We describe a directed search for continuous gravitational waves in data from the sixth initial LIGO science run. The target was the nearby globular cluster NGC 6544 at a distance of ≈ 2.7 kpc. The search covered a broad band of frequencies along with first and second frequency derivatives for a fixed sky position. The search coherently integrated data from the two LIGO interferometers over a time span of 9.2 days using the matched-filtering F-statistic. We found no gravitational-wave signals and set 95% confidence upper limits as stringent as 6.0e−25 on intrinsic strain and 8.5e−6 on fiducial ellipticity. These values beat the indirect limits from energy conservation for stars with characteristic spin-down ages older than 300 years and are within the range of theoretical predictions for possible neutron-star ellipticities. An important feature of this search was use of a barycentric resampling algorithm which substantially reduced computational cost; this method is used extensively in searches of Advanced LIGO and Virgo detector data.

Search for continuous gravitational waves from neutron stars in globular cluster NGC 6544

BRANCHESI, MARICA;CERBONI BAIARDI, LORENZO;GRECO, GIUSEPPE;GUIDI, GIANLUCA MARIA;HARMS, JAN;MARTELLI, FILIPPO;MONTANI, MATTEO;PIERGIOVANNI, FRANCESCO;STRATTA, MARIA GIULIANA;VETRANO, FLAVIO;VICERE', ANDREA;
2017-01-01

Abstract

We describe a directed search for continuous gravitational waves in data from the sixth initial LIGO science run. The target was the nearby globular cluster NGC 6544 at a distance of ≈ 2.7 kpc. The search covered a broad band of frequencies along with first and second frequency derivatives for a fixed sky position. The search coherently integrated data from the two LIGO interferometers over a time span of 9.2 days using the matched-filtering F-statistic. We found no gravitational-wave signals and set 95% confidence upper limits as stringent as 6.0e−25 on intrinsic strain and 8.5e−6 on fiducial ellipticity. These values beat the indirect limits from energy conservation for stars with characteristic spin-down ages older than 300 years and are within the range of theoretical predictions for possible neutron-star ellipticities. An important feature of this search was use of a barycentric resampling algorithm which substantially reduced computational cost; this method is used extensively in searches of Advanced LIGO and Virgo detector data.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11576/2644577
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