Structural and spectral properties of Galactic plane variable radio sources

Structural and spectral properties of Galactic plane variable radio sources

Yang, Jun (Joint Institute for VLBI ERIC; Chalmers University of Technology)
Chen, Yongjun (Chinese Academy of Sciences)
Gurvits, L. (TU Delft Astrodynamics & Space Missions; Joint Institute for VLBI ERIC)
Paragi, Zsolt (Joint Institute for VLBI ERIC)
Yang, Aiyuan (Max-Planck-Institute for Radio Astronomy)
Yang, Xiaolong (Chinese Academy of Sciences)
Shen, Zhiqiang (Chinese Academy of Sciences)

2022

In the time domain, the radio sky in particular along the Galactic plane direction may vary significantly because of various energetic activities associated with stars, stellar, and supermassive black holes. Multi-epoch Very Large Array surveys of the Galactic plane at 5.0 GHz enabled the finding of a catalogue of 39 variable radio sources in the flux density range 1-70 mJy. To probe their radio structures and spectra, we observed 17 sources with the very-long-baseline interferometric (VLBI) imaging technique and collected additional multifrequency data from the literature. We detected all of the sources at 5 GHz with the Westerbork Synthesis Radio Telescope, but only G23.6644-0.0372 with the European VLBI Network (EVN). Together with its decadal variability and multifrequency radio spectrum, we interpret it as an extragalactic peaked-spectrum source with a size of ≲10 pc. The remaining sources were resolved out by the long baselines of the EVN because of either strong scatter broadening at the Galactic latitude < 1° or intrinsically very extended structures on centi-arcsec scales. According to their spectral and structural properties, we find that the sample has a diverse nature. We notice two young H ii regions and spot a radio star and a candidate planetary nebula. The rest of the sources are very likely associated with radio active galactic nuclei (AGNs). Two of them also display arcsec-scale faint jet activity. The sample study indicates that AGNs are common place even among variable radio sources in the Galactic plane.

Galaxy: general
H ii regions
radio continuum: galaxies
radio continuum: stars
scattering

http://resolver.tudelft.nl/uuid:40630756-2ac0-45b9-a718-7f06da7c2959

https://doi.org/10.1093/mnras/stab3804

0035-8711

Monthly Notices of the Royal Astronomical Society, 511 (1), 280-294

Institutional Repository

journal article

© 2022 Jun Yang, Yongjun Chen, L. Gurvits, Zsolt Paragi, Aiyuan Yang, Xiaolong Yang, Zhiqiang Shen