurately recover cluster parameters with negligible bias. In realistic simulations of an SPT-like survey, with realizations of cosmic microwave background anisotropy, point sources, and atmosphere and instrumental noise at typical SPT-SZ survey levels, we find that YSZ is most accurately determined in an aperture comparable to the SPT beam size. We demonstrate the utility of this method to measure YSZ and to constrain mass scaling relations using X-ray mass estimates for a sample of 18 galaxy clusters from the SPT-SZ survey. Measuring YSZ within a 0.75' radius aperture, we find an intrinsic log-normal scatter of 21+/-11% in YSZ at a fixed mass. Measuring YSZ within a 0.3 Mpc projected radius (equivalent to 0.75' at the survey median redshift z = 0.6), we find a scatter of 26+/-9%. Prior to this study, the SPT observable found to have the lowest scatter with mass was cluster detection significance. We demonstrate, from both simulations and SPT observed clusters, that YSZ measured within an aperture comparable to the SPT beam size is equivalent, in terms of scatter with cluster mass, to SPT cluster detection significance.

astro-ph.CO↗

arXiv2013

A Measurement of the Cosmic Microwave Background Damping Tail from the 2500-square-degree SPT-SZ survey

We present a measurement of the cosmic microwave background (CMB) temperature power spectrum using data from the recently completed South Pole Telescope Sunyaev-Zel'dovich (SPT-SZ) survey. This measurement is made from observations of 2540 deg$^2$ of sky with arcminute resolution at $150\,$GHz, and improves upon previous measurements using the SPT by tripling the sky area. We report CMB temperature anisotropy power over the multipole range $650<\ell<3000$. We fit the SPT bandpowers, combined with the seven-year Wilkinson Microwave Anisotropy Probe (WMAP7) data, with a six-parameter LCDM cosmological model and find that the two datasets are consistent and well fit by the model. Adding SPT measurements significantly improves LCDM parameter constraints; in particular, the constraint on $θ_s$ tightens by a factor of 2.7. The impact of gravitational lensing is detected at $8.1\, σ$, the most significant detection to date. This sensitivity of the SPT+WMAP7 data to lensing by large-scale structure at low redshifts allows us to constrain the mean curvature of the observable universe with CMB data alone to be $Ω_k=-0.003^{+0.014}_{-0.018}$. Using the SPT+WMAP7 data, we measure the spectral index of scalar fluctuations to be $n_s=0.9623 \pm 0.0097$ in the LCDM model, a $3.9\,σ$ preference for a scale-dependent spectrum with $n_s<1$. The SPT measurement of the CMB damping tail helps break the degeneracy that exists between the tensor-to-scalar ratio $r$ and $n_s$ in large-scale CMB measurements, leading to an upper limit of $r<0.18$ (95%,C.L.) in the LCDM+$r$ model. Adding low-redshift measurements of the Hubble constant ($H_0$) and the baryon acoustic oscillation (BAO) feature to the SPT+WMAP7 data leads to further improvements. The combination of SPT+WMAP7+$H_0$+BAO constrains $n_s=0.9538 \pm 0.0081$ in the LCDM model, a $5.7\,σ$ detection of $n_s < 1$, ... [abridged]

astro-ph.CO↗

arXiv2013

Constraints on the CMB Temperature Evolution using Multi-Band Measurements of the Sunyaev Zel'dovich Effect with the South Pole Telescope

The adiabatic evolution of the temperature of the cosmic microwave background (CMB) is a key prediction of standard cosmology. We study deviations from the expected adiabatic evolution of the CMB temperature of the form $T(z) =T_0(1+z)^{1-α}$ using measurements of the spectrum of the Sunyaev Zel'dovich Effect with the South Pole Telescope (SPT). We present a method for using the ratio of the Sunyaev Zel'dovich signal measured at 95 and 150 GHz in the SPT data to constrain the temperature of the CMB. We demonstrate that this approach provides unbiased results using mock observations of clusters from a new set of hydrodynamical simulations. We apply this method to a sample of 158 SPT-selected clusters, spanning the redshift range $0.05 < z < 1.35$, and measure $α= 0.017^{+0.030}_{-0.028}$, consistent with the standard model prediction of $α=0$. In combination with other published results, we constrain $α= 0.011 \pm 0.016$, an improvement of $\sim 20\%$ over published constraints. This measurement also provides a strong constraint on the effective equation of state in models of decaying dark energy $w_\mathrm{eff} = -0.987^{+0.016}_{-0.017}$.

astro-ph.CO↗