NPA Seminar, Steven Murray, Arizona State University, “Forward Modelling Interferometric Observations of the EoR”

Abstract: 21cm observations of the Cosmic Dawn and Epoch of Reionization, via intensity mapping at z>6, offer a unique and exciting probe into the physics of stellar and galaxy formation and even cosmology. A range of instruments across the globe, including the highly targeted HERA experiment, are currently amassing a wealth of data – in which is buried the signature of the birth of the first stars. In order for this data to unveil new physical insights requires that we understand the many contaminants present in the data – arising from ‘foreground’ sources active at the same radio wavelengths as well as distortions of the signal incurred by the instrument itself. And that’s not all – we also require accurate models of the physics of the EoR itself in order to infer the phenomenological parameters involved.
In this seminar, I will give an overview of the efforts underway in the community – especially within HERA – to build complete forward models of the sky and instrument, for two purposes: i) validation of the analysis methods used to “remove” contaminants, and ii) Bayesian inference of the physical parameters. I will discuss some of the many challenges involved with this program, including the extreme accuracy required of foreground simulations, computational challenges of simulating terabytes of mock data, the complexity of instrumental models, and the difficulty of validating models of reionization itself. Despite these challenges, the community is making great headway, highlighted by the recent validation of the HERA analysis pipeline in support of HERA’s first data release.
Finally, I will look to the future and summarize what I believe to be the most promising avenues for improvement over the next few years.
Please email the host for the Zoom connection information.
Host: Michael Jewell, michael.jewell@yale.edu