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Journal Articles The Astrophysical Journal Year : 2022

MALS SALT-NOT Survey of MIR-selected Powerful Radio-bright AGN at 0 < z < 3.5

N. Gupta
  • Function : Author
G. Shukla
  • Function : Author
R. Srianand
  • Function : Author
A. J. Baker
  • Function : Author
J. P. U. Fynbo
  • Function : Author
E. Momjian
  • Function : Author
M. Hilton
  • Function : Author
T. Hussain
  • Function : Author
K. Moodley
  • Function : Author
H. -W. Chen
  • Function : Author
P. Deka
  • Function : Author
R. Dutta
  • Function : Author
J. Jose
  • Function : Author
G. I. G. Józsa
  • Function : Author
C. Kaski
  • Function : Author
H. -R. Klöckner
  • Function : Author
K. Knowles
  • Function : Author
S. Sikhosana
  • Function : Author
J. Wagenveld
  • Function : Author

Abstract

We present results of an optical spectroscopic survey using SALT and the Nordic Optical Telescope to build a Wide-field Infrared Survey Explorer mid-infrared color-based, dust-unbiased sample of powerful radio-bright (>200 mJy at 1.4 GHz) active galactic nuclei (AGN) for the MeerKAT Absorption Line Survey (MALS). Our sample has 250 AGN (median z = 1.8) showing emission lines, 26 with no emission lines, and 27 without optical counterparts. Overall, our sample is fainter (Δi = 0.6 mag) and redder (Δ(g-i) = 0.2 mag) than radio-selected quasars, and representative of fainter quasar population detected in optical surveys. About 20% of the sources are narrow-line AGN (NLAGN)-65% of these, at z < 0.5 are galaxies without strong nuclear emission, and 10% at z > 1.9, have emission line ratios similar to radio galaxies. The farthest NLAGN in our sample is M1513-2524 (z em = 3.132), and the largest radio source (size ~330 kpc) is M0909-3133 (z em = 0.884). We discuss in detail 110 AGN at 1.9 < z < 3.5. Despite representing the radio loudest quasars (median R = 3685), their Eddington ratios are similar to the Sloan Digital Sky Survey quasars having lower R. We detect four C IV broad-absorption line (BAL) QSOs, all among AGN with least R, and highest black hole masses and Eddington ratios. The BAL detection rate ( %) is consistent with that seen in extremely powerful (L 1.4GHz > 1025 W Hz-1) quasars. Using optical light curves, radio polarization, and γ-ray detections, we identify seven high-probability BL Lacertae objects. We also summarize the full MALS footprint to search for H I 21 cm and OH 18 cm lines at z < 2.
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insu-03717120 , version 1 (09-07-2022)

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N. Gupta, G. Shukla, R. Srianand, J. -K. Krogager, P. Noterdaeme, et al.. MALS SALT-NOT Survey of MIR-selected Powerful Radio-bright AGN at 0 < z < 3.5. The Astrophysical Journal, 2022, 929, ⟨10.3847/1538-4357/ac4220⟩. ⟨insu-03717120⟩
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