Collaborative Research: The Definitive Follow-up Campaign for Fast Radio Bursts

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Fast radio bursts (FRBs) are transient pulses of radio emission lasting only milliseconds. They are known to be coming from galaxies outside our own and are now a highly intense area of astrophysical pursuit, with over a thousand FRBs detected to date. A research team between the University of California Santa Cruz, Northwestern University and the Maria Mitchell Observatory (MMO) forms the core of the Fast and Fortunate for FRB Follow-up (F4) team, which has been funded by the NSF since 2019 to observe FRBs and associate them with their host galaxies. This has enabled the team to start to use FRB signals to probe the universe and to make a new census of the baryons (subatomic particles, mostly protons and neutrons) in a highly diffuse state outside of galaxies throughout the universe. This current NSF award extends this work to allow F4 to increase its observational impact by an order of magnitude through follow-up observations of two new surveys of precisely localized FRBs, allowing them to study cosmology, baryon distribution and identify FRB progenitors. This award will also support students in a postbaccalaureate 'Bridge' program hosted at the MMO for attracting and retaining talented and traditionally underrepresented students, with a long-term goal of increasing their participation and leadership in STEM fields. All of the investigators will engage in the many outreach activities of the MMO.During the period of this grant, the F4 team will acquire, analyze, and disseminate deep, multi-band imaging and spectroscopy on the host galaxies of hundreds of FRBs across the sky. For many tens of FRB fields, they will obtain imaging and multi-object spectroscopy to identify intervening galactic halos and map the foreground large-scale structure. These data and derived quantities (e.g. redshifts (z) and stellar masses), together with measurements of the FRBs (e.g. dispersion measure (DM) and rotation measure (RM)) will enable three major scientific thrusts: (1) cosmology: the first statistically robust determination of the Macquart relation (DM vs. z), leading to a new and complementary estimate of the Hubble parameter; (2) galaxy formation: inferring the radial distribution of baryons in galactic halos and constraining the magnetic fields and gas density of the circumgalactic medium; and (3) FRB progenitors: testing the many models invoked to produce FRBs and using rapid follow-up imaging at radio, optical and X-ray wavelengths to resolve FRB emission mechanisms.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.