Daily Image
18-10-2023
Luminous LOFAR compact radio sources in low mass galaxies
| Submitter: | Dany Vohl |
| Description: | In a recent paper (Vohl et al. 2023, A&A, in press), we identify a set of compact radio sources from the second data release of the LOFAR Two Meter Sky Survey (LoTSS, Shimwell et al. 2022) dwelling in dwarf galaxies, with radio luminosity exceeding that expected from star formation alone. Compact radio sources in dwarf galaxies are currently being of interest in two separate but potentially related contexts. Among the few handfuls of localised fast radio bursts, two repeating FRB sources are found in low mass, low metallicity galaxies, with bursts properties indicating they live in extreme magneto-ionic environments within their host galaxies, and both FRB sources are accompanied by a source of persistent radio emission (PRS) hinting towards a young and extremely energetic neutron star wind nebula or massive black holes origin. Meanwhile, active searches for massive black holes in dwarf galaxies are being conducted to answer questions about black hole growth and galaxy evolution. To further our understanding of the role of PRSs in the lifecycle of FRBs, and potentially black hole growth, this work provides a crucial sample allowing to further these investigations. By tapping into the wealth of information provided by LoTSS, the Census of the Local Universe (Cook et al. 2019), and other large surveys at various wavelengths, we investigate the potential nature of these sources, and evaluate their volumetric rate. While optical line-ratio diagnostics on the nebular lines from the host galaxies prefer a star-formation origin (against an AGN origin), future high angular resolution radio data are necessary to ascertain the origin of the radio sources—which we are now conducting. The image shows the current best locations of our candidate sources (x markers) within the optical footprint of their respective host galaxies taken from PanSTARRS (Chambers et al. 2016), along with other diagnostics such as angular separation between the radio source and the galaxy optical centre, the integrated radio flux, galaxy mass, redshift, and radio spectral index. |
| Copyright: | D. Vohl |
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