-
R Dünner,
M Hasselfield,
T ~A Marriage,
J Sievers,
V Acquaviva,
G ~E Addison,
P ~A ~R Ade,
P Aguirre,
M Amiri, J ~W Appel, [......],
S ~T Staggs,
D ~S Swetz,
E ~R Switzer,
R Thornton,
H Trac,
C Tucker,
R Warne,
G Wilson,
E Wollack,
Y Zhao
apj. 01/2013; 762:10.
-
D. S. Swetz,
P. A. R. Ade,
M. Amiri, J. W. Appel,
E. S. Battistelli,
B. Burger,
J. Chervenak,
M. J. Devlin,
S. R. Dicker,
W. B. Doriese, [......],
M. R. Nolta,
L. A. Page,
L. Parker,
S. T. Staggs,
O. Stryzak,
E. R. Switzer,
R. Thornton,
C. Tucker,
E. Wollack,
and Y. Zhao
[show abstract]
[hide abstract]
ABSTRACT: The Atacama Cosmology Telescope was designed to measure small-scale anisotropies in the cosmic microwave background and detect galaxy clusters through the Sunyaev-Zel'dovich effect. The instrument is located on Cerro Toco in the Atacama Desert, at an altitude of 5190 m. A 6 m off-axis Gregorian telescope feeds a new type of cryogenic receiver, the Millimeter Bolometer Array Camera. The receiver features three 1000-element arrays of transition-edge sensor bolometers for observations at 148 GHz, 218 GHz, and 277 GHz. Each detector array is fed by free space millimeter-wave optics. Each frequency band has a field of view of approximately 22' × 26'. The telescope was commissioned in 2007 and has completed its third year of operations. We discuss the major components of the telescope, camera, and related systems, and summarize the instrument performance.
The Astrophysical Journal Supplement Series 05/2011; 194(2):41. · 13.46 Impact Factor
-
A. D. Hincks,
V. Acquaviva,
P. A. R. Ade,
P. Aguirre,
M. Amiri, J. W. Appel,
L. F. Barrientos,
E. S. Battistelli,
J. R. Bond,
B. Brown, [......],
D. S. Swetz,
E. R. Switzer,
R. Thornton,
H. Trac,
C. Tucker,
L. Verde,
R. Warne,
G. Wilson,
E. Wollack,
and Y. Zhao
[show abstract]
[hide abstract]
ABSTRACT: The Atacama Cosmology Telescope (ACT) is currently observing the cosmic microwave background with arcminute resolution at 148 GHz, 218 GHz, and 277 GHz. In this paper, we present ACT's first results. Data have been analyzed using a maximum-likelihood map-making method which uses B-splines to model and remove the atmospheric signal. It has been used to make high-precision beam maps from which we determine the experiment's window functions. This beam information directly impacts all subsequent analyses of the data. We also used the method to map a sample of galaxy clusters via the Sunyaev-Zel'dovich (SZ) effect and show five clusters previously detected with X-ray or SZ observations. We provide integrated Compton-y measurements for each cluster. Of particular interest is our detection of the z = 0.44 component of A3128 and our current non-detection of the low-redshift part, providing strong evidence that the further cluster is more massive as suggested by X-ray measurements. This is a compelling example of the redshift-independent mass selection of the SZ effect.
The Astrophysical Journal Supplement Series 12/2010; 191(2):423. · 13.46 Impact Factor
-
T. A. Marriage,
V. Acquaviva,
P. A. R. Ade,
P. Aguirre,
M. Amiri, J. W. Appel,
L. F. Barrientos,
E. S. Battistelli,
J. R. Bond,
B Brown, [......],
S. T. Staggs,
D. S. Swetz,
E. R. Switzer,
R. Thornton,
H. Trac,
C. Tucker,
R. Warne,
G Wilson,
E. Wollack,
Y Zhao
[show abstract]
[hide abstract]
ABSTRACT: 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.
10/2010;
-
J. Dunkley,
R. Hlozek,
J. Sievers,
V. Acquaviva,
P. A. R. Ade,
P. Aguirre,
M. Amiri, J. W. Appel,
L. F. Barrientos,
E. S. Battistelli, [......],
D. N. Spergel,
S. T. Staggs,
D. S. Swetz,
E. R. Switzer,
R. Thornton,
H. Trac,
C. Tucker,
R. Warne,
E. Wollack,
Y Zhao
[show abstract]
[hide abstract]
ABSTRACT: We present cosmological parameters derived from the angular power spectrum of the cosmic microwave background (CMB) radiation observed at 148 GHz and 218 GHz over 296 deg^2 with the Atacama Cosmology Telescope (ACT) during its 2008 season. ACT measures fluctuations at scales 500<l<10000. We fit a model for the lensed CMB, Sunyaev-Zel'dovich (SZ), and foreground contribution to the 148 GHz and 218 GHz power spectra, including thermal and kinetic SZ, Poisson power from radio and infrared point sources, and clustered power from infrared point sources. The power from thermal and kinetic SZ at 148 GHz is estimated to be B_3000 = 6.8+-2.9 uK^2, where B_l=l(l+1)C_l/2pi. We estimate primary cosmological parameters from the 148 GHz spectrum, marginalizing over SZ and source power. The LCDM cosmological model is a good fit to the data, and LCDM parameters estimated from ACT+WMAP are consistent with the 7-year WMAP limits, with scale invariant n_s = 1 excluded at 99.7% CL (3sigma). A model with no CMB lensing is disfavored at 2.8sigma. By measuring the third to seventh acoustic peaks, and probing the Silk damping regime, the ACT data improve limits on cosmological parameters that affect the small-scale CMB power. The ACT data combined with WMAP give a 6sigma detection of primordial helium, with Y_P = 0.313+-0.044, and a 4sigma detection of relativistic species, assumed to be neutrinos, with Neff = 5.3+-1.3 (4.6+-0.8 with BAO+H0 data). From the CMB alone the running of the spectral index is constrained to be dn/dlnk = -0.034 +- 0.018, the limit on the tensor-to-scalar ratio is r<0.25 (95% CL), and the possible contribution of Nambu cosmic strings to the power spectrum is constrained to string tension Gmu<1.6 \times 10^-7 (95% CL). Comment: 20 pages, 13 figures. Submitted to ApJ. This paper is a companion to Hajian et al. (2010) and Das et al. (2010)
09/2010;
-
T. Essinger-Hileman, J. W. Appel,
J.A. Beall,
H. M. Cho,
J. Fowler,
M. Halpern,
M. Hasselfield,
K. D. Irwin,
T. A. Marriage,
M. D. Niemack,
L. Page,
L. P. Parker,
S. Pufu,
S. T. Staggs,
O. Stryzak,
C. Visnjic,
K. W. Yoon,
Y Zhao
[show abstract]
[hide abstract]
ABSTRACT: The Atacama B-mode Search (ABS) experiment is a 145 GHz polarimeter designed to measure the B-mode polarization of the Cosmic Microwave Background (CMB) at large angular scales. The ABS instrument will ship to the Atacama Desert of Chile fully tested and ready to observe in 2010. ABS will image large-angular-scale CMB polarization anisotropies onto a focal plane of 240 feedhorn-coupled, transition-edge sensor (TES) polarimeters, using a cryogenic crossed-Dragone design. The ABS detectors, which are fabricated at NIST, use orthomode transducers to couple orthogonal polarizations of incoming radiation onto separate TES bolometers. The incoming radiation is modulated by an ambient-temperature half-wave plate in front of the vacuum window at an aperture stop. Preliminary detector characterization indicates that the ABS detectors can achieve a sensitivity of 300 $\mu K \sqrt{s}$ in the field. This paper describes the ABS optical design and detector readout scheme, including feedhorn design and performance, magnetic shielding, focal plane architecture, and cryogenic electronics. Comment: 4 pages, 5 figures, Proceedings of the Thirteenth International Conference on Low-Temperature Detectors
08/2010;
-
T. A. Marriage,
J. B. Juin,
Y T Lin,
D. Marsden,
M. R. Nolta,
B. Partridge,
P. A. R. Ade,
P. Aguirre,
M. Amiri, J. W. Appel, [......],
S. T. Staggs,
D. S. Swetz,
E. R. Switzer,
R. Thornton,
H. Trac,
C. Tucker,
R. Warne,
G Wilson,
E. Wollack,
Y Zhao
[show abstract]
[hide abstract]
ABSTRACT: 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 $\alpha_{\rm 5-20} = -0.07 \pm 0.06$, $\alpha_{\rm
20-148} = -0.39 \pm0.04$, and $\alpha_{\rm 5-148} = -0.20 \pm 0.03$. 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 $C^{\rm Sync} = (2.8 \pm 0.3) \times
10^{-6} \micro\kelvin^2$.
J. Sievers D. N. Spergel E. R. Switzer. 07/2010; 192410510101910101510291(13).
-
D. S. Swetz,
P. A. R. Ade,
M. Amiri, J. W. Appel,
E. S. Battistelli,
B. Burger,
J. Chervenak,
M. J. Devlin,
S. R. Dicker,
W. B. Doriese, [......],
M. R. Nolta,
L. A. Page,
L. Parker,
S. T. Staggs,
O. Stryzak,
E. R. Switzer,
R. Thornton,
C. Tucker,
E. Wollack,
Y Zhao
[show abstract]
[hide abstract]
ABSTRACT: The Atacama Cosmology Telescope was designed to measure small-scale
anisotropies in the Cosmic Microwave Background and detect galaxy clusters
through the Sunyaev-Zel'dovich effect. The instrument is located on Cerro Toco
in the Atacama Desert, at an altitude of 5190 meters. A six-meter off-axis
Gregorian telescope feeds a new type of cryogenic receiver, the Millimeter
Bolometer Array Camera. The receiver features three 1000-element arrays of
transition-edge sensor bolometers for observations at 148 GHz, 218 GHz, and 277
GHz. Each detector array is fed by free space mm-wave optics. Each frequency
band has a field of view of approximately 22' x 26'. The telescope was
commissioned in 2007 and has completed its third year of operations. We discuss
the major components of the telescope, camera, and related systems, and
summarize the instrument performance.
07/2010;
-
J. W. Fowler,
V. Acquaviva,
P. A. R. Ade,
P. Aguirre,
M. Amiri, J. W. Appel,
L. F. Barrientos,
E. S. Battistelli,
J. R. Bond,
B Brown, [......],
E. R. Switzer,
R. Thornton,
H. Trac,
C. Tucker,
L. Verde,
R. Warne,
G Wilson,
E. Wollack,
Y Zhao,
the ACT Collaboration
[show abstract]
[hide abstract]
ABSTRACT: We present a measurement of the angular power spectrum of the cosmic microwave background (CMB) radiation observed at 148 GHz. The measurement uses maps with 1.4' angular resolution made with data from the Atacama Cosmology Telescope (ACT). The observations cover 228 square degrees of the southern sky, in a 4.2-degree-wide strip centered on declination 53 degrees South. The CMB at arcminute angular scales is particularly sensitive to the Silk damping scale, to the Sunyaev-Zel'dovich (SZ) effect from galaxy clusters, and to emission by radio sources and dusty galaxies. After masking the 108 brightest point sources in our maps, we estimate the power spectrum between 600 < \ell < 8000 using the adaptive multi-taper method to minimize spectral leakage and maximize use of the full data set. Our absolute calibration is based on observations of Uranus. To verify the calibration and test the fidelity of our map at large angular scales, we cross-correlate the ACT map to the WMAP map and recover the WMAP power spectrum from 250 < ell < 1150. The power beyond the Silk damping tail of the CMB is consistent with models of the emission from point sources. We quantify the contribution of SZ clusters to the power spectrum by fitting to a model normalized at sigma8 = 0.8. We constrain the model's amplitude ASZ < 1.63 (95% CL). If interpreted as a measurement of sigma8, this implies sigma8^SZ < 0.86 (95% CL) given our SZ model. A fit of ACT and WMAP five-year data jointly to a 6-parameter LCDM model plus terms for point sources and the SZ effect is consistent with these results. Comment: 15 pages, 8 figures. Accepted for publication in ApJ
01/2010;
-
J. E. Austermann,
M. D. Niemack, J. W. Appel,
J. A. Beall,
D. Becker,
D. A. Bennett,
B. A. Benson,
L. E. Bleem,
J. Britton,
J. E. Carlstrom, [......],
J. McMahon,
J. Mehl,
S. S. Meyer,
L. P. Parker,
S. M. Simon,
S. T. Staggs,
J. N. Ullom,
C. Visnjic,
K. W. Yoon,
Y. Zhao
[show abstract]
[hide abstract]
ABSTRACT: We are developing feedhorn‐coupled TES polarimeters to measure the polarization anisotropies of the cosmic microwave background (CMB) radiation. These devices will be deployed in arrays of hundreds to thousands and will be measured using multiplexed SQUID readout electronics. Since multiplexed devices share common circuitry, a high degree of uniformity is required in the electrothermal properties of the TES bolometers and readout circuits in order to operate all channels simultaneously with high sensitivity. Our cryogenic test bed can probe dozens of devices simultaneously, thus providing useful detector statistics on relatively short time scales. We describe the TES bolometer design and present dark (no optical loading) measurements of the electrical and thermal properties and uniformity of prototype bolometers across two 3‐inch diameter production wafers, including (standard deviation in parenthesis): TES transition temperature (∼1%), normal resistance (∼10%), thermal conductance (≲10%), time constant (∼20%), shunt resistance (≲5%), and noise properties.
AIP Conference Proceedings. 12/2009; 1185(1):498-501.
-
D. S. Swetz,
P. A. R. Ade,
C. Allen,
M. Amiri, J. W. Appel,
E. S. Battistelli,
B. Burger,
J. A. Chervenak,
A. J. Dahlen,
S. Das, [......],
N. Sehgal,
J. L. Sievers,
D. N. Spergel,
S. T. Staggs,
O. R. Stryzak,
E. R. Switzer,
R. J. Thornton,
C. Tucker,
E. J. Wollack,
Y. Zhao
[show abstract]
[hide abstract]
ABSTRACT: The Millimeter Bolometer Array Camera (MBAC) was commissioned in the fall of 2007 on the new 6-meter
Atacama Cosmology Telescope (ACT). The MBAC on the ACT will map the temperature anisotropies of the
Cosmic Microwave Background (CMB) with arc-minute resolution. For this first observing season, the MBAC
contained a diffraction-limited, 32 by 32 element, focal plane array of Transition Edge Sensor (TES) bolometers
for observations at 145 GHz. This array was coupled to the telescope with a series of cold, refractive, reimaging
optics. To meet the performance specifications, the MBAC employs four stages of cooling using closed-cycle
3He/4He sorption fridge systems in combination with pulse tube coolers. In this paper we present the design of
the instrument and discuss its performance during the first observing season. Finally, we report on the status
of the MBAC for the 2008 observing season, when the instrument will be upgraded to a total of three separate
1024-element arrays at 145 GHz, 220 GHz and 280 GHz.© (2008) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
08/2008;
-
A ~D Hincks,
P ~A ~R Ade,
C Allen,
M Amiri, J ~W Appel,
E ~S Battistelli,
B Burger,
J ~A Chervenak,
A ~J Dahlen,
S Denny, [......],
L ~P Parker,
A ~J Sederberg,
S ~T Staggs,
O ~R Stryzak,
D ~S Swetz,
E ~R Switzer,
R ~J Thornton,
C Tucker,
E ~J Wollack,
Y Zhao
Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series; 08/2008
-
D ~S Swetz,
P ~A ~R Ade,
C Allen,
M Amiri, J ~W Appel,
E ~S Battistelli,
B Burger,
J ~A Chervenak,
A ~J Dahlen,
S Das, [......],
N Sehgal,
J ~L Sievers,
D ~N Spergel,
S ~T Staggs,
O ~R Stryzak,
E ~R Switzer,
R ~J Thornton,
C Tucker,
E ~J Wollack,
Y Zhao
Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series; 08/2008
-
Y Zhao,
C Allen,
M Amiri, J ~W Appel,
E ~S Battistelli,
B Burger,
J ~A Chervenak,
A ~J Dahlen,
S Denny,
M ~J Devlin, [......],
M ~D Niemack,
L Page,
L ~P Parker,
A Sederberg,
S ~T Staggs,
O ~R Stryzak,
D ~S Swetz,
E ~R Switzer,
R ~J Thornton,
E ~J Wollack
Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series; 08/2008
-
E ~R Switzer,
C Allen,
M Amiri, J ~W Appel,
E ~S Battistelli,
B Burger,
J ~A Chervenak,
A ~J Dahlen,
S Das,
M ~J Devlin, [......],
C ~D Reintsema,
A ~J Sederberg,
J ~L Sievers,
D ~N Spergel,
S ~T Staggs,
O ~R Stryzak,
D ~S Swetz,
R ~J Thornton,
E ~J Wollack,
Y Zhao
Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series; 08/2008
-
R J Thornton,
P A R Ade,
C Allen,
M Amiri, J W Appel,
E S Battistelli,
B Burger,
J A Chervenak,
M J Devlin,
S R Dicker, [......],
L P Parker,
J Reidel,
C D Reintsema,
S T Staggs,
O R Stryzak,
D S Swetz,
E R Switzer,
C Tucker,
E J Wollack,
Y Zhao
[show abstract]
[hide abstract]
ABSTRACT: The 6-meter Atacama Cosmology Telescope will map the cosmic microwave background at millimeter wave-lengths. The commissioning instrument for the telescope, the Millimeter Bolometer Array Camera, is based on a refractive optical system which simultaneously images three separate fields of view at three different frequencies: 145, 220, and 280 GHz. Each frequency band contains around twelve individual optical elements at five different temperature stages ranging from 300 K to 300 mK and a 32 x 32 array of Transition Edge Sensor bolometers at 300 mK. We discuss the design of the close-packed on-axis optical design of the three frequencies. The thermal design and performance of the system are presented in the context of the scientific requirements and observing schedule. A major part of the design was the incorporation of multiple layers of magnetic shielding. We discuss Send correspondence to rthornton@wcupa.edu Copyright 2008 Society of Photo-Optical Instrumentation Engineers. This paper was published in the Proceedings of the Astronomical Instrumentation Conference (7020-7) and is made available as an electronic reprint with permission of SPIE. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited. the performance of the 145 GHz optical system in 2007 and the implementation of the additional two frequency channels in 2008.
