In this talk, I will introduce our work interpreting the PTA background as originating from SMBH binaries. Focusing on its interesting statistical properties, the implications for the environmental effects, possible eccentricity signatures and anisotropies in the background that could lead to differentiate it from a cosmological source.
Anisotropies play a central role in distinguishing between cosmological and astrophysical sources of the GWB, as detectable anisotropies are expected for a GWB from a population of supermassive black hole binaries (SMBHBs) but not for cosmological sources. We perform searches for anisotropies on simulated PTA datasets, showing that null detections for anisotropies in both current and...
The evidence for a stochastic gravitational wave background at nHz frequencies by Pulsar Timing Array (PTA) observations offers an opportunity to discover cosmological signals and threatens the observability of other subdominant gravitational waves (GWs). We explore prospects to constrain scalar-induced GWs associated with enhanced curvature perturbations in the primordial universe,...
Strong first-order phase transitions offer a compelling explanation for the stochastic gravitational wave background in the nano-Hertz range measured by pulsar timing arrays (PTA). In this talk, I will consider a classically conformal dark sector in which the breaking of a dark U(1) gauge symmetry gives rise to a gravitational wave background that can fit the PTA data and additionally sources...
In the NANOGrav 15-year New Physics analysis (arXiv:2306.16219), a log-uniform prior on $G\mu$ was imposed to determine upper limits on the tension of stable cosmic strings. Here, we examine the prior dependence of this bound through comparison with new upper limits obtained using a uniform prior on $G\mu$. New posterior distributions and upper limits on stable cosmic string tension were...
Ultra-light dark matter (ULDM) is a promising candidate for cosmological dark matter. If ULDM exists and interacts directly with ordinary matter, it could produce characteristic signals in the timing data of pulsars in binary systems.
In this talk, we review the latest results on how binary pulsars can constrain the ULDM parameter space through pulsar timing data and signal modeling. Our...
