An alternative accurate tracer of molecular clouds: the 'XCI-factor'

被引：64

作者：

Offner, Stella S. R. ^{[1
]}

Bisbas, Thomas G. ^{[2
]}

Bell, Tom A. ^{[3
]}

Viti, Serena ^{[2
]}

机构：

[1] Yale Univ, Dept Astron, New Haven, CT 06511 USA

[2] UCL, Dept Phys & Astron, London WC1E 6B, England

[3] CSIC, INTA, Ctr Astrobiol, E-28850 Madrid, Spain

来源：

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY | 2014年 / 440卷 / 01期

关键词：

astrochemistry; hydrodynamics; molecular processes; turbulence; stars: formation; ISM: molecules; photodissociation region (PDR); ATOMIC CARBON; I EMISSION; PHOTODISSOCIATION REGIONS; STAR-FORMATION; CO; ORION; GAS; ABUNDANCE; DATABASE; LINES;

D O I：

10.1093/mnrasl/slu013

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

We explore the utility of CI as an alternative high-fidelity gas-mass tracer for galactic molecular clouds. We evaluate the 'X-CI-factor' for the 609 mu m carbon line, the analogue of the CO 'X-factor', which is the ratio of the H-2 column density to the integrated (CO)-C-12(1-0) line intensity. We use 3D-PDR to post-process hydrodynamic simulations of turbulent, star-forming clouds. We compare the emission of CI and CO for model clouds irradiated by 1 and 10 times the average background and demonstrate that CI is a comparable or superior tracer of the molecular gas distribution for column densities up to 6 x 10(23) cm(-2). Our results hold for both reduced and full chemical networks. For our fiducial Galactic cloud, we derive an average X-CO of 3.0 x 10(20) cm(-2) K-1 km(-1) s and X-CI of 1.1 x 10(21) cm(-2) K-1 km(-1) s.

引用

页码：L81 / L85

页数：5

共 37 条

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