Let the Data Decide I: Designing a LISA-Inspired Pulsar Timing Data Analysis Software

Since its discovery in 2023 by pulsar timing array (PTA) experiments around the world, the characterization of the nanohertz gravitational wave background (GWB) has become a focus for many astrophysicists. PTAs continue to collect data on hundreds of unique pulsars, all of which need their own specialized timing models, on top of the effects caused by the GWB and potentially resolvable supermassive black hole binaries. Characterizing the GWB requires modeling and constraining the effects of each of these hundreds of parameters. Thus far, many PTAs opt to use a two-stage approach in which we model parameters intrinsic to each pulsar first, before anchoring these estimates in an all-pulsar GWB search. In this first talk on this project we describe the design of our novel approach adapted from prototype approaches to the LISA data analysis problem. Leveraging techniques like blocked-Gibbs sampling and conjugate priors for posterior draws, our approach enables simultaneous fitting to both intrinsic pulsar parameters and GWB parameters while also opening the door to more comprehensive pulsar models.