Resolved Molecular Gas and Star Formation Properties of the Strongly Lensed z = 2.26 Galaxy SDSS J0901+1814

Journal Article · Wed Jul 03 00:00:00 EDT 2019 · The Astrophysical Journal (Online)

DOI:https://doi.org/10.3847/1538-4357/ab22b9· OSTI ID:1557214

Sharon, Chelsea E.  ^[1]; Tagore, Amitpal S. ^[2]; Baker, Andrew J.  ^[3]; Rivera, Jesus  ^[3]; Keeton, Charles R.  ^[3]; Lutz, Dieter  ^[4]; Genzel, Reinhard  ^[4]; Wilner, David J.  ^[5]; Hicks, Erin K. S. ^[6]; Allam, Sahar S. ^[7]; Tucker, Douglas L. ^[7]

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1. Yale-NUS College (Singapore); McMaster Univ., Hamilton, ON (Canada)
2. Univ. of Manchester (United Kingdom)
3. Rutgers Univ., Piscataway, NJ (United States)
4. Max Planck Inst. fur Extraterrestrische Physik, Garching (Germany)
5. Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States)
6. Univ. of Alaska, Anchorage, AK (United States)
7. Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

We present ~1'' resolution (~2 kpc in the source plane) observations of the CO (1–0), CO (3–2), Hα, and [N II] lines in the strongly lensed z = 2.26 star-forming galaxy SDSS J0901+1814. We use these observations to constrain the lensing potential of a foreground group of galaxies, and our source-plane reconstructions indicate that SDSS J0901+1814 is a nearly face-on (i ≈ 30°) massive disk with r_1/2 ≳ 4 kpc for its molecular gas. Using our new magnification factors (μ_tot ≈ 30), we find that SDSS J0901+1814 has a star formation rate (SFR) of $${268}_{-61}^{+63}\,{M}_{\odot }\,{\mathrm{yr}}^{-1}$$, $${M}_{\mathrm{gas}}=({1.6}_{-0.2}^{+0.3})\times {10}^{11}({\alpha }_{\mathrm{CO}}/4.6)\,{M}_{\odot }$$, and $${M}_{\star }=({9.5}_{-2.8}^{+3.8})\times {10}^{10}\,{M}_{\odot }$$, which places it on the star-forming galaxy "main sequence." We use our matched high angular resolution gas and SFR tracers (CO and Hα, respectively) to perform a spatially resolved (pixel-by-pixel) analysis of SDSS J0901+1814 in terms of the Schmidt–Kennicutt relation. After correcting for the large fraction of obscured star formation ($${\mathrm{SFR}}_{{\rm{H}}\alpha }/{\mathrm{SFR}}_{\mathrm{TIR}}={0.054}_{-0.014}^{+0.015}$$), we find that SDSS J0901+1814 is offset from "normal" star-forming galaxies to higher star formation efficiencies independent of assumptions for the CO-to-H₂ conversion factor. Our mean best-fit index for the Schmidt–Kennicutt relation for SDSS J0901+1814, evaluated with different CO lines and smoothing levels, is $$\bar{n}=1.54\pm 0.13;$$ however, the index may be affected by gravitational lensing, and we find $$\bar{n}=1.24\pm 0.02$$ when analyzing the source-plane reconstructions. While the Schmidt–Kennicutt index largely appears unaffected by which of the two CO transitions we use to trace the molecular gas, the source-plane reconstructions and dynamical modeling suggest that the CO (1–0) emission is more spatially extended than the CO (3–2) emission.

• Research Organization: Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
• Sponsoring Organization: USDOE Office of Science (SC), High Energy Physics (HEP)
• Grant/Contract Number: AC02-07CH11359
• OSTI ID: 1557214
• Report Number(s): arXiv:1905.09845; FERMILAB-PUB-19-366-AE; 1743056
• Journal Information: The Astrophysical Journal (Online), Vol. 879, Issue 1; ISSN 1538-4357
• Publisher: Institute of Physics (IOP)
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS