Comparisons Between Resolved Star Formation Rate and Gas Tracers in the Strongly Lensed Galaxy SDSS J0901+1814 at Cosmic Noon

Journal Article · Mon Jul 01 00:00:00 EDT 2024 · Astrophys.J.

DOI:https://doi.org/10.3847/1538-4357/ad5ceb· OSTI ID:2563254

Chen, Qingxiang ^[1]; Sharon, Chelsea E. ^[1]; Algera, Hiddo S.B. ^[2]; Baker, Andrew J. ^[3]; Keeton, Charles R. ^[4]; Lutz, Dieter ^[5]; Liu, Daizhong ^[5]; Young, Anthony J. ^[4]; Tagore, Amitpal S. ^[6]; Rivera, Jesus ^[7]; Hicks, Erin K.S. ^[8]; Allam, Sahar S. ^[9]; Tucker, Douglas L. ^[9]

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1. Yale-NUS Coll.
2. Hiroshima U.; Natl. Astron. Observ. of Japan
3. Rutgers U., Piscataway; Cape Town U., Dept. Math.
4. Rutgers U., Piscataway
5. Garching, Max Planck Inst., MPE
6. Jodrell Bank
7. Swarthmore Coll.
8. Alaska U., Anchorage
9. Fermilab

We report new radio observations of SDSS J090122.37+181432.3, a strongly lensed star-forming galaxy at $z=2.26$. We image 1.4 GHz (L-band) and 3 GHz (S-band) continuum using the VLA and 1.2 mm (band 6) continuum with ALMA, in addition to the CO(7-6) and CI($${\rm ^3P_2\rightarrow ^3\!P_1}$$) lines, all at $$\lesssim1.^{\prime\prime}7$$ resolution. Based on the VLA integrated flux densities, we decompose the radio spectrum into its free-free (FF) and non-thermal components. The infrared-radio correlation (IRRC) parameter $$q_{\rm TIR}=2.65_{-0.31}^{+0.24}$$ is consistent with expectations for star forming galaxies. We obtain radio continuum-derived SFRs that are free of dust extinction, finding $$\rm {620}_{-220}^{+280}\,M_\odot\,yr^{-1}$$, $$\rm {230}_{-160}^{+570}\,M_\odot\,yr^{-1}$$, and $$\rm {280}_{-120}^{+460}\,M_\odot\,yr^{-1}$$ from the FF emission, non-thermal emission, and when accounting for both emission processes, respectively, in agreement with previous results. We estimate the gas mass from the CI($${\rm ^3P_2\rightarrow ^3\!P_1}$$) line as $$M_{\rm gas}=(1.2\pm0.2)\times10^{11}\,M_\odot$$, which is consistent with prior CO(1-0)-derived gas masses. Using our new IR and radio continuum data to map the SFR, we assess the dependence of the Schmidt-Kennicutt relation on choices of SFR and gas tracer for $$\sim{\rm kpc}$$ scales. The different SFR tracers yield different slopes, with the IR being the steepest, potentially due to highly obscured star formation in J0901. The radio continuum maps have the lowest slopes and overall fidelity for mapping the SFR, despite producing consistent total SFRs. We also find that the Schmidt-Kennicutt relation slope is flattest when using CO(7-6) or CI($${\rm ^3P_2\rightarrow ^3\!P_1}$$) to trace gas mass, suggesting that those transitions are not suitable for tracing the bulk molecular gas in galaxies like J0901.

• Research Organization: Alaska U., Anchorage; Cape Town U., Dept. Math.; Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States); Garching, Max Planck Inst., MPE; Hiroshima U.; Jodrell Bank; Natl. Astron. Observ. of Japan; Rutgers U., Piscataway; Swarthmore Coll.; Yale-NUS Coll.
• Sponsoring Organization: US Department of Energy
• Grant/Contract Number: 89243024CSC000002; AC02-07CH11359
• OSTI ID: 2563254
• Report Number(s): FERMILAB-PUB-24-1031-CSAID; oai:inspirehep.net:2914637; arXiv:2407.01685
• Journal Information: Astrophys.J., Journal Name: Astrophys.J. Vol. 972
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
high-redshift galaxies
molecular gas
radio continuum emission
star formation