1,272 research outputs found
Who Loses: An examination of losses in housing net worth, non-housing assets, and total savings from 2007 to 2008 among American families
This study models the loss in non-housing assets, increase in non-housing liabilities, and net change in housing value across people by education, ethnic, and occupational categories in the 2007-2008 collapse of Wall Street financial markets. Hypotheses of plausible loci of loss include the usual social categories. Findings do not confirm all of the common presuppositions—managerial class workers have among the largest losses, retirees somewhat limited losses, and losses by educational group decline with advancing education, with the possible exception of Ph.D. holders. The group which had the most severe losses in all asset categories was the armed forces. The magnitude of the suggested effects would indicate that additional policy attention should be targeted on military family outcomes under economic stress.housing net worth; non-household liabilities; non-household assets; occupational group; education level;
PyCBC Live: Rapid Detection of Gravitational Waves from Compact Binary Mergers
We introduce an efficient and straightforward technique for rapidly detecting
gravitational waves from compact binary mergers. We show that this method
achieves the low latencies required to alert electromagnetic partners of
candidate binary mergers, aids in data monitoring, and makes use of
multidetector networks for sky localization. This approach was instrumental to
the analysis of gravitational-wave candidates during the second observing run
of Advanced LIGO, including the period of coincident operation with Advanced
Virgo, and in particular the analysis of the first observed binary neutron star
merger GW170817, where it led to the first tightly localized sky map
() used to identify AT 2017gfo. Operation of this analysis
also enabled the initial discovery of GW170104 and GW170608 despite non-nominal
observing of the instrument.Comment: 10 pages, 5 figures, submitted to Physical Review
Investigating the noise residuals around the gravitational wave event GW150914
We use the Pearson cross-correlation statistic proposed by Liu and Jackson,
and employed by Creswell et al., to look for statistically significant
correlations between the LIGO Hanford and Livingston detectors at the time of
the binary black hole merger GW150914. We compute this statistic for the
calibrated strain data released by LIGO, using both the residuals provided by
LIGO and using our own subtraction of a maximum-likelihood waveform that is
constructed to model binary black hole mergers in general relativity. To assign
a significance to the values obtained, we calculate the cross-correlation of
both simulated Gaussian noise and data from the LIGO detectors at times during
which no detection of gravitational waves has been claimed. We find that after
subtracting the maximum likelihood waveform there are no statistically
significant correlations between the residuals of the two detectors at the time
of GW150914.Comment: 14 pages, 7 figures. Minor text and figure changes in final v3.
Notebooks for generating the results are available at
https://github.com/gwastro/gw150914_investigatio
Hierarchical approach to matched filtering using a reduced basis
Searching for gravitational waves from compact binary coalescences (CBC) is performed by matched filtering the observed strain data from gravitational-wave observatories against a discrete set of waveform templates designed to accurately approximate the expected gravitational-wave signal, and are chosen to efficiently cover a target search region. The computational cost of matched filtering scales with both the number of templates required to cover a parameter space and the in-band duration of the waveform. Both of these factors increase in difficulty as the current observatories improve in sensitivity, especially at low frequencies, and may pose challenges for third-generation observatories. Reducing the cost of matched filtering would make searches of future detector's data more tractable. In addition, it would be easier to conduct searches that incorporate the effects of eccentricity, precession or target light sources (e.g. subsolar). We present a hierarchical scheme based on a reduced bases method to decrease the computational cost of conducting a matched-filter based search. Compared to the current methods, we estimate without any loss in sensitivity, a speedup by a factor of 18 for sources with signal-to-noise ratio (SNR) of at least , and a factor of for SNR of at least 5. Our method is dominated by linear operations which are highly parallelizable. Therefore, we implement our algorithm using graphical processing units (GPUs) and evaluate commercially motivated metrics to demonstrate the efficiency of GPUs in CBC searches. Our scheme can be extended to generic CBC searches and allows for efficient matched filtering using GPUs
Search for gravitational waves from the coalescence of sub-solar mass binaries in the first half of Advanced LIGO and Virgo's third observing run
We present a search for gravitational waves from the coalescence of sub-solar
mass black hole binaries using data from the first half of Advanced LIGO and
Virgo's third observing run. The observation of a sub-solar mass black hole
merger may be an indication of primordial origin; primordial black holes may
contribute to the dark matter distribution. We search for black hole mergers
where the primary mass is and the secondary mass is . A variety of models predict the production and coalescence of
binaries containing primordial black holes; some involve dynamical assembly
which may allow for residual eccentricity to be observed. For component masses
, we also search for sources in eccentric orbits, measured at a
reference gravitational-wave frequency of 10 Hz, up to . We
find no convincing candidates and place new upper limits on the rate of
primordial black hole mergers. The merger rate of 0.5-0.5 (1.0-1.0)~
sources is Gpcyr. Our limits are times
more constraining than prior analyses. Finally, we demonstrate how our limits
can be used to constrain arbitrary models of the primordial black hole mass
distribution and merger rate.Comment: 7 pages, 3 figures, 1 table, v3 updated to match PRL, supplementary
materials at https://github.com/gwastro/subsolar-o3a-searc
Binary black hole spectroscopy : A no-hair test of GW190814 and GW190412
Gravitational waves provide a window to probe general relativity (GR) under extreme conditions. The recent observations of GW190412 and GW190814 are unique high-mass-ratio mergers that enable the observation of gravitational-wave harmonics beyond the dominant (ℓ,m)=(2,2) mode. Using these events, we search for physics beyond GR by allowing the source parameters measured from the subdominant harmonics to deviate from that of the dominant mode. All results are consistent with GR. We constrain the chirp mass as measured by the (ℓ,m)=(3,3) mode to be within 0-3+5% of the dominant mode when we allow both the masses and spins of the subdominant modes to deviate. If we allow only the mass parameters to deviate, we constrain the chirp mass of the (3,3) mode to be within ±1% of the expected value from GR. © 2020 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the "https://creativecommons.org/licenses/by/4.0/"Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Open access publication funded by the Max Planck Society
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