相关论文: Gravitational Waves from Broken Cosmic Strings: Th…
We investigate the generation of gravitational waves due to the gravitational instability of primordial density perturbations in an early matter-dominated era which could be detectable by experiments such as LIGO and LISA. We use…
Ultralight scalar fields around spinning black holes can trigger superradiant instabilities, forming a long-lived bosonic condensate outside the horizon. We use numerical solutions of the perturbed field equations and astrophysical models…
This paper presents an estimate for the spectral properties of the stochastic background of gravitational waves emitted by a population of hot, young, rapidly rotating neutron stars throughout the Universe undergoing $f$-mode instabilities,…
We investigate cosmic strings arising from a hierarchical gauge symmetry breaking sequence, $\mathrm{SU}(2) \times \mathrm{U}(1) \rightarrow \mathrm{U}(1) \times \mathrm{U}(1) \rightarrow \mathrm{U}(1)' \rightarrow \text{Nothing}$. This…
Metastable cosmic strings appear in models of new physics with a two-step symmetry breaking $G\to H\to 1$, where $\pi_1(H)\neq 0$ and $\pi_1(G)=0$. They decay via the monopole-antimonopole pair creation inside. Conventionally, the breaking…
Metastable strings can arise from a two-step symmetry breaking chain of the type $SU(2) \to U(1) \to 1$.They can decay through quantum tunneling by nucleating a monopole-antimonopole pair, and are prominent candidates for explaining the…
The breaking of an approximate discrete symmetry, the final stages of a first order phase transition, or a post-inflationary biased probability distribution for scalar fields are possible cosmological scenarios characterized by the presence…
We present recent results from searches by the LIGO Science Collaboration for bursts of gravitational-wave radiation, as well as the status of other ongoing searches. These include directed searches for bursts associated with observed…
Metastable cosmic strings are a common prediction of grand unified theories and act as a source of a gravitational-wave background (GWB) that can explain the 2023 pulsar timing array (PTA) signal. In this paper, we revisit the GWB signal…
String cosmology models predict a stochastic cosmic background of gravitational waves with a characteristic spectrum. I describe the background, present astrophysical and cosmological bounds on it, and outline how it may be possible to…
A generic consequence of supersymmetry is formation of a scalar condensate along the flat directions of the potential at the end of cosmological inflation. This condensate is usually unstable, and it can fragment into non-topological…
String cosmology models predict a relic background of gravitational wave produced during the dilaton-driven inflation. It's spectrum is most likely to be detected by ground gravitational wave laser interferometers (IFOs), like LIGO, Virgo,…
We derive analytical approximations to describe the ultra-high-frequency secondary peak of the stochastic gravitational wave background generated by cosmic strings that is sourced by loops created in the friction-dominated era. We show that…
Correlated red noise recently reported from pulsar timing observations may be an indication of stochastic gravitational waves emitted by cosmic strings that formed during a primordial phase transition near the Grand Unification energy…
Ultralight bosons can induce superradiant instabilities in spinning black holes, tapping their rotational energy to trigger the growth of a bosonic condensate. Possible observational imprints of these boson clouds include (i) direct…
We compute the contribution of kinks on cosmic string loops to stochastic background of gravitational waves (SBGW).We find that kinks contribute at the same order as cusps to the SBGW.We discuss the accessibility of the total background due…
The epoch when the Universe had a temperature higher than a GeV is long before any time at which we have reliable observations constraining the cosmological evolution. For example, the occurrence of a second burst of inflation (sometimes…
The symmetry breaking of grand unified gauge groups in the early Universe often leaves behind relic topological defects such as cosmic strings, domain walls, or monopoles. For some symmetry breaking chains, hybrid defects can form where…
A spectrum of relic stochastic gravitational radiation, strongly tilted towards high frequencies, and characterized by two basic parameters is shown to emerge in a class of string theory models. We estimate the required sensitivity for…
A wide variety of astrophysical and cosmological sources are expected to contribute to a stochastic gravitational-wave background. Following the observations of GW150914 and GW151226, the rate and mass of coalescing binary black holes…