文章基本信息

标题：Extreme conditions in the molecular gas of lensed star-forming galaxies at z ~3 ★
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作者：Paola Andreani ; Edwin Retana-Montenegro ; Zhi-Yu Zhang 等
期刊名称：Astronomy & Astrophysics
印刷版ISSN：0004-6361
电子版ISSN：1432-0746
出版年度：2018
卷号：615
DOI：10.1051/0004-6361/201732560
语种：English
出版社：EDP Sciences
摘要：Context.Atomic carbon can be an efficient tracer of the molecular gas mass, and when combined to the detection of high-J and low-J CO lines it yields also a sensitive probe of the power sources in the molecular gas of high-redshift galaxies.Aims.The recently installed SEPIA 5 receiver at the focus of the APEX telescope has opened up a new window at frequencies 159–211 GHz allowing the exploration of the atomic carbon in high-z galaxies, at previously inaccessible frequencies from the ground. We have targeted three gravitationally lensed galaxies at redshift of about 3 and conducted a comparative study of the observed high-J CO/CIratios with well-studied nearby galaxies.Methods.Atomic carbon (CI(2–1)) was detected in one of the three targets and marginally in a second, while in all three targets theJ= 7→6 CO line is detected.Results.The CO(7–6)/CI(2–1), CO(7–6)/CO(1–0) line ratios and the CO(7–6)/(far-IR continuum) luminosity ratio are compared to those of nearby objects. A large excitation status in the ISM of these high-z objects is seen, unless differential lensing unevenly boosts the CO line fluxes from the warm and dense gas more than the CO(1–0), CI(2–1), tracing a more widely distributed cold gas phase. We provide estimates of total molecular gas masses derived from the atomic carbon and the carbon monoxide CO(1–0), which within the uncertainties turn out to be equal.
关键词：Key wordsengalaxies: starburstgalaxies: ISMISM: moleculesISM: abundancessubmillimeter: galaxiestechniques: spectroscopic