-
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.
-
M. Roesch,
A. Benoit,
A. Bideaud,
N. Boudou,
M. Calvo,
A. Cruciani,
S. Doyle,
H. G. Leduc,
A. Monfardini,
L. Swenson,
S. Leclercq, P. Mauskopf,
K. F. Schuster,
for the NIKA collaboration
[show abstract]
[hide abstract]
ABSTRACT: Lumped-element kinetic inductance detectors(LEKIDs) have recently shown
considerable promise as direct absorption mm-wavelength detectors for
astronomical applications. One major research thrust within the N\'eel Iram
Kids Array (NIKA) collaboration has been to investigate the suitability of
these detectors for deployment at the 30-meter IRAM telescope located on Pico
Veleta in Spain. Compared to microwave kinetic inductance detectors (MKID),
using quarter wavelength resonators, the resonant circuit of a LEKID consists
of a discrete inductance and capacitance coupled to a feedline. A high and
constant current density distribution in the inductive part of these resonators
makes them very sensitive. Due to only one metal layer on a silicon substrate,
the fabrication is relatively easy. In order to optimize the LEKIDs for this
application, we have recently probed a wide variety of individual resonator and
array parameters through simulation and physical testing. This included
determining the optimal feed-line coupling, pixel geometry, resonator
distribution within an array (in order to minimize pixel cross-talk), and
resonator frequency spacing. Based on these results, a 144-pixel Aluminum array
was fabricated and tested in a dilution fridge with optical access, yielding an
average optical NEP of ~2E-16 W/Hz^1/2 (best pixels showed NEP = 6E-17 W/Hz^1/2
under 4-8 pW loading per pixel). In October 2010 the second prototype of LEKIDs
has been tested at the IRAM 30 m telescope. A new LEKID geometry for 2
polarizations will be presented. Also first optical measurements of a titanium
nitride array will be discussed.
12/2012;
-
M. Zemcov,
J. Aguirre,
J. Bock,
M. Bradford,
N. Czakon,
J. Glenn,
S. R. Golwala,
R. Lupu,
P. Maloney, P. Mauskopf,
E. Million,
E. J. Murphy,
B. Naylor,
H. Nguyen,
M. Rosenman,
J. Sayers,
K. S. Scott,
J. Zmuidzinas
[show abstract]
[hide abstract]
ABSTRACT: The Sunyaev-Zel'dovich (SZ) effect spectrum crosses through a null where
dT_CMB = 0 near nu_0 = 217 GHz. In a cluster of galaxies, nu_0 can be shifted
from the canonical thermal SZ effect value by corrections to the SZ effect
scattering due to the properties of the inter-cluster medium. We have measured
the SZ effect in the hot galaxy cluster RX J1347.5-1145 with Z-Spec, an R ~ 300
grating spectrometer sensitive between 185 and 305 GHz. These data comprise a
high spectral resolution measurement around the null of the SZ effect and
clearly exhibit the transition from negative to positive dT_CMB over the Z-Spec
band. The SZ null position is measured to be nu_0 = 225.8 \pm 2.5 (stat.) \pm
1.2 (sys.) GHz, which differs from the canonical null frequency by 3.0 sigma
and is evidence for modifications to the canonical thermal SZ effect shape.
Assuming the measured shift in nu_0 is due only to relativistic corrections to
the SZ spectrum, we place the limit T_e = 17.1 \pm 5.3 keV from the zero-point
measurement alone. By simulating the response of the instrument to the sky, we
are able to generate likelihood functions in {y_0, T_e, v_pec} space. For v_pec
= 0 km/s, we measure the best fitting SZ model to be y_0 = 4.6 (+0.6, -0.9) x
10^-4, T_e,0 = 15.2 (+12,-7.4) keV. When v_pec is allowed to vary, a most
probable value of v_pec = +450 \pm 810 km/s is found.
01/2012;
-
P ~G Martin,
A Roy,
S Bontemps,
M -A Miville-Deschênes,
P ~A ~R Ade,
J ~J Bock,
E ~L Chapin,
M ~J Devlin,
S ~R Dicker,
M Griffin, [......],
L Olmi,
G Patanchon,
M Rex,
D Scott,
C Semisch,
M ~D ~P Truch,
C Tucker,
G ~S Tucker,
M ~P Viero,
D ~V Wiebe
[show abstract]
[hide abstract]
ABSTRACT: The submillimeter opacity of dust in the diffuse interstellar medium (ISM) in the Galactic plane has been quantified using a pixel-by-pixel correlation of images of continuum emission with a proxy for column density. We used multi-wavelength continuum data: three Balloon-borne Large Aperture Submillimeter Telescope bands at 250, 350, and 500 $mu$m and one IRAS band at 100 $mu$m. The proxy is the near-infrared color excess, E(J - K $_s$), obtained from the Two Micron All Sky Survey. Based on observations of stars, we show how well this color excess is correlated with the total hydrogen column density for regions of moderate extinction. The ratio of emission to column density, the emissivity, is then known from the correlations, as a function of frequency. The spectral distribution of this emissivity can be fit by a modified blackbody, whence the characteristic dust temperature T and the desired opacity $sigma$$_e$(1200) at 1200 GHz or 250 $mu$m can be obtained. We have analyzed 14 regions near the Galactic plane toward the Vela molecular cloud, mostly selected to avoid regions of high column density (N $_H$ gt 10$^22$ cm$^-2$) and small enough to ensure a uniform dust temperature. We find $sigma$$_e$(1200) is typically (2-4) times 10$^-25$ cm$^2$ H$^-1$ and thus about 2-4 times larger than the average value in the local high Galactic latitude diffuse atomic ISM. This is strong evidence for grain evolution. There is a range in total power per H nucleon absorbed (and re-radiated) by the dust, reflecting changes in the strength of the interstellar radiation field and/or the dust absorption opacity. These changes in emission opacity and power affect the equilibrium T, which is typically 15 K, colder than at high latitudes. Our analysis extends, to higher opacity and lower temperature, the trend of increasing $sigma$$_e$(1200) with decreasing T that was found at high latitudes. The recognition of changes in the emission opacity raises a cautionary flag because all column densities deduced from dust emission maps, and the masses of compact structures within them, depend inversely on the value adopted.
apj. 01/2012; 751:28.
-
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. Monfardini,
A. Benoit,
A. Bideaud,
L. Swenson,
A. Cruciani,
P. Camus,
C. Hoffmann,
F. X. Désert,
S. Doyle,
P. Ade, [......],
A. Endo,
A. Baryshev,
J. J. A. Baselmans,
L. Ferrari,
S. J. C Yates,
O. Bourrion,
J. Macias-Perez,
C. Vescovi,
M. Calvo,
and C. Giordano
[show abstract]
[hide abstract]
ABSTRACT: The Néel IRAM KIDs Array (NIKA) is a fully integrated measurement system based on kinetic inductance detectors (KIDs) currently being developed for millimeter wave astronomy. The instrument includes dual-band optics allowing simultaneous imaging at 150 GHz and 220 GHz. The imaging sensors consist of two spatially separated arrays of KIDs. The first array, mounted on the 150 GHz branch, is composed of 144 lumped-element KIDs. The second array (220 GHz) consists of 256 antenna-coupled KIDs. Each of the arrays is sensitive to a single polarization; the band splitting is achieved by using a grid polarizer. The optics and sensors are mounted in a custom dilution cryostat, with an operating temperature of ~70 mK. Electronic readout is realized using frequency multiplexing and a transmission line geometry consisting of a coaxial cable connected in series with the sensor array and a low-noise 4 K amplifier. The dual-band NIKA was successfully tested in 2010 October at the Institute for Millimetric Radio Astronomy (IRAM) 30 m telescope at Pico Veleta, Spain, performing in-line with laboratory predictions. An optical NEP was then calculated to be around 2 × 10–16 W Hz–1/2 (at 1 Hz) while under a background loading of approximately 4 pW pixel–1. This improvement in comparison with a preliminary run (2009) verifies that NIKA is approaching the target sensitivity for photon-noise limited ground-based detectors. Taking advantage of the larger arrays and increased sensitivity, a number of scientifically relevant faint and extended objects were then imaged including the Galactic Center SgrB2 (FIR1), the radio galaxy Cygnus A, and the NGC1068 Seyfert galaxy. These targets were all observed simultaneously in the 150 GHz and 220 GHz atmospheric windows.
The Astrophysical Journal Supplement Series 05/2011; 194(2):24. · 13.46 Impact Factor
-
The COrE Collaboration,
C. Armitage-Caplan,
M. Avillez,
D. Barbosa,
A. Banday,
N. Bartolo,
R. Battye,
JP. Bernard,
P. de Bernardis,
S. Basak, [......],
S Ricciardi,
J. Rubino Martin,
M. Salatino,
P. Shellard,
R. Stompor,
L. Toffolatti J. Urrestilla,
B. Van Tent,
L. Verde,
B. Wandelt,
S. Withington
[show abstract]
[hide abstract]
ABSTRACT: COrE (Cosmic Origins Explorer) is a fourth-generation full-sky,
microwave-band satellite recently proposed to ESA within Cosmic Vision
2015-2025. COrE will provide maps of the microwave sky in polarization and
temperature in 15 frequency bands, ranging from 45 GHz to 795 GHz, with an
angular resolution ranging from 23 arcmin (45 GHz) and 1.3 arcmin (795 GHz) and
sensitivities roughly 10 to 30 times better than PLANCK (depending on the
frequency channel). The COrE mission will lead to breakthrough science in a
wide range of areas, ranging from primordial cosmology to galactic and
extragalactic science. COrE is designed to detect the primordial gravitational
waves generated during the epoch of cosmic inflation at more than $3\sigma $
for $r=(T/S)>=10^{-3}$. It will also measure the CMB gravitational lensing
deflection power spectrum to the cosmic variance limit on all linear scales,
allowing us to probe absolute neutrino masses better than laboratory
experiments and down to plausible values suggested by the neutrino oscillation
data. COrE will also search for primordial non-Gaussianity with significant
improvements over Planck in its ability to constrain the shape (and amplitude)
of non-Gaussianity. In the areas of galactic and extragalactic science, in its
highest frequency channels COrE will provide maps of the galactic polarized
dust emission allowing us to map the galactic magnetic field in areas of
diffuse emission not otherwise accessible to probe the initial conditions for
star formation. COrE will also map the galactic synchrotron emission thirty
times better than PLANCK. This White Paper reviews the COrE science program,
our simulations on foreground subtraction, and the proposed instrumental
configuration.
02/2011;
-
A. Monfardini,
A. Benoit,
A. Bideaud,
L. J. Swenson,
M. Roesch,
F. X. Desert,
S. Doyle,
A. Endo,
A. Cruciani,
P. Ade, [......],
L Ferrari,
C. Giordano,
C. Hoffmann,
S. Leclercq,
J. F. Macias-Perez, P. Mauskopf,
K. F. Schuster,
C. Tucker,
C. Vescovi,
S. J. C. Yates
[show abstract]
[hide abstract]
ABSTRACT: Context. The Neel IRAM KIDs Array (NIKA) is a fully-integrated measurement
system based on kinetic inductance detectors (KIDs) currently being developed
for millimeter wave astronomy. In a first technical run, NIKA was successfully
tested in 2009 at the Institute for Millimetric Radio Astronomy (IRAM) 30-meter
telescope at Pico Veleta, Spain. This prototype consisted of a 27-42 pixel
camera imaging at 150 GHz. Subsequently, an improved system has been developed
and tested in October 2010 at the Pico Veleta telescope. The instrument
upgrades included dual-band optics allowing simultaneous imaging at 150 GHz and
220 GHz, faster sampling electronics enabling synchronous measurement of up to
112 pixels per measurement band, improved single-pixel sensitivity, and the
fabrication of a sky simulator to replicate conditions present at the
telescope. Results. The new dual-band NIKA was successfully tested in October
2010, performing in-line with sky simulator predictions. Initially the sources
targeted during the 2009 run were re-imaged, verifying the improved system
performance. An optical NEP was then calculated to be around 2 \dot 10-16
W/Hz1/2. This improvement in comparison with the 2009 run verifies that NIKA is
approaching the target sensitivity for photon-noise limited ground-based
detectors. Taking advantage of the larger arrays and increased sensitivity, a
number of scientifically-relevant faint and extended objects were then imaged
including the Galactic Center SgrB2(FIR1), the radio galaxy Cygnus A and the
NGC1068 Seyfert galaxy. These targets were all observed simultaneously in the
150 GHz and 220 GHz atmospheric windows.
02/2011;
-
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
-
[show abstract]
[hide abstract]
ABSTRACT: We have recently designed, built and measured an alternative solution to the use of classical dielectric material in anti-reflection coatings. A metal-mesh pattern has been designed to cover a frequency band greater than 90%. We discuss measurements and illustrate the extension for bi-refringent materials.
Infrared Millimeter and Terahertz Waves (IRMMW-THz), 2010 35th International Conference on; 10/2010
-
[show abstract]
[hide abstract]
ABSTRACT: We report on the performance of a Nb voltage-biased superconducting bolometer cooled by a closed cycle pulse tube cooler. The VSB has a Tc ~ 8.1 K and an operating impedance of R ~ 800 Ω. A preliminary value for the system optical noise equivalent power (NEP) = 1.8 × 10<sup>-12</sup> WHz-1/2 and τ = 0.6 ms.
Infrared Millimeter and Terahertz Waves (IRMMW-THz), 2010 35th International Conference on; 10/2010
-
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;
-
B. Sibthorpe,
P. A. R. Ade,
J. J. Bock,
E. L. Chapin,
M. J. Devlin,
S. Dicker,
M. Griffin,
J. O. Gundersen,
M. Halpern,
P. C. Hargrave, [......],
G. Patanchon,
M. Rex,
A. Roy,
D. Scott,
C. Semisch,
M. D. P. Truch,
C. Tucker,
G. S. Tucker,
M. P. Viero,
and D. V. Wiebe
[show abstract]
[hide abstract]
ABSTRACT: We use new large area far infrared maps ranging from 65 to 500 μm obtained with the AKARI and the Balloon-borne Large Aperture Submillimeter Telescope missions to characterize the dust emission toward the Cassiopeia A supernova remnant (SNR). Using the AKARI high-resolution data we find a new "tepid" dust grain population at a temperature of ~35 K and with an estimated mass of 0.06 M ☉. This component is confined to the central area of the SNR and may represent newly formed dust in the unshocked supernova ejecta. While the mass of tepid dust that we measure is insufficient by itself to account for the dust observed at high redshift, it does constitute an additional dust population to contribute to those previously reported. We fit our maps at 65, 90, 140, 250, 350, and 500 μm to obtain maps of the column density and temperature of "cold" dust (near 16 K) distributed throughout the region. The large column density of cold dust associated with clouds seen in molecular emission extends continuously from the surrounding interstellar medium to project on the SNR, where the foreground component of the clouds is also detectable through optical, X-ray, and molecular extinction. At the resolution available here, there is no morphological signature to isolate any cold dust associated only with the SNR from this confusing interstellar emission. Our fit also recovers the previously detected "hot" dust in the remnant, with characteristic temperature 100 K.
The Astrophysical Journal 08/2010; 719(2):1553. · 6.02 Impact Factor
-
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;
-
A. Monfardini,
L. J. Swenson,
A. Bideaud,
F.-X. Désert,
S. J. C. Yates,
A. Benoit,
A. M. Baryshev,
J.J.A. Baselmans,
S. Doyle,
B Klein, [......],
C. Tucker,
P. Ade,
M. Calvo,
P. Camus,
C. Giordano,
R. Guesten,
C. Hoffmann,
S. Leclercq, P. Mauskopf,
K. F. Schuster
[show abstract]
[hide abstract]
ABSTRACT: Current generation millimeter wavelength detectors suffer from scaling limits
imposed by complex cryogenic readout electronics. To circumvent this it is
imperative to investigate technologies that intrinsically incorporate strong
multiplexing. One possible solution is the kinetic inductance detector (KID).
In order to assess the potential of this nascent technology, a prototype
instrument optimized for the 2 mm atmospheric window was constructed. Known as
the N\'eel IRAM KIDs Array (NIKA), it was recently tested at the Institute for
Millimetric Radio Astronomy (IRAM) 30-meter telescope at Pico Veleta, Spain.
The measurement resulted in the imaging of a number of sources, including
planets, quasars, and galaxies. The images for Mars, radio star MWC349, quasar
3C345, and galaxy M87 are presented. From these results, the optical NEP was
calculated to be around $1 \times 10^{-15}$ W$ / $Hz$^{1/2}$. A factor of 10
improvement is expected to be readily feasible by improvements in the detector
materials and reduction of performance-degrading spurious radiation.
04/2010;
-
P. De Bernardis,
D. Bagliani,
A. Bardi,
E. Battistelli,
M. Birkinshaw,
M. Calvo,
S. Colafrancesco,
A. Conte,
S. De Gregori,
M. De Petris, [......],
G. Savini,
A. Schillaci,
S. Spinelli,
A. Tartari,
M. Tavanti,
A. Tortora,
M. Vaccari,
R. Vaccarone,
M. Zannoni,
V. Zolesi
[show abstract]
[hide abstract]
ABSTRACT: The SAGACE experiment consists of a mm/sub-mm telescope with a 3-m diameter
primary mirror, coupled to a cryogenic multi-beam differential spectrometer.
SAGACE explores the sky in the 100-760 GHz frequency range, using four
diffraction-limited bolometer arrays. The instrument is designed to perform
spectroscopic surveys of the Sunyaev-Zeldovich effects of thousands of galaxy
clusters, of the spectral energy distribution of active galactic nuclei, and of
the [CII] line of a thousand galaxies in the redshift desert. In 2008 a full
phase-A study for a national small mission was completed and delivered to the
Italian Space Agency (ASI). We have shown that taking advantage of the
differential operation of the Fourier Transform Spectrometer, this ambitious
instrument can operate from a Molniya orbit, and can be built and operated
within the tight budget of a small mission.
02/2010;
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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;
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A. Roy,
P. A. R. Ade,
J. J. Bock,
E. L. Chapin,
M. J. Devlin,
S. R. Dicker,
M. Griffin,
J. O. Gundersen,
M. Halpern,
P. C. Hargrave, [......],
L. Olmi,
G. Patanchon,
M. Rex,
D. Scott,
C. Semisch,
M. D. P. Truch,
C. Tucker,
G. S. Tucker,
M. P. Viero,
D. V. Wiebe
[show abstract]
[hide abstract]
ABSTRACT: We report multi-wavelength power spectra of diffuse Galactic dust emission from Balloon-borne Large Aperture Submillimeter Telescope observations at 250, 350, and 500 mu m in Galactic plane fields in Cygnus X and Aquila. These submillimeter power spectra statistically quantify the self-similar structure observable over a broad range of scales and can be used to assess the cirrus noise which limits the detection of faint point sources. The advent of submillimeter surveys with the Herschel Space Observatory makes the wavelength dependence a matter of interest. We show that the observed relative amplitudes of the power spectra can be related through a spectral energy distribution (SED). Fitting a simple modified black body to this SED, we find the dust temperature in Cygnus X to be 19.8 +/- 1.5 K and in the Aquila region 16.8 +/- 0.8 K. Our empirical estimates provide important new insight into the substantial cirrus noise that will be encountered in forthcoming observations.
Astrophysical Journal. 01/2010; 708(2):1611-1620.
