A SPectroscopic Survey of Biased Halos in the Reionization Era (ASPIRE): Spectroscopically Complete Census of Obscured Cosmic Star Formation Rate Density at z = 4–6

A SPectroscopic Survey of Biased Halos in the Reionization Era (ASPIRE): Spectroscopically Complete Census of Obscured Cosmic Star Formation Rate Density at z = 4–6

We present a stringent measurement of the dust-obscured star formation rate density (SFRD) at z = 4–6 from the ASPIRE JWST Cycle-1 medium and ALMA Cycle-9 large program. We obtained JWST/NIRCam grism spectroscopy and ALMA 1.2 mm continuum map along 25 independent quasar sightlines, covering a total...

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Main Authors: Fengwu Sun, Feige Wang, Jinyi Yang, Jaclyn B. Champagne, Roberto Decarli, Xiaohui Fan, Eduardo Bañados, Zheng Cai, Luis Colina, Eiichi Egami, Joseph F. Hennawi, Xiangyu Jin, Hyunsung D. Jun, Yana Khusanova, Mingyu Li, Zihao Li, Xiaojing Lin, Weizhe Liu, Romain A. Meyer, Maria A. Pudoka, George H. Rieke, Yue Shen, Wei Leong Tee, Bram Venemans, Fabian Walter, Yunjing Wu, Huanian Zhang, Siwei Zou
Format: Article
Language:English
Published: IOP Publishing 2025-01-01
Series:The Astrophysical Journal
Subjects:
James Webb Space Telescope
Starburst galaxies
High-redshift galaxies
Luminous infrared galaxies
Galaxy evolution
Online Access:https://doi.org/10.3847/1538-4357/ad9d0e
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Summary:We present a stringent measurement of the dust-obscured star formation rate density (SFRD) at z = 4–6 from the ASPIRE JWST Cycle-1 medium and ALMA Cycle-9 large program. We obtained JWST/NIRCam grism spectroscopy and ALMA 1.2 mm continuum map along 25 independent quasar sightlines, covering a total survey area of  ∼35 arcmin ^2 where we search for dusty star-forming galaxies (DSFGs) at z = 0–7. We identify eight DSFGs in seven fields at z = 4–6 through the detection of H α or [O  iii ] λ 5008 lines, including fainter lines such as H β , [O  iii ] λ 4960, [N  ii ] λ 6585, and [S  ii ] λλ 6718,6733 for six sources. With this spectroscopically complete DSFG sample at z = 4–6 and negligible impact from cosmic variance (shot noise), we measure the infrared luminosity function (IRLF) down to L _IR  ∼ 2 × 10 ^11 L _⊙ . We find flattening of IRLF at z = 4–6 towards the faint end (power-law slope $\alpha =0.5{9}_{-0.45}^{+0.39}$ ). We determine the dust-obscured cosmic SFRD at this epoch to be $\mathrm{log}[{\rho }_{\mathrm{SFR},\mathrm{IR}}/({M}_{\odot }\,{\mathrm{yr}}^{-1}\,{\mathrm{Mpc}}^{-3})]=-1.5{2}_{-0.13}^{+0.14}$ . This is significantly higher than previous determinations using ALMA data in the Hubble Ultra Deep Field, which is void of DSFGs at z = 4–6 because of strong cosmic variance (shot noise). We conclude that the majority (66% ± 7%) of cosmic star formation at z  ∼ 5 is still obscured by dust. We also discuss the uncertainty of SFRD propagated from far-IR spectral energy distribution and IRLF at the bright end, which will need to be resolved with future ALMA and JWST observations.
ISSN:1538-4357

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