88 research outputs found
Geometric interpretation of toroidal compactifications of moduli of points in the line and cubic surfaces
It is known that some GIT compactifications associated to moduli spaces of
either points in the projective line or cubic surfaces are isomorphic to
Baily-Borel compactifications of appropriate ball quotients. In this paper, we
show that their respective toroidal compactifications are isomorphic to moduli
spaces of stable pairs as defined in the context of the MMP. Moreover, we give
a precise mixed-Hodge-theoretic interpretation of this isomorphism for the case
of eight labeled points in the projective line.Comment: 35 pages. Comments are welcom
The Atacama Cosmology Telescope: The LABOCA/ACT Survey of Clusters at All Redshifts
We present a multi-wavelength analysis of eleven Sunyaev Zel'dovich effect
(SZE)-selected galaxy clusters (ten with new data) from the Atacama Cosmology
Telescope (ACT) southern survey. We have obtained new imaging from the Large
APEX Bolometer Camera (345GHz; LABOCA) on the Atacama Pathfinder EXperiment
(APEX) telescope, the Australia Telescope Compact Array (2.1GHz; ATCA), and the
Spectral and Photometric Imaging Receiver (250, 350, and ;
SPIRE) on the Herschel Space Observatory. Spatially-resolved 345GHz SZE
increments with integrated S/N > 5 are found in six clusters. We compute 2.1GHz
number counts as a function of cluster-centric radius and find significant
enhancements in the counts of bright sources at projected radii . By extrapolating in frequency, we predict that the combined
signals from 2.1GHz-selected radio sources and 345GHz-selected SMGs contaminate
the 148GHz SZE decrement signal by ~5% and the 345GHz SZE increment by ~18%.
After removing radio source and SMG emission from the SZE signals, we use ACT,
LABOCA, and (in some cases) new Herschel SPIRE imaging to place constraints on
the clusters' peculiar velocities. The sample's average peculiar velocity
relative to the cosmic microwave background is .Comment: 19 pages, 11 figures, Accepted for Publication in The Astrophysical
Journa
Non-tuberculous mycobacterial pulmonary disease (NTM-PD): Epidemiology, diagnosis and multidisciplinary management
Non-tuberculous mycobacteria (NTM) are ubiquitous environmental organisms that can cause significant disease in both immunocompromised and immunocompetent individuals. The incidence of NTM pulmonary disease (NTM-PD) is rising globally. Diagnostic challenges persist and treatment efficacy is variable. This article provides an overview of NTM-PD for clinicians. We discuss how common it is, who is at risk, how it is diagnosed and the multidisciplinary approach to its clinical management. [Abstract copyright: Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.
The Atacama Cosmology Telescope: Two-Season ACTPol Spectra and Parameters
We present the temperature and polarization angular power spectra measured by
the Atacama Cosmology Telescope Polarimeter (ACTPol). We analyze night-time
data collected during 2013-14 using two detector arrays at 149 GHz, from 548
deg of sky on the celestial equator. We use these spectra, and the spectra
measured with the MBAC camera on ACT from 2008-10, in combination with Planck
and WMAP data to estimate cosmological parameters from the temperature,
polarization, and temperature-polarization cross-correlations. We find the new
ACTPol data to be consistent with the LCDM model. The ACTPol
temperature-polarization cross-spectrum now provides stronger constraints on
multiple parameters than the ACTPol temperature spectrum, including the baryon
density, the acoustic peak angular scale, and the derived Hubble constant.
Adding the new data to planck temperature data tightens the limits on damping
tail parameters, for example reducing the joint uncertainty on the number of
neutrino species and the primordial helium fraction by 20%.Comment: 23 pages, 25 figure
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: Millimeter Observations of a Population of Asteroids or: ACTeroids
We present fluxes and light curves for a population of asteroids at
millimeter (mm) wavelengths, detected by the Atacama Cosmology Telescope (ACT)
over 18, 000 deg2 of the sky using data from 2017 to 2021. We utilize high
cadence maps, which can be used in searching for moving objects such as
asteroids and trans-Neptunian Objects (TNOs), as well as for studying
transients. We detect 160 asteroids with a signal-to-noise of at least 5 in at
least one of the ACT observing bands, which are centered near 90, 150, and 220
GHz. For each asteroid, we compare the ACT measured flux to predicted fluxes
from the Near Earth Asteroid Thermal Model (NEATM) fit to WISE data. We confirm
previous results that detected a deficit of flux at millimeter wavelengths.
Moreover, we report a spectral characteristic to this deficit, such that the
flux is relatively lower at 150 and 220 GHz than at 90 GHz. Additionally, we
find that the deficit in flux is greater for S-type asteroids than for C-type.Comment: 15 pages, 9 Figures, 4 Table
The Atacama Cosmology Telescope: Detection of mm-wave transient sources
We report on the serendipitous discovery of three transient mm-wave sources
using data from the Atacama Cosmology Telescope. The first, detected at RA =
273.8138, dec = -49.4628 at total, brightened from less than 5
mJy to at least 1100 mJy at 150 GHz with an unknown rise time shorter than
thirteen days, during which the increase from 250 mJy to 1100 mJy took only 8
minutes. Maximum flux was observed on 2019-11-8. The source's spectral index in
flux between 90 and 150 GHz was positive, . The second,
detected at RA = 105.1584, dec = -11.2434 at total, brightened
from less than 20 mJy to at least 300 mJy at 150 GHz with an unknown rise time
shorter than eight days. Maximum flux was observed on 2019-12-15. Its spectral
index was also positive, . The third, detected at RA =
301.9952, dec = 16.1652 at total, brightened from less than 8
mJy to at least 300 mJy at 150 GHz over a day or less but decayed over a few
days. Maximum flux was observed on 2018-9-11. Its spectrum was approximately
flat, with a spectral index of . None of the sources were
polarized to the limits of these measurements. The two rising-spectrum sources
are coincident in position with M and K stars, while the third is coincident
with a G star.Comment: 8 pages, 4 figures, 1 tabl
New Science in Plain Sight : Citizen Scientists Lead to Discovery of Optical Structure in the Upper Atmosphere
A glowing ribbon of purple light running east-west in the night sky has recently been observed by citizen scientists. This narrow, subauroral, visible structure, distinct from the traditional auroral oval, was largely undocumented in the scientific literature and little was known about its formation. Amateur photo sequences showed colors distinctly different from common types of aurora and occasionally indicated magnetic field–aligned substructures. Observations from the Swarm satellite as it crossed the arc have revealed an unusual level of electron temperature enhancement and density depletion, along with a strong westward ion flow, indicating that a pronounced subauroral ion drift (SAID) is associated with this structure. These early results suggest the arc is an optical manifestation of SAID, presenting new opportunities for investigation of the dynamic SAID signatures from the ground. On the basis of the measured ion properties and original citizen science name, we propose to identify this arc as a Strong Thermal Emission Velocity Enhancement (STEVE)
The atacama cosmology telescope: lensing of CMB temperature and polarization derived from cosmic infrared background cross-correlation
We present a measurement of the gravitational lensing of the Cosmic Microwave Background (CMB) temperature and polarization fields obtained by cross-correlating the reconstructed convergence signal from the first season of Atacama Cosmology Telescope Polarimeter data at 146 GHz with Cosmic Infrared Background (CIB) fluctuations measured using the Planck satellite. Using an effective overlap area of 92.7 square degrees, we detect gravitational lensing of the CMB polarization by large-scale structure at a statistical significance of . Combining both CMB temperature and polarization data gives a lensing detection at significance. A B-mode polarization lensing signal is present with a significance of . We also present the first measurement of CMB lensing–CIB correlation at small scales corresponding to . Null tests and systematic checks show that our results are not significantly biased by astrophysical or instrumental systematic effects, including Galactic dust. Fitting our measurements to the best-fit lensing-CIB cross-power spectrum measured in Planck data, scaled by an amplitude A, gives (stat.) ± 0.06(syst.), consistent with the Planck results
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