GBT25B-380

GBT follow up of an extremely low-DM FRB

Abstract

On September 06, 2025, the CHIME telescope discovered an exceptionally low-dispersion fast radio burst (FRB). This implies a very nearby source. We then rapidly localised the source to ~0.3 arc minutes. Surprisingly, despite the low DM of 77.37 pc cm^-3, no obvious host galaxy was found within the localization region. This begs an intriguing question: Is FRB 250906 an extragalactic FRB or a pulsar hiding in the halo or nearby Milky Way satellite?

With 8 hours of GBT observations, we should be able to detect pulsars in the Milky Way halo and even bright pulsars in nearby galaxies. Furthermore, if repeat bursts are discovered without any periodicity, this is a strong indication that FRB 20250906 is likely an extragalactic FRB and provides one of the strongest constraints on the Galactic Halo's electron density to date.

At the same time as this proposal, we will submit a simultaneous DDT to the VLA for localization. However, these two campaigns are not dependent on one another.

Investigators

Name	Institution
Adam Dong *	Green Bank Observatory; British Columbia, University of
Wei Ng	Massachusetts Institute of Technology; McGill University
Kaitlyn Shin	Massachusetts Institute of Technology
Maxwell Fine	McGill University
Vicky Kaspi	McGill University
Adam Lanman	Massachusetts Institute of Technology
Amanda Cook	Toronto, University of
Sachin Pradeep Etakkepravan Thulicheri	McGill University
Jason Hessels	Netherlands Institute for Radio Astronomy; Amsterdam, Universiteit van

* indicates the PI