Speaker: Chen Yuan (ITP-Chinese Academy of Sciences)
Title: Non-tensorial gravitational wave background in NANOGrav 12.5-year data set
Abstract: The North American Nanohertz Observatory for Gravitational Waves (NANOGrav) collaboration has reported a strong evidence of a stochastic process, modeled as a power-law, with common amplitude and spectral index among all pulsars. However, there is no statistically significant evidence for quadrupolar spatial correlations and hence this process can not be explained by a gravitational-wave background (GWB) detection. We perform a search for an isotropic non-tensorial GWB allowed in general metric theories of gravity in the NANOGrav 12.5-year data set. By modeling the GWB as a power-law spectrum, we find strong Bayesian evidence for a spatially correlated process with scalar transverse (ST) correlations.
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