Showing papers by "Edward J. Wollack published in 2013"
University of British Columbia1, Johns Hopkins University2, Max Planck Society3, Institute for the Physics and Mathematics of the Universe4, Princeton University5, University of Toronto6, Perimeter Institute for Theoretical Physics7, University of Minnesota8, Goddard Space Flight Center9, University of Chicago10, Brown University11, University of California, Los Angeles12
TL;DR: In this paper, the authors present cosmological parameter constraints based on the final nine-year WMAP data, in conjunction with a number of additional cosmology data sets.
Abstract: We present cosmological parameter constraints based on the final nine-year WMAP data, in conjunction with a number of additional cosmological data sets. The WMAP data alone, and in combination, continue to be remarkably well fit by a six-parameter CDM model. When WMAP data are combined with measurements of the high-l cosmic microwave background (CMB) anisotropy, the baryon acoustic oscillation (BAO) scale, and the Hubble constant, the matter and energy densities, bh 2 , ch 2 , and , are each determined to a precision of 1.5%. The amplitude of the primordial spectrum is measured to within 3%, and there is now evidence for a tilt in the primordial spectrum at the 5 level, confirming the first detection of tilt based on the five-year WMAP data. At the end of the WMAP mission, the nine-year data decrease the allowable volume of the six-dimensional CDM parameter space by a factor of 68,000 relative to pre-WMAP measurements. We investigate a number of data combinations and show that their CDM parameter fits are consistent. New limits on deviations from the six-parameter model are presented, for example: the fractional contribution of tensor modes is limited to r < 0.13 (95% CL); the spatial curvature parameter is limited to k = 0.0027 +0.0039 0.0038 ; the summed mass of neutrinos is limited to P m < 0.44 eV (95% CL); and the number of relativistic species is found to lie within Ne = 3.84±0.40, when the full data are analyzed. The joint constraint on Ne and the primordial helium abundance, YHe, agrees with the prediction of standard Big Bang nucleosynthesis. We compare recent Planck measurements of the Sunyaev‐Zel’dovich eect with our seven-year measurements, and show their mutual agreement. Our analysis of the polarization pattern around temperature extrema is updated. This confirms a fundamental prediction of the standard cosmological model and provides a striking illustration of acoustic oscillations and adiabatic initial conditions in the early universe. Subject headings: cosmic microwave background, cosmology: observations, early universe, dark matter, space vehicles, space vehicles: instruments, instrumentation: detectors, telescopes
5,488 citations
Johns Hopkins University1, Princeton University2, University of British Columbia3, Perimeter Institute for Theoretical Physics4, University of Minnesota5, Max Planck Society6, University of Toronto7, Institute for the Physics and Mathematics of the Universe8, Goddard Space Flight Center9, University of Chicago10, Brown University11, University of California, Los Angeles12
TL;DR: The final nine-year maps and basic results from the Wilkinson Microwave Anisotropy Probe (WMAP) mission are presented in this paper, where the authors present a highly constrained Lambda-CDM cosmological model with precise and accurate parameters.
Abstract: We present the final nine-year maps and basic results from the Wilkinson Microwave Anisotropy Probe (WMAP) mission. The full nine-year analysis of the time-ordered data provides updated characterizations and calibrations of the experiment. We also provide new nine-year full sky temperature maps that were processed to reduce the asymmetry of the effective beams. Temperature and polarization sky maps are examined to separate cosmic microwave background (CMB) anisotropy from foreground emission, and both types of signals are analyzed in detail.We provide new point source catalogs as well as new diffuse and point source foreground masks. An updated template-removal process is used for cosmological analysis; new foreground fits are performed, and new foreground reduced are presented.We nowimplement an optimal C(exp -1)1 weighting to compute the temperature angular power spectrum. The WMAP mission has resulted in a highly constrained Lambda-CDM cosmological model with precise and accurate parameters in agreement with a host of other cosmological measurements. When WMAP data are combined with finer scale CMB, baryon acoustic oscillation, and Hubble constant measurements, we find that big bang nucleosynthesis is well supported and there is no compelling evidence for a non-standard number of neutrino species (N(sub eff) = 3.84 +/- 0.40). The model fit also implies that the age of the universe is (sub 0) = 13.772 +/- 0.059 Gyr, and the fit Hubble constant is H(sub 0) = 69.32 +/- 0.80 km/s/ Mpc. Inflation is also supported: the fluctuations are adiabatic, with Gaussian random phases; the detection of a deviation of the scalar spectral index from unity, reported earlier by the WMAP team, now has high statistical significance (n(sub s) = 0.9608+/-0.0080); and the universe is close to flat/Euclidean (Omega = −0.0027+0.0039/−0.0038). Overall, the WMAP mission has resulted in a reduction of the cosmological parameter volume by a factor of 68,000 for the standard six-parameter Lambda-CDM model, based on CMB data alone. For a model including tensors, the allowed seven-parameter volume has been reduced by a factor 117,000. Other cosmological observations are in accord with the CMB predictions, and the combined data reduces the cosmological parameter volume even further.With no significant anomalies and an adequate goodness of fit, the inflationary flat Lambda-CDM model and its precise and accurate parameters rooted in WMAP data stands as the standard model of cosmology.
2,622 citations
Princeton University1, University of British Columbia2, University of KwaZulu-Natal3, University of Nottingham4, Johns Hopkins University5, University of Oxford6, Pontifical Catholic University of Chile7, Carnegie Mellon University8, University of Toronto9, Sapienza University of Rome10, Lawrence Berkeley National Laboratory11, Argonne National Laboratory12, University of Pennsylvania13, National Institute of Standards and Technology14, Rutgers University15, University of Pittsburgh16, University of California, Santa Barbara17, Cornell University18, Haverford College19, Leiden University20, West Chester University of Pennsylvania21, Goddard Space Flight Center22
TL;DR: In this paper, the authors presented a catalog of 68 galaxy clusters, of which 19 are new discoveries, detected via the Sunyaev-Zel'dovich effect (SZ) at 148 GHz in the Atacama Cosmology Telescope (ACT) survey on the celestial equator.
Abstract: We present a catalog of 68 galaxy clusters, of which 19 are new discoveries, detected via the Sunyaev-Zel'dovich effect (SZ) at 148 GHz in the Atacama Cosmology Telescope (ACT) survey on the celestial equator. With this addition, the ACT collaboration has reported a total of 91 optically confirmed, SZ detected clusters. The 504 square degree survey region includes 270 square degrees of overlap with SDSS Stripe 82, permitting the confirmation of SZ cluster candidates in deep archival optical data. The subsample of 48 clusters within Stripe 82 is estimated to be 90% complete for M{sub 500c} > 4.5 × 10{sup 14}M{sub s}un and redshifts 0.15 < z < 0.8. While a full suite of matched filters is used to detect the clusters, the sample is studied further through a ''Profile Based Amplitude Analysis'' using a statistic derived from a single filter at a fixed θ{sub 500} = 5.'9 angular scale. This new approach incorporates the cluster redshift along with prior information on the cluster pressure profile to fix the relationship between the cluster characteristic size (R{sub 500}) and the integrated Compton parameter (Y{sub 500}). We adopt a one-parameter family of ''Universal Pressure Profiles'' (UPP) with associated scaling laws, derived frommore » X-ray measurements of nearby clusters, as a baseline model. Three additional models of cluster physics are used to investigate a range of scaling relations beyond the UPP prescription. Assuming a concordance cosmology, the UPP scalings are found to be nearly identical to an adiabatic model, while a model incorporating non-thermal pressure better matches dynamical mass measurements and masses from the South Pole Telescope. A high signal to noise ratio subsample of 15 ACT clusters with complete optical follow-up is used to obtain cosmological constraints. We demonstrate, using fixed scaling relations, how the constraints depend on the assumed gas model if only SZ measurements are used, and show that constraints from SZ data are limited by uncertainty in the scaling relation parameters rather than sample size or measurement uncertainty. We next add in seven clusters from the ACT Southern survey, including their dynamical mass measurements, which are based on galaxy velocity dispersions and thus are independent of the gas physics. In combination with WMAP7 these data simultaneously constrain the scaling relation and cosmological parameters, yielding 68% confidence ranges described by σ{sub 8} = 0.829 ± 0.024 and Ω{sub m} = 0.292 ± 0.025.. We consider these results in the context of constraints from CMB and other cluster studies. The constraints arise mainly due to the inclusion of the dynamical mass information and do not require strong priors on the SZ scaling relation parameters. The results include marginalization over a 15% bias in dynamical masses relative to the true halo mass. In an extension to ΛCDM that incorporates non-zero neutrino mass density, we combine our data with WMAP7, Baryon Acoustic Oscillation data, and Hubble constant measurements to constrain the sum of the neutrino mass species to be Σ{sub ν}m{sub ν} < 0.29 eV (95% confidence limit)« less
537 citations
Princeton University1, University of Toronto2, City University of New York3, University of British Columbia4, University of Oxford5, Cardiff University6, Pontifical Catholic University of Chile7, Sapienza University of Rome8, Carnegie Mellon University9, University of Pittsburgh10, Goddard Space Flight Center11, Johns Hopkins University12, Lawrence Berkeley National Laboratory13, Argonne National Laboratory14, University of Pennsylvania15, National Institute of Standards and Technology16, Max Planck Society17, University of KwaZulu-Natal18, University of Nottingham19, University of Miami20, National Institute of Astrophysics, Optics and Electronics21, Rutgers University22, West Chester University of Pennsylvania23, Columbia University24, Academia Sinica Institute of Astronomy and Astrophysics25, University of Tokyo26, University of California, Santa Barbara27, Arizona State University28, Cornell University29, Haverford College30, Stony Brook University31, University of Massachusetts Amherst32
TL;DR: In this article, a model of primary cosmological and secondary foreground parameters is fit to the map power spectra and lensing deflection power spectrum, including contributions from both the thermal Sunyaev-Zeldovich (tSZ) effect and the kinematic SZ effect, Poisson and correlated anisotropy from unresolved infrared sources, radio sources and the correlation between the tSZ effect and infrared sources.
Abstract: We present constraints on cosmological and astrophysical parameters from high-resolution microwave background maps at 148 GHz and 218 GHz made by the Atacama Cosmology Telescope (ACT) in three seasons of observations from 2008 to 2010. A model of primary cosmological and secondary foreground parameters is fit to the map power spectra and lensing deflection power spectrum, including contributions from both the thermal Sunyaev-Zeldovich (tSZ) effect and the kinematic Sunyaev-Zeldovich (kSZ) effect, Poisson and correlated anisotropy from unresolved infrared sources, radio sources, and the correlation between the tSZ effect and infrared sources. The power l2Cl/2π of the thermal SZ power spectrum at 148 GHz is measured to be 3.4±1.4 μK2 at l = 3000, while the corresponding amplitude of the kinematic SZ power spectrum has a 95% confidence level upper limit of 8.6 μK2. Combining ACT power spectra with the WMAP 7-year temperature and polarization power spectra, we find excellent consistency with the LCDM model. We constrain the number of effective relativistic degrees of freedom in the early universe to be Neff = 2.79±0.56, in agreement with the canonical value of Neff = 3.046 for three massless neutrinos. We constrain the sum of the neutrino masses to be Σmν < 0.39 eV at 95% confidence when combining ACT and WMAP 7-year data with BAO and Hubble constant measurements. We constrain the amount of primordial helium to be Yp = 0.225±0.034, and measure no variation in the fine structure constant α since recombination, with α/α0 = 1.004±0.005. We also find no evidence for any running of the scalar spectral index, dns/dln k = −0.004±0.012.
451 citations
TL;DR: In this article, the temperature power spectra of the cosmic microwave background (CMB) derived from the three seasons of data from the Atacama Cosmology Telescope (ACT) at 148 GHz and 218 GHz, as well as the cross-frequency spectrum between the two channels are presented.
Abstract: We present the temperature power spectra of the cosmic microwave background (CMB) derived from the three seasons of data from the Atacama Cosmology Telescope (ACT) at 148 GHz and 218 GHz, as well as the cross-frequency spectrum between the two channels. We detect and correct for contamination due to the Galactic cirrus in our equatorial maps. We present the results of a number of tests for possible systematic error and conclude that any effects are not significant compared to the statistical errors we quote. Where they overlap, we cross-correlate the ACT and the South Pole Telescope (SPT) maps and show they are consistent. The measurements of higher-order peaks in the CMB power spectrum provide an additional test of the Lambda CDM cosmological model, and help constrain extensions beyond the standard model. The small angular scale power spectrum also provides constraining power on the Sunyaev-Zel'dovich effects and extragalactic foregrounds. We also present a measurement of the CMB gravitational lensing convergence power spectrum at 4.6-sigma detection significance.
233 citations
University of Oxford1, Princeton University2, University of British Columbia3, Carnegie Mellon University4, Sapienza University of Rome5, University of Toronto6, Argonne National Laboratory7, Lawrence Berkeley National Laboratory8, University of Pennsylvania9, Pontifical Catholic University of Chile10, National Institute of Standards and Technology11, Johns Hopkins University12, Rutgers University13, University of Pittsburgh14, University of California, Santa Barbara15, University of KwaZulu-Natal16, Cornell University17, Haverford College18, Stony Brook University19, Goddard Space Flight Center20
TL;DR: The Atacama Cosmology Telescope has measured the angular power spectra of microwave fluctuations to arcminute scales at frequencies of 148 and 218 GHz, from three seasons of data.
Abstract: The Atacama Cosmology Telescope has measured the angular power spectra of microwave fluctuations to arcminute scales at frequencies of 148 and 218 GHz, from three seasons of data. At small scales the fluctuations in the primordial Cosmic Microwave Background (CMB) become increasingly obscured by extragalactic foregounds and secondary CMB signals. We present results from a nine-parameter model describing these secondary effects, including the thermal and kinematic Sunyaev-Zel'dovich (tSZ and kSZ) power; the clustered and Poisson-like power from Cosmic Infrared Background (CIB) sources, and their frequency scaling; the tSZ-CIB correlation coefficient; the extragalactic radio source power; and thermal dust emission from Galactic cirrus in two different regions of the sky. In order to extract cosmological parameters, we describe a likelihood function for the ACT data, fitting this model to the multi-frequency spectra in the multipole range 500 < l < 10000. We extend the likelihood to include spectra from the South Pole Telescope at frequencies of 95, 150, and 220 GHz. Accounting for different radio source levels and Galactic cirrus emission, the same model provides an excellent fit to both datasets simultaneously, with χ2/dof= 675/697 for ACT, and 96/107 for SPT. We then use the multi-frequency likelihood to estimate the CMB power spectrum from ACT in bandpowers, marginalizing over the secondary parameters. This provides a simplified `CMB-only' likelihood in the range 500 < l < 3500 for use in cosmological parameter estimation.
189 citations
Pontifical Catholic University of Chile1, Leiden University2, Rutgers University3, University of British Columbia4, Johns Hopkins University5, University of Oxford6, University of Toronto7, University of California, Berkeley8, University of Pennsylvania9, University of Nottingham10, Princeton University11, University of Pittsburgh12, University of California, Santa Barbara13, University of KwaZulu-Natal14, National Institute of Standards and Technology15, Haverford College16, West Chester University of Pennsylvania17, Carnegie Mellon University18, Goddard Space Flight Center19
TL;DR: In this paper, the authors presented the first dynamical mass estimates and scaling relations for a sample of Sunyaev-Zel'dovich effect (SZE) selected galaxy clusters, which consists of 16 massive clusters detected with the Atacama Cosmology Telescope (ACT) over a 455 deg2 area of the southern sky.
Abstract: We present the first dynamical mass estimates and scaling relations for a sample of Sunyaev-Zel'dovich effect (SZE) selected galaxy clusters. The sample consists of 16 massive clusters detected with the Atacama Cosmology Telescope (ACT) over a 455 deg2 area of the southern sky. Deep multi-object spectroscopic observations were taken to secure intermediate-resolution (R ~ 700-800) spectra and redshifts for 60 member galaxies on average per cluster. The dynamical masses M 200c of the clusters have been calculated using simulation-based scaling relations between velocity dispersion and mass. The sample has a median redshift z = 0.50 and a median mass with a lower limit , consistent with the expectations for the ACT southern sky survey. These masses are compared to the ACT SZE properties of the sample, specifically, the match-filtered central SZE amplitude , the central Compton parameter y 0, and the integrated Compton signal Y 200c , which we use to derive SZE-mass scaling relations. All SZE estimators correlate with dynamical mass with low intrinsic scatter ( 20%), in agreement with numerical simulations. We explore the effects of various systematic effects on these scaling relations, including the correlation between observables and the influence of dynamically disturbed clusters. Using the three-dimensional information available, we divide the sample into relaxed and disturbed clusters and find that ~50% of the clusters are disturbed. There are hints that disturbed systems might bias the scaling relations, but given the current sample sizes, these differences are not significant; further studies including more clusters are required to assess the impact of these clusters on the scaling relations.
154 citations
TL;DR: An AR coating for curved silicon optics comprised of subwavelength features cut into the lens surface with a custom three-axis silicon dicing saw is presented, and measurements of the optical properties of silicon at millimeter wavelengths at cryogenic and room temperatures are presented.
Abstract: The increasing scale of cryogenic detector arrays for submillimeter and millimeter wavelength astrophysics has led to the need for large aperture, high index of refraction, low loss, cryogenic refracting optics. Silicon with n=3.4, low loss, and high thermal conductivity is a nearly optimal material for these purposes but requires an antireflection (AR) coating with broad bandwidth, low loss, low reflectance, and a matched coefficient of thermal expansion. We present an AR coating for curved silicon optics comprised of subwavelength features cut into the lens surface with a custom three-axis silicon dicing saw. These features constitute a metamaterial that behaves as a simple dielectric coating. We have fabricated silicon lenses as large as 33.4 cm in diameter with micromachined layers optimized for use between 125 and 165 GHz. Our design reduces average reflections to a few tenths of a percent for angles of incidence up to 30° with low cross polarization. We describe the design, tolerance, manufacture, and measurements of these coatings and present measurements of the optical properties of silicon at millimeter wavelengths at cryogenic and room temperatures. This coating and lens fabrication approach is applicable from centimeter to submillimeter wavelengths and can be used to fabricate coatings with greater than octave bandwidth.
128 citations
University of Oxford1, Princeton University2, Carnegie Mellon University3, Sapienza University of Rome4, University of Toronto5, Johns Hopkins University6, University of California, Berkeley7, University of Pennsylvania8, Pontifical Catholic University of Chile9, University of British Columbia10, National Institute of Standards and Technology11, University of Pittsburgh12, University of KwaZulu-Natal13, Cornell University14, Stony Brook University15, Leiden University16, Goddard Space Flight Center17
TL;DR: In this article, the results from the WMAP, ACT and SPT experiments were used to constrain the effective number of relativistic species to be N$eff}$=3.40, in agreement with the standard model of light neutrinos.
Abstract: Recent data from the WMAP, ACT and SPT experiments provide precise measurements of the cosmic microwave background temperature power spectrum over a wide range of angular scales. The combination of these observations is well fit by the standard, spatially flat {$Lambda$}CDM cosmological model, constraining six free parameters to within a few percent. The scalar spectral index, n$_s$=0.9690{plusmn}0.0089, is less than unity at the 3.5{$σ$} level, consistent with simple models of inflation. The damping tail of the power spectrum at high resolution, combined with the amplitude of gravitational lensing measured by ACT and SPT, constrains the effective number of relativistic species to be N$_{eff}$=3.28{plusmn}0.40, in agreement with the standard model{
squo}s three species of light neutrinos.
105 citations
Pontifical Catholic University of Chile1, University of British Columbia2, Princeton University3, Johns Hopkins University4, University of Toronto5, Rutgers University6, University of Oxford7, Cardiff University8, Sapienza University of Rome9, University of Pittsburgh10, Goddard Space Flight Center11, University of California, Berkeley12, University of Pennsylvania13, National Institute of Standards and Technology14, Max Planck Society15, University of KwaZulu-Natal16, University of Nottingham17, University of Miami18, National Institute of Astrophysics, Optics and Electronics19, Columbia University20, University of California, Santa Barbara21, Haverford College22, West Chester University of Pennsylvania23, Harvard University24, University of Massachusetts Amherst25
TL;DR: In this article, the Atacama Cosmology Telescope (ACT) data were collected for 136 days, producing a total of 142h of data (11 TB for the 148 GHz band only), with a daily average of 10.5 h of observation.
Abstract: We present a description of the data reduction and mapmaking pipeline used for the 2008 observing season of the Atacama Cosmology Telescope (ACT). The data presented here at 148 GHz represent 12% or the 90 TB collected by ACT from 2007 to 2010. In 2008 we observed for 136 days, producing a total of 142h of data (11 TB for the 148 GHz band only), with a daily average of 10.5 h of observation. From these, 108.5 h were devoted to 850 sq deg stripe (11.2 h by 9 deg.1) centered on a declination of -52 deg.7, while 175 h were devoted to a 280 square deg stripe (4.5 h by 4 deg.8) centered at the celestial equator. We discuss sources of statistical and systematic noise, calibration, telescope pointing and data selection. Out of 1260 survey hours and 1024 detectors per array, 816 h and 593 effective detectors remain after data selection for this frequency band, yielding a 38 % survey efficiency. The total sensitivity in 2008, determined from the noise level between 5 Hz and 20 Hz in the time-ordered data stream (TOD), is 32 muK square root of s in CMB units. Atmospheric brightness fluctuations constitute the main contaminant in the data and dominate the detector and noise covariance at low frequencies in the TOD. The maps were made by solving the lease squares problem using the Preconditioned Conjugate Gradient method, incorporating the details of the detector and noise correlations. Cross-correlation with WMAP sky maps as well as analysis from simulations reveal the our maps are unbiased at l > 300. This paper accompanies the public release of the 148 GHz southern stripe maps from 2008. The techniques described here will be applied to future maps and data releases.
85 citations
Rutgers University1, Leiden University2, Pontifical Catholic University of Chile3, Carnegie Mellon University4, University of Toronto5, Johns Hopkins University6, Argonne National Laboratory7, University of Pennsylvania8, University of British Columbia9, University of KwaZulu-Natal10, University of Pittsburgh11, University of California, Santa Barbara12, National Institute of Standards and Technology13, Cornell University14, Princeton University15, Haverford College16, Goddard Space Flight Center17
TL;DR: In this article, the optical and X-ray properties of 68 galaxy clusters selected via the Sunyaev-Zel'dovich (SZ) effect at 148 GHz by the Atacama Cosmology Telescope (ACT) are presented.
Abstract: We present the optical and X-ray properties of 68 galaxy clusters selected via the Sunyaev-Zel'dovich (SZ) effect at 148 GHz by the Atacama Cosmology Telescope (ACT). Our sample, from an area of 504 deg$^{2}$ centered on the celestial equator, is divided into two regions. The main region uses 270 deg$^{2}$ of the ACT survey that overlaps with the co-added ugriz imaging from the Sloan Digital Sky Survey (SDSS) over Stripe 82 plus additional near-infrared pointed observations with the Apache Point Observatory 3.5 m telescope. We confirm a total of 49 clusters to z {ap} 1.3, of which 22 (all at z {gt} 0.55) are new discoveries. For the second region, the regular-depth SDSS imaging allows us to confirm 19 more clusters up to z {ap} 0.7, of which 10 systems are new. We present the optical richness, photometric redshifts, and separation between the SZ position and the brightest cluster galaxy (BCG). We find no significant offset between the cluster SZ centroid and BCG location and a weak correlation between optical richness and SZ-derived mass. We also present X-ray fluxes and luminosities from the ROSAT All Sky Survey which confirm that this is a massive sample. One of the newly discovered clusters, ACT-CL J0044.4+0113 at z = 1.1 (photometric), has an integrated XMM-Newton X-ray temperature of kT$_X$ = 7.9 {plusmn} 1.0 keV and combined mass of M $_{200a }$ = 8.2$^{+3.3}$ $_{-2.5}$ { imes} 10$^{14}$ h $^{-1}$ $_{70}$ M $_{⊙}$, placing it among the most massive and X-ray-hot clusters known at redshifts beyond z = 1. We also highlight the optically rich cluster ACT-CL J2327.4-0204 (RCS2 2327) at z = 0.705 (spectroscopic) as the most significant detection of the whole equatorial sample with a Chandra-derived mass of M $_{200a }$ = 1.9$^{+0.6}$ $_{-0.4}$ { imes} 10$^{15}$ h $^{-1}$ $_{70}$ M $_{⊙}$, placing it in the ranks of the most massive known clusters like El Gordo and the Bullet Cluster.
Harvard University1, University of Chicago2, Max Planck Society3, Tohoku University4, KEK5, California Institute of Technology6, Columbia University7, Princeton University8, University of Miami9, Arizona State University10, University of Oslo11, McGill University12, University of Toronto13, University of Oxford14, University of Concepción15, University of Chile16, Stanford University17, University of Manchester18, University of Michigan19, Fermilab20, Goddard Space Flight Center21, University of the Western Cape22
TL;DR: The Q/U Imaging ExperimenT (QUIET) as mentioned in this paper was designed to measure polarization in the Cosmic Microwave Background, targeting the imprint of inflationary gravitational waves at large angular scales ( approx 1 deg.).
Abstract: The Q/U Imaging ExperimenT (QUIET) is designed to measure polarization in the Cosmic Microwave Background, targeting the imprint of inflationary gravitational waves at large angular scales ( approx 1 deg.) . Between 2008 October and 2010 December, two independent receiver arrays were deployed sequentially on a 1.4 m side-fed Dragonian telescope. The polarimeters which form the focal planes use a highly compact design based on High Electron Mobility Transistors (HEMTs) that provides simultaneous measurements of the Stokes parameters Q, U, and I in a single module. The 17-element Q-band polarimeter array, with a central frequency of 43.1 GHz, has the best sensitivity (69 micro Ks(exp 1/2)) and the lowest instrumental systematic errors ever achieved in this band, contributing to the tensor-to-scalar ratio at r < 0.1. The 84-element W-band polarimeter array has a sensitivity of 87 micro Ks(exp 1/2) at a central frequency of 94.5 GHz. It has the lowest systematic errors to date, contributing at r < 0.01 (QUIET Collaboration 2012) The two arrays together cover multipoles in the range l approximately equals 25-975 . These are the largest HEMT-ba.sed arrays deployed to date. This article describes the design, calibration, performance of, and sources of systematic error for the instrument,
Princeton University1, University of Oxford2, Carnegie Mellon University3, University of British Columbia4, Sapienza University of Rome5, University of Toronto6, University of California, Berkeley7, University of Pennsylvania8, Pontifical Catholic University of Chile9, Johns Hopkins University10, University of Nottingham11, Rutgers University12, University of Pittsburgh13, University of Tokyo14, Academia Sinica Institute of Astronomy and Astrophysics15, University of California, Santa Barbara16, University of KwaZulu-Natal17, National Institute of Standards and Technology18, Haverford College19, Goddard Space Flight Center20
TL;DR: In this paper, the authors present the measured Sunyaev-Zel'dovich (SZ) flux from 474 optically selected MaxBCG clusters that fall within the Atacama Cosmology Telescope (ACT) Equatorial survey region.
Abstract: We present the measured Sunyaev-Zel'dovich (SZ) flux from 474 optically selected MaxBCG clusters that fall within the Atacama Cosmology Telescope (ACT) Equatorial survey region. The ACT Equatorial region used in this analysis covers 510 deg2and overlaps Stripe 82 of the Sloan Digital Sky Survey. We also present the measured SZ flux stacked on 52 X-ray-selected MCXC clusters that fall within the ACT Equatorial region and an ACT Southern survey region covering 455 deg2. We find that the measured SZ flux from the X-ray-selected clusters is consistent with expectations. However, we find that the measured SZ flux from the optically selected clusters is both significantly lower than expectations and lower than the recovered SZ flux measured by the Planck satellite. Since we find a lower recovered SZ signal than Planck, we investigate the possibility that there is a significant offset between the optically selected brightest cluster galaxies (BCGs) and the SZ centers, to which ACT is more sensitive due to its finer resolution. Such offsets can arise due to either an intrinsic physical separation between the BCG and the center of the gas concentration or from misidentification of the cluster BCG. We find that the entire discrepancy for both ACT and Planck can be explained by assuming that the BCGs are offset from the SZ maxima with a uniform random distribution between 0 and 1.5 Mpc. Such large offsets between gas peaks and BCGs for optically selected cluster samples seem unlikely given that we find the physical separation between BCGs and X-ray peaks for an X-ray-selected subsample of MaxBCG clusters to have a much narrower distribution that peaks within 0.2 Mpc. It is possible that other effects are lowering the ACT and Planck signals by the same amount, with offsets between BCGs and SZ peaks explaining the remaining difference between ACT and Planck measurements. Several effects that can lower the SZ signal equally for both ACT and Planck, but not explain the difference in measured signals, include a larger percentage of false detections in the MaxBCG sample, a lower normalization of the mass-richness relation, radio or infrared galaxy contamination of the SZ flux, and a low intrinsic SZ signal. In the latter two cases, the effects would need to be preferentially more significant in the optically selected MaxBCG sample than in the MCXC X-ray sample.
University of British Columbia1, Princeton University2, University of KwaZulu-Natal3, University of Toronto4, University of California, Berkeley5, Argonne National Laboratory6, University of Pennsylvania7, University of Oxford8, Pontifical Catholic University of Chile9, National Institute of Standards and Technology10, Johns Hopkins University11, University of California, Santa Barbara12, Cornell University13, Haverford College14, Stony Brook University15, Goddard Space Flight Center16
TL;DR: In this article, the Atacama Cosmology Telescope (ACT) beam profiles and window functions were measured using the Fourier Transform Transform Transform (FTT) model for each season of observations.
Abstract: We describe the measurement of the beam profiles and window functions for the Atacama Cosmology Telescope (ACT), which operated from 2007 to 2010 with kilopixel bolometer arrays centered at 148, 218, and 277 GHz. Maps of Saturn are used to measure the beam shape in each array and for each season of observations. Radial profiles are transformed to Fourier space in a way that preserves the spatial correlations in the beam uncertainty to derive window functions relevant for angular power spectrum analysis. Several corrections are applied to the resulting beam transforms, including an empirical correction measured from the final cosmic microwave background (CMB) survey maps to account for the effects of mild pointing variation and alignment errors. Observations of Uranus made regularly throughout each observing season are used to measure the effects of atmospheric opacity and to monitor deviations in telescope focus over the season. Using the WMAP-based calibration of the ACT maps to the CMB blackbody, we obtain precise measurements of the brightness temperatures of the Uranus and Saturn disks at effective frequencies of 149 and 219 GHz. For Uranus we obtain thermodynamic brightness temperatures T(149/U) = 106.7 +/- 2.2 K and T(219/U) = 100.1 +/- 3.1 K. For Saturn, we model the effects of the ring opacity and emission using a simple model and obtain resulting (unobscured) disk temperatures of T(149/S) = 137.3 +/- 3.2 K and T(219/S) = 137.3 +/- 4.7 K.
University of British Columbia1, Princeton University2, University of KwaZulu-Natal3, University of Nottingham4, Johns Hopkins University5, University of Oxford6, Pontifical Catholic University of Chile7, Carnegie Mellon University8, University of Toronto9, Sapienza University of Rome10, Argonne National Laboratory11, Lawrence Berkeley National Laboratory12, University of Pennsylvania13, National Institute of Standards and Technology14, Rutgers University15, University of Pittsburgh16, University of California, Santa Barbara17, Cornell University18, Haverford College19, Leiden University20, West Chester University of Pennsylvania21, Goddard Space Flight Center22
TL;DR: In this paper, the authors presented a catalog of 68 galaxy clusters, of which 19 are new discoveries, detected via the Sunyaev-Zel'dovich effect (SZ) at 148 GHz in the Atacama Cosmology Telescope (ACT) survey of 504 square degrees on the celestial equator.
Abstract: [Abridged] We present a catalog of 68 galaxy clusters, of which 19 are new discoveries, detected via the Sunyaev-Zel'dovich effect (SZ) at 148 GHz in the Atacama Cosmology Telescope (ACT) survey of 504 square degrees on the celestial equator. A subsample of 48 clusters within the 270 square degree region overlapping SDSS Stripe 82 is estimated to be 90% complete for M_500c > 4.5e14 Msun and 0.15 < z < 0.8. While matched filters are used to detect the clusters, the sample is studied further through a "Profile Based Amplitude Analysis" using a single filter at a fixed \theta_500 = 5.9' angular scale. This new approach takes advantage of the "Universal Pressure Profile" (UPP) to fix the relationship between the cluster characteristic size (R_500) and the integrated Compton parameter (Y_500). The UPP scalings are found to be nearly identical to an adiabatic model, while a model incorporating non-thermal pressure better matches dynamical mass measurements and masses from the South Pole Telescope. A high signal to noise ratio subsample of 15 ACT clusters is used to obtain cosmological constraints. We first confirm that constraints from SZ data are limited by uncertainty in the scaling relation parameters rather than sample size or measurement uncertainty. We next add in seven clusters from the ACT Southern survey, including their dynamical mass measurements based on galaxy velocity dispersions. In combination with WMAP7 these data simultaneously constrain the scaling relation and cosmological parameters, yielding \sigma_8 = 0.829 \pm 0.024 and \Omega_m = 0.292 \pm 0.025. The results include marginalization over a 15% bias in dynamical mass relative to the true halo mass. In an extension to LCDM that incorporates non-zero neutrino mass density, we combine our data with WMAP7+BAO+Hubble constant measurements to constrain \Sigma m_
u < 0.29 eV (95% C. L.).
Princeton University1, University of Toronto2, City University of New York3, University of British Columbia4, University of Oxford5, Cardiff University6, Pontifical Catholic University of Chile7, Sapienza University of Rome8, Carnegie Mellon University9, University of Pittsburgh10, Goddard Space Flight Center11, Johns Hopkins University12, Argonne National Laboratory13, Lawrence Berkeley National Laboratory14, University of Pennsylvania15, National Institute of Standards and Technology16, Max Planck Society17, University of KwaZulu-Natal18, University of Nottingham19, University of Miami20, National Institute of Astrophysics, Optics and Electronics21, Rutgers University22, West Chester University of Pennsylvania23, Columbia University24, University of Tokyo25, Academia Sinica Institute of Astronomy and Astrophysics26, University of California, Santa Barbara27, Arizona State University28, Cornell University29, Haverford College30, Stony Brook University31, University of Massachusetts Amherst32
TL;DR: In this paper, a model of primary cosmological and secondary foreground parameters is fit to the map power spectra and lensing deflection power spectrum, including contributions from both the thermal Sunyaev-Zeldovich (tSZ) effect and the kinematic SZ effect, Poisson and correlated anisotropy from unresolved infrared sources, radio sources and the correlation between the tSZ effect and infrared sources.
Abstract: We present constraints on cosmological and astrophysical parameters from high-resolution microwave background maps at 148 GHz and 218 GHz made by the Atacama Cosmology Telescope (ACT) in three seasons of observations from 2008 to 2010. A model of primary cosmological and secondary foreground parameters is fit to the map power spectra and lensing deflection power spectrum, including contributions from both the thermal Sunyaev-Zeldovich (tSZ) effect and the kinematic Sunyaev-Zeldovich (kSZ) effect, Poisson and correlated anisotropy from unresolved infrared sources, radio sources, and the correlation between the tSZ effect and infrared sources. The power ell^2 C_ell/2pi of the thermal SZ power spectrum at 148 GHz is measured to be 3.4 +\- 1.4 muK^2 at ell=3000, while the corresponding amplitude of the kinematic SZ power spectrum has a 95% confidence level upper limit of 8.6 muK^2. Combining ACT power spectra with the WMAP 7-year temperature and polarization power spectra, we find excellent consistency with the LCDM model. We constrain the number of effective relativistic degrees of freedom in the early universe to be Neff=2.79 +\- 0.56, in agreement with the canonical value of Neff=3.046 for three massless neutrinos. We constrain the sum of the neutrino masses to be Sigma m_nu < 0.39 eV at 95% confidence when combining ACT and WMAP 7-year data with BAO and Hubble constant measurements. We constrain the amount of primordial helium to be Yp = 0.225 +\- 0.034, and measure no variation in the fine structure constant alpha since recombination, with alpha/alpha0 = 1.004 +/- 0.005. We also find no evidence for any running of the scalar spectral index, dns/dlnk = -0.004 +\- 0.012.
TL;DR: In this article, the first deep field observations at 2 mm were obtained using the GISMO camera at a wavelength of 2 mm centered on the Hubble Deep Field (HDF) in the GOODS-N field.
Abstract: We present deep continuum observations using the GISMO camera at a wavelength of 2 mm centered on the Hubble Deep Field (HDF) in the GOODS-N field. These are the first deep field observations ever obtained at this wavelength. The 1 sigma sensitivity in the innermost approx. 4 arcminutes of the 7 utes map is approx. 135 uJy/beam, a factor of three higher in flux/beam sensitivity than the deepest available SCUBA 850 um observations, and almost a factor of four higher in flux / beam sensitivity than the combined MAMBO/AzTEC 1.2 mm observations of this region. Our source extraction algorithm identifies 12 sources directly, and another 3 through correlation with known sources at 1.2 mm and 850 um. Five of the directly detected GISMO sources have counterparts in the MAMBO/AzTEC catalog, and four of those also have SCUBA counterparts. HDF850.1, one of the first blank-field detected submillimeter galaxies, is now detected at 2 mm. The median redshift of all sources with counterparts of known redshifts is med(z) = 2.91 +/- 0.94. Statistically, the detections are most likely real for 5 of the seven 2 mm sources without shorter wavelength counterparts, while the probability for none of them being real is negligible.
University of Nottingham1, University of KwaZulu-Natal2, University of British Columbia3, Leiden University4, Rutgers University5, Pontifical Catholic University of Chile6, University of Toronto7, Carnegie Mellon University8, Johns Hopkins University9, Argonne National Laboratory10, Lawrence Berkeley National Laboratory11, University of Pennsylvania12, National Institute of Standards and Technology13, University of Pittsburgh14, Academia Sinica Institute of Astronomy and Astrophysics15, University of California, Santa Barbara16, Cornell University17, Princeton University18, Goddard Space Flight Center19
TL;DR: In this paper, the stellar mass component of galaxy clusters selected via the Sunyaev-Zel-dovich (SZ) effect was measured using 3.6 m and 4.5 m photometry from the Spitzer Space Telescope.
Abstract: We present a first measurement of the stellar mass component of galaxy clusters selected via the Sunyaev-Zel’dovich (SZ) effect, using 3.6 m and 4.5 m photometry from the Spitzer Space Telescope. Our sample consists of 14 clusters detected by the Atacama Cosmology Telescope (ACT), which span the redshift range 0:27 < z < 1:07 (median z = 0:50), and have dynamical mass measurements, accurate to about 30 per cent, with median M500 = 6:9 10 14 M . We measure the 3.6 m and 4.5 m galaxy luminosity functions, finding the characteristic magnitude (m ) and faint-end slope (a) to be similar to those for IR-selected cluster samples. We perform the first measurements of the scaling of SZ-observables (Y500 and y0) with both brightest cluster galaxy (BCG) stellar mass and total cluster stellar mass (M star ). We find a significant correlation between BCG stellar mass and Y500 (E(z) 2=3 D 2 Y500 µ M 1:2 0:6 ), although we are not able to obtain a strong constraint on the slope of the relation due to the small sample size. Additionally, we obtain E(z) 2=3 D 2 Y500 µ M star 500 1:0 0:6 for
TL;DR: Microspec as discussed by the authors is a new class of submillimeter and millimeter (250-700 μm) spectrometer, in which the wavelength separation and detection of incident light is done on a single substrate.
Abstract: Microspec is a new class of submillimeter and millimeter (250-700 μm wavelength) spectrometer, in which the wavelength separation and detection of incident light is done on a single substrate. The instrument is designed for space exploration by offering high spectral resolving power over a broad band, while being orders of magnitude smaller in mass and volume than the present state-of-the-art. The key enabling components for Microspec are background-limited microwave kinetic inductance detectors, which operate over the full bandwidth of the spectrometer. Here we present our fabrication strategy for making these sensitive detectors. A microstrip architecture utilizing a 0.45-μm crystalline silicon dielectric with a molybdenum nitride kinetic inductor material has been adopted. We have optimized wafer-scale lithographic patterning, and have developed processes that allow us to minimize surface roughness that may contribute to detector noise. Additionally, we have optimized the low-temperature wafer bonding process; this process allows us to build superconductors on both sides of the silicon dielectric layer. We present a final fabricated device and resonator operation at cryogenic temperatures.
Institute for the Physics and Mathematics of the Universe1, University of Tokyo2, Princeton University3, Carnegie Mellon University4, University of Toronto5, Johns Hopkins University6, University of Nottingham7, University of KwaZulu-Natal8, Rutgers University9, Pontifical Catholic University of Chile10, Academia Sinica Institute of Astronomy and Astrophysics11, University of California, Santa Barbara12, National Institutes of Natural Sciences, Japan13, National Institute of Standards and Technology14, University of Pennsylvania15, Leiden University16, Goddard Space Flight Center17
TL;DR: In this article, a weak lensing measurement of ACT-CL J0022.2 0036 is presented, where the authors use a Gauss-Laguerre shapel et al. method to measure shapes of galaxy images, where they fit galaxy images in different exposures simultaneously to obtain best-fit ellipticities.
Abstract: We present a Subaru weak lensing measurement of ACT-CL J0022.2 0036, one of the most luminous, high-redshift (z = 0.81) Sunyaev-Zel’dovich (SZ) clusters discovered in the 268 deg 2 equatorial region survey of the Atacama Cosmology Telescope that overlaps with SDSS Stripe 82 field. Ours is the first weak lensing study with Subar u at such high redshifts. For the weak lensing analysis using i ′ -band images, we use a model-fitting (Gauss-Laguerre shapel et) method to measure shapes of galaxy images, where we fit galaxy images in different exposures simultaneously to obtain best-fit ellipticities ta king into account the different PSFs in each exposure. We also take into account the astrometric distortion effect on galaxy images by performing the model fitting in the world coordinate s ystem. To select background galaxies behind the cluster at z = 0.81, we use photometric redshift (photo-z) estimates �
TL;DR: In this paper, the authors present work on the fabrication of micromachined silicon, producing conductive quarter-wave backshort assemblies for the Cosmology Large Angular Scale Surveyor (CLASS) 40 GHz focal plane, which will measure the polarization of the cosmic microwave background to search for evidence for gravitational waves from a posited epoch of inflation early in the Universe's history.
Abstract: The Cosmology Large Angular Scale Surveyor (CLASS) is a ground-based instrument that will measure the polarization of the cosmic microwave background to search for evidence for gravitational waves from a posited epoch of inflation early in the Universe's history. This measurement will require integration of superconducting transition-edge sensors with microwave waveguide inputs with excellent control of systematic errors, such as unwanted coupling to stray signals at frequencies outside of a precisely defined microwave band. To address these needs, we present work on the fabrication of micromachined silicon, producing conductive quarter-wave backshort assemblies for the CLASS 40 GHz focal plane. Each 40 GHz backshort assembly consists of three degeneratively doped silicon wafers. Two spacer wafers are micromachined with through-wafer vias to provide a 2.04-mm-long square waveguide delay section. The third wafer terminates the waveguide delay in a short. The three wafers are bonded at the wafer level by Au-Au thermal compression bonding then aligned and flip chip bonded to the CLASS detector at the chip level. The micromachining techniques used have been optimized to create high aspect ratio waveguides, silicon pillars, and relief trenches with the goal of providing improved out of band signal rejection. We will discuss the fabrication of integrated CLASS superconducting detector chips with the quarter-wave backshort assemblies.
University of California, San Diego1, Cardiff University2, California Institute of Technology3, Harvard University4, Jet Propulsion Laboratory5, Princeton University6, French Alternative Energies and Atomic Energy Commission7, University of California, Berkeley8, Stanford University9, University of Chicago10, KEK11, University of Paris-Sud12, University of Minnesota13, Goddard Space Flight Center14
TL;DR: In this paper, the design and performance of a wide bandwidth linear polarization modulator based on the Faraday effect is described and verified through high signal-to-noise detection of Galactic polarization using two of the six FRMs during four observing runs in 2006.
Abstract: The design and performance of a wide bandwidth linear polarization modulator based on the Faraday effect is described. Faraday Rotation Modulators (FRMs) are solid-state polarization switches that are capable of modulation up to 10 kHz. Six FRMs were utilized during the 2006 observing season in the Background Imaging of Cosmic Extragalactic Polarization (BICEP) experiment; three FRMs were used at each of BICEP's 100 and 150 GHz frequency bands. The technology was verified through high signal-to-noise detection of Galactic polarization using two of the six FRMs during four observing runs in 2006. The features exhibit strong agreement with BICEP's measurements of the Galaxy using non-FRM pixels and with the Galactic polarization models. This marks the first detection of high signal-to-noise mm-wave celestial polarization using fast, active optical modulation. The performance of the FRMs during periods when they were not modulated was also analyzed and compared to results from BICEP's 43 pixels without FRMs.
TL;DR: In this paper, an antireflection (AR) coating for curved silicon optics comprised of subwavelength features cut into the lens surface with a custom three axis silicon dicing saw is presented.
Abstract: The increasing scale of cryogenic detector arrays for sub-millimeter and millimeter wavelength astrophysics has led to the need for large aperture, high index of refraction, low loss, cryogenic refracting optics. Silicon with n = 3.4, low loss, and relatively high thermal conductivity is a nearly optimal material for these purposes, but requires an antireflection (AR) coating with broad bandwidth, low loss, low reflectance, and a matched coefficient of thermal expansion. We present an AR coating for curved silicon optics comprised of subwavelength features cut into the lens surface with a custom three axis silicon dicing saw. These features constitute a metamaterial that behaves as a simple dielectric coating. We have fabricated and coated silicon lenses as large as 33.4 cm in diameter with coatings optimized for use between 125-165 GHz. Our design reduces average reflections to a few tenths of a percent for angles of incidence up to 30 degrees with low cross-polarization. We describe the design, tolerance, manufacture, and measurements of these coatings and present measurements of the optical properties of silicon at millimeter wavelengths at cryogenic and room temperatures. This coating and lens fabrication approach is applicable from centimeter to sub-millimeter wavelengths and can be used to fabricate coatings with greater than octave bandwidth.
TL;DR: The design and validation of a dual polarization source for waveguide-coupled millimeter and sub-millimeter wave cryogenic sensors is presented and the use of low thermal conductivity Kevlar threads for the kinematic mount effectively decouples the absorber from the sensor cold stage.
Abstract: The design and validation of a dual polarization source for waveguide-coupled millimeter and sub-millimeter wave cryogenic sensors is presented. The thermal source is a waveguide mounted absorbing conical dielectric taper. The absorber is thermally isolated with a kinematic suspension that allows the guide to be heat sunk to the lowest bath temperature of the cryogenic system. This approach enables the thermal emission from the metallic waveguide walls to be subdominant to that from the source. The use of low thermal conductivity Kevlar threads for the kinematic mount effectively decouples the absorber from the sensor cold stage. Hence, the absorber can be heated to significantly higher temperatures than the sensor with negligible conductive loading. The kinematic suspension provides high mechanical repeatability and reliability with thermal cycling. A 33-50 GHz blackbody source demonstrates an emissivity of 0.999 over the full waveguide band where the dominant deviation from unity arrises from the waveguide ohmic loss. The observed thermal time constant of the source is 40 s when the absorber temperature is 15 K. The specific heat of the lossy dielectric MF-117 is well approximated by $C_v(T)=0.12\,T\,^{2.06}$ mJ g$^{-1}$ K$^{-1}$ between 3.5 K and 15 K.
TL;DR: In this article, a dual polarization source for waveguide-coupled millimeter and sub-millimeter wave cryogenic sensors is presented, which enables the thermal emission from the metallic waveguide walls to be subdominant to that from the source.
Abstract: The design and validation of a dual polarization source for waveguide-coupled millimeter and sub-millimeter wave cryogenic sensors is presented. The thermal source is a waveguide mounted absorbing conical dielectric taper. The absorber is thermally isolated with a kinematic suspension that allows the guide to be heat sunk to the lowest bath temperature of the cryogenic system. This approach enables the thermal emission from the metallic waveguide walls to be subdominant to that from the source. The use of low thermal conductivity Kevlar threads for the kinematic mount effectively decouples the absorber from the sensor cold stage. Hence, the absorber can be heated to significantly higher temperatures than the sensor with negligible conductive loading. The kinematic suspension provides high mechanical repeatability and reliability with thermal cycling. A 33-50 GHz blackbody source demonstrates an emissivity of 0.999 over the full waveguide band where the dominant deviation from unity arises from the waveguide ohmic loss. The observed thermal time constant of the source is 40 s when the absorber temperature is 15 K. The specific heat of the lossy dielectric MF-117 is well approximated by Cv(T) = 0.12 T(exp 2.06) mJ/g/K between 3.5 K and 15 K.
Princeton University1, University of British Columbia2, University of KwaZulu-Natal3, University of Toronto4, University of California, Berkeley5, Argonne National Laboratory6, University of Pennsylvania7, University of Oxford8, Pontifical Catholic University of Chile9, National Institute of Standards and Technology10, Johns Hopkins University11, University of California, Santa Barbara12, Cornell University13, Haverford College14, Stony Brook University15, Goddard Space Flight Center16
TL;DR: In this article, the Atacama Cosmology Telescope (ACT) beam profiles and window functions were measured for the last decade with kilo-pixel bolometer arrays centered at 148, 218, and 277 GHz.
Abstract: We describe the measurement of the beam profiles and window functions for the Atacama Cosmology Telescope (ACT), which operated from 2007 to 2010 with kilo-pixel bolometer arrays centered at 148, 218, and 277 GHz. Maps of Saturn are used to measure the beam shape in each array and for each season of observations. Radial profiles are transformed to Fourier space in a way that preserves the spatial correlations in the beam uncertainty, to derive window functions relevant for angular power spectrum analysis. Several corrections are applied to the resulting beam transforms, including an empirical correction measured from the final CMB survey maps to account for the effects of mild pointing variation and alignment errors. Observations of Uranus made regularly throughout each observing season are used to measure the effects of atmospheric opacity and to monitor deviations in telescope focus over the season. Using the WMAP-based calibration of the ACT maps to the CMB blackbody, we obtain precise measurements of the brightness temperatures of the Uranus and Saturn disks at effective frequencies of 149 and 219 GHz. For Uranus we obtain thermodynamic brightness temperatures T_U^{149} = 106.7 \pm 2.2 K and T_U^{219} = 100.1 \pm 3.1 K. For Saturn, we model the effects of the ring opacity and emission using a simple model and obtain resulting (unobscured) disk temperatures of T_S^{149} = 137.3 \pm 3.2 K and T_S^{219} = 137.3 \pm 4.7 K.
TL;DR: ACTPol, a polarization sensitive receiver for the Atacama Cosmology Telescope, is designed to make sensitive maps of the cosmic microwave background anisotropies at arcminute scales and millimeter wavelengths by employing three arrays of superconducting transition edge sensor (TES) detectors.
Abstract: ACTPol, a polarization sensitive receiver for the Atacama Cosmology Telescope, is designed to make sensitive maps of the cosmic microwave background anisotropies at arcminute scales and millimeter wavelengths by employing three arrays of superconducting transition edge sensor (TES) detectors. The ACTPol TES bolometers have a target superconducting transition temperature of 150 mK and will be cooled to a bath temperature of 100 mK with a dilution refrigerator enabling increased array sensitivity. Each array will consist of ~1000 TES detectors coupled to a micromachined silicon feedhorn stack via superconducting ortho-mode transducers and transmission lines. The superconducting detectors of the first ACTPol array have been characterized in their final receiver configuration with measurements of key TES parameters including the transition temperature, saturation power, and thermal conductance.
TL;DR: The Optical Properties of Astronomical Silicates with Infrared Techniques program utilizes multiple instruments to provide spectral data over a wide range of temperatures and wavelengths as mentioned in this paper, including vector network analyzer and Fourier transform spectroscopy transmission, and reflection/scattering measurements.
Abstract: The Optical Properties of Astronomical Silicates with Infrared Techniques program utilizes multiple instruments to provide spectral data over a wide range of temperatures and wavelengths. Experimental methods include Vector Network Analyzer and Fourier transform spectroscopy transmission, and reflection/scattering measurements. From this data, we can determine the optical parameters for the index of refraction, n, and the absorption coefficient, k. The analysis of the laboratory transmittance data for each sample type is based upon different mathematical models, which are applied to each data set according to their degree of coherence. Presented here are results from iron silicate dust grain analogs, in several sample preparations and at temperatures ranging from 5 to 300 K, across the infrared and millimeter portion of the spectrum (from 2.5 to 10,000/micron or 4000 to 1/cm).
TL;DR: The Optical Properties of Astronomical Silicates with Infrared Techniques (OPASI-T) program utilizes multiple instruments to provide spectral data over a wide range of temperature and wavelengths.
Abstract: The Optical Properties of Astronomical Silicates with Infrared Techniques (OPASI-T) program utilizes multiple instruments to provide spectral data over a wide range of temperature and wavelengths. Experimental methods include Vector Network Analyzer (VNA) and Fourier Transform Spectroscopy (FTS) transmission, and reflection/scattering measurements. From this data, we can determine the optical parameters for the index of refraction, \textit{n}, and the absorption coefficient, \textit{k}. The analysis of the laboratory transmittance data for each sample type is based upon different mathematical models, which are applied to each data set according to their degree of coherence. Presented here are results from iron silicate dust grain analogs, in several sample preparations and at temperatures ranging from 5--300 K, across the infrared and millimeter portion of the spectrum (from 2.5--10,000 \mic\ or 4,000--1 \wvn).
TL;DR: In this article, a fabrication methodology for realizing compact planar filters embedded in the wall of the detector enclosure whose tailored response controls the propagation of light through the far infrared is discussed.
Abstract: Optimal performance of background limited thermal detectors requires adequate control over all relevant sources of incident electromagnetic radiation. In addition to the radiant power incident from the scene of interest, undesired or spurious power can potentially couple to the sensor via its bias and readout circuitry employed to operate the device. One means of limiting the contribution of this stray radiation is to filter or block leakage associated with electrical connections in the detector environment. Here we discuss a fabrication methodology for realizing compact planar filters embedded in the wall of the detector enclosure whose tailored response controls the propagation of light through the far infrared. This approach consists of fabricating an array of boxed-stripline transmission line blocking filters to control thermal radiation incident via this path. Topologically, each superconducting center conductor is encased by a silicon dioxide dielectric insulator and surrounded by a metallic shield to form a single mode transmission line structure. We report on achieved attenuation and return loss and find that it replicates simulated data to a high degree.