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        High-resolution VLA Imaging of Obscured Quasars : Young Radio Jets Caught in a Dense ISM

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        2004.07914v1.pdf (PDF, 11Mb)
        Patil_2020_ApJ_896_18.pdf (PDF, 2Mb)
        Author
        Patil, Pallavi
        Nyland, Kristina
        Whittle, Mark
        Lonsdale, Carol
        Lacy, Mark
        Lonsdale, Colin
        Mukherjee, Dipanjan
        Trapp, A. C.
        Kimball, Amy E.
        Lanz, Lauranne
        Wilkes, Belinda J.
        Blain, Andrew
        Harwood, Jeremy J.
        Efstathiou, Andreas
        Vlahakis, Catherine
        Attention
        2299/23006
        Abstract
        We present new subarcsecond-resolution Karl G. Jansky Very Large Array (VLA) imaging at 10 GHz of 155 ultraluminous (L bol ∼ 1011.7-1014.2 L o˙) and heavily obscured quasars with redshifts z ∼ 0.4-3. The sample was selected to have extremely red mid-infrared-optical color ratios based on data from the Wide-Field Infrared Survey Explorer (WISE) along with a detection of bright, unresolved radio emission from the NRAO VLA Sky Survey (NVSS) or Faint Images of the Radio Sky at Twenty cm Survey. Our high-resolution VLA observations have revealed that the majority of the sources in our sample (93 out of 155) are compact on angular scales <0.″2 (≤1.7 kpc at z ∼ 2). The radio luminosities, linear extents, and lobe pressures of our sources are similar to young radio active galactic nuclei (e.g., gigahertz-peaked spectrum [GPS] and compact steep-spectrum [CSS] sources), but their space density is considerably lower. Application of a simple adiabatic lobe expansion model suggests relatively young dynamical ages (∼104-7 yr), relatively high ambient ISM densities (∼1-104 cm-3), and modest lobe expansion speeds (∼30-10,000 km s-1). Thus, we find our sources to be consistent with a population of newly triggered, young jets caught in a unique evolutionary stage in which they still reside within the dense gas reservoirs of their hosts. Based on their radio luminosity function and dynamical ages, we estimate that only ∼20% of classical large-scale FR I/II radio galaxies could have evolved directly from these objects. We speculate that the WISE-NVSS sources might first become GPS or CSS sources, of which some might ultimately evolve into larger radio galaxies.
        Publication date
        2020-06-10
        Published in
        The Astrophysical Journal
        Published version
        https://doi.org/10.3847/1538-4357/ab9011
        Other links
        http://hdl.handle.net/2299/23006
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