{
  "id": "2501.14026",
  "version": "v1",
  "published": "2025-01-23T19:00:06.000Z",
  "updated": "2025-01-23T19:00:06.000Z",
  "title": "Luminous Mid-IR Selected Type-2 Quasars at Cosmic Noon in SDSS Stripe82 I: Selection, Composite Photometry, and Spectral Energy Distributions",
  "authors": [
    "Ben Wang",
    "Joseph F. Hennawi",
    "Zheng Cai",
    "Gordon T. Richards",
    "Jan-Torge Schindler",
    "Nadia L. Zakamska",
    "Yuzo Ishikawa",
    "Hollis B. Akins",
    "Zechang Sun"
  ],
  "categories": [
    "astro-ph.GA",
    "astro-ph.CO"
  ],
  "abstract": "We analyze 23 spectroscopically confirmed Type-2 quasars (QSOs) selected from the WISE 22$\\rm \\mu$m band in the SDSS Stripe 82 region, focusing on their multi-band photometry and spectral energy distributions (SEDs). These objects were selected to be IR-luminous ($\\rm flux_{W4} > 5mJy$, i.e., $12.62 < W4 < 14.62 \\rm\\ AB \\, magnitude$), optically faint ($r > 23$) or with red color ($r - W4 >8.38$). Gemini/GNIRS observations were conducted for all 24 candidates, and 18/24 were also observed with Keck/LRIS. The observations confirm 23 to be real Type-2 QSOs in the redshift range $0.88 - 2.99$ (12 are at $z>2$). We collect multi-band photometry and conduct SED fitting. The composite photometry probes the wavelength from 0.1$\\rm \\mu$m to 10$\\rm \\mu$m at the rest frame. The IR emission is dominated by dust torus implying an average torus luminosity for the sample of $L_{\\rm torus} 10^{46.84} \\rm erg/s$. The origin of the rest-UV/optical light is not definitive, but we present three possible scenarios: scattered light, stellar emission, and the reddened accretion disk. Assuming an obscured:unobscured ratio of approximately 1:1, our targets have $L_{\\rm bol} = 10^{46.28} \\rm erg \\,s^{-1} - 10^{47.49} \\rm erg \\,s^{-1}$ and around SMBH masses $\\rm 10^{8.18} M_{\\odot} - 10^{9.39} M_{\\odot}$, assuming they accreate at the Eddington limit. Compared to previous Type-2 AGN SEDs, our targets have a brighter dust torus and redder optical-IR color. By comparing the SED to the results from JWST `little red dots' (LRDs), we find that these IR-selected Type-2 QSOs have similar SED shapes to the LRDs. This pilot Type-2 QSO survey demonstrates that mid-IR selection is an efficient way to find luminous Type-2 QSOs at $z>2$. Finally, the composite photometry and Type-2 QSOs SED model generated by this sample provide a guide for finding more Type-2 QSOs at higher redshift.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2025-01-23T19:00:06.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "spectral energy distributions",
      "composite photometry",
      "cosmic noon",
      "sdss stripe82",
      "luminous mid-ir"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}