Gravitational wave astrophysics with pulsar timing arrays

Mingarelli, Chiara Maria Francesca (2014). Gravitational wave astrophysics with pulsar timing arrays. University of Birmingham. Ph.D.

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Abstract

This thesis focuses on gravitational wave (GW) astrophysics with Pulsar Timing Arrays (PTAs). Firstly it is shown that anisotropy in the GW background may be present, and that its characterization at different angular scales carries important information. The standard analysis for isotropic backgrounds is then generalized by decomposing the angular distribution of the GW energy density into multipole moments. Generalized overlap reduction functions (ORFs) are computed for a generic level of anisotropy and PTA configuration.
A rigorous analysis is then done of the assumptions made when calculating ORFs. It is shown that correlated phase changes introduce previously unmodeled effects for pulsars pairs separated by less than a radiation wavelength.
The research then turns to the study of continuous GW sources from supermassive black hole binaries (SMBHBs). Here it shown that the detection of GWs from SMBHB systems can yield direct information about the masses and spins of the black holes, provided that the GW-induced timing fluctuations both at the pulsar and at Earth are detected. This in turn provides a map of the nonlinear dynamics of the gravitational field and a new avenue to tackle open problems in astrophysics connected to the formation and evolution of SMBHs.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):