Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userA search of the Orion spur for continuous gravitational waves using a loosely coherent algorithm on data from LIGO interferometers
153
0
0.0
(
0
)
Added by
Vladimir Dergachev Ph.D.
Publication date
2015
fields
Physics
and research's language is
English
Ask ChatGPT about the research
No Arabic abstract
We report results of a wideband search for periodic gravitational waves from isolated neutron stars within the Orion spur towards both the inner and outer regions of our Galaxy. As gravitational waves interact very weakly with matter, the search is unimpeded by dust and concentrations of stars. One search disk (A) is $6.87^circ$ in diameter and centered on $20^textrm{h}10^textrm{m}54.71^textrm{s}+33^circ3325.29$, and the other (B) is $7.45^circ$ in diameter and centered on $8^textrm{h}35^textrm{m}20.61^textrm{s}-46^circ4925.151$. We explored the frequency range of 50-1500 Hz and frequency derivative from $0$ to $-5times 10^{-9}$ Hz/s. A multi-stage, loosely coherent search program allowed probing more deeply than before in these two regions, while increasing coherence length with every stage. Rigorous followup parameters have winnowed initial coincidence set to only 70 candidates, to be examined manually. None of those 70 candidates proved to be consistent with an isolated gravitational wave emitter, and 95% confidence level upper limits were placed on continuous-wave strain amplitudes. Near $169$ Hz we achieve our lowest 95% CL upper limit on worst-case linearly polarized strain amplitude $h_0$ of $6.3times 10^{-25}$, while at the high end of our frequency range we achieve a worst-case upper limit of $3.4times 10^{-24}$ for all polarizations and sky locations.
rate research
Read More
We report results of a search for continuous gravitational waves from a region covering the globular cluster Terzan 5 and the galactic center. Continuous gravitational waves are expected from fast-spinning, slightly non-axisymmetric isolated neutron stars as well as more exotic objects. The regions that we target are believed to be unusually abundant in neutron stars. We use a new loosely coherent search method that allows to reach unprecedented levels of sensitivity for this type of search. The search covers the frequency band 475-1500 Hz and frequency time derivatives in the range of [-3e-8, +1e-9] Hz/s, which is a parameter range not explored before with the depth reached by this search. As to be expected with only a few months of data from the same observing run, it is very difficult to make a confident detection of a continuous signal over such a large parameter space. A list of parameter space points that passed all the thresholds of this search is provided. We follow-up the most significant outlier on the newly released O2 data and cannot confirm it. We provide upper limits on the gravitational wave strength of signals as a function of signal frequency.
We report on an all-sky search for periodic gravitational waves in the frequency range $mathrm{50-1000 Hz}$ with the first derivative of frequency in the range $-8.9 times 10^{-10}$ Hz/s to zero in two years of data collected during LIGOs fifth science run. Our results employ a Hough transform technique, introducing a $chi^2$ test and analysis of coincidences between the signal levels in years 1 and 2 of observations that offers a significant improvement in the product of strain sensitivity with compute cycles per data sample compared to previously published searches. Since our search yields no surviving candidates, we present results taking the form of frequency dependent, 95$%$ confidence upper limits on the strain amplitude $h_0$. The most stringent upper limit from year 1 is $1.0times 10^{-24}$ in the $mathrm{158.00-158.25 Hz}$ band. In year 2, the most stringent upper limit is $mathrm{8.9times10^{-25}}$ in the $mathrm{146.50-146.75 Hz}$ band. This improved detection pipeline, which is computationally efficient by at least two orders of magnitude better than our flagship Einstein$@$Home search, will be important for quick-look searches in the Advanced LIGO and Virgo detector era.
We report on an all-sky search for continuous gravitational waves in the frequency band 20-2000,Hz and with a frequency time derivative in the range of $[-1.0, +0.1]times10^{-8}$,Hz/s. Such a signal could be produced by a nearby, spinning and slightly non-axisymmetric isolated neutron star in our galaxy. This search uses the LIGO data from the first six months of Advanced LIGOs and Advanced Virgos third observational run, O3. No periodic gravitational wave signals are observed, and 95% confidence-level (CL) frequentist upper limits are placed on their strengths. The lowest upper limits on worst-case (linearly polarized) strain amplitude $h_0$ are $~1.7times10^{-25}$ near 200,Hz. For a circularly polarized source (most favorable orientation), the lowest upper limits are $sim6.3times10^{-26}$. These strict frequentist upper limits refer to all sky locations and the entire range of frequency derivative values. For a population-averaged ensemble of sky locations and stellar orientations, the lowest 95% CL upper limits on the strain amplitude are $sim1.times10^{-25}$. These upper limits improve upon our previously published all-sky results, with the greatest improvement (factor of $sim$2) seen at higher frequencies, in part because quantum squeezing has dramatically improved the detector noise level relative to the second observational run, O2. These limits are the most constraining to date over most of the parameter space searched.
We present the results of a directed search for continuous gravitational waves from unknown, isolated neutron stars in the Galactic Center region, performed on two years of data from LIGOs fifth science run from two LIGO detectors. The search uses a semi-coherent approach, analyzing coherently 630 segments, each spanning 11.5 hours, and then incoherently combining the results of the single segments. It covers gravitational wave frequencies in a range from 78 to 496 Hz and a frequency-dependent range of first order spindown values down to -7.86 x 10^-8 Hz/s at the highest frequency. No gravitational waves were detected. We place 90% confidence upper limits on the gravitational wave amplitude of sources at the Galactic Center. Placing 90% confidence upper limits on the gravitational wave amplitude of sources at the Galactic Center, we reach ~3.35x10^-25 for frequencies near 150 Hz. These upper limits are the most constraining to date for a large-parameter-space search for continuous gravitational wave signals.
We present results of a search for periodic gravitational wave signals with frequency between 20 and 400 Hz, from the neutron star in the supernova remnant G347.3-0.5, using LIGO O2 public data. The search is deployed on the volunteer computing project Einstein@Home, with thousands of participants donating compute cycles to make this endevour possible. We find no significant signal candidate and set the most constraining upper limits to date on the amplitude of gravitational wave signals from the target, corresponding to deformations below $10^{-6}$ in a large part of the band. At the frequency of best strain sensitivity, near $166$ Hz, we set 90% confidence upper limits on the gravitational wave intrinsic amplitude of $h_0^{90%}approx 7.0times10^{-26}$. Over most of the frequency range our upper limits are a factor of 20 smaller than the indirect age-based upper limit.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
