Einstein@Home search for periodic gravitational waves in LIGO S4 data

Abstract

A search for periodic gravitational waves, from sources such as isolated rapidly spinning neutron stars, was carried out using 510 h of data from the fourth LIGO science run (S4). The search was for quasimonochromatic waves in the frequency range from 50 to 1500 Hz, with a linear frequency drift f˙ (measured at the solar system barycenter) in the range -f/τ<f˙<0.1f/τ, where the minimum spin-down age τ was 1000 yr for signals below 300 Hz and 10 000 yr above 300 Hz. The main computational work of the search was distributed over approximately 100 000 computers volunteered by the general public. This large computing power allowed the use of a relatively long coherent integration time of 30 h, despite the large parameter space searched. No statistically significant signals were found. The sensitivity of the search is estimated, along with the fraction of parameter space that was vetoed because of contamination by instrumental artifacts. In the 100 to 200 Hz band, more than 90% of sources with dimensionless gravitational-wave strain amplitude greater than 10-23 would have been detected

Searching for gravitational waves from Cassiopeia A with LIGO

“…The LSC uses both fully coherent [1][2][3][4][5] and semi-coherent [6][7][8][9] methods to search for periodic gravitational waves. Semi-coherent methods are computationally cheaper than coherent methods, but coherent methods can achieve greater sensitivity if the cost is feasible.…”

“…where μ is the mismatch and we have performed the integral in equation (24) of [34] using the ranges (9) and discarding the lower bound on frequency, which is only a few per cent correction. We determine the highest frequency derivative needed by finding k such that γ kk 2 k > μ, where k is the range of the kth frequency derivative and we take μ to be 20% (typical for periodic signal searches).…”

“…The LIGO Scientific Collaboration (LSC) has so far published three types of searches for periodic gravitational waves (GWs): searches for known non-accreting pulsars [1][2][3][4], for the non-pulsing low-mass x-ray binary Sco X-1 [5,6] and all-sky searches for as yet unknown neutron stars [5,[7][8][9]. The first and last types of searches are approaching the indirect upper limits on gravitational wave emission inferred from the observed spindowns (spin frequency derivatives) of pulsars and supernova-based estimates of the neutron star population of the galaxy [5].…”

First low-frequency Einstein@Home all-sky search for continuous gravitational waves in Advanced LIGO data

“…A number of all-sky searches have been carried out on initial LIGO data, [2][3][4][5][6][7][8][9][10][11][12][13][14][15], of which [2,3,7,9,14] also ran on Einstein@Home. Einstein@Home is a distributed computing project which uses the idle time of computers volunteered by the general public to search for GWs.…”

A hierarchical search for gravitational waves from supermassive black hole binary mergers

“…Thus, the computational cost of a naive implementation of a matched filtered search would be formidable. For example if we were to conduct a one stage match-filtered search on the MLDC 1B dataset to get parameter accuracies to similar levels to those we quote in our results section we estimate that you would require 10 19 templates. Of course detecting a signal as loud as the ones used in the MLDC requires significantly less templates, and can be done by placing templates in mass space only.…”