Chemistry and Physics publications

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Browsing Chemistry and Physics publications by Author "Aasi, J."

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    Directed search for continuous gravitational waves from the galactic center
    (American Physical Society, 2013) Aasi, J.; Abadie, J.; Abbott, B.; Abbott, R.; Abbott, T.; Abernathy, M.; Accadia, T.; Acernese, F.; Adams, C.; Adams, T.; Adhikari, R.; Affeldt, C.; Agathos, M.; Aggarwal, N.; Aguiar, O.; Ajith, P.; Allen, B.; Allocca, A.; Amador Ceron, E.; Amariutei, D.; et al.
    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 LIGO’s fifth science run from two LIGO detectors. The search uses a semicoherent 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 firstorder spindown values down to -7:86 * 10-8 Hz=s at the highest frequency. No gravitational waves were detected. The 90% confidence upper limits on the gravitational wave amplitude of sources at the Galactic center are ~3:35 * 10-25 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.
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    Parameter estimation for compact binary coalescence signals with the first generation gravitational-wave detector network
    (American Physical Soc, 2013) Aasi, J.; Munch, J.; Ottaway, D.; Veitch, P.
    Compact binary systems with neutron stars or black holes are one of the most promising sources for ground-based gravitational-wave detectors. Gravitational radiation encodes rich information about source physics; thus parameter estimation and model selection are crucial analysis steps for any detection candidate events. Detailed models of the anticipated waveforms enable inference on several parameters, such as component masses, spins, sky location and distance, that are essential for new astrophysical studies of these sources. However, accurate measurements of these parameters and discrimination of models describing the underlying physics are complicated by artifacts in the data, uncertainties in the waveform models and in the calibration of the detectors. Here we report such measurements on a selection of simulated signals added either in hardware or software to the data collected by the two LIGO instruments and the Virgo detector during their most recent joint science run, including a "blind injection" where the signal was not initially revealed to the collaboration. We exemplify the ability to extract information about the source physics on signals that cover the neutron-star and black-hole binary parameter space over the component mass range 1 M⊙-25 M⊙ and the full range of spin parameters. The cases reported in this study provide a snapshot of the status of parameter estimation in preparation for the operation of advanced detectors. © 2013 American Physical Society.