Universidad de Granada Digibug
 

Repositorio Institucional de la Universidad de Granada >
1.-Investigación >
Departamentos, Grupos de Investigación e Institutos >
Departamento de Física Teórica y del Cosmos >
DFTC - Artículos >

Please use this identifier to cite or link to this item: http://hdl.handle.net/10481/28391

Title: Tracing molecular gas mass in extreme extragalactic environments: an observational study
Authors: Zhu, Ming
Papadopoulos, Padeli P.
Xilouris, Emmanuel M.
Kuno, N.
Lisenfeld, Ute
Issue Date: 2009
Abstract: We present a new observational study of the CO(1-0) line emission as an H2 gas mass tracer under extreme conditions in extragalactic environments. Our approach is to study the full neutral interstellar medium (H2, HI and dust) of two galaxies whose bulk interstellar medium (ISM) resides in environments that mark (and bracket) the excitation extremes of the ISM conditions found in infrared luminous galaxies, the starburst NGC3310 and the quiescent spiral NGC157. Our study maintains a robust statistical notion of the so-called X factor (i.e. a large ensemble of clouds is involved) while exploring its dependency on the very different average ISM conditions prevailing within these two systems. These are constrained by fully-sampled CO(3-2) and CO(1-0) observations, at a matched beam resolution of Half Power Beam Width 15", obtained with the JCMT the Nobeyama 45-m telescope, combined with sensitive 850 and 450 micron dust emission and HI interferometric images which allow a complete view of all the neutral ISM components. We found an X factor varying by a factor of 5 within the spiral galaxy NGC157 and about 2 times lower than the Galactic value in NGC3310. In addition, the dust emission spectrum in NGC3310 shows a pronounced submm "excess". We explain and fit this by an enhanced abundance of Very Small Grains (VSGs). The alternative approach to interpret this excess as very cold dust would yield a cold dust temperature of 5-11 K with a correspondingly very low gas-to-dust mass ratio of 5-43, very unlikely for this starburst galaxy with low metallicity.
Sponsorship: U.L. acknowledges financial support from the research project AYA2007-67625-C02-02 from the Spanish Ministerio de Ciencia y Educación and from the Junta de Anaducía.
Publisher: American Astronomical Society; Institute of Physics (IOP)
Keywords: Dust
Extinction
Galaxies
NGC 157
NGC 3310
ISM
Spiral
Staburst
Radio lines
URI: http://hdl.handle.net/10481/28391
ISSN: 0004-637X
1538-4357
Rights : Creative Commons Attribution-NonCommercial-NoDerivs 3.0 License
Citation: Zhu, M.; et al. Tracing molecular gas mass in extreme extragalactic environments: an observational study. Astrophysical Journal, 706(2): 941-959 (2009). [http://hdl.handle.net/10481/28391]
Appears in Collections:DFTC - Artículos

Files in This Item:

File Description SizeFormat
Zhu_Moleculargas.pdf610.79 kBAdobe PDFView/Open
Recommend this item

This item is licensed under a Creative Commons License
Creative Commons

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.

 

Valid XHTML 1.0! OpenAire compliant DSpace Software Copyright © 2002-2007 MIT and Hewlett-Packard - Feedback

© Universidad de Granada