Radio Spectra of Luminous, Heavily Obscured WISE-NVSS Selected Quasars

Abstract

We present radio spectra spanning $0.1-10$ GHz for the sample of heavily obscured luminous quasars with extremely red mid-infrared-optical colors and compact radio emission. The spectra are constructed from targeted 10 GHz observations and archival radio survey data, which together yield $6-11$ flux density measurements for each object. Our suite of Python tools for modeling the radio spectra is publicly available on Github. Our primary result is that most (61%) of the sample have peaked or curved radio spectra and many (36%) could be classified as Gigahertz Peaked Spectrum (GPS) sources. This indicates compact emission regions likely arising from recently triggered radio jets. Assuming synchrotron self-absorption (SSA) generates the peaks, we infer compact source sizes ($3-100$ pc) with strong magnetic fields ($6-100$ mG) and young ages ($30-10^4$ years). Conversely, free-free absorption (FFA) could also create peaks due to the high column densities associated with the deeply embedded nature of the sample. However, we find no correlations between the existence or frequency of the peaks and any parameters of the MIR emission. The high-frequency spectral indices are steep ($\alpha \approx -1$) and correlate, weakly, with the ratio of MIR photon energy density to magnetic energy density, suggesting that the spectral steepening could arise from inverse Compton scattering off the intense MIR photon field. This study provides a foundation for combining multi-frequency and mixed-resolution radio survey data for understanding the impact of young radio jets on the ISM and star formation rates of their host galaxies.

48 pages, 17 figures, published in Astrophysical Journal

References in corpus (36)

• The NumPy array: a structure for efficient numerical computation
• GaLactic and Extragalactic All-sky Murchison Widefield Array (GLEAM) survey I: A low-frequency extragalactic catalogue
• The LOFAR Two-metre Sky Survey -- V. Second data release
• The Optical to Mid-Infrared Extinction Law Based on the APOGEE, Gaia DR2, Pan-STARRS1, SDSS, APASS, 2MASS and WISE Surveys
• Distant Radio Galaxies and their Environments
• The Last of FIRST: The Final Catalog and Source Identifications
• Australian Square Kilometre Array Pathfinder: I. System Description
• The Rapid ASKAP Continuum Survey I: Design and First Results
• The Very Large Array Low-frequency Sky Survey Redux (VLSSr)
• Science With The Australian Square Kilometre Array Pathfinder
• Compact steep-spectrum and peaked-spectrum radio sources
• The Dynamic Evolution of Young Extragalactic Radio Sources
• The First Hyper-Luminous Infrared Galaxy Discovered by WISE
• Deep ATLAS radio observations of the CDFS-SWIRE field
• Extragalactic Peaked-Spectrum Radio Sources at Low Frequencies
• The Most Luminous Galaxies Discovered by WISE
• An excess of dusty starbursts related to the Spiderweb galaxy
• Submillimeter Follow-up of WISE-Selected Hyperluminous Galaxies
• LOFAR/H-ATLAS: A deep low-frequency survey of the Herschel-ATLAS North Galactic Pole field
• Relativistic jet feedback II: Relationship to gigahertz peak spectrum and compact steep spectrum radio galaxies
• The LOFAR LBA Sky Survey I. survey description and preliminary data release
• A search for distant radio galaxies from SUMSS and NVSS: III. radio spectral energy distributions and the z-alpha correlation
• Quasars That Have Transitioned from Radio-quiet to Radio-loud on Decadal Timescales Revealed by VLASS and FIRST
• Search and modelling of remnant radio galaxies in the LOFAR Lockman Hole field
• Simulating the dynamics and non-thermal emission of relativistic magnetised jets I. Dynamics
• The life cycle of radio galaxies in the LOFAR Lockman Hole field
• Are young radio sources in equipartition?
• The Spectral Variability of the GHz-Peaked Spectrum Radio Source PKS 1718-649 and a Comparison of Absorption Models
• Submillimetre observations of WISE/radio-selected AGN and their environments
• High-resolution VLA Imaging of Obscured Quasars: Young Radio Jets Caught in a Dense ISM
• Caltech-NRAO Stripe 82 Survey (CNSS) Paper V: AGNs that transitioned to radio-loud state
• The first VLBI image of an Infrared-Faint Radio Source
• Radio spectrum evolution and magnetic field in extreme GPS radio sources. The case of RXJ1459+3337
• The radio spectral energy distribution of infrared-faint radio sources
• WISE Mid-Infrared Properties of compact Active Galactic Nuclei selected from the high-radio-frequency AT20G Survey
• The black hole masses of extremely luminous radio-WISE selected galaxies

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