-
[show abstract]
[hide abstract]
ABSTRACT: We cross-correlate the 100 um Improved Reprocessing of the IRAS Survey (IRIS)
map and galaxy clusters at 0.1 < z < 0.3 in the maxBCG catalogue taken from the
Sloan Digital Sky Survey, measuring an angular cross-power spectrum over
multipole moments 150 < l < 3000 at a total significance of over 40 sigma. The
cross-spectrum, which arises from the spatial correlation between unresolved
dusty galaxies that make up the cosmic infrared background (CIB) in the IRIS
map and the galaxy clusters, is well-fit by a single power law with an index of
-1.28 +/- 0.12, similar to the clustering of unresolved galaxies from
cross-correlating far-infrared and submillimetre maps at longer wavelengths.
Using a recent, phenomenological model for the spectral and clustering
properties of the IRIS galaxies, we constrain the large-scale bias of the
maxBCG clusters to be 2.6 +/- 1.4, consistent with existing analyses of the
real-space cluster correlation function. The success of our method suggests
that future CIB-optical cross-correlations using Planck and Herschel data will
significantly improve our understanding of the clustering and redshift
distribution of the faint CIB sources.
03/2013;
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Erminia Calabrese,
Renée A. Hlozek,
Nick Battaglia,
Elia S. Battistelli,
J. Richard Bond,
Jens Chluba,
Devin Crichton,
Sudeep Das,
Mark J. Devlin,
Joanna Dunkley, [......],
Michael R. Nolta,
Lyman A. Page,
Neelima Sehgal,
Blake D. Sherwin,
Jonathan L. Sievers,
Cristóbal Sifón,
David N. Spergel,
Suzanne T. Staggs,
Eric R. Switzer,
Edward J. Wollack
[show abstract]
[hide abstract]
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 LCDM cosmological model, constraining six
free parameters to within a few percent. The scalar spectral index, n_s =
0.9690 +/- 0.0089, is less than unity at the 3.6 sigma 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 +/- 0.40, in agreement with the standard model's three species of
light neutrinos.
02/2013;
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Sudeep Das,
Thibaut Louis,
Michael R. Nolta,
Graeme E. Addison,
Elia S. Battistelli,
J Richard Bond,
Erminia Calabrese,
Devin Crichton Mark J. Devlin,
Simon Dicker,
Joanna Dunkley, [......],
Neelima Sehgal,
Blake D. Sherwin,
Jonathan L. Sievers,
David N. Spergel,
Suzanne T. Staggs,
Daniel S. Swetz,
Eric R. Switzer,
Robert Thornton,
Hy Trac,
Ed Wollack
[show abstract]
[hide abstract]
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.
01/2013;
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Jonathan L. Sievers,
Renée A. Hlozek,
Michael R. Nolta,
Viviana Acquaviva,
Graeme E. Addison,
Peter A. R. Ade,
Paula Aguirre,
Mandana Amiri,
John William Appel,
L. Felipe Barrientos, [......],
Robert Thornton,
Hy Trac,
Carole Tucker,
Masao Uehara,
Katerina Visnjic,
Ryan Warne,
Grant Wilson,
Ed Wollack,
Yue Zhao,
Caroline Zuncke
[show abstract]
[hide abstract]
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
percent 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/alpha_0 = 1.004+/- 0.005. We also find no
evidence for any running of the scalar spectral index, dns/dln k = -0.004 +/-
0.012.
01/2013;
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Matthew Hasselfield,
Matt Hilton,
Tobias A. Marriage,
Graeme E. Addison,
L. Felipe Barrientos,
Nick Battaglia,
Elia S. Battistelli,
J. Richard Bond,
Devin Crichton,
Sudeep Das, [......],
Blake D. Sherwin,
Jon Sievers,
Cristóbal Sifón,
David N. Spergel,
Suzanne T. Staggs,
Daniel S. Swetz,
Eric R. Switzer,
Robert Thornton,
Hy Trac,
Edward J. Wollack
[show abstract]
[hide abstract]
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 break the
degeneracy between the cluster extent (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
complete, 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_\nu < 0.29 eV (95% C. L.).
01/2013;
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Matt Hilton,
Matthew Hasselfield,
Cristóbal Sifón,
Andrew J. Baker,
L. Felipe Barrientos,
Nicholas Battaglia,
J. Richard Bond,
Devin Crichton,
Sudeep Das,
Mark J. Devlin, [......],
Danica Marsden,
Felipe Menanteau,
Kavilan Moodley,
Michael D. Niemack,
Mike R. Nolta,
Lyman A. Page,
Erik D. Reese,
Jon Sievers,
David N. Spergel,
Edward J. Wollack
[show abstract]
[hide abstract]
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 um and 4.5
um 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 x 10^{14}
MSun. We measure the 3.6 um and 4.5 um galaxy luminosity functions, finding the
characteristic magnitude (m*) and faint-end slope (alpha) 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 (M500star). We find a
significant correlation between BCG stellar mass and Y500 (E(z)^{-2/3} DA^2
Y500 ~ 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} DA^2 Y500 ~ M500star^{1.0 +/- 0.6} for the
scaling with total stellar mass. The mass fraction in stars spans the range
0.006-0.034, with the second ranked cluster in terms of dynamical mass (ACT-CL
J0237-4939) having an unusually low total stellar mass and the lowest stellar
mass fraction. For the five clusters with gas mass measurements available in
the literature, we see no evidence for a shortfall of baryons relative to the
cosmic mean value.
01/2013;
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Felipe Menanteau,
Cristóbal Sifón,
L. Felipe Barrientos,
Nicholas Battaglia,
J. Richard Bond,
Devin Crichton,
Sudeep Das,
Mark J. Devlin,
Rolando Dünner,
Megan Gralla, [......],
Michael R. Nolta,
Lyman A. Page,
Bruce Partridge,
Erik D. Reese,
Benjamin L. Schmitt,
Jon Sievers,
David N. Spergel,
Suzanne T. Staggs,
Eric Switzer,
Edward J. Wollack
[show abstract]
[hide abstract]
ABSTRACT: We present the optical and X-ray properties of 68 galaxy clusters selected
via the Sunyaev-Zel'dovich Effect at 148 GHz by the Atacama Cosmology Telescope
(ACT). Our sample, from an area of 504 square degrees centered on the celestial
equator, is divided into two regions. The main region uses 270 square degrees
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-meter telescope. We confirm
a total of 49 clusters to z~1.3, of which 22 (all at z>0.55) are new
discoveries. For the second region the regular-depth SDSS imaging allows us to
confirm 19 more clusters up to z~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+/-1.0
keV and combined mass of M_200a=8.2(-2.5,+3.3)x10^14 M_sun/h70 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(-0.4,+0.6)x10^15 M_sun/h70,
comparable to some of the most massive known clusters like "El Gordo" and the
Bullet Cluster.
10/2012;
-
Hironao Miyatake,
Atsushi J. Nishizawa,
Masahiro Takada,
Rachel Mandelbaum,
Sogo Mineo,
Hiroaki Aihara,
David N. Spergel,
Steven J. Bickerton,
J. Richard Bond, Amir Hajian, [......],
Felipe Menanteau,
Satoshi Miyazaki,
Kavilan Moodley,
Michael D. Niemack,
Masamune Oguri,
Paul A. Price,
Erik D. Reese,
Cristobal Sifon,
Edward J. Wollack,
Naoki Yasuda
[show abstract]
[hide abstract]
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. For the weak lensing analysis using i'-band images, we use a
model-fitting (Gauss-Laguerre shapelet) method to measure shapes of galaxy
images, where we fit galaxy images in different exposures simultaneously to
obtain best-fit ellipticities taking 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 system. To
select background galaxies behind the cluster at z=0.81, we use photometric
redshift (photo-z) estimates for every galaxy derived from the co-added images
of multi-passband Br'i'z'Y, with PSF matching/homogenization. After a photo-z
cut for background galaxy selection, we detect the tangential weak lensing
distortion signal with a total signal-to-noise ratio of about 3.7. By fitting a
Navarro-Frenk-White model to the measured shear profile, we find the cluster
mass to be M_200\bar{\rho}_m = [7.5^+3.2_-2.8(stat.)^+1.3_-0.6(sys.)] x 10^14
M_\odot/h. The weak lensing-derived mass is consistent with previous mass
estimates based on the SZ observation, with assumptions of hydrostatic
equilibrium and virial theorem, as well as with scaling relations between SZ
signal and mass derived from weak lensing, X-ray, and velocity dispersion,
within the measurement errors. We also show that the existence of ACT-CL
J0022.2-0036 at z=0.81 is consistent with the cluster abundance prediction of
the \Lambda-dominated cold dark matter structure formation model. We thus
demonstrate the capability of Subaru-type ground-based images for studying weak
lensing of high-redshift clusters.
09/2012;
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Rolando Dünner,
Matthew Hasselfield,
Tobias A. Marriage,
Jon Sievers,
Viviana Acquaviva,
Graeme E. Addison,
Peter A. R. Ade,
Paula Aguirre,
Mandana Amiri,
John William Appel, [......],
Suzanne T. Staggs,
Daniel S. Swetz,
Eric R. Switzer,
Robert Thornton,
Hy Trac,
Carole Tucker,
Ryan Warne,
Grant Wilson,
Ed Wollack,
Yue Zhao
[show abstract]
[hide abstract]
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% of the 90 TB collected by ACT from
2007 to 2010. In 2008 we observed for 136 days, producing a total of 1423 hours
of data (11 TB for the 148 GHz band only), with a daily average of 10.5 hours
of observation. From these, 1085 hours were devoted to a 850 deg^2 stripe (11.2
hours by 9.1 deg) centered on a declination of -52.7 deg, while 175 hours were
devoted to a 280 deg^2 stripe (4.5 hours by 4.8 deg) 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 hours 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 micro-Kelvin sqrt{s} in CMB units.
Atmospheric brightness fluctuations constitute the main contaminant in the data
and dominate the detector noise covariance at low frequencies in the TOD. The
maps were made by solving the least-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 that our maps are unbiased at multipoles ell > 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.
07/2012;
-
Blake D. Sherwin,
Sudeep Das, Amir Hajian,
Graeme Addison,
J. Richard Bond,
Devin Crichton,
Mark J. Devlin,
Joanna Dunkley,
Megan B. Gralla,
Mark Halpern, [......],
Michael D. Niemack,
Lyman A. Page,
Erik D. Reese,
Neelima Sehgal,
Jon Sievers,
Cristobal Sifon,
David N. Spergel,
Suzanne T. Staggs,
Eric R. Switzer,
Ed Wollack
[show abstract]
[hide abstract]
ABSTRACT: We measure the cross-correlation of Atacama Cosmology Telescope CMB lensing
convergence maps with quasar maps made from the Sloan Digital Sky Survey DR8
SDSS-XDQSO photometric catalog. The CMB lensing-quasar cross-power spectrum is
detected for the first time at a significance of 3.8 sigma, which directly
confirms that the quasar distribution traces the mass distribution at high
redshifts z>1. Our detection passes a number of null tests and systematic
checks. Using this cross-power spectrum, we measure the amplitude of the linear
quasar bias assuming a template for its redshift dependence, and find the
amplitude to be consistent with an earlier measurement from clustering; at
redshift z ~ 1.4, the peak of the distribution of quasars in our maps, our
measurement corresponds to a bias of b = 2.5 +/- 0.6. With the signal-to-noise
ratio on CMB lensing measurements likely to improve by an order of magnitude
over the next few years, our results demonstrate the potential of CMB lensing
cross-correlations to probe astrophysics at high redshifts.
07/2012;
-
Neelima Sehgal,
Graeme Addison,
Nick Battaglia,
Elia S. Battistelli,
J. Richard Bond,
Sudeep Das,
Mark J. Devlin,
Joanna Dunkley,
Rolando Dünner,
Megan Gralla, [......],
Bruce Partridge,
Erik D. Reese,
Blake D. Sherwin,
Jon Sievers,
Cristóbal Sifón,
David N. Spergel,
Suzanne T. Staggs,
Daniel S. Swetz,
Eric R. Switzer,
Ed Wollack
[show abstract]
[hide abstract]
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 square degrees and 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 square degrees. 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
measurements. (Abridged)
05/2012;
-
Michael J. Wilson,
Blake D. Sherwin,
J. Colin Hill,
Graeme Addison,
Nick Battaglia,
J. Richard Bond,
Sudeep Das,
Mark J. Devlin,
Joanna Dunkley,
Rolando Dunner, [......],
Bruce Partridge,
Erik D. Reese,
Neelima Sehgal,
Jon Sievers,
David N. Spergel,
Suzanne T. Staggs,
Daniel S. Swetz,
Eric R. Switzer,
Hy Trac,
Ed Wollack
[show abstract]
[hide abstract]
ABSTRACT: We present a detection of the unnormalized skewness <T^3> induced by the
thermal Sunyaev-Zel'dovich (tSZ) effect in filtered Atacama Cosmology Telescope
(ACT) 148 GHz cosmic microwave background temperature maps. Contamination due
to infrared and radio sources is minimized by template subtraction of resolved
sources and by constructing a mask using outlying values in the 218 GHz
(tSZ-null) ACT maps. We measure <T^3>= -31 +- 6 \mu K^3 (measurement error
only) or +- 14 \mu K^3 (including cosmic variance error) in the filtered ACT
data, a 5-sigma detection. We show that the skewness is a sensitive probe of
sigma_8, and use analytic calculations and tSZ simulations to obtain
cosmological constraints from this measurement. From this signal alone we infer
a value of sigma_8= 0.79 +0.03 -0.03 (68 % C.L.) +0.06 -0.06 (95 % C.L.). Our
results demonstrate that measurements of non-Gaussianity can be a useful method
for characterizing the tSZ effect and extracting the underlying cosmological
information.
03/2012;
-
Nick Hand,
Graeme E. Addison,
Eric Aubourg,
Nick Battaglia,
Elia S. Battistelli,
Dmitry Bizyaev,
J. Richard Bond,
Howard Brewington,
Jon Brinkmann,
Benjamin R. Brown, [......],
Stephanie Snedden,
David N. Spergel,
Suzanne T. Staggs,
Daniel S. Swetz,
Eric R. Switzer,
Hy Trac,
Benjamin A. Weaver,
Edward J. Wollack,
Christophe Yeche,
Caroline Zunckel
[show abstract]
[hide abstract]
ABSTRACT: Using high-resolution microwave sky maps made by the Atacama Cosmology
Telescope, we for the first time present strong evidence for motions of galaxy
clusters and groups via microwave background temperature distortions due to the
kinematic Sunyaev-Zel'dovich effect. Galaxy clusters are identified by their
constituent luminous galaxies observed by the Baryon Oscillation Spectroscopic
Survey, part of the Sloan Digital Sky Survey III. We measure the mean pairwise
momentum of clusters, with a probability of the signal being due to random
errors of 0.002, and the signal is consistent with the growth of cosmic
structure in the standard model of cosmology.
03/2012;
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Cristobal Sifon,
Felipe Menanteau,
Matthew Hasselfield,
Tobias A. Marriage,
John P. Hughes,
L. Felipe Barrientos,
Jorge Gonzalez,
Leopoldo Infante,
Graeme E. Addison,
Andrew J. Baker, [......],
Lyman A. Page,
Bruce Partridge,
Erik D. Reese,
Neelima Sehgal,
Jon Sievers,
David N. Spergel,
Suzanne T. Staggs,
Robert J. Thornton,
Hy Trac,
Edward Wollack
[show abstract]
[hide abstract]
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 sq. deg. 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 M_200c~12e14 Msun/h70
with a lower limit M_200c~6e14 Msun/h70, 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 y~, the central Compton parameter y0, 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 3-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.
01/2012;
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Amir Hajian,
Marco P. Viero,
Graeme Addison,
Paula Aguirre,
John William Appel,
Nick Battaglia,
James J. Bock,
J. Richard Bond,
Sudeep Das,
Mark J. Devlin, [......],
Guillaume Patanchon,
Douglas Scott,
Neelima Sehgal,
Jon Sievers,
David N. Spergel,
Suzanne T. Staggs,
Daniel S. Swetz,
Eric R. Switzer,
Robert Thornton,
and Ed Wollack
[show abstract]
[hide abstract]
ABSTRACT: We present measurements of the auto- and cross-frequency correlation power spectra of the cosmic (sub)millimeter background at 250, 350, and 500 μm (1200, 860, and 600 GHz) from observations made with the Balloon-borne Large Aperture Submillimeter Telescope (BLAST); and at 1380 and 2030 μm (218 and 148 GHz) from observations made with the Atacama Cosmology Telescope (ACT). The overlapping observations cover 8.6 deg2 in an area relatively free of Galactic dust near the south ecliptic pole. The ACT bands are sensitive to radiation from the cosmic microwave background, to the Sunyaev-Zel'dovich effect from galaxy clusters, and to emission by radio and dusty star-forming galaxies (DSFGs), while the dominant contribution to the BLAST bands is from DSFGs. We confirm and extend the BLAST analysis of clustering with an independent pipeline and also detect correlations between the ACT and BLAST maps at over 25σ significance, which we interpret as a detection of the DSFGs in the ACT maps. In addition to a Poisson component in the cross-frequency power spectra, we detect a clustered signal at 4σ, and using a model for the DSFG evolution and number counts, we successfully fit all of our spectra with a linear clustering model and a bias that depends only on redshift and not on scale. Finally, the data are compared to, and generally agree with, phenomenological models for the DSFG population. This study demonstrates the constraining power of the cross-frequency correlation technique to constrain models for the DSFGs. Similar analyses with more data will impose tight constraints on future models.
The Astrophysical Journal 12/2011; 744(1):40. · 6.02 Impact Factor
-
Amir Hajian,
Viviana Acquaviva,
Peter A. R. Ade,
Paula Aguirre,
Mandana Amiri,
John William Appel,
L. Felipe Barrientos,
Elia S. Battistelli,
John R. Bond,
Ben Brown, [......],
David N. Spergel,
Suzanne T. Staggs,
Daniel S. Swetz,
Eric R. Switzer,
Robert Thornton,
Hy Trac,
Carole Tucker,
Ryan Warne,
Ed Wollack,
and Yue Zhao
[show abstract]
[hide abstract]
ABSTRACT: We present a new calibration method based on cross-correlations with the Wilkinson Microwave Anisotropy Probe (WMAP) and apply it to data from the Atacama Cosmology Telescope (ACT). ACT's observing strategy and map-making procedure allows an unbiased reconstruction of the modes in the maps over a wide range of multipoles. By directly matching the ACT maps to WMAP observations in the multipole range of 400 < l < 1000, we determine the absolute calibration with an uncertainty of 2% in temperature. The precise measurement of the calibration error directly impacts the uncertainties in the cosmological parameters estimated from the ACT power spectra. We also present a combined map based on ACT and WMAP data that has a high signal-to-noise ratio over a wide range of multipoles.
The Astrophysical Journal 10/2011; 740(2):86. · 6.02 Impact Factor
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Felipe Menanteau,
John P. Hughes,
Cristobal Sifon,
Matt Hilton,
Jorge Gonzalez,
Leopoldo Infante,
L. Felipe Barrientos,
Andrew J. Baker,
John R. Bond,
Sudeep Das, [......],
Kavilan Moodley,
Michael D. Niemack,
Michael R. Nolta,
Lyman A. Page,
Erik D. Reese,
Neelima Sehgal,
Jon Sievers,
David N. Spergel,
Suzanne T. Staggs,
Edward Wollack
[show abstract]
[hide abstract]
ABSTRACT: We present a detailed analysis from new multi-wavelength observations of the
exceptional galaxy cluster ACT-CL J0102-4915 "El Gordo," likely the most
massive, hottest, most X-ray luminous and brightest Sunyaev-Zeldovich (SZ)
effect cluster known at z>0.6. The Atacama Cosmology Telescope collaboration
discovered El Gordo as the most significant SZ decrement in a sky survey area
of 755 deg^2. Our VLT/FORS2 spectra of 89 member galaxies yield a cluster
redshift, z=0.870, and velocity dispersion, s=1321+/-106 km/s. Our Chandra
observations reveal a hot and X-ray luminous system with an integrated
temperature of Tx=14.5+/-1.0 keV and 0.5-2.0 keV band luminosity of
Lx=(2.19+/-0.11)x10^45 h70^-2 erg/s. We obtain several statistically consistent
cluster mass estimates; using mass scaling relations with velocity dispersion,
X-ray Yx, and integrated SZ, we estimate a cluster mass of
M200a=(2.16+/-0.32)x10^15 M_sun/h70. The Chandra and VLT/FORS2 optical data
also reveal that El Gordo is undergoing a major merger between components with
a mass ratio of approximately 2 to 1. The X-ray data show significant
temperature variations from a low of 6.6+/-0.7 keV at the merging low-entropy,
high-metallicity, cool core to a high of 22+/-6 keV. We also see a wake in the
X-ray surface brightness caused by the passage of one cluster through the
other. Archival radio data at 843 MHz reveal diffuse radio emission that, if
associated with the cluster, indicates the presence of an intense double radio
relic, hosted by the highest redshift cluster yet. El Gordo is possibly a
high-redshift analog of the famous Bullet Cluster. Such a massive cluster at
this redshift is rare, although consistent with the standard L-CDM cosmology in
the lower part of its allowed mass range. Massive, high-redshift mergers like
El Gordo are unlikely to be reproduced in the current generation of numerical
N-body cosmological simulations.
09/2011;
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Graeme E. Addison,
Joanna Dunkley, Amir Hajian,
Marco Viero,
J. Richard Bond,
Sudeep Das,
Mark Devlin,
Mark Halpern,
Adam Hincks,
Renée Hlozek,
Tobias A. Marriage,
Kavilan Moodley,
Lyman A. Page,
Erik D. Reese,
Douglas Scott,
David N. Spergel,
Suzanne T. Staggs,
Edward Wollack
[show abstract]
[hide abstract]
ABSTRACT: We perform a combined fit to angular power spectra of unresolved infrared
(IR) point sources from the Planck satellite (at 217, 353, 545 and 857 GHz,
over angular scales 100 < l < 2200), the Balloon-borne Large-Aperture
Submillimeter Telescope (BLAST; 250, 350 and 500 um; 1000 < l < 9000), and from
correlating BLAST and Atacama Cosmology Telescope (ACT; 148 and 218 GHz) maps.
We find that the clustered power over the range of angular scales and
frequencies considered is well fit by a simple power law of the form C_l
\propto l^-n with n = 1.25 +/- 0.06. While the IR sources are understood to lie
at a range of redshifts, with a variety of dust properties, we find that the
frequency dependence of the clustering power can be described by the square of
a modified blackbody, nu^beta B(nu,T_eff), with a single emissivity index beta
= 2.20 +/- 0.07 and effective temperature T_eff = 9.7 K. Our predictions for
the clustering amplitude are consistent with existing ACT and South Pole
Telescope results at around 150 and 220 GHz, as is our prediction for the
effective dust spectral index, which we find to be alpha_150-220 = 3.68 +/-
0.07 between 150 and 220 GHz. Our constraints on the clustering shape and
frequency dependence can be used to model the IR clustering as a contaminant in
Cosmic Microwave Background anisotropy measurements. The combined Planck and
BLAST data also rule out a linear bias clustering model.
08/2011;
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Erik D. Reese,
Tony Mroczkowski,
Felipe Menanteau,
Matt Hilton,
Jonathan Sievers,
Paula Aguirre,
John William Appel,
Andrew J. Baker,
J. Richard Bond,
Sudeep Das, [......],
Felipe Rojas,
Neelima Sehgal,
Cristobal Sifon,
David N. Spergel,
Suzanne T. Staggs,
Daniel S. Swetz,
Eric R. Switzer,
Robert Thornton,
Hy Trac,
Edward J. Wollack
[show abstract]
[hide abstract]
ABSTRACT: We present follow-up observations with the Sunyaev-Zel'dovich Array (SZA) of
optically-confirmed galaxy clusters found in the equatorial survey region of
the Atacama Cosmology Telescope (ACT): ACT-CL J0022-0036, ACT-CL J2051+0057,
and ACT-CL J2337+0016. ACT-CL J0022-0036 is a newly-discovered, massive (10^15
Msun), high-redshift (z=0.81) cluster revealed by ACT through the
Sunyaev-Zel'dovich effect (SZE). Deep, targeted observations with the SZA allow
us to probe a broader range of cluster spatial scales, better disentangle
cluster decrements from radio point source emission, and derive more robust
integrated SZE flux and mass estimates than we can with ACT data alone. For the
two clusters we detect with the SZA we compute integrated SZE signal and derive
masses from the SZA data only. ACT-CL J2337+0016, also known as Abell 2631, has
archival Chandra data that allow an additional X-ray-based mass estimate.
Optical richness is also used to estimate cluster masses and shows good
agreement with the SZE and X-ray-based estimates. Based on the point sources
detected by the SZA in these three cluster fields and an extrapolation to ACT's
frequency, we estimate that point sources could be contaminating the SZE
decrement at the <= 20% level for some fraction of clusters.
08/2011;
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Blake D Sherwin,
Joanna Dunkley,
Sudeep Das,
John W Appel,
J Richard Bond,
C Sofia Carvalho,
Mark J Devlin,
Rolando Dünner,
Thomas Essinger-Hileman,
Joseph W Fowler, [......],
Benjamin L Schmitt,
Neelima Sehgal,
Jon Sievers,
David N Spergel,
Suzanne T Staggs,
Daniel S Swetz,
Eric R Switzer,
Robert Thornton,
Katerina Visnjic,
Ed Wollack
[show abstract]
[hide abstract]
ABSTRACT: For the first time, measurements of the cosmic microwave background radiation (CMB) alone favor cosmologies with w = -1 dark energy over models without dark energy at a 3.2-sigma level. We demonstrate this by combining the CMB lensing deflection power spectrum from the Atacama Cosmology Telescope with temperature and polarization power spectra from the Wilkinson Microwave Anisotropy Probe. The lensing data break the geometric degeneracy of different cosmological models with similar CMB temperature power spectra. Our CMB-only measurement of the dark energy density Ω(Λ) confirms other measurements from supernovae, galaxy clusters, and baryon acoustic oscillations, and demonstrates the power of CMB lensing as a new cosmological tool.
Physical Review Letters 07/2011; 107(2):021302. · 7.37 Impact Factor
