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1. A repeating fast radio burst associated with a persistent radio source

   https://doi.org/10.1038/s41586-022-04755-5  

   Niu, C.-H.; Aggarwal, K.; Li, D.; Zhang, X.; Chatterjee, S.; Tsai, C.-W.; Yu, W.; Law, C. J.; Burke-Spolaor, S.; Cordes, J. M.; et al (June 2022, Nature)

   Abstract The dispersive sweep of fast radio bursts (FRBs) has been used to probe the ionized baryon content of the intergalactic medium 1 , which is assumed to dominate the total extragalactic dispersion. Although the host-galaxy contributions to the dispersion measure appear to be small for most FRBs 2 , in at least one case there is evidence for an extreme magneto-ionic local environment 3,4 and a compact persistent radio source 5 . Here we report the detection and localization of the repeating FRB 20190520B, which is co-located with a compact, persistent radio source and associated with a dwarf host galaxy of high specific-star-formation rate at a redshift of 0.241 ± 0.001. The estimated host-galaxy dispersion measure of approximately $${903}_{-111}^{+72}$$ 903 − 111 + 72 parsecs per cubic centimetre, which is nearly an order of magnitude higher than the average of FRB host galaxies 2,6 , far exceeds the dispersion-measure contribution of the intergalactic medium. Caution is thus warranted in inferring redshifts for FRBs without accurate host-galaxy identifications. 

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2. A Radio Study of Persistent Radio Sources in Nearby Dwarf Galaxies: Implications for Fast Radio Bursts

   https://doi.org/10.3847/1538-4357/ad6568  

   Dong_董, Y_雨欣; Eftekhari, T.; Fong, W.; Bhandari, S.; Berger, E.; Ould-Boukattine, O_S; Hessels, J_W_T; Sridhar, N.; Reines, A.; Margalit, B.; et al (September 2024, The Astrophysical Journal)

   Abstract We present 1–12 GHz Karl G. Jansky Very Large Array observations of nine off-nuclear persistent radio sources (PRSs) in nearby (z≲ 0.055) dwarf galaxies, along with high-resolution European VLBI Network observations for one of them at 1.7 GHz. We explore the plausibility that these PRSs are associated with fast radio burst (FRB) sources by examining their properties—physical sizes, host-normalized offsets, spectral energy distributions (SEDs), radio luminosities, and light curves—and compare them to those of the PRSs associated with FRB 20121102A and FRB 20190520B, two known active galactic nuclei (AGN), and one likely AGN in our sample with comparable data, as well as other radio transients exhibiting characteristics analogous to FRB-PRSs. We identify a single source in our sample, J1136+2643, as the most promising FRB-PRS, based on its compact physical size and host-normalized offset. We further identify two sources, J0019+1507 and J0909+5655, with physical sizes comparable to FRB-PRSs, but which exhibit large offsets and flat spectral indices potentially indicative of a background AGN origin. We test the viability of neutron star wind nebula and hypernebula models for J1136+2643 and find that the physical size, luminosity, and SED of J1136+2643 are broadly consistent with these models. Finally, we discuss the alternative interpretation that the radio sources are instead powered by accreting massive black holes, and we outline future prospects and follow-up observations for differentiating between these scenarios. 

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3. A repeating fast radio burst in a dense environment with a compact persistent radio source

   Burke-Spolaor, Sarah (October 2021, ArXivorg)

   The dispersive sweep of fast radio bursts (FRBs) has been used to probe the ionized baryon content of the intergalactic medium, which is assumed to dominate the total extragalactic dispersion. While the host galaxy contributions to dispersion measure (DM) appear to be small for most FRBs, in at least one case there is evidence for an extreme magneto-ionic local environment and a compact persistent radio source. Here we report the detection and localization of the repeating FRB 20190520B, which is co-located with a compact, persistent radio source and associated with a dwarf host galaxy of high specific star formation rate at a redshift z=0.241±0.001. The estimated host galaxy DM~≈903+72−111~pc~cm−3, nearly an order of magnitude higher than the average of FRB host galaxies, far exceeds the DM contribution of the intergalactic medium. Caution is thus warranted in inferring redshifts for FRBs without accurate host galaxy identifications. The dense FRB environment and the association with a compact persistent radio source may point to a distinctive origin or an earlier evolutionary stage for this FRB source. 

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4. A Radio-Frequency-over-Fiber link for large-array radio astronomy applications

   https://doi.org/10.1088/1748-0221/8/10/T10003  

   Mena, J; Bandura, K; Cliche, J -F; Dobbs, M; Gilbert, A; Tang, Q Y (October 2013, Journal of Instrumentation)

   null (Ed.)
5. Radio Galaxy Zoo: Claran – a deep learning classifier for radio morphologies

   https://doi.org/10.1093/mnras/sty2646  

   Wu, Chen; Wong, Oiwei Ivy; Rudnick, Lawrence; Shabala, Stanislav S; Alger, Matthew J; Banfield, Julie K; Ong, Cheng Soon; White, Sarah V; Garon, Avery F; Norris, Ray P; et al (October 2018, Monthly Notices of the Royal Astronomical Society)