LIGO Seminar

https://caltech.zoom.us/j/87546916051?pwd=aTByZU5WamhUKzlkRVY2bW05bytDdz09

Speaker: Leo Tsukada

Title: bhpwave: Toward unified Bayesian parameter inference of stochastic gravitational wave backgrounds

The gravitational waves (GWs) originating from compact binary coalescences have been consistently detected during the past and current observing runs by LIGO-Virgo-KAGRA (LVK) collaboration. Moreover, the recent announcement regarding strong evidence for an stochastic gravitational-wave background (SGWB) by several pulsar timing array collaborations is indicative of marginal detection of an SGWB, introducing a potential new avenue in the nHz frequency band to observe GWs.

Motivated by this excitement, in the context of the SGWB search by the current ground-based detectors, I describe an ongoing study to generalize a parameter inference framework for an anisotropic SGWB. Conceptually, this framework is an extension of the Bayesian inference for isotropic component of an SGWB, which was performed for the past observing runs by the LVK collaboration. Throughout this study, an anisotropy of the SGWB energy is characterized by the spherical harmonics (SPH) basis, which saves computational cost substantially during the likelihood evaluation. To begin with, I present the formalism to search and infer the parameters for a signal model with a fixed anisotropic distribution on the sky, e.g. the Galactic plane. Additionally, this formalism can be extended to include non-GR polarizations such as scalar and vector modes. As future prospect, I brainstorm some ideas to further extend the formalism to directly infer the SPH coefficients of the SGWB's anisotropy as well as its angular power spectrum.