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

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

2024 March 10 | Guillermo Barro, Pablo G. Pérez-González, Dale D. Kocevski, Elizabeth J. McGrath, Jonathan R. Trump, Raymond C. Simons, Rachel S. Somerville, L. Y. Aaron Yung, Pablo Arrabal Haro, Hollis B. Akins, Michaela B. Bagley, Nikko J. Cleri, Luca Costantini, Kelcy Davis, Mark Dickinson, Steve L. Finkelstein, Mauro Giavalisco, Carlos Gómez-Guijarro, Nimish P. Hathi, Michaela Hirschmann, Benne W. Holwerda, Marc Huertas-Company, Jeyhan S. Kartaltepe, Anton M. Koekemoer, Ray A. Lucas, Casey Papovich, Nor Pirzkal, Lise-Marie Seill, Sandro Tacchella, Stijn Wuyts, Stephen M. Wilkins, Alexander de la Vega, Guang Yang, Jorge A. Zavala
This paper investigates a new population of extremely red objects (EROs) discovered by the James Webb Space Telescope (JWST) based on their NIRCam colors (F277W − F444W > 1.5 mag). The authors identify 37 EROs in the Cosmic Evolution Early Release Science Survey (CEERS) field with photometric redshifts between 5 < z < 7, having a median redshift of 6.9. These EROs exhibit bimodal spectral energy distributions (SEDs) with blue short-wavelength colors (F150W − F200W ∼ 0 mag) and red, steep slopes in the rest-frame optical. All EROs are unresolved, point-like sources in all NIRCam bands. The authors analyze the SEDs of eight EROs using MIRI and NIRSpec observations, finding that both dusty galaxies and obscured active galactic nuclei (AGNs) provide good fits but with different stellar properties. The study concludes that the unresolved sizes of the EROs are more suggestive of AGNs, and if confirmed, the presence of log M_s/M_☉ ≥ 10.5 would significantly increase the number density of massive galaxies at z > 7. The paper also discusses the potential contamination by brown dwarfs and the implications of these findings for the stellar masses and number densities of the sample.This paper investigates a new population of extremely red objects (EROs) discovered by the James Webb Space Telescope (JWST) based on their NIRCam colors (F277W − F444W > 1.5 mag). The authors identify 37 EROs in the Cosmic Evolution Early Release Science Survey (CEERS) field with photometric redshifts between 5 < z < 7, having a median redshift of 6.9. These EROs exhibit bimodal spectral energy distributions (SEDs) with blue short-wavelength colors (F150W − F200W ∼ 0 mag) and red, steep slopes in the rest-frame optical. All EROs are unresolved, point-like sources in all NIRCam bands. The authors analyze the SEDs of eight EROs using MIRI and NIRSpec observations, finding that both dusty galaxies and obscured active galactic nuclei (AGNs) provide good fits but with different stellar properties. The study concludes that the unresolved sizes of the EROs are more suggestive of AGNs, and if confirmed, the presence of log M_s/M_☉ ≥ 10.5 would significantly increase the number density of massive galaxies at z > 7. The paper also discusses the potential contamination by brown dwarfs and the implications of these findings for the stellar masses and number densities of the sample.
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[slides and audio] Extremely Red Galaxies at z %3D 5%E2%80%939 with MIRI and NIRSpec%3A Dusty Galaxies or Obscured Active Galactic Nuclei%3F