Abstract
We present Atacama Large Millimeter/submillimeter Array (ALMA) 870 μm (345 GHz) data for 49 high-redshift (0.47 < z < 2.85), luminous () radio-powerful active galactic nuclei (AGNs), obtained to constrain cool dust emission from starbursts concurrent with highly obscured radiative-mode black hole (BH) accretion in massive galaxies that possess a small radio jet. The sample was selected from the Wide-field Infrared Survey Explorer with extremely steep (red) mid-infrared colors and with compact radio emission from NVSS/FIRST. Twenty-six sources are detected at 870 μm, and we find that the sample has large mid- to far-infrared luminosity ratios, consistent with a dominant and highly obscured quasar. The rest-frame 3 GHz radio powers are and all sources are radio-intermediate or radio-loud. BH mass estimates are 7.7 < log(MBH/M⊙) < 10.2. The rest-frame 1–5 μm spectral energy distributions are very similar to the "Hot DOGs" (hot dust-obscured galaxies), and steeper (redder) than almost any other known extragalactic sources. ISM masses estimated for the ALMA-detected sources are 9.9 < log (MISM/M⊙) < 11.75 assuming a dust temperature of 30 K. The cool dust emission is consistent with star formation rates reaching several thousand M⊙ yr−1, depending on the assumed dust temperature, but we cannot rule out the alternative that the AGN powers all the emission in some cases. Our best constrained source has radiative transfer solutions with approximately equal contributions from an obscured AGN and a young (10–15 Myr) compact starburst.
Highlights
Central questions concerning coeval galaxy and supermassive black hole (SMBH) evolution include the relative timescales and mechanisms for stellar mass and black hole (BH) mass building including the roles and duty cycles of (a) secular versus merger-triggered mechanisms for driving material into the central regions; (b) “radiative-mode” versus “jet-mode” BH accretion modes and rates; and (c) “quasarmode” versus “radio-mode” feedback mechanisms, all as a function of epoch, galaxy mass, and galaxy environment
We have selected a sample of extremely red, luminous, RP sources in the 0.5 < z < 3 redshift range using Wide-field Infrared Survey Explorer (WISE) MIR colors and the NVSS and FIRST 20 cm radio surveys
We present Atacama Large Millimeter/submillimeter Array (ALMA) 870 μm photometry for 49 southern sources from the total sample of 156 red sources, and redshifts for 45 of them from a combination of optical and near-infrared spectroscopy
Summary
Central questions concerning coeval galaxy and supermassive black hole (SMBH) evolution include the relative timescales and mechanisms for stellar mass and black hole (BH) mass building including the roles and duty cycles of (a) secular versus merger-triggered mechanisms for driving material into the central regions; (b) “radiative-mode” versus “jet-mode” BH accretion modes and rates; and (c) “quasarmode” versus “radio-mode” feedback mechanisms, all as a function of epoch, galaxy mass, and galaxy environment. Jet-mode radio AGNs are thought to be highly effective in maintaining galaxies free of new gas and star formation via “radio-mode” kinetic feedback, i.e. jet inflation of bubbles in the surrounding hot intergalactic gas (Croton 2006; Cattaneo & Teyssier 2007; Fabian 2010). Radiative-mode, or “quasar-mode,” AGNs have higher accretion rates from a thin accretion disk whose radiation powers the narrow- and broad-line regions, and which is fed through a surrounding dusty torus or “torus-like” structure. Quasar-mode accretion has a lower duty cycle than jet-mode, occurring when large amounts of material are available for accretion onto the SMBH. Quasar-mode AGNs are capable of powering efficient feedback into the host galaxy via thermal winds from the accretion disk, disrupting star formation and ejecting gas. Powerful jets are found in ∼10% of radiatively efficient
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