The black hole masses of extremely luminous radio-WISE selected galaxies. Issue 1 (11th January 2021)

• Record Type: Journal Article
• Authors: Ferris, E R; Blain, A W; Assef, R J; Hatch, N A; Kimball, A; Kim, M; Sajina, A; Silva, A; Stern, D; Diaz-Santos, T; Tsai, C-W; Wylezalek, D
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 502:Issue 1(2021)
• Page Start: 1527
• Page End: 1548
• Publication Date: 2021-01-11
• Subjects: galaxies: active -- galaxies: evolution -- infrared: galaxies; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/stab048
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: We present near-IR photometry and spectroscopy of 30 extremely luminous radio and mid-IR-selected galaxies. With bolometric luminosities exceeding ∼10 13 $\rm {L_{\odot }}$ and redshifts ranging from z = 0.880 to 2.853, we use Very Large Telescope instruments X-shooter and Infrared Spectrometer and Array Camera to investigate this unique population of galaxies. Broad multicomponent emission lines are detected in 18 galaxies and we measure the near-IR lines $\rm {H\, \rm {\beta }}$, $\rm{[O\, {\small III}]}\, \rm {\lambda }\rm {\lambda }4959, 5007$, and $\rm {H\, \rm {\alpha }}$ in 6, 15, and 13 galaxies, respectively, with 10 $\rm {Ly\, \alpha }$ and 5 C iv lines additionally detected in the UVB arm. We use the broad $\rm{[O\, {\small III}]}\, \rm {\lambda }5007$ emission lines as a proxy for the bolometric active galactic nucleus luminosity, and derive lower limits to supermassive black hole masses of 10 7.9 –10 9.4 M⊙ with expectations of corresponding host masses of 10 10.4 –10 12.0 M⊙ . We measure $\rm {\lambda }_{Edd}$ > 1 for eight of these sources at a 2σ significance. Near-IR photometry and SED fitting are used to compare stellar masses directly. We detect both Balmer lines in five galaxies and use these to infer a mean visual extinction of AV = 2.68 mag. Due to non-detections and uncertainties in our ${\rm H}\, \beta$ emission line measurements, we simulate a broad ${\rm H}\, \beta$ line of FWHM = 1480 $\rm {kms^{-1}}$ to estimate extinction for all sources with measured ${\rm H}\, \alpha$ emission. We then use this to infer a mean AV = 3.62 mag, demonstrating the highly obscured nature of these galaxies, with the consequence of increasing our estimates of black hole masses by a 0.5 orders of magnitude in the most extreme and obscured cases.