Cross-correlation search for a hot spot of gravitational waves

Dhurandhar, S.; Tagoshi, Hideyuki; Okada, Yuta; Kanda, Nobuyuki; Takahashi, Hideya

doi:10.1103/physrevd.84.083007

Cited by 19 publications

(27 citation statements)

References 28 publications

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“…Low-mass isolated NSs are relatively promising gravitational-wave sources because they are more deformable and their crusts can support larger ellipticities, generating stronger gravitational-wave signals (Horowitz 2010 the characteristic gravitational-wave amplitude depends on a (generally unknown) geometrical factor involving the orientation of the NS and the antenna pattern of the detectors (see e.g. Bonazzola & Gourgoulhon 1996;Dhurandhar et al 2011). It has recently been proposed that gravitational-wave measurements of a stochastic gravitational-wave background from rotating NSs could be used to constrain the average NS ellipticity, and (if constraints on the masses can be obtained) these measurements could also constrain η.…”

Section: Discussionmentioning

confidence: 99%

Low-mass neutron stars: universal relations, the nuclear symmetry energy and gravitational radiation

Silva

Sotani

Berti

2016

Mon. Not. R. Astron. Soc.

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The lowest neutron star masses currently measured are in the range 1.0 − 1.1 M ⊙ , but these measurement have either large uncertainties or refer to isolated neutron stars. The recent claim of a precisely measured mass M/M ⊙ = 1.174±0.004 (Martinez et al. 2015) in a double neutron star system suggests that low-mass neutron stars may be an interesting target for gravitational-wave detectors. Furthermore, Sotani et al. (2014) recently found empirical formulas relating the mass and surface redshift of nonrotating neutron stars to the star's central density and to the parameter η ≡ (K 0 L 2 ) 1/3 , where K 0 is the incompressibility of symmetric nuclear matter and L is the slope of the symmetry energy at saturation density. Motivated by these considerations, we extend the work by Sotani et al. (2014) to slowly rotating and tidally deformed neutron stars. We compute the moment of inertia, quadrupole moment, quadrupole ellipticity, tidal and rotational Love number and apsidal constant of slowly rotating neutron stars by integrating the Hartle-Thorne equations at second order in rotation, and we fit all of these quantities as functions of η and of the central density. These fits may be used to constrain η, either via observations of binary pulsars in the electromagnetic spectrum, or via near-future observations of inspiralling compact binaries in the gravitationalwave spectrum.

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Section: Discussionmentioning

confidence: 99%

Low-mass neutron stars: universal relations, the nuclear symmetry energy and gravitational radiation

Silva

Sotani

Berti

2016

Mon. Not. R. Astron. Soc.

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“…where βð≤ 1Þ is the orientation factor [25], I is its principal moment of inertia, r is the distance to the source, G is the Newton's gravitational constant, c is the speed of light, and ϵ is the ellipticity. By combining Eq.…”

Section: Source Modelmentioning

confidence: 99%

Measuring neutron-star ellipticity with measurements of the stochastic gravitational-wave background

et al. 2014

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Galactic neutron stars are a promising source of gravitational waves in the analysis band of detectors such as Laser Interferometer Gravitational-Wave Observatory (LIGO) and Virgo. Previous searches for gravitational waves from neutron stars have focused on the detection of individual neutron stars, which are either nearby or highly nonspherical. Here, we consider the stochastic gravitational-wave signal arising from the ensemble of Galactic neutron stars. Using a population synthesis model, we estimate the single-sigma sensitivity of current and planned gravitational-wave observatories to average neutron star ellipticity ϵ as a function of the number of in-band Galactic neutron stars N tot . For the plausible case of N tot ≈ 53000, and assuming one year of observation time with colocated initial LIGO detectors, we find it to be σ ϵ ¼ 2.1 × 10 −7 , which is comparable to current bounds on some nearby neutron stars. (The current best 95% upper limits are ϵ ≲ 7 × 10 −8 .) It is unclear if Advanced LIGO can significantly improve on this sensitivity using spatially separated detectors. For the proposed Einstein Telescope, we estimate that σ ϵ ¼ 5.6 × 10 −10 . Finally, we show that stochastic measurements can be combined with measurements of individual neutron stars in order to estimate the number of in-band Galactic neutron stars. In this way, measurements of stochastic gravitational waves provide a complementary tool for studying Galactic neutron stars.

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“…LIGO [3] and Virgo [4] radiometer searches for persistent gravitational waves have yielded limits on the gravitational-wave strain from targets including Scorpius X-1, the Galactic Center, and Supernova 1987A [5]. Radiometer searches are also sensitive to hot spots created from the superposition of many persistent sources [6][7][8]. By restricting the timescale of integration, the same method has been applied to search for relatively long-lived ∼10-1000 s gravitationalwave transients [9], e.g., associated with long gammaray bursts [10].…”

Section: Introductionmentioning

confidence: 99%

All-sky, narrowband, gravitational-wave radiometry with folded data

et al. 2015

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Gravitational-wave radiometry is a powerful tool by which weak signals with unknown signal morphologies are recovered through a process of cross correlation. Radiometry has been used, e.g., to search for persistent signals from known neutron stars such as Scorpius X-1. In this paper, we demonstrate how a more ambitious search-for persistent signals from unknown neutron starscan be efficiently carried out using folded data, in which an entire ∼year-long observing run is represented as a single sidereal day. The all-sky, narrowband radiometer search described here will provide a computationally tractable means to uncover gravitational-wave signals from unknown, nearby neutron stars in binary systems, which can have modulation depths of ≈0.1-2 Hz. It will simultaneously provide a sensitive search algorithm for other persistent, narrowband signals from unexpected sources.

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Cross-correlation search for a hot spot of gravitational waves

Cited by 19 publications

References 28 publications

Low-mass neutron stars: universal relations, the nuclear symmetry energy and gravitational radiation

Low-mass neutron stars: universal relations, the nuclear symmetry energy and gravitational radiation

Measuring neutron-star ellipticity with measurements of the stochastic gravitational-wave background

All-sky, narrowband, gravitational-wave radiometry with folded data

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