25 research outputs found
A Search for Cosmic Microwave Background Anisotropies on Arcminute Scales with Bolocam
We have surveyed two science fields totaling one square degree with Bolocam
at 2.1 mm to search for secondary CMB anisotropies caused by the Sunyaev-
Zel'dovich effect (SZE). The fields are in the Lynx and Subaru/XMM SDS1 fields.
Our survey is sensitive to angular scales with an effective angular multipole
of l_eff = 5700 with FWHM_l = 2800 and has an angular resolution of 60
arcseconds FWHM. Our data provide no evidence for anisotropy. We are able to
constrain the level of total astronomical anisotropy, modeled as a flat
bandpower in C_l, with frequentist 68%, 90%, and 95% CL upper limits of 590,
760, and 830 uKCMB^2. We statistically subtract the known contribution from
primary CMB anisotropy, including cosmic variance, to obtain constraints on the
SZE anisotropy contribution. Now including flux calibration uncertainty, our
frequentist 68%, 90% and 95% CL upper limits on a flat bandpower in C_l are
690, 960, and 1000 uKCMB^2. When we instead employ the analytic spectrum
suggested by Komatsu and Seljak (2002), and account for the non-Gaussianity of
the SZE anisotropy signal, we obtain upper limits on the average amplitude of
their spectrum weighted by our transfer function of 790, 1060, and 1080
uKCMB^2. We obtain a 90% CL upper limit on sigma8, which normalizes the power
spectrum of density fluctuations, of 1.57. These are the first constraints on
anisotropy and sigma8 from survey data at these angular scales at frequencies
near 150 GHz.Comment: 68 pages, 17 figures, 2 tables, accepted for publication in Ap
A Fluctuation Analysis of the Bolocam 1.1mm Lockman Hole Survey
We perform a fluctuation analysis of the 1.1mm Bolocam Lockman Hole Survey,
which covers 324 square arcmin to a very uniform point source-filtered RMS
noise level of 1.4 mJy/beam. The fluctuation analysis has the significant
advantage of utilizing all of the available data. We constrain the number
counts in the 1-10 mJy range, and derive significantly tighter constraints than
in previous work: the power-law index is 2.7 (+0.18, -0.15), while the
amplitude is equal to 1595 (+85,-238) sources per mJy per square degree, or
N(>1 mJy) = 940 (+50,-140) sources/square degree (95% confidence). Our results
agree extremely well with those derived from the extracted source number counts
by Laurent et al (2005). Our derived normalization is about 2.5 times smaller
than determined by MAMBO at 1.2mm by Greve et al (2004). However, the
uncertainty in the normalization for both data sets is dominated by the
systematic (i.e., absolute flux calibration) rather than statistical errors;
within these uncertainties, our results are in agreement. We estimate that
about 7% of the 1.1mm background has been resolved at 1 mJy.Comment: To appear in the Astrophysical Journal; 22 pages, 9 figure
Studies of atmospheric noise on Mauna Kea at 143 GHz with Bolocam
We report measurements of the fluctuations in atmospheric emission (atmospheric noise) above Mauna Kea recorded with Bolocam at 143 GHz. These data were collected in November and December of 2003 with Bolocam mounted on the Caltech Submillimeter Observatory (CSO), and span approximately 40 nights. Below ≃ 0.5 Hz, the data time-streams are dominated by the f-δ atmospheric noise in all observing conditions. We were able to successfully model the atmospheric fluctuations using a Kolmogorov-Taylor turbulence model for a thin wind-driven screen in approximately half of our data. Based on this modeling, we developed several algorithms to remove the atmospheric noise, and the best results were achieved when we described the fluctuations using a low-order polynomial in detector position over the 8 arcminute focal plane. However, even with these algorithms, we were not able to reach photon-background-limited instrument photometer (BLIP) performance at frequencies below ≃ 0.5 Hz in any observing conditions. Therefore, we conclude that BLIP performance is not possible from the CSO below ≃ 0.5 Hz for broadband 150 GHz receivers with subtraction of a spatial atmospheric template on scales of several arcminutes
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Antenna-coupled TES bolometers for the SPIDER experiment
SPIDER is a proposed balloon-borne experiment designed to search for the imprints of gravity waves on the polarization of the cosmic microwave background radiation. The required wide frequency coverage, large number of sensitive detectors, and the stringent power constraints on a balloon are made possible by antenna-coupled TES bolometers. Several prototype devices have been fabricated and optically characterized. Their spectral and angular responses agree well with the theoretical expectations
The Bolocam Lockman Hole Millimeter-Wave Galaxy Survey: Galaxy Candidates and Number Counts
We present results of a new deep 1.1 mm survey using Bolocam, a
millimeter-wavelength bolometer array camera designed for mapping large fields
at fast scan rates, without chopping. A map, galaxy candidate list, and derived
number counts are presented. This survey encompasses 324 arcmin^2 to an rms
noise level (filtered for point sources) of 1.4 mJy/beam and includes the
entire regions surveyed by the published 8 mJy 850 micron JCMT SCUBA and 1.2 mm
IRAM MAMBO surveys. We reduced the data using a custom software pipeline to
remove correlated sky and instrument noise via a principal component analysis.
Extensive simulations and jackknife tests were performed to confirm the
robustness of our source candidates and estimate the effects of false
detections, bias, and completeness. In total, 17 source candidates were
detected at a significance > 3.0 sigma, with six expected false detections.
Nine candidates are new detections, while eight candidates have coincident
SCUBA 850 micron and/or MAMBO 1.2 mm detections. From our observed number
counts, we estimate the underlying differential number count distribution of
submillimeter galaxies and find it to be in general agreement with previous
surveys. Modeling the spectral energy distributions of these submillimeter
galaxies after observations of dusty nearby galaxies suggests extreme
luminosities of L = 1.0-1.6 x 10^13 L_solar and, if powered by star formation,
star formation rates of 500-800 M_solar/yr.Comment: In press (to appear in Astrophysical Journal: 1 May 2005, v624, 1
issue); 21 pages, 15 figures, 3 table
Studies of Millimeter-Wave Atmospheric Noise Above Mauna Kea
We report measurements of the fluctuations in atmospheric emission
(atmospheric noise) above Mauna Kea recorded with Bolocam at 143 and 268 GHz
from the Caltech Submillimeter Observatory (CSO). The 143 GHz data were
collected during a 40 night observing run in late 2003, and the 268 GHz
observations were made in early 2004 and early 2005 over a total of 60 nights.
Below 0.5 Hz, the data time-streams are dominated by atmospheric noise in all
observing conditions. The atmospheric noise data are consistent with a
Kolmogorov-Taylor (K-T) turbulence model for a thin wind-driven screen, and the
median amplitude of the fluctuations is 280 mK^2 rad^(-5/3) at 143 GHz and 4000
mK^2 rad^(-5/3) at 268 GHz. Comparing our results with previous ACBAR data, we
find that the normalization of the power spectrum of the atmospheric noise
fluctuations is a factor of 80 larger above Mauna Kea than above the South Pole
at millimeter wavelengths. Most of this difference is due to the fact that the
atmosphere above the South Pole is much drier than the atmosphere above Mauna
Kea. However, the atmosphere above the South Pole is slightly more stable as
well: the fractional fluctuations in the column depth of precipitable water
vapor are a factor of sqrt(2) smaller at the South Pole compared to Mauna Kea.
Based on our atmospheric modeling, we developed several algorithms to remove
the atmospheric noise, and the best results were achieved when we described the
fluctuations using a low-order polynomial in detector position over the 8
arcmin field of view (FOV). However, even with these algorithms, we were not
able to reach photon-background-limited instrument photometer (BLIP)
performance at frequencies below 0.5 Hz in any observing conditions.Comment: 48 pages, 16 figures, accepted for publication in Ap
Studies of atmospheric noise on Mauna Kea at 143 GHz with Bolocam
We report measurements of the fluctuations in atmospheric emission (atmospheric noise) above Mauna Kea recorded with Bolocam at 143 GHz. These data were collected in November and December of 2003 with Bolocam mounted on the Caltech Submillimeter Observatory (CSO), and span approximately 40 nights. Below ≃ 0.5 Hz, the data time-streams are dominated by the f-δ atmospheric noise in all observing conditions. We were able to successfully model the atmospheric fluctuations using a Kolmogorov-Taylor turbulence model for a thin wind-driven screen in approximately half of our data. Based on this modeling, we developed several algorithms to remove the atmospheric noise, and the best results were achieved when we described the fluctuations using a low-order polynomial in detector position over the 8 arcminute focal plane. However, even with these algorithms, we were not able to reach photon-background-limited instrument photometer (BLIP) performance at frequencies below ≃ 0.5 Hz in any observing conditions. Therefore, we conclude that BLIP performance is not possible from the CSO below ≃ 0.5 Hz for broadband 150 GHz receivers with subtraction of a spatial atmospheric template on scales of several arcminutes
The ethics of manhood in post-war Huambo, Angola
This thesis considers the impact of a long civil war on the masculinities performed by war veterans in Huambo, Angola. In particular, it looks at how the social transformations of war, and the particular courses veterans took through them, affected how certain aspects of the performance of senior masculinities were ethically problematised. Based on a year's ethnographic fieldwork carried out in 2012, it traces the life histories of veterans of the MPLA government's Forças Armadas pela Libertação de Angola (FAPLA), from birth until the time of fieldwork, and explores how the gendered consequences of war played out in everyday life ten years after the civil war came to an end. Firstly, it explores the historical and biographical constitution of these men's ethical sensibilities, exploring the layered influences of social patterns of different historical periods, and the moral upbringing of particular veterans and their subsequent evolution through the war. Secondly, it turns to an examination of the principal ethical challenges facing these veterans in 2012, especially those related to wartime urbanisation and the changing social valuation of money, and their effects on veterans' status as elder men and husband-providers. Thirdly, it considers two influential styles of masculinity adopted in response to these challenges: the companionatelymarried churchgoing man, and the womanising drinker, discussing the different ways that these styles engaged with the social legacies of the war. Finally, it considers the main ethical influence on public respectability for these men, which constituted the main dividing line between these different styles – that of the churches, and accounts for their continuing moral authority. The thesis seeks to contribute to literatures on masculinities, war and military service in Africa, and to demonstrate the insights that the lenses of gender and ethics can bring to an understanding of Angola's post-war transition
Velocidad de corrosión de una aleación base plomo en una solución de ácido sulfúrico a diferentes temperaturas
A study of the scattering of valve regulated lead acid batteries in a string
International audienceScattering of the electrical characteristics or performances of VRLA batteries was measured on string with 24 batteries in series, using new batteries from three different manufacturers. Data on open-circuit voltage, and float conditions (currents and voltages) were collected and discussed