A High Incidence of Dusty Hα Emitters at z > 3 Among UltraVISTA Dropout Galaxies in COSMOS Revealed by JWST
We have characterized 26 Spitzer/IRAC-selected sources from the SMUVS program that are undetected in the UltraVISTA DR5 H - and/or K _s -band images, covering 94 arcmin ^2 of the COSMOS field, which have deep multiwavelength JWST photometry. We analyzed the JWST/NIRCam imaging fr...
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| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
IOP Publishing
2024-01-01
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| Series: | The Astrophysical Journal |
| Subjects: | |
| Online Access: | https://doi.org/10.3847/1538-4357/ad2c0b |
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| Summary: | We have characterized 26 Spitzer/IRAC-selected sources from the SMUVS program
that are undetected in the UltraVISTA DR5 H -
and/or K _s -band images, covering 94 arcmin ^2 of the COSMOS field,
which have deep multiwavelength JWST photometry. We analyzed the JWST/NIRCam
imaging from the PRIMER survey and ancillary HST data to reveal the properties
of these galaxies from spectral energy distribution (SED) fitting. We find that
the majority of these galaxies are detected by NIRCam at λ < 2 μ m, with only four
remaining as near-infrared dropouts in the deeper JWST images. Our results
indicate that the UltraVISTA dropouts candidates are primarily located at z > 3 and are characterized by high dust
extinctions, with a typical color excess E ( B − V ) = 0.5 ± 0.3 and
stellar mass $\mathrm{log}({M}_{* }/{M}_{\odot })=9.5\pm 1.0$ . Remarkably, ∼75% of these sources show a flux enhancement
between the observed photometry and modeled continuum SED that can be attributed
to H α emission in the corresponding NIRCam bands.
The derived (H α + N [ ii ] + S
[ ii ]) rest-frame equivalent widths and H α star formation rates (SFRs) span values ∼100–2200 Å and ∼5–375 M _⊙ yr ^−1 , respectively. The locations of these sources on
the SFR– M _* plane indicate that 35% of them are starbursts, 40% are
main-sequence galaxies, and the remaining 25% are located in the star formation
valley. Our sample includes one active galactic nucleus and six submillimeter
sources, as revealed from ancillary X-ray and submillimeter photometry. The high
dust extinctions combined with the flux boosting from H α emission explain why these sources are relatively bright Spitzer
galaxies and yet unidentified in the ultradeep UltraVISTA near-infrared
images. |
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| ISSN: | 1538-4357 |