Related papers: More accurate gravitational wave backgrounds from …
Models of string cosmology predict a stochastic background of gravitational waves with a spectrum that is strongly tilted towards high frequencies. I give simple approximate expressions for spectral densities of the cosmic background which…
Recently, pulsar timing array (PTA) experiments have provided compelling evidence for the existence of the nanohertz stochastic gravitational wave background (SGWB). In this work, we demonstrated that cosmic string loops generated from…
We investigate the constraints that can be placed on the cosmic string tension by using the current Pulsar Timing Array limits on the stochastic gravitational wave background (SGWB). We have developed a code to compute the spectrum of…
Global cosmic strings are generically predicted in particle physics beyond the Standard Model, e.g., a post-inflationary global $U(1)$ symmetry breaking which may associate with axion-like dark matter. We demonstrate that although…
In this paper, following the previous study, we evaluate the spectrum of gravitational wave background generated by domain walls which are produced if some discrete symmetry is spontaneously broken in the early universe. We apply two…
We compute the gravitational waveform produced by cosmic superstring reconnections. This is done by first constructing the superstring reconnection trajectory, which closely resembles that of classical, instantaneous reconnection but with…
We consider strings with the Nambu action as extremal surfaces in a given space-time, thus, we ignore their back reaction. Especially, we look for strings sharing one symmetry with the underlying space-time. If this is a non-null symmetry,…
We perform a direct search for an isotropic stochastic gravitational-wave background (SGWB) produced by cosmic strings in the Parkes Pulsar Timing Array second data release. We find no evidence for such an SGWB, and therefore place $95\%$…
The advent of gravitational-wave (GW) astronomy has presented us with a completely new means for observing the Universe, allowing us to probe its structure and evolution like never before. In this thesis, we explore three distinct but…
The production of a primordial stochastic gravitational-wave background by processes occuring in the early Universe is expected in a broad range of models. Observing this background would open a unique window onto the Universe's…
We study the stochastic gravitational wave background sourced by a network of cosmic superstrings and demonstrate that incorporating higher-mass string species, beyond the fundamental string, is crucial for accurately modelling the…
The collection of gravitational waves (GWs) that are either too weak or too numerous to be individually resolved is commonly referred to as the gravitational-wave background (GWB). A confident detection and model-driven characterization of…
We derive a full analytical approximation to the stochastic gravitational wave background generated by the loops that are produced throughout the cosmological evolution of cosmic string networks. We show that this approximation not only…
We calculate the power spectrum of the stochastic gravitational wave (GW) background expected from kink-kink collisions on infinite cosmic strings. Intersections in the cosmic string network continuously generate kinks, which emit GW bursts…
Given the recent detection of gravitational waves from individual sources it is almost a certainty that some form of background of gravitational waves will be detected in future. The most promising candidate for such a detection are…
Cosmic strings play a crucial role in enhancing our understanding of the fundamental structure and evolution of the universe, unifying our knowledge of cosmology, and potentially unveiling new physical laws and phenomena. The advent and…
Searches for primordial gravitational waves have resulted in constraints in a large frequency range from a variety of sources. The standard Cosmic Microwave Background (CMB) technique is to parameterise the tensor power spectrum in terms of…
As one of the detection targets of all gravitational wave detectors at present, stochastic gravitational wave background (SGWB) provides us an important way to understand the evolution of our universe. In this paper, we explore the…
The general properties of the gravity wave backgrounds of cosmological origin are reviewed and briefly discussed, with emphasis on the relic background expected from an early pre-big bang phase typical of string cosmology models.
We examine the spectrum of gravitational radiation emitted by a network of cosmic strings, with emphasis on the observational constraints and the opportunities for detection. The analysis improves over past work, as we use a…