2025MNRAS.539.1562W -
Mon. Not. R. Astron. Soc., 539, 1562-1594 (2025/May-2)
Luminous mid-IR-selected type 2 quasars at cosmic noon in SDSS Stripe 82 - I. Selection, composite photometry, and spectral energy distributions.
WANG B., HENNAWI J.F., CAI Z., RICHARDS G.T., SCHINDLER J.-T., ZAKAMSKA N.L., ISHIKAWA Y., AKINS H.B. and SUN Z.
Abstract (from CDS):
We analyse 23 spectroscopically confirmed type 2 quasars (QSOs) selected from Wide-field Infrared Survey Explorer 22 $\rm{\mu m}$ band in the Sloan Digital Sky Survey Stripe 82 region, focusing on their multiband photometry and spectral energy distributions (SEDs). The 24 candidates were selected to be infrared (IR) luminous (${\rm flux}_{W4} > 5 \, {\rm mJy}$), optically faint ($r > 23$), or with red colour ($r - W4 >8.38$). Gemini/Gemini Near-InfraRed Spectrograph and Keck/Low-Resolution Imaging Spectrometer observations confirm 23 to be type 2 QSOs at $z = 0.88 \!-\! 3.49$. Multiband photometry is used for SED fitting, covering 0.1-10 $\mu$m in the rest frame. The IR emission is dominated by the dust torus, with an average luminosity of $L_{\rm torus} = 10^{46.84} \, \rm erg\, s^{-1}$. We present three possibilities for the origin of the rest-ultraviolet/optical: scattered light, stellar emission, and the reddened accretion disc. Assuming an obscured:unobscured ratio of 1:1, the targets have bolometric luminosities of $L_{\rm bol} = 10^{46.28} \!-\! 10^{48.08} \, \rm erg\, s^{-1}$ and supermassive black hole masses of $10^{8.18} \!-\! 10^{9.98} \, {\rm M}_{\odot }$, averaging $L_{\rm bol} = 10^{47.04} \, {\rm erg\,s^{-1}}$ and $M_{\rm BH} = 10^{8.94} \, {\rm M}_{\odot }$, assuming the Eddington limit. Compared to previous type 2 active galactic nuclei SEDs, our targets have a brighter dust torus and redder optical-IR colour. By comparing the SED to JWST 'little red dots' (LRDs), we find that these IR-selected type 2 QSOs have similar SED shapes to the LRDs. This survey demonstrates mid-IR selection as an efficient method to find luminous type 2 QSOs and the composite photometry generated by this sample provides a guide for finding more type 2 QSOs at higher redshift in the future.
Abstract Copyright:
© 2025 The Author(s). The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society.
Journal keyword(s):
galaxies: high-redshift - quasars: emission lines - quasars: general - quasars: supermassive black holes - infrared: galaxies
Simbad objects:
25
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