Daily Image
07-01-2025
A repeating fast radio burst source in a low-luminosity dwarf galaxy
| Submitter: | Jason Hessels & Danté Hewitt |
| Description: | Sometimes you need to dig really deep to see what's going on. In a paper recently published in the Astrophysical Journal Letters by just-graduated API/ASTRON PhD candidate Danté Hewitt (Hewitt et al. 2024; https://iopscience.iop.org/article/10.3847/2041-8213/ad8ce1), we identify the host galaxy of the repeating fast radio burst source FRB 20190208A. The localisation of the radio burst was achieved with the European VLBI Network (EVN) as part of the PRECISE project. However, when we first observed this field with MMT, we found no obvious host galaxy, down to a magnitude of about 26 mag. Our curiosity drove us to obtain a much deeper image: a 3-hr integration with the 10-m GTC telescope on La Palma, which reached a limiting magnitude of roughly 28 mag. This is pretty much the deepest optical image that can currently be obtained from the surface of the Earth! The ultra-deep optical image revealed a faint source, exactly at the radio-derived position of FRB 20190208A. Based on the dispersion measure (DM) of the bursts, we estimate that the redshift range of the source is about z = 0.1 - 0.8, depending on how much DM is contained in the host galaxy. This means that FRB 20190208A's host galaxy is at least a factor of a few less luminous than all other known FRB hosts, and potentially even >10x less luminous. What is an FRB doing in such a puny dwarf galaxy? It's possible that the low-metallicity that is typically associated with dwarf galaxies is the reason: low-metallicity environments allow for the formation of exceptionally massive stars, which may create extremely magnetised and rapidly spinning neutron stars when they go supernova. This possibility is also supported by a couple other repeating FRBs that are known to be hosted in dwarf galaxies, and which are associated with persistent radio emission that may indicate a hyper-luminous nebula surrounding the burst engine. To better establish the properties of the host galaxy, we're going to need the power of JWST, and we've applied for follow-up observations to do so. |
| Copyright: | Hessels/Hewitt/ASTRON |
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