A Caltech Library Service

The art of modelling CO, [C I], and [C II] in cosmological galaxy formation models

Popping, Gergö and Narayanan, Desika and Somerville, Rachel S. and Faisst, Andreas L. and Krumholz, Mark R. (2019) The art of modelling CO, [C I], and [C II] in cosmological galaxy formation models. Monthly Notices of the Royal Astronomical Society, 482 (4). pp. 4906-4932. ISSN 0035-8711. doi:10.1093/mnras/sty2969.

[img] PDF - Published Version
See Usage Policy.

[img] PDF - Accepted Version
See Usage Policy.


Use this Persistent URL to link to this item:


The advent of new sub-millimetre (sub-mm) observational facilities has stimulated the desire to model the sub-mm line emission of galaxies within cosmological galaxy formation models. This is typically done by applying sub-resolution recipes to describe the properties of the unresolved interstellar medium (ISM). While there is freedom in how one implements sub-resolution recipes, the impact of various choices has yet to be systematically explored. We combine a semi-analytic model of galaxy formation with chemical equilibrium networks and numerical radiative transfer models and explore how different choices for the sub-resolution modelling affect the predicted CO, [C I], and [C II] emission of galaxies. A key component for a successful model includes a molecular cloud mass–size relation and scaling for the ultraviolet and cosmic ray radiation field that depend on local ISM properties. Our most successful model adopts a Plummer radial density profile for gas within molecular clouds. Different assumptions for the clumping of gas within molecular clouds and changes in the molecular cloud mass distribution function hardly affect the CO, [C I], and [C II] luminosities of galaxies. At fixed star formation rate, the [C II]–SFR ratio of galaxies scales inversely with the pressure acting on molecular clouds, increasing the molecular clouds density and hence decreasing the importance of [C II] line cooling. We find that it is essential that a wide range of sub-mm emission lines arising in vastly different phases of the ISM are used as model constraints in order to limit the freedom in sub-grid choices.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Popping, Gergö0000-0003-1151-4659
Narayanan, Desika0000-0002-7064-4309
Faisst, Andreas L.0000-0002-9382-9832
Krumholz, Mark R.0000-0003-3893-854X
Alternate Title:The art of modeling CO, [CI], and [CII] in cosmological galaxy formation models
Additional Information:© 2018 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model ( Accepted 2018 October 31. Received 2018 October 31; in original form 2018 May 25. Published: 06 November 2018. GP thanks Karen Olsen for providing a [C II] data compilation and for organizing the ‘Walking the line 2018’ conference which stimulated the creation of this work. GP thanks Anita Zanella for providing the [C II] luminosities of z ∼ 2 galaxies prior to publication. The authors thank Romeel Davé, Gordon Stacey, and Chris Faesi for useful discussions and the referee for their comments that improved this work. DN was funded in part by grants from the US National Science Foundation via awards AST-1724864 and AST-1715206 and the Space Telescope Science Institute via award HST AR-13906.0001 and HST AR-15043.0001. RSS thanks the Downsbrough family for their generous support. The simulations in this paper were run on Rusty, supported by the Center for Computational Astrophysics, Flatiron Institute and on Draco, supported by the Max Planck Gesellschaft. Part of the writing of this manuscript was performed during an extended stay at the Munich Institute for Astronomy and Particle Physics as part of the workshop ‘The Interstellar Medium of High Redshift Galaxies’.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
NASA Hubble FellowshipHST AR-13906.0001
NASA Hubble FellowshipHST AR-15043.0001
Downsbrough FamilyUNSPECIFIED
Subject Keywords:ISM: atoms – ISM: lines and bands – ISM: molecules –Galaxy: formation – galaxies: evolution – galaxies: ISM
Issue or Number:4
Record Number:CaltechAUTHORS:20190411-110313060
Persistent URL:
Official Citation:Gergö Popping, Desika Narayanan, Rachel S Somerville, Andreas L Faisst, Mark R Krumholz, The art of modelling CO, [C I], and [C II] in cosmological galaxy formation models, Monthly Notices of the Royal Astronomical Society, Volume 482, Issue 4, February 2019, Pages 4906–4932,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:94657
Deposited By: Tony Diaz
Deposited On:11 Apr 2019 18:13
Last Modified:16 Nov 2021 17:06

Repository Staff Only: item control page