Universität zu Köln

Mao, Rui-Qing, Schulz, Andreas, Henkel, Christian, Mauersberger, Rainer and Muders, Dirk (2010). AN EXTRAGALACTIC (CO)-C-12 J=3-2 SURVEY WITH THE HEINRICH HERTZ TELESCOPE. Astrophys. J., 724 (2). S. 1336 - 1357. BRISTOL: IOP PUBLISHING LTD. ISSN 0004-637X

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Abstract

We present results of a (12)COJ= 3-2 survey of 125 nearby galaxies obtained with the 10 m Heinrich Hertz Telescope, with the aim to characterize the properties of warm and dense molecular gas in a large variety of environments. With an angular resolution of 22 '', (CO)-C-12 3-2 emission was detected in 114 targets. Based on 61 galaxies observed with equal beam sizes the (12)CO3-2/1-0 integrated line intensity ratio R-31 is found to vary from 0.2 to 1.9, with an average value of 0.81. No correlations are found for R-31 to Hubble-type and far-infrared luminosity. Possible indications for a correlation with inclination angle and the 60 mu m/100 mu m color temperature of the dust are not significant. Higher R-31 ratios than in normal galaxies, hinting at enhanced molecular excitation, may be found in galaxies hosting active galactic nuclei. Even higher average values are determined for galaxies with bars or starbursts, the latter being identified by the ratio of infrared luminosity versus isophotal area, log [(L-FIR/L-circle dot)/(D-25(2)/kpc(2))] > 7.25. (U)LIRGs are found to have the highest averaged R-31 value. This may be a consequence of particularly vigorous star formation activity, triggered by galaxy interaction and merger events. The nuclear CO luminosities are slightly sublinearly correlated with the global FIR luminosity in both the (12)COJ = 3-2 and the 1-0 lines. The slope of the log-log plots rises with compactness of the respective galaxy sub-sample, indicating a higher average density and a larger fraction of thermalized gas in distant luminous galaxies. While linear or sublinear correlations for the (CO)-C-12 J = 3-2 line can be explained, if the bulk of the observed J = 3-2 emission originates from the molecular gas with densities below the critical one, the case of the (CO)-C-12 J = 1-0 line with its small critical density remains a puzzle.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Mao, Rui-Qing UNSPECIFIED UNSPECIFIED UNSPECIFIED Schulz, Andreas UNSPECIFIED UNSPECIFIED UNSPECIFIED Henkel, Christian UNSPECIFIED UNSPECIFIED UNSPECIFIED Mauersberger, Rainer UNSPECIFIED UNSPECIFIED UNSPECIFIED Muders, Dirk UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-491139
DOI:	10.1088/0004-637X/724/2/1336
Journal or Publication Title:	Astrophys. J.
Volume:	724
Number:	2
Page Range:	S. 1336 - 1357
Date:	2010
Publisher:	IOP PUBLISHING LTD
Place of Publication:	BRISTOL
ISSN:	0004-637X
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language EARLY-TYPE GALAXIES; LUMINOUS INFRARED GALAXIES; NEARBY SPIRAL GALAXIES; DENSE MOLECULAR GAS; STAR-FORMATION RATE; DOUBLE-BARRED GALAXIES; CO EMISSION; VIRGO CLUSTER; PHOTODISSOCIATION REGIONS; ULTRALUMINOUS GALAXIES Multiple languages Astronomy & Astrophysics Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/49113