Gravitational Waves from Single Neutron Stars: An Advanced Detector Era Survey

Glampedakis, Kostas; Gualtieri, Leonardo

doi:10.1007/978-3-319-97616-7_12

Cited by 79 publications

(99 citation statements)

References 299 publications

(529 reference statements)

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“…These upper limits in a large frequency band [300 -700] Hz correspond to an ellipticity smaller than ∼ 10 −5 , which is the maximum expected ellipticity for a normal NS [8]. Higher maximum ellipticities are predicted for NS with more exotic equation of state [7].…”

Section: Discussionmentioning

confidence: 85%

“…Several different mechanisms have been proposed to explain the existence of the star asymmetry which triggers the GW emission [6,7]. This can be caused by the presence of elastic stresses, strong internal magnetic fields not aligned to the star rotation axis, free precession with respect to the star rotation axis, excitation of long- * ornella.juliana.piccinni@roma1.infn.it lasting r-mode oscillations and the accretion of matter from a companion star, e.g.…”

Section: Introductionmentioning

confidence: 99%

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Directed search for continuous gravitational-wave signals from the Galactic Center in the Advanced LIGO second observing run

et al. 2020

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In this work we present the results of a search for continuous gravitational waves from the Galactic Center using LIGO O2 data. The search uses the Band-Sampled-Data directed search pipeline, which performs a semi-coherent wide-parameter-space search, exploiting the robustness of the Frequency-Hough transform algorithm. The search targets signals emitted by isolated asymmetric spinning neutron stars, located within the few inner parsecs of the Galactic Center. The frequencies covered in this search range between 10 Hz and 710 Hz with a spin-down range from −1.8 × 10 −9 Hz/s to 3.7 × 10 −11 Hz/s. No continuous wave signal has been detected and upper limits on the gravitational wave amplitude are presented. The most stringent upper limit at 95% confidence level, for Livingston detector, is ∼ 1.4 × 10 −25 at 163 Hz. To date, this is the most sensitive directed search for continuous gravitational-wave signals from the Galactic Center and the first search of this kind using LIGO second observing run.

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Section: Discussionmentioning

confidence: 85%

Section: Introductionmentioning

confidence: 99%

Directed search for continuous gravitational-wave signals from the Galactic Center in the Advanced LIGO second observing run

et al. 2020

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“…Isolated neutron stars may emit GWs through various processes (Please see [15] and references therein for a comprehensive discussion). A neutron star may sustain a deformation in some cases, and if not axisymmetric with respect to its rotation axis, then emit GWs.…”

Section: Continuous Gravitational Wavesmentioning

confidence: 99%

“…As opposed to GW signals from binary coalescence, which are short lived, the continuous gravitational waves are due to intrinsic deformations or other phenomena of the compact star itself, and may last decades or centuries. The cause for these continuous GWs may be due to various distinct phenomena-stellar seismic activity, mode instabilities, mountains, oscillations or glitches in the angular velocity (see for instance [13][14][15] and references therein). There has been rapid progress in this area, with many recent searches [16][17][18], and future third-generation GW detectors, such as the Einstein Telescope, expected to significantly improve the sensitivity and reach in the relevant frequency bands [19][20][21][22].…”

Section: Introductionmentioning

confidence: 99%

Continuous gravitational waves and magnetic monopole signatures from single neutron stars

2020

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Future observations of continuous gravitational waves from single neutron stars, apart from their monumental astrophysical significance, could also shed light on fundamental physics and exotic particle states. One such avenue is based on the fact that magnetic fields cause deformations of a neutron star, which results in a magnetic-field-induced quadrupole ellipticity. If the magnetic and rotation axes are different, this quadrupole ellipticity may generate continuous gravitational waves which may last decades, and may be observable in current or future detectors. Light, milli-magnetic monopoles, if they exist, could be pair-produced non-perturbatively in the extreme magnetic fields of neutron stars, such as magnetars. This non-perturbative production furnishes a new, direct dissipative mechanism for the neutron star magnetic fields. Through their consequent effect on the magnetic-fieldinduced quadrupole ellipticity, they may then potentially leave imprints in the early stage continuous gravitational wave emissions. We speculate on this possibility in the present study, by considering some of the relevant physics and taking a very simplified toy model of a magnetar as the prototypical system. Preliminary indications are that new-born millisecond magnetars could be promising candidates to look for such imprints. Deviations from conventional evolution, and comparatively abrupt features in the early stage gravitational waveforms, distinct from other astrophysical contributions, could be distinguishable signatures for these exotic monopole states.

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“…Such deformations are colloquially termed 'mountains'. See Glampedakis & Gualtieri (2018) for a review.…”

Section: Introductionmentioning

confidence: 99%

Gravitational waves from magnetically induced thermal neutron star mountains

Osborne

Jones

2020

Monthly Notices of the Royal Astronomical Society

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Many low-mass X-ray binary (LMXB) systems are observed to contain rapidly spinning neutron stars. The spin frequencies of these systems may be limited by the emission of gravitational waves. This can happen if their mass distribution is sufficiently non-axisymmetric. It has been suggested that such 'mountains' may be created via temperature non-axisymmetries, but estimates of the likely level of temperature asymmetry have been lacking. To remedy this, we examine a simple symmetry breaking mechanism, where an internal magnetic field makes the thermal conductivity tensor direction-dependent. We find that the internal magnetic field strengths required to build the mountains of the necessary size are very large, about four orders of magnitude larger than the inferred external field strengths. We also examine how non-axisymmetric surface temperature profiles, as might be caused by magnetic funnelling of the accretion flow, lead to internal temperature asymmetries, but find that for realistic parameters the induced non-axisymmetries are very small. We conclude that, in the context of this work at least, very large internal magnetic fields are required to generate mountains of the necessary size.

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Gravitational Waves from Single Neutron Stars: An Advanced Detector Era Survey

Cited by 79 publications

References 299 publications

Directed search for continuous gravitational-wave signals from the Galactic Center in the Advanced LIGO second observing run

Directed search for continuous gravitational-wave signals from the Galactic Center in the Advanced LIGO second observing run

Continuous gravitational waves and magnetic monopole signatures from single neutron stars

Gravitational waves from magnetically induced thermal neutron star mountains

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