60 research outputs found
Horn Coupled Multichroic Polarimeters for the Atacama Cosmology Telescope Polarization Experiment
Multichroic polarization sensitive detectors enable increased sensitivity and
spectral coverage for observations of the Cosmic Microwave Background (CMB). An
array optimized for dual frequency detectors can provide 1.7 times gain in
sensitivity compared to a single frequency array. We present the design and
measurements of horn coupled multichroic polarimeters encompassing the 90 and
150 GHz frequency bands and discuss our plans to field an array of these
detectors as part of the ACTPol project
Photon-noise limited sensitivity in titanium nitride kinetic inductance detectors
We demonstrate photon-noise limited performance at sub-millimeter wavelengths
in feedhorn-coupled, microwave kinetic inductance detectors (MKIDs) made of a
TiN/Ti/TiN trilayer superconducting film, tuned to have a transition
temperature of 1.4~K. Micro-machining of the silicon-on-insulator wafer
backside creates a quarter-wavelength backshort optimized for efficient
coupling at 250~\micron. Using frequency read out and when viewing a variable
temperature blackbody source, we measure device noise consistent with photon
noise when the incident optical power is ~0.5~pW, corresponding to noise
equivalent powers ~3 W/. This
sensitivity makes these devices suitable for broadband photometric applications
at these wavelengths
Epizootic of beak deformities in wild birds: a review of avian keratin disorder worldwide
An epizootic of debilitating beak deformities in wild birds has been documented in recent decades. Avian keratin disorder (AKD) is characterized by overgrowth of beak keratin and was first observed in clusters among Black-capped Chickadees (Poecile atricapillus) in Alaska. The prevalence of beak deformities is higher among Black-capped Chickadees and American Crows (Corvus brachyrhynchos) in Alaska than in any other population ever recorded. Reports of birds with similar beak deformities have also been documented across North America, in South America, and in Europe. We compiled reports from community-science programs, bird monitoring studies, and scientific literature to summarize the current geographic scope and bird species affected by AKD-like beak deformities. From 1946 to 2021, >3,300 community-science observers reported 290 species with beak deformities, comprising >4,000 birds in Alaska, 1,900 elsewhere in North America, and >1,700 from outside of North America. We also examined the occurrence of beak deformities in populations of Red-tailed Hawks (Buteo jamaicensis) in the Pacific Northwest, Red-cockaded Woodpeckers (Dryobates borealis) in North Carolina, and Austral Thrushes (Turdus falcklandii) in Patagonia. Clinical signs of AKD in Black-capped Chickadees have been strongly associated with the occurrence of a novel picornavirus, which has now been detected in multiple species exhibiting morphologically similar beak deformities. Our detailed compilation, including geographic occurrence of individuals and species apparently affected, will help identify research and conservation actions required to evaluate and mitigate impacts of beak deformities on wild birds.Fil: Gerik, Daniel. United States Geological Survey; Estados UnidosFil: Van Hemert, Caroline. United States Geological Survey; Estados UnidosFil: Handel, Collen. United States Geological Survey; Estados UnidosFil: Lawson, Becki. Zoological Society of London. Institute of Zoology; Reino UnidoFil: Walters, Jeff. Virginia Tech University; Estados UnidosFil: Brust, Kerry. Sandhills Ecological Institute; Estados UnidosFil: Prinz, Anna. Sandhills Ecological Institute; Estados UnidosFil: Van Lanen, Andy. Sandhills Ecological Institute; Estados UnidosFil: Schillaci, Jessie. Directorate of Public Works; Estados UnidosFil: Cottrell, Susan. Falcon Research Group; Estados UnidosFil: Anderson, Clifford. Falcon Research Group; Estados UnidosFil: Gorosito, Cristian Andrés. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Centro de Investigación Esquel de Montaña y Estepa Patagónica. Universidad Nacional de la Patagonia "San Juan Bosco". Centro de Investigación Esquel de Montaña y Estepa Patagónica; ArgentinaFil: Cueto, Víctor. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Centro de Investigación Esquel de Montaña y Estepa Patagónica. Universidad Nacional de la Patagonia "San Juan Bosco". Centro de Investigación Esquel de Montaña y Estepa Patagónica; ArgentinaFil: Zylberberg, Maxine. University of California; Estados Unidos20th Alaska Bird ConferenceAnchorageEstados UnidosUS Fish and Wildlife Service's Migratory Bird Management Divisio
The Atacama Cosmology Telescope: Two-Season ACTPol Lensing Power Spectrum
We report a measurement of the power spectrum of cosmic microwave background
(CMB) lensing from two seasons of Atacama Cosmology Telescope Polarimeter
(ACTPol) CMB data. The CMB lensing power spectrum is extracted from both
temperature and polarization data using quadratic estimators. We obtain results
that are consistent with the expectation from the best-fit Planck LCDM model
over a range of multipoles L=80-2100, with an amplitude of lensing A_lens =
1.06 +/- 0.15 (stat.) +/- 0.06 (sys.) relative to Planck. Our measurement of
the CMB lensing power spectrum gives sigma_8 Omega_m^0.25 = 0.643 +/- 0.054;
including baryon acoustic oscillation scale data, we constrain the amplitude of
density fluctuations to be sigma_8 = 0.831 +/- 0.053. We also update
constraints on the neutrino mass sum. We verify our lensing measurement with a
number of null tests and systematic checks, finding no evidence of significant
systematic errors. This measurement relies on a small fraction of the ACTPol
data already taken; more precise lensing results can therefore be expected from
the full ACTPol dataset.Comment: 17 pages, 11 figures, to be submitted to Physical Review
Design of 280 GHz feedhorn-coupled TES arrays for the balloon-borne polarimeter SPIDER
We describe 280 GHz bolometric detector arrays that instrument the
balloon-borne polarimeter SPIDER. A primary science goal of SPIDER is to
measure the large-scale B-mode polarization of the cosmic microwave background
in search of the cosmic-inflation, gravitational-wave signature. 280 GHz
channels aid this science goal by constraining the level of B-mode
contamination from galactic dust emission. We present the focal plane unit
design, which consists of a 1616 array of conical, corrugated feedhorns
coupled to a monolithic detector array fabricated on a 150 mm diameter silicon
wafer. Detector arrays are capable of polarimetric sensing via waveguide
probe-coupling to a multiplexed array of transition-edge-sensor (TES)
bolometers. The SPIDER receiver has three focal plane units at 280 GHz, which
in total contains 765 spatial pixels and 1,530 polarization sensitive
bolometers. By fabrication and measurement of single feedhorns, we demonstrate
14.7 FHWM Gaussian-shaped beams with 1% ellipticity in a 30%
fractional bandwidth centered at 280 GHz. We present electromagnetic
simulations of the detection circuit, which show 94% band-averaged,
single-polarization coupling efficiency, 3% reflection and 3% radiative loss.
Lastly, we demonstrate a low thermal conductance bolometer, which is
well-described by a simple TES model and exhibits an electrical noise
equivalent power (NEP) = 2.6 10 W/,
consistent with the phonon noise prediction.Comment: Proceedings of SPIE Astronomical Telescopes + Instrumentation 201
The Atacama Cosmology Telescope: Mitigating the impact of extragalactic foregrounds for the DR6 CMB lensing analysis
We investigate the impact and mitigation of extragalactic foregrounds for the
CMB lensing power spectrum analysis of Atacama Cosmology Telescope (ACT) data
release 6 (DR6) data. Two independent microwave sky simulations are used to
test a range of mitigation strategies. We demonstrate that finding and then
subtracting point sources, finding and then subtracting models of clusters, and
using a profile bias-hardened lensing estimator, together reduce the fractional
biases to well below statistical uncertainties, with the inferred lensing
amplitude, , biased by less than . We also show
that another method where a model for the cosmic infrared background (CIB)
contribution is deprojected and high frequency data from Planck is included has
similar performance. Other frequency-cleaned options do not perform as well,
incurring either a large noise cost, or resulting in biased recovery of the
lensing spectrum. In addition to these simulation-based tests, we also present
null tests performed on the ACT DR6 data which test for sensitivity of our
lensing spectrum estimation to differences in foreground levels between the two
ACT frequencies used, while nulling the CMB lensing signal. These tests pass
whether the nulling is performed at the map or bandpower level. The
CIB-deprojected measurement performed on the DR6 data is consistent with our
baseline measurement, implying contamination from the CIB is unlikely to
significantly bias the DR6 lensing spectrum. This collection of tests gives
confidence that the ACT DR6 lensing measurements and cosmological constraints
presented in companion papers to this work are robust to extragalactic
foregrounds.Comment: Companion paper to Qu et al and Madhavacheril et a
The Atacama Cosmology Telescope: Modeling the Gas Thermodynamics in BOSS CMASS galaxies from Kinematic and Thermal Sunyaev-Zel'dovich Measurements
The thermal and kinematic Sunyaev-Zel'dovich effects (tSZ, kSZ) probe the
thermodynamic properties of the circumgalactic and intracluster medium (CGM and
ICM) of galaxies, groups, and clusters, since they are proportional,
respectively, to the integrated electron pressure and momentum along the
line-of-sight. We present constraints on the gas thermodynamics of CMASS
galaxies in the Baryon Oscillation Spectroscopic Survey (BOSS) using new
measurements of the kSZ and tSZ signals obtained in a companion paper.
Combining kSZ and tSZ measurements, we measure within our model the amplitude
of energy injection , where is the stellar
mass, to be , and the amplitude of the
non-thermal pressure profile to be (2),
indicating that less than 20% of the total pressure within the virial radius is
due to a non-thermal component. We estimate the effects of including baryons in
the modeling of weak-lensing galaxy cross-correlation measurements using the
best fit density profile from the kSZ measurement. Our estimate reduces the
difference between the original theoretical model and the weak-lensing galaxy
cross-correlation measurements in arXiv:1611.08606 by half, but does not fully
reconcile it. Comparing the kSZ and tSZ measurements to cosmological
simulations, we find that they under predict the CGM pressure and to a lesser
extent the CGM density at larger radii. This suggests that the energy injected
via feedback models in the simulations that we compared against does not
sufficiently heat the gas at these radii. We do not find significant
disagreement at smaller radii. These measurements provide novel tests of
current and future simulations. This work demonstrates the power of joint, high
signal-to-noise kSZ and tSZ observations, upon which future cross-correlation
studies will improve.Comment: Accepted for publication in Physical Review D. Editors' Suggestion.
New Fig. 1-2, Tab.
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