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High-Frequency Measurements Of The Spectrum Of Sagittarius A*
We report near-simultaneous interferometric measurements of the spectrum of Sagittarius A* over the 5-354 GHz range and single-dish observations that have yielded the first detection of Sgr A* at 850 GHz. We confirm that Sgr A*'s spectrum rises more steeply at short millimeter wavelengths than at centimeter wavelengths, leading to a near-millimeter/submillimeter excess that dominates its luminosity. Below 900 GHz, Sgr A*'s observed luminosity is 70 +/- 30 L.. A new upper limit to Sgr A*'s 24.3 mu m flux, together with a compilation of other extant IR data, imply a far-infrared spectral turnover, which can result from either an intrinsic synchrotron cutoff or excess extinction near Sgr A*. If the former applies, Sgr A*'s total synchrotron luminosity is <10(3) L., while in the latter case it is <3 x 10(4) L. if spherical symmetry also applies.NSF AST96-15025, AST96-13717Astronom
DASI Three-Year Cosmic Microwave Background Polarization Results
We present the analysis of the complete 3-year data set obtained with the
Degree Angular Scale Interferometer (DASI) polarization experiment, operating
from the Amundsen-Scott South Pole research station. Additional data obtained
at the end of the 2002 Austral winter and throughout the 2003 season were added
to the data from which the first detection of polarization of the cosmic
microwave background radiation was reported. The analysis of the combined data
supports, with increased statistical power, all of the conclusions drawn from
the initial data set. In particular, the detection of E-mode polarization is
increased to 6.3 sigma confidence level, TE cross-polarization is detected at
2.9 sigma, and B-mode polarization is consistent with zero, with an upper limit
well below the level of the detected E-mode polarization. The results are in
excellent agreement with the predictions of the cosmological model that has
emerged from CMB temperature measurements. The analysis also demonstrates that
contamination of the data by known sources of foreground emission is
insignificant.Comment: 13 pages Latex, 10 figures, submitted to Ap
DASI First Results: A Measurement of the Cosmic Microwave Background Angular Power Spectrum
We present measurements of anisotropy in the Cosmic Microwave Background
(CMB) from the first season of observations with the Degree Angular Scale
Interferometer (DASI). The instrument was deployed at the South Pole in the
austral summer 1999--2000, and made observations throughout the following
austral winter. We have measured the angular power spectrum of the CMB in the
range 100<l<900 with high signal-to-noise. In this paper we review the
formalism used in the analysis, in particular the use of constraint matrices to
project out contaminants such as ground and point source signals, and to test
for correlations with diffuse foreground templates. We find no evidence of
foregrounds other than point sources in the data, and find a maximum likelihood
temperature spectral index beta = -0.1 +/- 0.2 (1 sigma), consistent with CMB.
We detect a first peak in the power spectrum at l approx 200, in agreement with
previous experiments. In addition, we detect a peak in the power spectrum at l
approx 550 and power of similar magnitude at l approx 800 which are consistent
with the second and third harmonic peaks predicted by adiabatic inflationary
cosmological models.Comment: 8 pages, 1 figure, minor changes in response to referee comment
High Frequency Cluster Radio Galaxies: Luminosity Functions and Implications for SZE Selected Cluster Samples
We study the overdensity of point sources in the direction of X-ray-selected
galaxy clusters from the Meta-Catalog of X-ray detected Clusters of galaxies
(MCXC; ) at South Pole Telescope (SPT) and Sydney
University Molonglo Sky Survey (SUMSS) frequencies. Flux densities at 95, 150
and 220 GHz are extracted from the 2500 deg SPT-SZ survey maps at the
locations of SUMSS sources, producing a multi-frequency catalog of radio
galaxies. In the direction of massive galaxy clusters, the radio galaxy flux
densities at 95 and 150 GHz are biased low by the cluster Sunyaev-Zel'dovich
Effect (SZE) signal, which is negative at these frequencies. We employ a
cluster SZE model to remove the expected flux bias and then study these
corrected source catalogs. We find that the high frequency radio galaxies are
centrally concentrated within the clusters and that their luminosity functions
(LFs) exhibit amplitudes that are characteristically an order of magnitude
lower than the cluster LF at 843 MHz. We use the 150 GHz LF to estimate the
impact of cluster radio galaxies on an SPT-SZ like survey. The radio galaxy
flux typically produces a small bias on the SZE signal and has negligible
impact on the observed scatter in the SZE mass-observable relation. If we
assume there is no redshift evolution in the radio galaxy LF then
percent of the clusters would be lost from the sample. Allowing for redshift
evolution of the form increases the incompleteness to
percent. Improved constraints on the evolution of the cluster radio galaxy LF
require a larger cluster sample extending to higher redshift.Comment: Submitted to MNRA
Application of a Self-Similar Pressure Profile to Sunyaev-Zel'dovich Effect Data from Galaxy Clusters
We investigate the utility of a new, self-similar pressure profile for
fitting Sunyaev-Zel'dovich (SZ) effect observations of galaxy clusters. Current
SZ imaging instruments - such as the Sunyaev-Zel'dovich Array (SZA) - are
capable of probing clusters over a large range in physical scale. A model is
therefore required that can accurately describe a cluster's pressure profile
over a broad range of radii, from the core of the cluster out to a significant
fraction of the virial radius. In the analysis presented here, we fit a radial
pressure profile derived from simulations and detailed X-ray analysis of
relaxed clusters to SZA observations of three clusters with exceptionally high
quality X-ray data: A1835, A1914, and CL J1226.9+3332. From the joint analysis
of the SZ and X-ray data, we derive physical properties such as gas mass, total
mass, gas fraction and the intrinsic, integrated Compton y-parameter. We find
that parameters derived from the joint fit to the SZ and X-ray data agree well
with a detailed, independent X-ray-only analysis of the same clusters. In
particular, we find that, when combined with X-ray imaging data, this new
pressure profile yields an independent electron radial temperature profile that
is in good agreement with spectroscopic X-ray measurements.Comment: 28 pages, 6 figures, accepted by ApJ for publication (probably April
2009
Financial development and economic growth : long-run equilibrium and transitional dynamics
We analyze the impact of financial development on economic growth. Differently from previous studies that focus mainly on balanced growth path outcomes, we also analyze the transitional dynamics of our model economy by using a finance-extended Uzawa-Lucas framework where financial intermediation affects both human and physical capital accumulation. We show that, under certain rather general conditions, economic growth may turn out to be non-monotonically related to financial development (as suggested by the most recent empirical evidence) and that too much finance may be detrimental to growth. We also show that the degree of financial development may affect the speed of convergence, which suggests that finance may play a crucial role in determining the length of the recovery process associated with exogenous shocks. Moreover, in a special case of the model, we observe that, under a realistic set of parameters, social welfare decreases with financial development, meaning that even when finance positively affects economic growth the short term costs associated with financial activities more than compensate their long run benefits
A Multi-Wavelength Mass Analysis of RCS2 J232727.6-020437, a ~3x10M Galaxy Cluster at z=0.7
We present an initial study of the mass and evolutionary state of a massive
and distant cluster, RCS2 J232727.6-020437. This cluster, at z=0.6986, is the
richest cluster discovered in the RCS2 project. The mass measurements presented
in this paper are derived from all possible mass proxies: X-ray measurements,
weak-lensing shear, strong lensing, Sunyaev Zel'dovich effect decrement, the
velocity distribution of cluster member galaxies, and galaxy richness. While
each of these observables probe the mass of the cluster at a different radius,
they all indicate that RCS2 J232727.6-020437 is among the most massive clusters
at this redshift, with an estimated mass of M_200 ~3 x10^15 h^-1 Msun. In this
paper, we demonstrate that the various observables are all reasonably
consistent with each other to within their uncertainties. RCS2 J232727.6-020437
appears to be well relaxed -- with circular and concentric X-ray isophotes,
with a cool core, and no indication of significant substructure in extensive
galaxy velocity data.Comment: 19 pages, 15 figures, submitted to ApJ on March 5, 2015; in press.
Manuscript revised following the referee revie
First Intrinsic Anisotropy Observations with the Cosmic Background Imager
We present the first results of observations of the intrinsic anisotropy of
the cosmic microwave background radiation with the Cosmic Background Imager
from a site at 5080 m altitude in northern Chile. Our observations show a sharp
decrease in C_l in the range l=400 - 1500. The broadband amplitudes we have
measured are deltaT(band) = 58.7 (-6.3, +7.7) microK for l = 603 (-166, +180)
and 29.7 (-4.2, +4.8) microK for l = 1190 (-224, +261), where these are
half-power widths in l. Such a decrease in power at high l is one of the
fundamental predictions of the standard cosmological model, and these are the
first observations which cover a broad enough l range to show this decrease in
a single experiment. The C_l we have measured enable us to place limits on the
density parameter, Omega(tot) = 0.7 (90% confidence).Comment: 5 pages including 2 figures. Corrected an error in the comparison
with Boomerang and Maxim
The Cosmic Background Imager
Design and performance details are given for the Cosmic Background Imager
(CBI), an interferometer array that is measuring the power spectrum of
fluctuations in the cosmic microwave background radiation (CMBR) for multipoles
in the range 400 < l < 3500. The CBI is located at an altitude of 5000 m in the
Atacama Desert in northern Chile. It is a planar synthesis array with 13 0.9-m
diameter antennas on a 6-m diameter tracking platform. Each antenna has a
cooled, low-noise receiver operating in the 26-36 GHz band. Signals are
cross-correlated in an analog filterbank correlator with ten 1 GHz bands. This
allows spectral index measurements which can be used to distinguish CMBR
signals from diffuse galactic foregrounds. A 1.2 kHz 180-deg phase switching
scheme is used to reject cross-talk and low-frequency pick-up in the signal
processing system. The CBI has a 3-axis mount which allows the tracking
platform to be rotated about the optical axis, providing improved (u,v)
coverage and a powerful discriminant against false signals generated in the
receiving electronics. Rotating the tracking platform also permits polarization
measurements when some of the antennas are configured for the orthogonal
polarization.Comment: 14 pages. Accepted for publication in PASP. See also
http://www.astro.caltech.edu/~tjp/CBI
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