We would like to invite you to the annual NASA-PEER Post-bac Symposium! Over the past year, our cohort of post-bac researchers have been conducting research on exciting projects including studying our own lunar surface, distant galaxies, and the early universe.

To celebrate what the post-bacs have accomplished, NASA-PEER is hosting the second annual Post-bac Research Symposium. The event will begin with short talks where each post-bac will give an overview of their research, followed by a poster session with refreshments. You are free to come for the entire event or drop-by as your schedule allows.

We hope you come to support these early career researchers beginning their science careers at Goddard.

The NANOGrav Experiment: Current Results and Future Directions
Chiara Mingarelli (Yale University)

Galaxy mergers are a standard aspect of galaxy formation and evolution, and most (likely all) large galaxies contain supermassive black holes. As part of the merging process, the supermassive black holes in-spiral together and eventually merge, generating a background of gravitational radiation in the nanohertz regime. An array of precisely timed pulsars spread across the sky can form a galactic-scale gravitational wave detector in the nanohertz band. I describe the current efforts to develop and extend the pulsar timing array concept, together with recent evidence for a gravitational wave background, and what the immediate future holds.

Local Dwarf Galaxies as Laboratories to Understand Massive Stars and the ISM in the Early Universe
Grace Telford (Princeton University)

Feedback from low-metallicity massive stars regulates the evolution of both dwarf and high-redshift galaxies. To understand those processes requires robust models of the metal-poor ISM in which stars form and of massive stars' winds and ionizing spectra. Yet, these models remain entirely theoretical and uncertain due to a lack of observational constraints in the extremely low-metallicity regime. In this talk, I will present a suite of JWST, HST, and Keck observations of the nearby 3% Solar metallicity galaxy Leo P. First, I will describe novel constraints on the wind properties and ionizing spectrum of the galaxy's only O-type star from modeling HST/COS and Keck/KCWI spectroscopy. This star is part of the Treasury of Extremely Metal-Poor O Stars (TEMPOS), a Large Treasury HST program that will extend this initial analysis to a much larger sample at ~5-10% Solar metallicity. I will then present new JWST/MIRI-MRS observations of Leo P, which enabled the first detection of cold molecular hydrogen at such low metallicity via rotationally excited emission from the photodissociation region illuminated by the O star. Our detailed understanding of that star's UV radiation from the HST data constrains the temperature and mass of the detected molecular hydrogen, providing a benchmark for models of the ISM at the very low metallicities typical at high redshift. Leo P showcases the potential of the metal-poor dwarf galaxies in our backyard to inform models of early galaxies.