Mapping the baryons with millisecond radio flashes: FRB cosmology via DSA-110

Harvard University, Cambridge MA

Investigators

Abstract

Fast Radio Bursts (FRBs) are enigmatic pulses of radio waves that come from the distant Universe. In addition to the mystery of what produces them, FRBs can be used as a powerful tool to probe the missing ordinary matter in the Universe. This is the so-called "missing baryon problem", which has posed a challenge to astronomers for decades. The research team at Harvard University have a large data sample of FRBs thanks to the Deep Synoptic Array, an array of radio telescopes near Big Pine, California. They will use this sample to answer critical questions in the distribution of cosmic baryons. These investigations should mature the field of FRB cosmology and prepare the ground for the next generation of radio telescopes, such as the DSA-2000 to be built in Nevada. The team will create interactive 3D visualizations of the baryon cosmic web, with the goal of engaging the public and the broader scientific community. This proposal will use a large existing sample of localized Fast Radio Bursts (FRBs) to measure and map the Universe’s "missing" baryons. FRBs are millisecond radio pulses whose physical origin remains a key mystery in astronomy. Independent of their origins, the dispersion measure of FRBs directly probes all ionized gas between the observer and the source. To fully realize the long-sought goal of FRB cosmology requires a larger sample and new statistical methods that incorporate knowledge of intervening galaxies in their line-of-sight. The proposing team will use a growing catalog of localized FRBs discovered by the 110-antenna Deep Synoptic Array (DSA-110) to measure the distribution of baryons in the cosmic web. The current sample of roughly 70 localized FRBs is expected to double in the next twelve months, thanks to a significant increase in the number of DSA antennas. By 2027, the number of localized FRBs will exceed several thousand, as CHIME/VLBI, CHORD, and the DSA-2000 come online. The coming onslaught of localized FRBs and all-sky galaxy surveys requires a new framework for inferring cosmological gas parameters from observations. This work will be bolstered by forward-modelled mock FRB surveys in cosmological simulations such as MilleniumTNG. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.