Searches for continuous gravitational waves from nine young supernova remnants

We describe directed searches for continuous gravitational waves (GWs) in data from the sixth Laser Interferometer Gravitational-wave Observatory (LIGO) science data run. The targets were nine young supernova remnants not associated with pulsars; eight of the remnants are associated with non-pulsing suspected neutron stars. One targetʼs parameters are uncertain enough to warrant two searches, for a total of 10. Each search covered a broad band of frequencies and first and second frequency derivatives for a fixed sky direction. The searches coherently integrated data from the two LIGO interferometers over time spans from 5.3–25.3 days using the matched-filtering F-statistic. We found no evidence of GW signals. We set 95% confidence upper limits as strong (low) as 4 × 10−25 on intrinsic strain, 2 × 10−7 on fiducial ellipticity, and 4 × 10−5 on r-mode amplitude. These beat the indirect limits from energy conservation and are within the range of theoretical predictions for neutron-star ellipticities and r-mode amplitudes.publishedVersionFil: Domínguez, Alfredo Eduardo. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina.Fil: Domínguez, Alfredo Eduardo. Argentinian Gravitational Wave Group; Argentina.Fil: Maglione, César Germán. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina.Fil: Maglione, César Germán. Argentinian Gravitational Wave Group; Argentina.Fil: Ortega Larcher, Walter Emanuel. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina.Fil: Ortega Larcher, Walter Emanuel. Argentinian Gravitational Wave Group; Argentina.Fil: Quiroga, Gonzalo Damián. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina.Fil: Quiroga, Gonzalo Damián. Argentinian Gravitational Wave Group; Argentina.Fil: Reula, Oscar Alejandro. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina.Fil: Reula, Oscar Alejandro. Argentinian Gravitational Wave Group; Argentina.Otras Ciencias Física

Directed search for gravitational waves from Scorpius X-1 with initial LIGO data

We present results of a search for continuously emitted gravitational radiation, directed at the brightest low-mass x-ray binary, Scorpius X-1. Our semicoherent analysis covers 10 days of LIGO S5 data ranging from 50–550 Hz, and performs an incoherent sum of coherent F -statistic power distributed amongst frequency-modulated orbital sidebands. All candidates not removed at the veto stage were found to be consistent with noise at a 1% false alarm rate. We present Bayesian 95% confidence upper limits on gravitational-wave strain amplitude using two different prior distributions: a standard one, with no a priori assumptions about the orientation of Scorpius X-1; and an angle-restricted one, using a prior derived from electromagnetic observations. Median strain upper limits of 1.3 × 10−24 and 8 × 10−25 are reported at 150 Hz for the standard and angle-restricted searches respectively. This proof-of-principle analysis was limited to a short observation time by unknown effects of accretion on the intrinsic spin frequency of the neutron star, but improves upon previous upper limits by factors of ∼1.4 for the standard, and 2.3 for the angle-restricted search at the sensitive region of the detector.publishedVersionFil: Domínguez, Alfredo Eduardo. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina.Fil: Domínguez, Alfredo Eduardo. Argentinian Gravitational Wave Group; Argentina.Fil: Maglione, César Germán. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina.Fil: Maglione, César Germán. Argentinian Gravitational Wave Group; Argentina.Fil: Ortega Larcher, Walter Emanuel. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina.Fil: Ortega Larcher, Walter Emanuel. Argentinian Gravitational Wave Group; Argentina.Fil: Quiroga, Gonzalo Damián. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina.Fil: Quiroga, Gonzalo Damián. Argentinian Gravitational Wave Group; Argentina.Fil: Reula, Oscar Alejandro. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina.Fil: Reula, Oscar Alejandro. Argentinian Gravitational Wave Group; Argentina.Otras Ciencias Física

Advanced LIGO

The Advanced LIGO gravitational wave detectors are second-generation instruments designed and built for the two LIGO observatories in Hanford, WA and Livingston, LA, USA. The two instruments are identical in design, and are specialized versions of a Michelson interferometer with 4 km long arms. As in Initial LIGO, Fabry–Perot cavities are used in the arms to increase the interaction time with a gravitational wave, and power recycling is used to increase the effective laser power. Signal recycling has been added in Advanced LIGO to improve the frequency response. In the most sensitive frequency region around 100 Hz, the design strain sensitivity is a factor of 10 better than Initial LIGO. In addition, the low frequency end of the sensitivity band is moved from 40 Hz down to 10 Hz. All interferometer components have been replaced with improved technologies to achieve this sensitivity gain. Much better seismic isolation and test mass suspensions are responsible for the gains at lower frequencies. Higher laser power, larger test masses and improved mirror coatings lead to the improved sensitivity at mid and high frequencies. Data collecting runs with these new instruments are planned to begin in mid-2015.submittedVersionFil: Domínguez, Alfredo Eduardo. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina.Fil: Domínguez, Alfredo Eduardo. Argentinian Gravitational Wave Group; Argentina.Fil: Maglione, César Germán. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina.Fil: Maglione, César Germán. Argentinian Gravitational Wave Group; Argentina.Fil: Ortega Larcher, Walter Emanuel. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina.Fil: Ortega Larcher, Walter Emanuel. Argentinian Gravitational Wave Group; Argentina.Fil: Quiroga, Gonzalo Damián. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina.Fil: Quiroga, Gonzalo Damián. Argentinian Gravitational Wave Group; Argentina.Fil: Reula, Oscar Alejandro. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina.Fil: Reula, Oscar Alejandro. Argentinian Gravitational Wave Group; Argentina.Física de Partículas y Campo