55 research outputs found
Performance and on-sky optical characterization of the SPTpol instrument
In January 2012, the 10m South Pole Telescope (SPT) was equipped with a
polarization-sensitive camera, SPTpol, in order to measure the polarization
anisotropy of the cosmic microwave background (CMB). Measurements of the
polarization of the CMB at small angular scales (~several arcminutes) can
detect the gravitational lensing of the CMB by large scale structure and
constrain the sum of the neutrino masses. At large angular scales (~few
degrees) CMB measurements can constrain the energy scale of Inflation. SPTpol
is a two-color mm-wave camera that consists of 180 polarimeters at 90 GHz and
588 polarimeters at 150 GHz, with each polarimeter consisting of a dual
transition edge sensor (TES) bolometers. The full complement of 150 GHz
detectors consists of 7 arrays of 84 ortho-mode transducers (OMTs) that are
stripline coupled to two TES detectors per OMT, developed by the TRUCE
collaboration and fabricated at NIST. Each 90 GHz pixel consists of two
antenna-coupled absorbers coupled to two TES detectors, developed with Argonne
National Labs. The 1536 total detectors are read out with digital
frequency-domain multiplexing (DfMUX). The SPTpol deployment represents the
first on-sky tests of both of these detector technologies, and is one of the
first deployed instruments using DfMUX readout technology. We present the
details of the design, commissioning, deployment, on-sky optical
characterization and detector performance of the complete SPTpol focal plane.Comment: 15 pages, 6 figures. Conference: SPIE Astronomical Telescopes and
Instrumentation 201
Design and characterization of 90 GHz feedhorn-coupled TES polarimeter pixels in the SPTpol camera
The SPTpol camera is a two-color, polarization-sensitive bolometer receiver,
and was installed on the 10 meter South Pole Telescope in January 2012. SPTpol
is designed to study the faint polarization signals in the Cosmic Microwave
Background, with two primary scientific goals. One is to constrain the
tensor-to-scalar ratio of perturbations in the primordial plasma, and thus
constrain the space of permissible inflationary models. The other is to measure
the weak lensing effect of large-scale structure on CMB polarization, which can
be used to constrain the sum of neutrino masses as well as other growth-related
parameters. The SPTpol focal plane consists of seven 84-element monolithic
arrays of 150 GHz pixels (588 total) and 180 individual 90 GHz single-pixel
modules. In this paper we present the design and characterization of the 90 GHz
modules
Feedhorn-coupled TES polarimeter camera modules at 150 GHz for CMB polarization measurements with SPTpol
The SPTpol camera is a dichroic polarimetric receiver at 90 and 150 GHz.
Deployed in January 2012 on the South Pole Telescope (SPT), SPTpol is looking
for faint polarization signals in the Cosmic Microwave Background (CMB). The
camera consists of 180 individual Transition Edge Sensor (TES) polarimeters at
90 GHz and seven 84-polarimeter camera modules (a total of 588 polarimeters) at
150 GHz. We present the design, dark characterization, and in-lab optical
properties of the 150 GHz camera modules. The modules consist of
photolithographed arrays of TES polarimeters coupled to silicon platelet arrays
of corrugated feedhorns, both of which are fabricated at NIST-Boulder. In
addition to mounting hardware and RF shielding, each module also contains a set
of passive readout electronics for digital frequency-domain multiplexing. A
single module, therefore, is fully functional as a miniature focal plane and
can be tested independently. Across the modules tested before deployment, the
detectors average a critical temperature of 478 mK, normal resistance R_N of
1.2 Ohm, unloaded saturation power of 22.5 pW, (detector-only) optical
efficiency of ~ 90%, and have electrothermal time constants < 1 ms in
transition.Comment: 15 pages, 11 figure
Extragalactic millimeter-wave point source catalog, number counts and statistics from 771 square degrees of the SPT-SZ Survey
We present a point source catalog from 771 square degrees of the South Pole
Telescope Sunyaev Zel'dovich (SPT-SZ) survey at 95, 150, and 220 GHz. We detect
1545 sources above 4.5 sigma significance in at least one band. Based on their
relative brightness between survey bands, we classify the sources into two
populations, one dominated by synchrotron emission from active galactic nuclei,
and one dominated by thermal emission from dust-enshrouded star-forming
galaxies. We find 1238 synchrotron and 307 dusty sources. We cross-match all
sources against external catalogs and find 189 unidentified synchrotron sources
and 189 unidentified dusty sources. The dusty sources without counterparts are
good candidates for high-redshift, strongly lensed submillimeter galaxies. We
derive number counts for each population from 1 Jy down to roughly 9, 5, and 11
mJy at 95, 150, and 220 GHz. We compare these counts with galaxy population
models and find that none of the models we consider for either population
provide a good fit to the measured counts in all three bands. The disparities
imply that these measurements will be an important input to the next generation
of millimeter-wave extragalactic source population models.Comment: 23 pages, 8 figures, submitted to Ap
South Pole Telescope Software Systems: Control, Monitoring, and Data Acquisition
We present the software system used to control and operate the South Pole
Telescope. The South Pole Telescope is a 10-meter millimeter-wavelength
telescope designed to measure anisotropies in the cosmic microwave background
(CMB) at arcminute angular resolution. In the austral summer of 2011/12, the
SPT was equipped with a new polarization-sensitive camera, which consists of
1536 transition-edge sensor bolometers. The bolometers are read out using 36
independent digital frequency multiplexing (\dfmux) readout boards, each with
its own embedded processors. These autonomous boards control and read out data
from the focal plane with on-board software and firmware. An overall control
software system running on a separate control computer controls the \dfmux
boards, the cryostat and all other aspects of telescope operation. This control
software collects and monitors data in real-time, and stores the data to disk
for transfer to the United States for analysis
A Measurement of the Correlation of Galaxy Surveys with CMB Lensing Convergence Maps from the South Pole Telescope
We compare cosmic microwave background lensing convergence maps derived from South Pole Telescope (SPT) data with galaxy survey data from the Blanco Cosmology Survey, WISE, and a new large Spitzer/IRAC field designed to overlap with the SPT survey. Using optical and infrared catalogs covering between 17 and 68 deg^2 of sky, we detect a correlation between the SPT convergence maps and each of the galaxy density maps at >4σ, with zero correlation robustly ruled out in all cases. The amplitude and shape of the cross-power spectra are in good agreement with theoretical expectations and the measured galaxy bias is consistent with previous work. The detections reported here utilize a small fraction of the full 2500 deg^2 SPT survey data and serve as both a proof of principle of the technique and an illustration of the potential of this emerging cosmological probe
Optical Spectroscopy and Velocity Dispersions of Galaxy Clusters from the SPT-SZ Survey
We present optical spectroscopy of galaxies in clusters detected through the
Sunyaev-Zel'dovich (SZ) effect with the South Pole Telescope (SPT). We report
our own measurements of spectroscopic cluster redshifts, and velocity
dispersions each calculated with more than member galaxies. This catalog
also includes dispersions of SPT-observed clusters previously reported in
the literature. The majority of the clusters in this paper are SPT-discovered;
of these, most have been previously reported in other SPT cluster catalogs, and
five are reported here as SPT discoveries for the first time. By performing a
resampling analysis of galaxy velocities, we find that unbiased velocity
dispersions can be obtained from a relatively small number of member galaxies
(), but with increased systematic scatter. We use this analysis to
determine statistical confidence intervals that include the effect of
membership selection. We fit scaling relations between the observed cluster
velocity dispersions and mass estimates from SZ and X-ray observables. In both
cases, the results are consistent with the scaling relation between velocity
dispersion and mass expected from dark-matter simulations. We measure a
30% log-normal scatter in dispersion at fixed mass, and a 10%
offset in the normalization of the dispersion-mass relation when compared to
the expectation from simulations, which is within the expected level of
systematic uncertainty.Comment: Accepted to ApJ. 20 pages, 6 figure
A Massive, Cooling-Flow-Induced Starburst in the Core of a Highly Luminous Galaxy Cluster
In the cores of some galaxy clusters the hot intracluster plasma is dense
enough that it should cool radiatively in the cluster's lifetime, leading to
continuous "cooling flows" of gas sinking towards the cluster center, yet no
such cooling flow has been observed. The low observed star formation rates and
cool gas masses for these "cool core" clusters suggest that much of the cooling
must be offset by astrophysical feedback to prevent the formation of a runaway
cooling flow. Here we report X-ray, optical, and infrared observations of the
galaxy cluster SPT-CLJ2344-4243 at z = 0.596. These observations reveal an
exceptionally luminous (L_2-10 keV = 8.2 x 10^45 erg/s) galaxy cluster which
hosts an extremely strong cooling flow (dM/dt = 3820 +/- 530 Msun/yr). Further,
the central galaxy in this cluster appears to be experiencing a massive
starburst (740 +/- 160 Msun/yr), which suggests that the feedback source
responsible for preventing runaway cooling in nearby cool core clusters may not
yet be fully established in SPT-CLJ2344-4243. This large star formation rate
implies that a significant fraction of the stars in the central galaxy of this
cluster may form via accretion of the intracluster medium, rather than the
current picture of central galaxies assembling entirely via mergers.Comment: 11 pages, 3 figures, 1 table. Supplemental material contains 15
additional pages. Published in Natur
- …