An evolving photoelectric efficiency at cosmic noon?. Issue Volume 15:Issue S352(2019) (June 2019)

• Record Type: Journal Article
• Authors: McKinney, Jed; Pope, Alexandra; Armus, Lee; Chary, Ranga; Dickinson, Mark; Kirkpatrick, Allison
• Editors: da Cunha, Elisabete; Hodge, Jacqueline; Afonso, José; Pentericci, Laura; Sobral, David
• Is Part Of: Proceedings of the International Astronomical Union. Volume 15:Issue S352(2019)
• Page Start: 243
• Page End: 245
• Publication Date: 2019-06
• Subjects: galaxies: high-redshift, -- galaxies: individual, -- galaxies: ISM, -- galaxies: starburst; Astronomy -- Congresses; Astronomy -- Periodicals; 520
• DOI: 10.1017/S1743921319008925
• Languages: English
• ISSNs: 1743-9213

Abstract

Abstract: To sustain star formation rates (SFRs) of hundreds to thousands of solar masses per year over millions of years, a galaxy must efficiently cool its gas. At z ∼ 2, the peak epoch for stellar mass assembly, tracers of gas heating and cooling remain largely unexplored. For one z ∼ 2 starburst galaxy GS IRS20, we present Spitzer IRS spectroscopy of Polycyclic Aromatic Hydrocarbon (PAH) emission, and ALMA observations of [C II] 158 μ m fine-structure emission which we use to probe ISM heating/cooling. Coupled with an unusually warm dust component, the ratio of [C II] /PAH emission suggests a low photolelectric efficiency, and/or the importance of cooling from other far-IR lines in this galaxy. A low photoelectric efficiency at z ∼ 2 could be key for the peak in the SFR density of the universe by decoupling stellar radiation from ISM gas temperatures.