What Is the Nature of Little Red Dots and what Is Not, MIRI SMILES Edition

Authors

• Pablo G. Pérez-González, CSIC-INTA - Centro de Astrobiología (CAB)
• Guillermo Barro, University of the PacificFollow
• George H. Rieke, The University of Arizona
• Jianwei Lyu, The University of Arizona
• Marcia Rieke, The University of Arizona
• Stacey Alberts, The University of Arizona
• Christina C. Williams, NOIRLab
• Kevin Hainline, The University of Arizona
• Fengwu Sun, The University of Arizona
• Dávid Puskás, University of Cambridge
• Marianna Annunziatella, CSIC-INTA - Centro de Astrobiología (CAB)
• William M. Baker, University of Cambridge
• Andrew J. Bunker, University of Oxford
• Eiichi Egami, The University of Arizona
• Zhiyuan Ji, The University of Arizona
• Benjamin D. Johnson, Harvard-Smithsonian Center for Astrophysics
• Brant Robertson, University of California, Santa Cruz
• Bruno Rodríguez Del Pino, CSIC-INTA - Centro de Astrobiología (CAB)
• Wiphu Rujopakarn, National Astronomical Research Institute of Thailand
• Irene Shivaei, CSIC-INTA - Centro de Astrobiología (CAB)
• Sandro Tacchella, University of Cambridge

Document Type

Article

Publication Title

Astrophysical Journal

Department

Physics

ISSN

15384357

Volume

968

Issue

1

DOI

10.3847/1538-4357/ad38bb

First Page

1

Last Page

33

Publication Date

6-4-2024

Abstract

We study 31 little red dots (LRD) detected by JADES/NIRCam and covered by the SMILES/MIRI survey, of which ∼70% are detected in the two bluest MIRI bands and 40% in redder MIRI filters. The median/quartiles redshifts are z = 6.9 5.9 7.7 (55% spectroscopic). The spectral slopes flatten in the rest-frame near-infrared, consistent with a 1.6 μm stellar bump but bluer than direct pure emission from active galactic nuclei (AGN) tori. The apparent dominance of stellar emission at these wavelengths for many LRDs expedites stellar mass estimation: the median/quartiles are log M ⋆ / M ⊙ = 9.4 9.1 9.7 . The number density of LRDs is 10^−4.0±0.1 Mpc⁻³, accounting for 14% ± 3% of the global population of galaxies with similar redshifts and masses. The rest-frame near-/mid-infrared (2-4 μm) spectral slope reveals significant amounts of warm dust (bolometric attenuation ∼3-4 mag). Our spectral energy distribution modeling implies the presence of <0.4 kpc diameter knots, heated by either dust-enshrouded OB stars or an AGN producing a similar radiation field, obscured by A(V) > 10 mag. We find a wide variety in the nature of LRDs. However, the best-fitting models for many of them correspond to extremely intense and compact starburst galaxies with mass-weighted ages 5-10 Myr, very efficient in producing dust, with their global energy output dominated by the direct (in the flat rest-frame ultraviolet and optical spectral range) and dust-recycled emission from OB stars with some contribution from an obscured AGN (in the infrared).

Creative Commons License

This work is licensed under a Creative Commons Attribution 4.0 International License.

Recommended Citation

Pérez-González, Pablo G.; Barro, Guillermo; Rieke, George H.; Lyu, Jianwei; Rieke, Marcia; Alberts, Stacey; Williams, Christina C.; Hainline, Kevin; Sun, Fengwu; Puskás, Dávid; Annunziatella, Marianna; Baker, William M.; Bunker, Andrew J.; Egami, Eiichi; Ji, Zhiyuan; Johnson, Benjamin D.; Robertson, Brant; Rodríguez Del Pino, Bruno; Rujopakarn, Wiphu; Shivaei, Irene; and Tacchella, Sandro, "What Is the Nature of Little Red Dots and what Is Not, MIRI SMILES Edition" (2024). Pacific Faculty Work. 116.
https://scholarlycommons.pacific.edu/all-faculty/116