Gravitational waves from nonradial oscillations of stochastically accreting neutron stars

Abstract

Oscillating neutron stars are sources of continuous gravitational waves. We study analytically the excitation of stellar oscillations by the mechanical impact on the stellar surface of ''clumps'' of stochastically accreted matter. We calculate the waveform and spectrum of the gravitational wave signal emitted by the accretion-driven pulsations. Results are generated for an idealised model of a nonrotating, unmagnetised, one-component star with uniform polytropic index $n_{\mathrm{poly}}$ assuming Newtonian gravity and the Cowling approximation. We find that the excited mode amplitudes grow with increasing $n_{\mathrm{poly}}$ and mode order $n$. The gravitational wave signal forms a sequence of amplitude-modulated packets for $n_{\mathrm{poly}}=1$, lasting $\sim 10^{-3}$s after each impact. The gravitational wave strain increases with increasing $n_{\mathrm{poly}}$, but decreases with increasing $n$ and increasing multipole order $l$ for $n_{\mathrm{poly}}=1$. In the observing band of current long-baseline interferometers, $g$-modes emit higher, narrower peaks in the amplitude spectral density than $f$- and $p$-modes, with the highest peaks reaching $\sim 10^{-26}$Hz${}^{-1/2}$ for modes with damping time ${\tau }_{nl}\sim 10^8$yr. The root-mean-square strain $h_{\text{rms}}$, calculated by summing over modes with $2\le l\le 4$ and ${\tau }_{nl}\le 10^8$yr, spans the range $10^{-33}\le h_{\text{rms}}\le 10^{-32}$ for $1\le n_{\text{poly}}\le 2$.

arXiv comment18 pages, 8 figures. accepted in MNRAS

References in corpus (61)

• Neutron Star Structure and the Equation of State
• Science Case for the Einstein Telescope
• Observing binary inspiral in gravitational radiation: One interferometer
• A new class of unstable modes of rotating relativistic stars
• The Equation of State of Hot, Dense Matter and Neutron Stars
• Open data from the first and second observing runs of Advanced LIGO and Advanced Virgo
• Gravitational Radiation and Rotation of Accreting Neutron Stars
• Gravitational waves from hot young rapidly rotating neutron stars
• Gravitational Radiation Instability in Hot Young Neutron Stars
• Sensitivity and Performance of the Advanced LIGO Detectors in the Third Observing Run
• Deformations of Accreting Neutron Star Crusts and Gravitational Wave Emission
• Three-dimensional Simulations of Disk Accretion to an Inclined Dipole: I. Magnetospheric Flow at Different Theta
• Resonant Oscillations and Tidal Heating in Coalescing Binary Neutron Stars
• Detecting gravitational wave emission from the known accreting neutron stars
• The inverse problem for pulsating neutron stars: A ``fingerprint analysis'' for the supranuclear equation of state
• Thermonuclear burst oscillations
• Accretion to Magnetized Stars through the Rayleigh-Taylor Instability: Global Three-Dimensional Simulations
• Nonlinear mode coupling in rotating stars and the r-mode instability in neutron stars
• On the dynamics of superfluid neutron star cores
• Mountains on Neutron Stars: Accreted vs. Non-Accreted crusts
• Oscillations of alpha UMa and other red giants
• Torsional Oscillations of Relativistic Stars with Dipole Magnetic Fields
• Gravitational Radiation from an Accreting Millisecond Pulsar with a Magnetically Confined Mountain
• A reflection model for the cyclotron lines in the spectra of X-ray pulsars
• QPOs during magnetar flares are not driven by mechanical normal modes of the crust
• TIDAL AND TIDAL-RESONANT EFFECTS IN COALESCING BINARIES
• Searches for Continuous-Wave Gravitational Radiation
• The dynamics of pulsar glitches: Contrasting phenomenology with numerical evolutions
• All-sky search for continuous gravitational waves from isolated neutron stars using Advanced LIGO and Advanced Virgo O3 data
• R-Modes on Rapidly Rotating, Relativistic Stars: I. Do Type-I Bursts Excite Modes in the Neutron-Star Ocean?
• Review of the Advanced LIGO gravitational wave observatories leading to observing run four
• Probing neutron star superfluidity with gravitational-wave data
• Detecting gravitational waves from mountains on neutron stars in the Advanced Detector Era
• Accretion, Outflows, and Winds of Magnetized Stars
• Resonant Tidal Excitations of Inertial Modes in Coalescing Neutron Star Binaries
• Towards real neutron star seismology: Accounting for elasticity and superfluidity
• On the excitation of f-modes and torsional modes by magnetar giant flares
• Search for continuous gravitational waves from 20 accreting millisecond X-ray pulsars in O3 LIGO data
• Adiabatic oscillations of non-rotating superfluid neutron stars
• On the radiation beaming of bright X-ray pulsars and constraints on neutron star mass-radius relation
• Gravitational waves from transient neutron star f-mode oscillations
• Coupling of Radial and Axial non-Radial Oscillations of Compact Stars: Gravitational Waves from first-order Differential Rotation
• Axisymmetric oscillations of magnetic neutron stars
• Search for Continuous Gravitational Waves from Scorpius X-1 in LIGO O2 Data
• Quadrupole moment of a magnetically confined mountain on an accreting neutron star: effect of the equation of state
• Search of the Early O3 LIGO Data for Continuous Gravitational Waves from the Cassiopeia A and Vela Jr. Supernova Remnants
• Accretion-driven gravitational radiation from nonrotating compact objects. Infalling quadrupolar shells
• Dynamical tides in neutron stars: The impact of the crust
• Search for gravitational waves from five low mass X-ray binaries in the second Advanced LIGO observing run with an improved hidden Markov model
• Transient gravitational waves from pulsar post-glitch recoveries
• First searches for gravitational waves from r-modes of the Crab pulsar
• Quasi-normal modes of superfluid neutron stars
• Gravitational waves from magnetically-induced thermal neutron star mountains
• Driving and damping mechanisms in hybrid pressure-gravity modes pulsators
• Multi-messenger Emission from Tidal Waves in Neutron Star Oceans
• Search for continuous gravitational waves from PSR J0437$-$4715 with a hidden Markov model in O3 LIGO data
• Formulating the r-mode problem for slowly rotating neutron stars
• Superburst oscillations: ocean and crustal modes excited by Carbon-triggered Type I X-ray bursts
• Magnetospheric Flows in X-ray Pulsars I: Instability at super-Eddington regime of accretion
• Gravitational Radiation Evolution of Accreting Neutron Stars
• Nonradial modes in RR Lyrae stars

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