10 research outputs found
The Atacama Cosmology Telescope: Extragalactic Sources at 148 GHz in the 2008 Survey
We report on extragalactic sources detected in a 455 square-degree map of the
southern sky made with data at a frequency of 148 GHz from the Atacama
Cosmology Telescope 2008 observing season. We provide a catalog of 157 sources
with flux densities spanning two orders of magnitude: from 15 to 1500 mJy.
Comparison to other catalogs shows that 98% of the ACT detections correspond to
sources detected at lower radio frequencies. Three of the sources appear to be
associated with the brightest cluster galaxies of low redshift X-ray selected
galaxy clusters. Estimates of the radio to mm-wave spectral indices and
differential counts of the sources further bolster the hypothesis that they are
nearly all radio sources, and that their emission is not dominated by
re-emission from warm dust. In a bright (>50 mJy) 148 GHz-selected sample with
complete cross-identifications from the Australia Telescope 20 GHz survey, we
observe an average steepening of the spectra between 5, 20, and 148 GHz with
median spectral indices of , , and . When the
measured spectral indices are taken into account, the 148 GHz differential
source counts are consistent with previous measurements at 30 GHz in the
context of a source count model dominated by radio sources. Extrapolating with
an appropriately rescaled model for the radio source counts, the Poisson
contribution to the spatial power spectrum from synchrotron-dominated sources
with flux density less than 20 mJy is C^{\rm Sync} = (2.8 \pm 0.3) \times
10^{-6} \micro\kelvin^2.Comment: Accepted to Ap
The Atacama Cosmology Telescope: Cosmological parameters from three seasons of data
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.Comment: 26 pages, 22 figures. This paper is a companion to Das et al. (2013)
and Dunkley et al. (2013). Matches published JCAP versio
The Atacama Cosmology Telescope: Data Characterization and Map Making
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.Comment: 20 pages, 18 figures, 6 tables, an ACT Collaboration pape
The Atacama Cosmology Telescope: Sunyaev Zel'dovich Selected Galaxy Clusters at 148 GHz in the 2008 Survey
We report on twenty-three clusters detected blindly as Sunyaev-Zel'dovich
(SZ) decrements in a 148 GHz, 455 square-degree map of the southern sky made
with data from the Atacama Cosmology Telescope 2008 observing season. All SZ
detections announced in this work have confirmed optical counterparts. Ten of
the clusters are new discoveries. One newly discovered cluster, ACT-CL
J0102-4915, with a redshift of 0.75 (photometric), has an SZ decrement
comparable to the most massive systems at lower redshifts. Simulations of the
cluster recovery method reproduce the sample purity measured by optical
follow-up. In particular, for clusters detected with a signal-to-noise ratio
greater than six, simulations are consistent with optical follow-up that
demonstrated this subsample is 100% pure. The simulations further imply that
the total sample is 80% complete for clusters with mass in excess of 6x10^14
solar masses referenced to the cluster volume characterized by five hundred
times the critical density. The Compton y -- X-ray luminosity mass comparison
for the eleven best detected clusters visually agrees with both self-similar
and non-adiabatic, simulation-derived scaling laws.Comment: 13 pages, 7 figures, Accepted for publication in Ap
The Atacama Cosmology Telescope: Cosmology from Galaxy Clusters Detected via the Sunyaev-Zel'dovich Effect
We present constraints on cosmological parameters based on a sample of
Sunyaev-Zel'dovich-selected galaxy clusters detected in a millimeter-wave
survey by the Atacama Cosmology Telescope. The cluster sample used in this
analysis consists of 9 optically-confirmed high-mass clusters comprising the
high-significance end of the total cluster sample identified in 455 square
degrees of sky surveyed during 2008 at 148 GHz. We focus on the most massive
systems to reduce the degeneracy between unknown cluster astrophysics and
cosmology derived from SZ surveys. We describe the scaling relation between
cluster mass and SZ signal with a 4-parameter fit. Marginalizing over the
values of the parameters in this fit with conservative priors gives sigma_8 =
0.851 +/- 0.115 and w = -1.14 +/- 0.35 for a spatially-flat wCDM cosmological
model with WMAP 7-year priors on cosmological parameters. This gives a modest
improvement in statistical uncertainty over WMAP 7-year constraints alone.
Fixing the scaling relation between cluster mass and SZ signal to a fiducial
relation obtained from numerical simulations and calibrated by X-ray
observations, we find sigma_8 = 0.821 +/- 0.044 and w = -1.05 +/- 0.20. These
results are consistent with constraints from WMAP 7 plus baryon acoustic
oscillations plus type Ia supernoava which give sigma_8 = 0.802 +/- 0.038 and w
= -0.98 +/- 0.053. A stacking analysis of the clusters in this sample compared
to clusters simulated assuming the fiducial model also shows good agreement.
These results suggest that, given the sample of clusters used here, both the
astrophysics of massive clusters and the cosmological parameters derived from
them are broadly consistent with current models.Comment: 12 pages, 7 figures. Submitted to Ap
Obsessive-Compulsive Disorder Misdiagnosis among Mental Healthcare Providers in Latin America
Mental healthcare professionals often have limited awareness of different obsessive-compulsive disorder (OCD) symptom presentations, which may contribute to years between OCD symptom onset and treatment initiation. While research has identified high rates of OCD misdiagnosis among clinicians from the United States and Canada, research on OCD symptom awareness among healthcare providers in Latin American (LATAM) regions is limited. In this study, LATAM mental healthcare providers (N = 83) provided diagnostic impressions based on five OCD vignettes: three with symptoms centered on taboo thoughts (sexual, harming others, and religion/scrupulosity) and two about contamination or symmetry obsessions. Rates of incorrect (non-OCD) diagnoses were significantly higher for the taboo thoughts vignettes (sexual, 52.7%; harm/aggression, 42.0%; and religious, 34.7%) vs. contamination obsessions (11.0%) and symmetry obsessions (6.9%). The OCD vignette depicting sexual obsessions was often attributed to a paraphilic disorder (36.5%). Bachelor\u27s level clinicians had significantly lower odds of accurately identifying all three vignettes related to taboo thoughts compared to respondents with a graduate degree. Accurate identification of the three taboo vignettes was also associated with first-line psychological treatment recommendations (i.e., cognitive-behavioral therapy) even when controlling for respondents\u27 theoretical orientation. Exposure was rarely mentioned when clinicians were prompted to provide treatment recommendations for each vignette (8-9% of the time for symmetry and contamination vignettes, 5-7% for taboo though vignettes). Like clinicians in the United States and Canada, mental health professionals in LATAM may misidentify OCD symptom presentations, particularly sexual obsessions, highlighting a need for education and training
Parent-led, Stepped-care Cognitive-behavioral Therapy for Youth with Autism and Co-occurring Anxiety: Study Rationale and Method
Anxiety disorders affect up to 50% of individuals with autism spectrum disorder (ASD) and are significantly impairing to the person affected, as well as to their loved ones. Cognitive-behavioral therapy (CBT) has been established as the gold-standard treatment for anxiety disorders among typically developing youth and adults, and demonstrates similar efficacy among youth with high-functioning autism (HFA). Many CBT interventions utilize a “full-package” treatment approach to treat co-occurring anxiety in youth with ASD. However, these service delivery systems are often therapist-intensive, costly, and impractical, thereby compromising full engagement and treatment adherence. This paper describes the design, rationale, and methodology of a study examining stepped-care CBT for youth with HFA and co-occurring anxiety – a clinical trial examining the efficacy of low-intensity, parent-led CBT as the first line of treatment and utilizing a more intensive, therapist-led intervention for nonresponders. The study will evaluate the potential benefits of stepped-care and parent-led therapist-assisted interventions, predictors of treatment response, and the economic value of using a stepped-care model. Implications for practice will be discussed
The Atacama Cosmology Telescope: Calibration with WMAP Using Cross-Correlations
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 mapmaking
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 ATACAMA COSMOLOGY TELESCOPE: COSMOLOGY FROM GALAXY CLUSTERS DETECTED VIA THE SUNYAEV-ZEL'DOVICH EFFECT
We present constraints on cosmological parameters based on a sample of Sunyaev-Zel'dovich-selected (SZ-selected) galaxy clusters detected in a millimeter-wave survey by the Atacama Cosmology Telescope. The cluster sample used in this analysis consists of nine optically confirmed high-mass clusters comprising the high-significance end of the total cluster sample identified in 455 deg(2) of sky surveyed during 2008 at 148 GHz. We focus on the most massive systems to reduce the degeneracy between unknown cluster astrophysics and cosmology derived from SZ surveys. We describe the scaling relation between cluster mass and SZ signal with a four-parameter fit. Marginalizing over the values of the parameters in this fit with conservative priors gives sigma(8) = 0.851 +/- 0.115 and omega = -1.14 +/- 0.35 for a spatially flat wCDM cosmological model with Wilkinson Microwave Anisotropy Probe (WMAP) seven-year priors on cosmological parameters. This gives a modest improvement in statistical uncertainty over WMAP seven-year constraints alone. Fixing the scaling relation between the cluster mass and SZ signal to a fiducial relation obtained from numerical simulations and calibrated by X-ray observations, we find sigma(8) = 0.821 +/- 0.044 and omega = -1.05 +/- 0.20. These results are consistent with constraints from WMAP7 plus baryon acoustic oscillations plus Type Ia supernova which give sigma(8) = 0.802 +/- 0.038 and omega = -0.98 +/- 0.053. A stacking analysis of the clusters in this sample compared to clusters simulated assuming the fiducial model also shows good agreement. These results suggest that, given the sample of clusters used here, both the astrophysics of massive clusters and the cosmological parameters derived from them are broadly consistent with current models
THE ATACAMA COSMOLOGY TELESCOPE: CALIBRATION WITH THE WILKINSON MICROWAVE ANISOTROPY PROBE
We present a new calibration method based on cross-correlations with 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 < ell < 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
high signal-to-noise over a wide range of multipoles.Comment: Submitted to ApJ. This is a companion to Das et al (2010) and Dunkley
et al (2010