82 research outputs found
Policy Process Editor for P3BM Software
A computer program enables generation, in the form of graphical representations of process flows with embedded natural-language policy statements, input to a suite of policy-, process-, and performance-based management (P3BM) software. This program (1) serves as an interface between users and the Hunter software, which translates the input into machine-readable form; and (2) enables users to initialize and monitor the policy-implementation process. This program provides an intuitive graphical interface for incorporating natural-language policy statements into business-process flow diagrams. Thus, the program enables users who dictate policies to intuitively embed their intended process flows as they state the policies, reducing the likelihood of errors and reducing the time between declaration and execution of policy
The Atacama Cosmology Telescope: Dusty Star-Forming Galaxies and Active Galactic Nuclei in the Southern Survey
We present a catalog of 191 extragalactic sources detected by the Atacama
Cosmology Telescope (ACT) at 148 GHz and/or 218 GHz in the 2008 Southern
survey. Flux densities span 14-1700 mJy, and we use source spectral indices
derived using ACT-only data to divide our sources into two sub-populations: 167
radio galaxies powered by central active galactic nuclei (AGN), and 24 dusty
star-forming galaxies (DSFGs). We cross-identify 97% of our sources (166 of the
AGN and 19 of the DSFGs) with those in currently available catalogs. When
combined with flux densities from the Australian Telescope 20 GHz survey and
follow-up observations with the Australia Telescope Compact Array, the
synchrotron-dominated population is seen to exhibit a steepening of the slope
of the spectral energy distribution from 20 to 148 GHz, with the trend
continuing to 218 GHz. The ACT dust-dominated source population has a median
spectral index of 3.7+0.62-0.86, and includes both local galaxies and sources
with redshifts as great as 5.6. Dusty sources with no counterpart in existing
catalogs likely belong to a recently discovered subpopulation of DSFGs lensed
by foreground galaxies or galaxy groups.Comment: 13 pages, 8 figures, 4 table
The Atacama Cosmology Telescope: the stellar content of galaxy clusters selected using the Sunyaev-Zel'dovich effect
We present a first measurement of the stellar mass component of galaxy
clusters selected via the Sunyaev-Zel'dovich (SZ) effect, using 3.6 um and 4.5
um photometry from the Spitzer Space Telescope. Our sample consists of 14
clusters detected by the Atacama Cosmology Telescope (ACT), which span the
redshift range 0.27 < z < 1.07 (median z = 0.50), and have dynamical mass
measurements, accurate to about 30 per cent, with median M500 = 6.9 x 10^{14}
MSun. We measure the 3.6 um and 4.5 um galaxy luminosity functions, finding the
characteristic magnitude (m*) and faint-end slope (alpha) to be similar to
those for IR-selected cluster samples. We perform the first measurements of the
scaling of SZ-observables (Y500 and y0) with both brightest cluster galaxy
(BCG) stellar mass and total cluster stellar mass (M500star). We find a
significant correlation between BCG stellar mass and Y500 (E(z)^{-2/3} DA^2
Y500 ~ M*^{1.2 +/- 0.6}), although we are not able to obtain a strong
constraint on the slope of the relation due to the small sample size.
Additionally, we obtain E(z)^{-2/3} DA^2 Y500 ~ M500star^{1.0 +/- 0.6} for the
scaling with total stellar mass. The mass fraction in stars spans the range
0.006-0.034, with the second ranked cluster in terms of dynamical mass (ACT-CL
J0237-4939) having an unusually low total stellar mass and the lowest stellar
mass fraction. For the five clusters with gas mass measurements available in
the literature, we see no evidence for a shortfall of baryons relative to the
cosmic mean value.Comment: Accepted for publication in MNRAS; 12 pages, 10 figure
Cosmological Parameters from Pre-Planck CMB Measurements
Recent data from the WMAP, ACT and SPT experiments provide precise
measurements of the cosmic microwave background temperature power spectrum over
a wide range of angular scales. The combination of these observations is well
fit by the standard, spatially flat LCDM cosmological model, constraining six
free parameters to within a few percent. The scalar spectral index, n_s =
0.9690 +/- 0.0089, is less than unity at the 3.6 sigma level, consistent with
simple models of inflation. The damping tail of the power spectrum at high
resolution, combined with the amplitude of gravitational lensing measured by
ACT and SPT, constrains the effective number of relativistic species to be
N_eff = 3.28 +/- 0.40, in agreement with the standard model's three species of
light neutrinos.Comment: 5 pages, 4 figure
The Atacama Cosmology Telescope: Sunyaev-Zel'dovich Selected Galaxy Clusters at 148 GHz from Three Seasons of Data
[Abridged] We present a catalog of 68 galaxy clusters, of which 19 are new
discoveries, detected via the Sunyaev-Zel'dovich effect (SZ) at 148 GHz in the
Atacama Cosmology Telescope (ACT) survey of 504 square degrees on the celestial
equator. A subsample of 48 clusters within the 270 square degree region
overlapping SDSS Stripe 82 is estimated to be 90% complete for M_500c > 4.5e14
Msun and 0.15 < z < 0.8. While matched filters are used to detect the clusters,
the sample is studied further through a "Profile Based Amplitude Analysis"
using a single filter at a fixed \theta_500 = 5.9' angular scale. This new
approach takes advantage of the "Universal Pressure Profile" (UPP) to fix the
relationship between the cluster characteristic size (R_500) and the integrated
Compton parameter (Y_500). The UPP scalings are found to be nearly identical to
an adiabatic model, while a model incorporating non-thermal pressure better
matches dynamical mass measurements and masses from the South Pole Telescope. A
high signal to noise ratio subsample of 15 ACT clusters is used to obtain
cosmological constraints. We first confirm that constraints from SZ data are
limited by uncertainty in the scaling relation parameters rather than sample
size or measurement uncertainty. We next add in seven clusters from the ACT
Southern survey, including their dynamical mass measurements based on galaxy
velocity dispersions. In combination with WMAP7 these data simultaneously
constrain the scaling relation and cosmological parameters, yielding \sigma_8 =
0.829 \pm 0.024 and \Omega_m = 0.292 \pm 0.025. The results include
marginalization over a 15% bias in dynamical mass relative to the true halo
mass. In an extension to LCDM that incorporates non-zero neutrino mass density,
we combine our data with WMAP7+BAO+Hubble constant measurements to constrain
\Sigma m_\nu < 0.29 eV (95% C. L.).Comment: 32 pages, 21 figures To appear in J. Cosmology and Astroparticle
Physic
The Atacama Cosmology Telescope: Dynamical Masses and Scaling Relations for a Sample of Massive Sunyaev-Zel'dovich Effect Selected Galaxy Clusters
We present the first dynamical mass estimates and scaling relations for a
sample of Sunyaev-Zel'dovich effect (SZE) selected galaxy clusters. The sample
consists of 16 massive clusters detected with the Atacama Cosmology Telescope
(ACT) over a 455 sq. deg. area of the southern sky. Deep multi-object
spectroscopic observations were taken to secure intermediate-resolution
(R~700-800) spectra and redshifts for ~60 member galaxies on average per
cluster. The dynamical masses M_200c of the clusters have been calculated using
simulation-based scaling relations between velocity dispersion and mass. The
sample has a median redshift z=0.50 and a median mass M_200c~12e14 Msun/h70
with a lower limit M_200c~6e14 Msun/h70, consistent with the expectations for
the ACT southern sky survey. These masses are compared to the ACT SZE
properties of the sample, specifically, the match-filtered central SZE
amplitude y, the central Compton parameter y0, and the integrated Compton
signal Y_200c, which we use to derive SZE-Mass scaling relations. All SZE
estimators correlate with dynamical mass with low intrinsic scatter (<~20%), in
agreement with numerical simulations. We explore the effects of various
systematic effects on these scaling relations, including the correlation
between observables and the influence of dynamically disturbed clusters. Using
the 3-dimensional information available, we divide the sample into relaxed and
disturbed clusters and find that ~50% of the clusters are disturbed. There are
hints that disturbed systems might bias the scaling relations but given the
current sample sizes these differences are not significant; further studies
including more clusters are required to assess the impact of these clusters on
the scaling relations.Comment: 15 pages, 4 figures. Accepted for publication in The Astrophysical
Journal; matches published version. Full Table 8 with complete spectroscopic
member sample available in machine-readable form in the journal site and upon
request to C. Sif\'o
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
A measurement of the millimetre emission and the Sunyaev-Zel'dovich effect associated with low-frequency radio sources
We present a statistical analysis of the millimetre-wavelength properties of 1.4GHz-selected sources and a detection of the Sunyaev–Zel’dovich (SZ) effect associated with the haloes that host them. We stack data at 148, 218 and 277GHz from the Atacama Cosmology Telescope at the positions of a large sample of radio AGN selected at 1.4GHz. The thermal SZ effect associated with the haloes that host the AGN is detected at the 5σ level through its spectral signature, representing a statistical detection of the SZ effect in some of the lowest mass haloes (average M 200 ≈ 10 13 M. h −1 70 ) studied to date. The relation between the SZ effect and mass (based on weak lensing measurements of radio galaxies) is consistent with that measured by Planck for local bright galaxies. In the context of galaxy evolution models, this study confirms that galaxies with radio AGN also typically support hot gaseous haloes. Adding Herschel observations allows us to show that the SZ signal is not significantly contaminated by dust emission. Finally, we analyse the contribution of radio sources to the angular power spectrum of the cosmic microwave background
A Measurement of the Millimeter Emission and the Sunyaev-Zel'dovich Effect Associated with Low-Frequency Radio Sources
We present a statistical analysis of the millimeter-wavelength properties of 1.4 GHz-selected sources and a detection of the Sunyaev-Zel'dovich effect associated with the halos that host them. We stack data at 148, 218 and 277 GHz from the Atacama Cosmology Telescope at the positions of a large sample of radio AGN selected at 1.4 GHz. The thermal Sunyaev-Zel'dovich (SZ) effect associated with the halos that host the AGN is detected at the 5 sigma level through its spectral signature, representing a statistical detection of the SZ effect in some of the lowest mass halos (average M(sub 200) approximately equals 10(sup 13) solar mass h(sub 70)(exp 1) ) studied to date. The relation between the SZ effect and mass (based on weak lensing measurements of radio galaxies) is consistent with that measured by Planck for local bright galaxies. In the context of galaxy evolution models, this study confirms that galaxies with radio AGN also typically support hot gaseous halos. Adding Herschel observations allows us to show that the SZ signal is not significantly contaminated by dust emission. Finally, we analyze the contribution of radio sources to the angular power spectrum of the cosmic microwave background
A Measurement of the Millimeter Emission and the Sunyaev-zel'dovich Effect Associated with Low-frequency Radio Sources
We present a statistical analysis of the millimeter-wavelength properties of 1.4 GHz-selected sources and a detection of the Sunyaev-Zel'dovich Effect associated with the halos that host them. The Atacama Cosmology Telescope (ACT) has conducted a survey at 148 GHz, 218 GHz and 277 GHz along the celestial equator. Using samples of radio sources selected at 1.4 GHz from the Faint Images of the Radio Sky at Twenty-Centimeters (FIRST) Survey and the National Radio Astronomy Observatory Very Large Array Sky Survey (NVSS), we measure the stacked 148, 218 and 277 GHz flux densities for sources with 1.4 GHz flux densities ranging from 5 to 200 mJy. At these flux densities, the radio source population is dominated by active galactic nuclei (AGN), with both steep and at spectrum populations, which have combined radio-to-millimeter spectral indices ranging from 0.5 to 0.95, reecting the prevalence of steep spectrum sources at high flux densities and the presence of at spectrum sources at lower flux densities. The thermal Sunyaev-Zelapos;dovich (SZ) eect associated with the halos that host the AGN is detected at the 5 level through its spectral signature. When we compare the SZ eect with weak lensing measurements of radio galaxies, we find that the relation between the two is consistent with that measured by Planck for local bright galaxies. We present a detection of the SZ eect in some of the lowest mass halos (average M(sub 200) approx. equals 10(exp 13) solar M h(sup-1) (sub 70) ) studied to date. This detection is particularly important in the context of galaxy evolution models, as it confirms that galaxies with radio AGN also typically support hot gaseous halos. With Herschel* observations, we show that the SZ detection is not significantly contaminated by dusty galaxies or by dust associated with the AGN or galaxies hosting the AGN. We show that 5 mJy < S(sub 1:4) < 200 mJy radio sources contribute l(l +1)C(sub l)/(2 pi ) = 0:37+/- 0:03 micro K(exp 2) to the angular power spectrum at l = 3000 at 148 GHz, after accounting for the SZ effect associated with their host halos
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