2021/08/19 by E. Järvelä, Järvelä, Emilia, M. Berton +3 · 1 citation
Physics and Astronomy · #Astrophysics and Cosmic Phenomena #Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences #Galaxies: Formation, Evolution, Phenomena #Radio Astronomy Observations and Technology
paper · pdf · doi:10.48550/arxiv.2108.08521
openalex publication_date 2021/08/19 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Narrow-line Seyfert 1 (NLS1) galaxies are active galactic nuclei (AGN)\nbelieved to be in the early stages of their evolution. A fraction of them have\nbeen found to host relativistic jets. Due to the lack of large-scale diffuse\nradio emission they are believed to be experiencing one of their first activity\ncycles, and can offer us an opportunity to study the early evolution of more\npowerful AGN, such as radio galaxies and flat-spectrum radio quasars. Recently,\na group of intriguing jetted NLS1s was discovered: based on high radio\nfrequency data they host relativistic jets, but in the JVLA observations they\nall showed steep radio spectra at least up to 9.0~GHz, indicating very strong\nabsorption at these frequencies. In this paper we study a subset of these\nsources in detail by employing spatially resolved radio spectral index maps at\ncentral frequencies of 1.6, 5.2, and 9.0~GHz. With spectral index maps we can\ndisentangle the different radio emission components over the radio-emitting\nregion, and get insights into the production mechanisms of radio emission. In\naddition, we study their host galaxies in relation to the radio emission to\ninvestigate if the host can provide us additional information regarding the\norigin of the radio emission, or the launching mechanism of the jets. It is\nfascinating how different the sources studied are, and certainly more,\nespecially wide frequency-range, and high-resolution observations will be\nneeded to understand their history and current properties, such as the reason\nbehind the extraordinary radio spectra.\n