Searching for Black Holes and Other Massive, Compact Bodies Using the Gravitational Waves from Binary Inspirals

Citation

Ryan, Fintan Danh (1997) Searching for Black Holes and Other Massive, Compact Bodies Using the Gravitational Waves from Binary Inspirals. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/3n38-zg42. https://resolver.caltech.edu/CaltechTHESIS:09062017-160111338

Abstract

We consider several issues involved with searching for and studying different types of compact bodies using the gravitational waves from binary inspirals. In Chapter 2, we use a radiation­ reaction force formalism to compute (to leading post-Newtonian order) the inspiral evolution of a circular, nonequatorial orbit around a spinning black hole. We find that an initially circular orbit remains circular under radiation reaction and is driven towards anti-alignment with the black hole's spin direction. In Chapter 3, we apply this same formalism to orbits which are elliptical as well as nonequatorial. In addition, we prove that circular orbits remain circular exactly. In Chapter 4, we show that all the multipole moments of a massive, compact body (whose gravita­tional field is stationary, axially symmetric, and reflection symmetric across the equatorial plane) can be determined from the gravitational waves produced by a much less massive, compact object inspiraling in a contracting circle in the equatorial plane. We show that the moments are encoded in the waves' evolution in (at least) four independent functions of the gravitational-wave frequency: the gravitational-wave energy, the precession frequency of the orbit when slightly eccentric, the precession frequency of the orbit when slightly nonequatorial, and the gravitational-wave phase evolution. In Chapter 5, we compute the structure and the multipole moments of a spinning boson star with large self-interaction. We find that only three moments are needed to specify all the star's properties, and that the pattern of moments is very different from that for black holes. In Chapter 6, we estimate how accurately a gravitational-wave detector can estimate the multipole moments of the central body from the gravitational waves produced by an inspiraling compact object. We find that, typically, a space-based detector such as LISA (as opposed to an Earth-based detector such as LIGO) is necessary to get accurate enough measurements of the multipole moments so as to search for massive, compact, non-black-hole objects. In Chapter 7, as a model for computing the full details of the gravitational waves from an orbital inspiral, we compute the scalar waves produced by a scalar charge in a circular, equatorial orbit around a body with arbitrary multipole moments.

Thesis Files