Extremely Red Galaxies at z = 5–9 with MIRI and NIRSpec: Dusty Galaxies or Obscured Active Galactic Nuclei?

Abstract We study a new population of extremely red objects (EROs) recently discovered by the James Webb Space Telescope (JWST) based on their NIRCam colors F277W − F444W > 1.5 mag. We find 37 EROs in the Cosmic Evolution Early Release Science Survey (CEERS) field with F444W < 28 mag and photometric redshifts between 5 < z < 7, with median z = 6.9 − 1.6 + 1.0 . Surprisingly, despite their red long-wavelength colors, these EROs have blue short-wavelength colors (F150W − F200W ∼ 0 mag) indicative of bimodal spectral energy distributions (SEDs) with a red, steep slope in the rest-frame optical, and a blue, flat slope in the rest-frame UV. Moreover, all these EROs are unresolved, point-like…

• NA
  National Aeronautics and Space Administration

  Award: JWST-ERS-1345
• ST
  Space Telescope Science Institute

  Award: JWST-ERS-1345
• UO
  University of California Observatories
• SA
  Science and Technology Facilities Council

  Award: ST/X001040/1
• AE
  Agencia Estatal de Investigación

  Awards: AEI/10.13039/501100011033, 501100011033, 10.13039/501100011033, MCIN/AEI/10.13039/501100011033, 13039, 10.13039, AEI/10, 13039/501100011033, AEI/10., PID2022-139567NB-I00