Présidents de session
Invited talk: Reconciling Pulsar Timing Arrays Observations with Supermassive Black Hole Binary Predictions
- Hippolyte QUELQUEJAY
Description
In June 2023, the Pulsar Timing Array (PTA) collaborations reported the first strong evidence of the presence of a stochastic gravitational wave background (GWB) in the nanohertz band. Assuming that the common stochastic signal induced by gravitational waves is isotropic, stationary, and unpolarized, the collaborations were able to constrain its power spectral density. The obtained spectrum is in tension with theoretical predictions from the local population of supermassive black hole binaries: the power spectrum is not as red as expected, and its amplitude at 1/year is too high.
In this talk, I will present some caveats regarding PTA data analysis methods that could lead to such tensions. We will discuss the impact of the spectral inference methods used by PTAs and show the potential bias they can induce in the interpretation of their data. We will then present the impact of the intrinsic pulsar noise modeling on the GWB spectral inference. In particular, we find that the solar wind modeling used in the EPTA data is insufficient. The inclusion of a more accurate solar wind model leads to a steeper and weaker (at 1/year) GWB power spectrum.
