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

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 th...

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Published in:The Astrophysical journal 2024-06, Vol.968 (1), p.4
Main Authors: 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, Tacchella, Sandro, Willmer, Christopher N. A., Willott, Chris
Format: Article
Language:English
Subjects:
Active galactic nuclei
Broad band photometry
Compact galaxies
Dust
Emission
Emissions
Galaxies
Galaxy ages
Galaxy evolution
Galaxy formation
Galaxy stellar content
High-redshift galaxies
James Webb Space Telescope
Massive stars
Quartiles
Spectral energy distribution
Starburst galaxies
Stellar mass
Stellar populations
Toruses
Wavelengths
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Summary: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 μ m 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 μ m) spectral slope reveals significant amounts of warm dust (bolometric attenuation ∼3–4 mag). Our spectral energy distribution modeling implies the presence of 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).
ISSN:0004-637X
1538-4357
DOI:10.3847/1538-4357/ad38bb