We present component-separated maps of the primary cosmic microwave background/kinematic Sunyaev–Zel’dovich (SZ) amplitude and the thermal SZ Compton-y parameter, created using data from the South ...Pole Telescope (SPT) and the Planck satellite. These maps, which cover the ∼2500 deg2 of the southern sky imaged by the SPT-SZ survey, represent a significant improvement over previous such products available in this region by virtue of their higher angular resolution (1.′25 for our highest-resolution Compton-y maps) and lower noise at small angular scales. In this work we detail the construction of these maps using linear combination techniques, including our method for limiting the correlation of our lowest-noise Compton-y map products with the cosmic infrared background. We perform a range of validation tests on these data products to test our sky modeling and combination algorithms, and we find good performance in all of these tests. Recognizing the potential utility of these data products for a wide range of astrophysical and cosmological analyses, including studies of the gas properties of galaxies, groups, and clusters, we make these products publicly available at http://pole.uchicago.edu/public/data/sptsz_ymap and on the NASA/LAMBDA website.
We present a demonstration of delensing the observed cosmic microwave background (CMB) B-mode polarization anisotropy. This process of reducing the gravitational-lensing-generated B-mode component ...will become increasingly important for improving searches for the B modes produced by primordial gravitational waves. In this work, we delens B-mode maps constructed from multi-frequency SPTpol observations of a 90 deg2 patch of sky by subtracting a B-mode template constructed from two inputs: SPTpol E-mode maps and a lensing potential map estimated from the Herschel 500 m map of the cosmic infrared background. We find that our delensing procedure reduces the measured B-mode power spectrum by % in the multipole range this is shown to be consistent with expectations from simulations and to be robust against systematics. The null hypothesis of no delensing is rejected at . Furthermore, we build and use a suite of realistic simulations to study the general properties of the delensing process and find that the delensing efficiency achieved in this work is limited primarily by the noise in the lensing potential map. We demonstrate the importance of including realistic experimental non-idealities in the delensing forecasts used to inform instrument and survey-strategy planning of upcoming lower-noise experiments, such as CMB-S4.
We explore extensions to the ΛCDM cosmology using measurements of the cosmic microwave background (CMB) from the recent SPT-SZ survey, along with data from WMAP7 and measurements of H {sub 0} and ...baryon acoustic oscillation (BAO). We check for consistency within ΛCDM between these data sets, and find some tension. The CMB alone gives weak support to physics beyond ΛCDM, due to a slight trend relative to ΛCDM of decreasing power toward smaller angular scales. While it may be due to statistical fluctuation, this trend could also be explained by several extensions. We consider running of the primordial spectral index (dn{sub s} /dln k), as well as two extensions that modify the damping tail power (the primordial helium abundance Y{sub p} and the effective number of neutrino species N {sub eff}) and one that modifies the large-scale power due to the integrated Sachs-Wolfe effect (the sum of neutrino masses ∑m {sub ν}). These extensions have similar observational consequences and are partially degenerate when considered simultaneously. Of the six one-parameter extensions considered, we find CMB to have the largest preference for dn{sub s} /dln k with –0.046 < dn{sub s} /dln k < –0.003 at 95% confidence, which strengthens to a 2.7σ indication of dn{sub s} /dln k < 0 from CMB+BAO+H {sub 0}. Detectable dn{sub s} /dln k ≠ 0 is difficult to explain in the context of single-field, slow-roll inflation models. We find N {sub eff} = 3.62 ± 0.48 for the CMB, which tightens to N {sub eff} = 3.71 ± 0.35 from CMB+BAO+H {sub 0}. Larger values of N {sub eff} relieve the mild tension between CMB, BAO, and H {sub 0}. When the Sunyaev-Zel'dovich selected galaxy cluster abundances (SPT{sub CL}) data are also included, we obtain N {sub eff} = 3.29 ± 0.31. Allowing for ∑m {sub ν} gives a 3.0σ detection of ∑m {sub ν} > 0 from CMB+BAO+H {sub 0} +SPT{sub CL}. The median value is (0.32 ± 0.11) eV, a factor of six above the lower bound set by neutrino oscillation observations. All data sets except H {sub 0} show some preference for massive neutrinos; data combinations including H {sub 0} favor nonzero masses only if BAO data are also included. We also constrain the two-parameter extensions N {sub eff} + ∑m {sub ν} and N {sub eff} + Y{sub p} to explore constraints on additional light species and big bang nucleosynthesis, respectively.
In the cores of some clusters of galaxies the hot intracluster plasma is dense enough that it should cool radiatively in the cluster's lifetime, leading to continuous 'cooling flows' of gas sinking ...towards the cluster centre, yet no such cooling flow has been observed. The low observed star-formation rates and cool gas masses for these 'cool-core' clusters suggest that much of the cooling must be offset by feedback to prevent the formation of a runaway cooling flow. Here we report X-ray, optical and infrared observations of the galaxy cluster SPT-CLJ2344-4243 (ref. 11) at redshift z = 0.596. These observations reveal an exceptionally luminous (8.2 × 10(45) erg s(-1)) galaxy cluster that hosts an extremely strong cooling flow (around 3,820 solar masses a year). Further, the central galaxy in this cluster appears to be experiencing a massive starburst (formation of around 740 solar masses a year), which suggests that the feedback source responsible for preventing runaway cooling in nearby cool-core clusters may not yet be fully established in SPT-CLJ2344-4243. This large star-formation rate implies that a significant fraction of the stars in the central galaxy of this cluster may form through accretion of the intracluster medium, rather than (as is currently thought) assembling entirely via mergers.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
ABSTRACT 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 0.85 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 Sunyaev-Zeldovich (SZ) signatures in SPT data, and rule out the null hypothesis of no lensing at 3.1 . The lensing-derived mass estimate for the full cluster sample is consistent with that inferred from the SZ flux: (68% C.L., statistical error only).
We present cosmological constraints based on the cosmic microwave background (CMB) lensing potential power spectrum measurement from the recent 500 deg2 SPTpol survey, the most precise CMB lensing ...measurement from the ground to date. We fit a flat ΛCDM model to the reconstructed lensing power spectrum alone and in addition with other data sets: baryon acoustic oscillations (BAO), as well as primary CMB spectra from Planck and SPTpol. The cosmological constraints based on SPTpol and Planck lensing band powers are in good agreement when analyzed alone and in combination with Planck full-sky primary CMB data. With weak priors on the baryon density and other parameters, the SPTpol CMB lensing data alone provide a 4% constraint on . Jointly fitting with BAO data, we find , , and , up to away from the central values preferred by Planck lensing + BAO. However, we recover good agreement between SPTpol and Planck when restricting the analysis to similar scales. We also consider single-parameter extensions to the flat ΛCDM model. The SPTpol lensing spectrum constrains the spatial curvature to be and the sum of the neutrino masses to be eV at 95% C.L. (with Planck primary CMB and BAO data), in good agreement with the Planck lensing results. With the differences in the signal-to-noise ratio of the lensing modes and the angular scales covered in the lensing spectra, this analysis represents an important independent check on the full-sky Planck lensing measurement.
We present a catalog of galaxy cluster candidates, selected through their Sunyaev-Zel'dovich (SZ) effect signature in the first 720 deg2 of the South Pole Telescope (SPT) survey. This area was mapped ...with the SPT in the 2008 and 2009 austral winters to a depth of ~18 mu KCMB-arcmin at 150 GHz; 550 deg2 of it was also mapped to ~44 mu KCMB-arcmin at 95 GHz. We report photometrically derived redshifts for confirmed clusters and redshift lower limits for the remaining candidates. The catalog extends to high redshift with a median redshift of z = 0.55 and maximum confirmed redshift of z = 1.37. Forty-five of the clusters have counterparts in the ROSAT bright or faint source catalogs from which we estimate X-ray fluxes. A multi-wavelength observation program to improve the cluster mass calibration will make it possible to realize the full potential of the final 2500 deg2 SPT cluster catalog to constrain cosmology.
We present Atacama Large Millimeter/submillimeter Array (ALMA) 860 mu m imaging of four high-redshift (z = 2.8-5.7) dusty sources that were detected using the South Pole Telescope (SPT) at 1.4 mm and ...are not seen in existing radio to far-infrared catalogs. At 1".5 resolution, the ALMA data reveal multiple images of each submillimeter source, separated by l"-3", consistent with strong lensing by intervening galaxies visible in near-IR imaging of these sources. We describe a gravitational lens modeling procedure that operates on the measured visibilities and incorporates self-calibration-like antenna phase corrections as part of the model optimization, which we use to interpret the source structure. Lens models indicate that SPT0346-52, located at z = 5.7, is one of the most luminous and intensely star-forming sources in the universe with a lensing corrected FIR luminosity of 3.7 x 10 super(13) L sub(middot in circle) and star formation surface density of 4200 M sub(middot in circle) yr super(-1) kpc super(-2). We find magnification factors of 5 to 22, with lens Einstein radii of 1".1-2".0 and Einstein enclosed masses of 1.6-7.2 x 10 super(11) M sub(middot in circle). These observations confirm the lensing origin of these objects, allow us to measure their intrinsic sizes and luminosities, and demonstrate the important role that ALMA will play in the interpretation of lensed submillimeter sources.
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 Delta *mK 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 X 1014 M h --1 at z = 0.6. This completeness threshold pushes to lower mass with increasing redshift, dropping to ~4 X 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 Delta *s8 = 0.81 ? 0.09 and w = --1.07 ? 0.29, a ~50% improvement in precision on both parameters over WMAP7 alone.
We use measurements from the South Pole Telescope (SPT) Sunyaev-Zel'dovich (SZ) cluster survey in combination with X-ray measurements to constrain cosmological parameters. We present a statistical ...method that fits for the scaling relations of the SZ and X-ray cluster observables with mass while jointly fitting for cosmology. The method is generalizable to multiple cluster observables, and self-consistently accounts for the effects of the cluster selection and uncertainties in cluster mass calibration on the derived cosmological constraints. We apply this method to a data set consisting of an SZ-selected catalog of 18 galaxy clusters at z > 0.3 from the first 178 deg{sup 2} of the 2500 deg{sup 2} SPT-SZ survey, with 14 clusters having X-ray observations from either Chandra or XMM-Newton. Assuming a spatially flat {Lambda}CDM cosmological model, we find the SPT cluster sample constrains {sigma}{sub 8}({Omega} {sub m}/0.25){sup 0.30} = 0.785 {+-} 0.037. In combination with measurements of the cosmic microwave background (CMB) power spectrum from the SPT and the seven-year Wilkinson Microwave Anisotropy Probe data, the SPT cluster sample constrains {sigma}{sub 8} = 0.795 {+-} 0.016 and {Omega} {sub m} = 0.255 {+-} 0.016, a factor of 1.5 improvement on each parameter over the CMB data alone. We consider several extensions beyond the {Lambda}CDM model by including the following as free parameters: the dark energy equation of state (w), the sum of the neutrino masses ({Sigma}m {sub {nu}}), the effective number of relativistic species (N {sub eff}), and a primordial non-Gaussianity (f {sub NL}). We find that adding the SPT cluster data significantly improves the constraints on w and {Sigma}m {sub {nu}} beyond those found when using measurements of the CMB, supernovae, baryon acoustic oscillations, and the Hubble constant. Considering each extension independently, we best constrain w = -0.973 {+-} 0.063 and the sum of neutrino masses {Sigma}m {sub {nu}} < 0.28 eV at 95% confidence, a factor of 1.25 and 1.4 improvement, respectively, over the constraints without clusters. Assuming a {Lambda}CDM model with a free N {sub eff} and {Sigma}m {sub {nu}}, we measure N {sub eff} = 3.91 {+-} 0.42 and constrain {Sigma}m {sub {nu}} < 0.63 eV at 95% confidence. We also use the SPT cluster sample to constrain f {sub NL} = -220 {+-} 317, consistent with zero primordial non-Gaussianity. Finally, we discuss the current systematic limitations due to the cluster mass calibration, and future improvements for the recently completed 2500 deg{sup 2} SPT-SZ survey. The survey has detected {approx}500 clusters with a median redshift of {approx}0.5 and a median mass of {approx}2.3 Multiplication-Sign 10{sup 14} M {sub Sun} h {sup -1} and, when combined with an improved cluster mass calibration and existing external cosmological data sets will significantly improve constraints on w.
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