CO excitation of normal star-forming galaxies out to z=1.5 as regulated by the properties of their interstellar medium

	CO excitation of normal star-forming galaxies out to z=1.5 as regulated by the properties of their interstellar medium
	Daddi, E.1; Dannerbauer, H.2; Liu, D.1,3,4,5 ; Aravena, M.6; Bournaud, F.1; Walter, F.7; Riechers, D.8; Magdis, G.9,16; Sargent, M.10; Bethermin, M.11
刊名	ASTRONOMY & ASTROPHYSICS
	2015-05-01
卷号	577 页码:A46
关键词	galaxies: evolution galaxies: high-redshift galaxies: starburst galaxies: star formation submillimeter: galaxies
英文摘要	We investigate the CO excitation of normal (near-IR selected BzK) star-forming (SF) disk galaxies at z = 1.5 using IRAM Plateau de Bure observations of the CO[2-1], CO[3-2], and CO[5-4] transitions for four galaxies, including VLA observations of CO[1-0] for three of them, with the aim of constraining the average state of H-2 gas. By exploiting previous knowledge of the velocity range, spatial extent, and size of the CO emission, we measure reliable line fluxes with a signal-to-noise ratio > 4-7 for individual transitions. While the average CO spectral line energy distribution (SLED) has a subthermal excitation similar to the Milky Way (MW) up to CO[3-2], we show that the average CO[5-4] emission is four times stronger than assuming MW excitation. This demonstrates that there is an additional component of more excited, denser, and possibly warmer molecular gas. The ratio of CO[5-4] to lower-J CO emission is lower than in local (ultra-)luminous infrared galaxies (ULIRGs) and high-redshift starbursting submillimeter galaxies, however, and appears to be closely correlated with the average intensity of the radiation field < U > and with the star formation surface density, but not with the star formation efficiency. The luminosity of the CO[5-4] transition is found to be linearly correlated with the bolometric infrared luminosity over four orders of magnitudes. For this transition, z = 1.5 BzK galaxies follow the same linear trend as local spirals and (U)LIRGs and high-redshift star-bursting submillimeter galaxies. The CO[5-4] luminosity is thus empirically related to the dense gas and might be a more convenient way to probe it than standard high-density tracers that are much fainter than CO. We see excitation variations among our sample galaxies that can be linked to their evolutionary state and clumpiness in optical rest-frame images. In one galaxy we see spatially resolved excitation variations, where the more highly excited part of the galaxy corresponds to the location of massive SF clumps. This provides support to models that suggest that giant clumps are the main source of the high-excitation CO emission in high-redshift disk-like galaxies.
学科主题	天文和天体物理
WOS标题词	Science & Technology ; Physical Sciences
类目[WOS]	Astronomy & Astrophysics
研究领域[WOS]	Astronomy & Astrophysics
关键词[WOS]	LUMINOUS INFRARED GALAXIES ; HIGH-REDSHIFT GALAXIES ; EXTRAGALACTIC LEGACY SURVEY ; MASS-METALLICITY RELATION ; MOLECULAR GAS FRACTIONS ; ACTIVE GALACTIC NUCLEI ; LYMAN BREAK GALAXIES ; FMOS-COSMOS SURVEY ; GREATER-THAN 2 ; SIMILAR-TO 1.5
收录类别	SCI
语种	英语
WOS记录号	WOS:000353579600045
内容类型	期刊论文
源URL	[http://libir.pmo.ac.cn/handle/332002/14861]
专题	中国科学院紫金山天文台
作者单位	1.Univ Paris Diderot, CEA Saclay, Lab AIM, CNRS,Irfu SAp, F-91191 Gif Sur Yvette, France 2.Univ Vienna, Inst Astrophys, A-1180 Vienna, Austria 3.Chinese Acad Sci, Purple Mt Observ, Nanjing 210008, Peoples R China 4.Chinese Acad Sci, Radio Astron Lab, Nanjing 210008, Peoples R China 5.Grad Univ Chinese Acad Sci, Beijing 10049, Peoples R China 6.Univ Diego Portales, Fac Ingn, Nucleo Astron, Santiago, Chile 7.Max Planck Inst Astron, D-69117 Heidelberg, Germany 8.Cornell Univ, Dept Astron, Ithaca, NY 14853 USA 9.Univ Oxford, Dept Phys, Oxford OX1 3RH, England 10.Univ Sussex, Ctr Astron, Dept Phys & Astron, Brighton BN1 9QH, E Sussex, England
推荐引用方式 GB/T 7714	Daddi, E.,Dannerbauer, H.,Liu, D.,et al. CO excitation of normal star-forming galaxies out to z=1.5 as regulated by the properties of their interstellar medium[J]. ASTRONOMY & ASTROPHYSICS,2015,577:A46.
APA	Daddi, E..,Dannerbauer, H..,Liu, D..,Aravena, M..,Bournaud, F..,...&Krips, M..(2015).CO excitation of normal star-forming galaxies out to z=1.5 as regulated by the properties of their interstellar medium.ASTRONOMY & ASTROPHYSICS,577,A46.
MLA	Daddi, E.,et al."CO excitation of normal star-forming galaxies out to z=1.5 as regulated by the properties of their interstellar medium".ASTRONOMY & ASTROPHYSICS 577(2015):A46.