The AstroSat Observatory

Singh, K. P.

doi:10.1007/978-981-16-4544-0_31-1

Cited by 1 publication

(3 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Precise X-ray timing observations, with instruments such as RXTE [1], NICER [2] and AstroSat [3,4], shed light on neutron-star dynamics and processes related to the star's spin. Relevant phenomena range from waves in the star's ocean (at low densities) to spin variations (such as pulsar glitches) and oscillation modes driven unstable by gravitationalwave emission (depending on viscous processes in the high-density core).…”

Section: Contextmentioning

confidence: 99%

“…Since Equation ( 16) limits to the associated Legendre equation when q = 0, we note that class (i) limit to λ = l(l + 1) and can be identified as the familiar polar modes of a spherical star. 4 In general, this includes f -, pand (in the presence of stratification) g-modes. Although in principle, we would anticipate the high-frequency solutions to be excluded via Equation ( 6), the perturbation equations in the traditional approximation do permit such oscillations (as we have shown in Appendix A).…”

Section: Solutions Of Laplace's Tidal Equationmentioning

confidence: 99%

“…In relaxing the Cowling approximation, the linearised gravitational potential must be determined from Poisson's equation, which spoils the radial and angular separation that we have arrived at. 4 In the geophysics literature, these particular solutions are referred to as "gravity waves" (see, e.g., Ref. [25]).…”

Section: Appendix a Plane-wave Analysismentioning

confidence: 99%

See 2 more Smart Citations

Modelling Neutron-Star Ocean Dynamics

et al. 2023

View full text Add to dashboard Cite

We revisit the calculation of mode oscillations in the ocean of a rotating neutron star, which may be excited during thermonuclear X-ray bursts. Our present theoretical understanding of ocean modes relies heavily on the traditional approximation commonly employed in geophysics. The approximation elegantly decouples the radial and angular sectors of the perturbation problem by neglecting the vertical contribution from the Coriolis force. However, as the implicit assumptions underlying it are not as well understood as they ought to be, we examine the traditional approximation and discuss the associated mode solutions. The results demonstrate that, while the approximation may be appropriate in certain contexts, it may not be accurate for rapidly rotating neutron stars. In addition, using the shallow-water approximation, we show analytically how the solutions that resemble r-modes change their nature in neutron-star oceans to behave like gravity waves. We also outline a simple prescription for lifting Newtonian results in a shallow ocean to general relativity, making the result more realistic.

show abstract