We systematically study the late-time tails of scalar waves propagating in neutron star spacetimes. We consider uniform density neutron stars, for which the background spacetime is analytic and the compaction of the star can be varied continuously between the Newtonian limit 2M/R≪1 and the relativistic Buchdahl limit 2M/R=8/9. We study the reflection of a finite wave packet off neutron stars of different compactions 2M/R and find that a Newtonian, an intermediate, and a highly relativistic regime can be clearly distinguished. In the highly relativistic regime, the reflected signal is dominated by quasi-periodic peaks, which originate from the wave packet bouncing back and forth between the center of the star and the maximum of the background curvature potential at R∼3M. Between these peaks, the field decays according to a power law. In the Buchdahl limit 2M/R→8/9 the light travel time between the center and the maximum or the curvature potential grows without bound, so that the first peak arrives only at infinitely late time. The modes of neutron stars can therefore no longer be excited in the ultra-relativistic limit, and it is in this sense that the late-time radiative decay from neutron stars loses all its features and gives rise to power-law tails reminiscent of Schwarzschild black holes.
|Original language||English (US)|
|Number of pages||8|
|Journal||Physical Review D - Particles, Fields, Gravitation and Cosmology|
|State||Published - Oct 15 2000|
ASJC Scopus subject areas
- Nuclear and High Energy Physics
- Physics and Astronomy (miscellaneous)