Upper bounds on r-mode amplitudes from observations of low-mass X-ray binary neutron stars

Abstract

We present upper limits on the amplitude of r-mode oscillations, and gravitational-radiation-induced spin-down rates, in low mass X-ray binary neutron stars, under the assumption that the quiescent neutron star luminosity is powered by dissipation from a steady-state r-mode. For masses $<2M_{\odot }$ we find dimensionless r-mode amplitudes in the range from about $1\times 10^{-8}$ to $1.5\times 10^{-6}$. For the accreting millisecond X-ray pulsar sources with known quiescent spin-down rates these limits suggest that $\lesssim 1$ of the observed rate can be due to an unstable r-mode. Interestingly, the source with the highest amplitude limit, NGC 6440, could have an r-mode spin-down rate comparable to the observed, quiescent rate for SAX J1808-3658. Thus, quiescent spin-down measurements for this source would be particularly interesting. For all sources considered here our amplitude limits suggest that gravitational wave signals are likely too weak for detection with Advanced LIGO. Our highest mass model ($2.21M_{\odot }$) can support enhanced, direct Urca neutrino emission in the core and thus can have higher r-mode amplitudes. Indeed, the inferred r-mode spin-down rates at these higher amplitudes are inconsistent with the observed spin-down rates for some of the sources, such as IGR J00291+5934 and XTE J1751-305. In the absence of other significant sources of internal heat, these results could be used to place an upper limit on the masses of these sources if they were made of hadronic matter, or alternatively it could be used to probe the existence of exotic matter in them if their masses were known.

11 pages, 2 figures, Published in ApJ, More extended discussion compared to v1

References in corpus (9)

• The ATNF Pulsar Catalogue
• Detecting gravitational wave emission from the known accreting neutron stars
• Mountains on Neutron Stars: Accreted vs. Non-Accreted crusts
• Constraining the physics of the r-mode instability in neutron stars with X-ray and UV observations
• A decade of timing an accretion-powered millisecond pulsar: The continuing spin down and orbital evolution of SAX J1808.4-3658
• 3PF2 pairing in high-density neutron matter
• LOFT: the Large Observatory For X-ray Timing
• The quiescent X-ray properties of the accreting millisecond X-ray pulsar and eclipsing binary Swift J1749.4-2807
• ASTROSAT: Some Key Science Prospects

Cited by in corpus (55)

• QCD and strongly coupled gauge theories: challenges and perspectives
• Theory and evidence of global Rossby waves in upper main-sequence stars: r-mode oscillations in many Kepler stars
• The Spin Distribution of Fast Spinning Neutron Stars in Low Mass X-Ray Binaries: Evidence for Two Sub-Populations
• Search for gravitational waves from Scorpius X-1 in the first Advanced LIGO observing run with a hidden Markov model
• Superfluidity and Superconductivity in Neutron Stars
• Detecting gravitational waves from mountains on neutron stars in the Advanced Detector Era
• The Elasticity of Nuclear Pasta
• R-modes in neutron stars: Theory and observations
• Signatures for quark matter from multi-messenger observations
• Explaining observations of rapidly rotating neutron stars in LMXBs
• A new mechanism for saturating unstable r-modes in neutron stars
• Characteristics of hybrid compact stars with a sharp hadron-quark interface
• Implications of an r-mode in XTE J1751-305: Mass, radius and spin evolution
• What the Timing of Millisecond Pulsars Can Teach us about Their Interior
• Superradiance in rotating stars and pulsar-timing constraints on dark photons
• A Non-radial Oscillation Mode in an Accreting Millisecond Pulsar?
• Discovery of a Neutron Star Oscillation Mode During a Superburst
• Instability windows and evolution of rapidly rotating neutron stars
• Gravitational waves within the magnetar model of superluminous supernovae and gamma-ray bursts
• Excitation of a nonradial mode in a millisecond X-ray pulsar XTE J1751-305
• Are gravitational waves spinning down PSR J1023+0038?
• Chandra studies of the globular cluster 47 Tucanae: A deeper X-ray source catalogue, five new X-ray counterparts to millisecond radio pulsars, and new constraints to r-mode instability window
• Gravitational wave emission from oscillating millisecond pulsars
• R-mode astronomy
• Phase conversion dissipation in multicomponent compact stars
• Timing the pulsations of the accreting millisecond pulsar SAX J1808.4-3658 during its 2019 outburst
• Ultra-compact X-ray binaries as dual-line gravitational-wave sources
• R-modes and neutron star recycling scenario
• New possible class of neutron stars: hot and fast non-accreting rotators
• X-ray bounds on the r-mode amplitude in millisecond pulsars
• Temperature-dependent r-modes in superfluid neutron stars stratified by muons
• Strengthening the bounds on the r-mode amplitude with X-ray observations of millisecond pulsars
• XMM-Newton detection and spectrum of the second fastest spinning pulsar PSR J0952-0607
• Gravitational waves from rapidly rotating neutron stars
• Where Are the r-modes? Chandra Observations of Millisecond Pulsars
• The r-mode instability windows of strange stars
• Coherent timing of the accreting millisecond pulsar NGC 6440 X-2
• Influence of the nuclear matter equation of state on the r-mode instability using the finite-range simple effective interaction
• Limits on Magnetic Field Amplification from the r-Mode Instability
• Temperature-dependent oscillation modes in rotating superfluid neutron stars
• Probing the physics of newly born magnetars through observation of superluminous supernovae
• Evolution of newborn rapidly rotating magnetars: effects of r-mode and fall-back accretion
• Hydrogen-triggered X-ray Bursts from SAX J1808.4-3658? The Onset of Nuclear Burning
• Probing dense matter in compact star cores with radio pulsar data
• Radiation driven instability of rapidly rotating relativistic stars: criterion and evolution equations via multipolar expansion of gravitational waves
• On the initial spin periods of magnetars born in weak supernova explosions and their gravitational wave radiation
• Long term evolution of CFS-unstable neutron stars and role of differential rotation on short time-scales
• Viscous damping of r-modes and emission of gravitational waves
• R-mode instability in compact stars
• Gravitational waves from r-mode instability of massive young sub- and super-Chandrasekhar white dwarfs
• Continuous gravitational waves from thermal mountains on accreting neutron stars: effect of the nuclear pasta phase
• Gravitational waves associated with the r-mode instability from neutron star-white dwarf mergers
• Rossby modes in neutron stars as sources of gravitational waves
• Observability of sharp phase transitions in neutron stars
• Braking indices as probes of r-mode spin-down in young pulsars