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On the Extreme Radio Quiescence of Little Red Dots
* 1 , 1 , 1 , 2
1  Konkoly Observatory, HUN-REN Research Centre For Astronomy and Earth Sciences, 1121 Budapest, Hungary
2  Department of Astronomy, Institute of Physics and Astronomy, ELTE Eötvös Loránd University, Budapest, Hungary
Academic Editor: Paola Marziani

Abstract:

Observations with the James Webb Space Telescope (JWST) led to the discovery of a new population of high-redshift sources, referred to as little red dots (LRDs). These are a mysterious class of objects that appear to be extremely compact in size, show excess ultraviolet emission, have a red optical continuum in the rest-frame, and exhibit broad line spectral features. They were discovered as part of an effort to characterise distant galaxies that might represent an early stage in galaxy evolution. Since their discovery, there has been significant interest in understanding the physical processes behind the observed characteristics. Are these galaxies rapidly forming stars? Do they host accreting supermassive black holes that power active galactic nuclei? Or do they represent another type of galaxy altogether? As radio observations are crucial in distinguishing between these possibilities, an extensive sample of LRDs were studied utilising radio maps from the Faint Images of the Radio Sky at Twenty-centimeters (FIRST) survey and the Very Large Array Sky Survey (VLASS). Investigating both the individual and statistical properties of LRDs in radio wavebands, the results were compared to and discussed with respect to those of known high-redshift AGN. Due to their extreme quiescence in the radio regime, we discuss various scenarios and hypoteses to explain the 'LRD phenomenon'.

Keywords: little red dots; tidal disruption events; radio continuum; high redshift
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