Universität zu Köln

Hill, Alex S., Mac Low, Mordecai-Mark ORCID: 0000-0003-0064-4060, Gatto, Andrea and Ibanez-Mejia, Juan C. (2018). Effect of the Heating Rate on the Stability of the Three-phase Interstellar Medium. Astrophys. J., 862 (1). BRISTOL: IOP PUBLISHING LTD. ISSN 1538-4357

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Abstract

We investigate the impact of the far-UV (FUV) heating rate on the stability of the three-phase interstellar medium using three-dimensional simulations of a 1 kpc(2), vertically extended domain. The FUV heating rate sets the range of thermal pressures across which the cold (similar to 10(2) K) and warm (similar to 10(4) K) neutral media (CNM and WNM) can coexist in equilibrium. Even absent a variable star formation rate regulating the FUV heating rate, the gas physics keeps the pressure in the two-phase regime: because radiative heating and cooling processes happen on shorter timescales than sound wave propagation, turbulent compressions tend to keep the interstellar medium within the CNM-WNM pressure regime over a wide range of heating rates. The thermal pressure is set primarily by the heating rate with little influence from the hydrostatics. The vertical velocity dispersion adjusts as needed to provide hydrostatic support given the thermal pressure: when the turbulent pressure <rho > sigma(2)(z) is calculated over scales >= 500 pc, the thermal plus turbulent pressure approximately equals the weight of the gas. The warm gas volume filling fraction is 0.2 < f(w) < 0.8 over a factor of less than three in heating rate, with f(w) near unity at higher heating rates and near zero at lower heating rates. We suggest that cosmological simulations that do not resolve the CNM should maintain an interstellar thermal pressure within the two-phase regime.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Hill, Alex S. UNSPECIFIED UNSPECIFIED UNSPECIFIED Mac Low, Mordecai-Mark UNSPECIFIED orcid.org/0000-0003-0064-4060 UNSPECIFIED Gatto, Andrea UNSPECIFIED UNSPECIFIED UNSPECIFIED Ibanez-Mejia, Juan C. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-179598
DOI:	10.3847/1538-4357/aacce2
Journal or Publication Title:	Astrophys. J.
Volume:	862
Number:	1
Date:	2018
Publisher:	IOP PUBLISHING LTD
Place of Publication:	BRISTOL
ISSN:	1538-4357
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language NEUTRAL ATOMIC PHASES; SUPERNOVA-DRIVEN ISM; HIGH-VELOCITY CLOUDS; MULTIPHASE STRUCTURE; HALO INTERACTION; GALACTIC HALO; MODELS; GAS; SIMULATIONS; EVOLUTION Multiple languages Astronomy & Astrophysics Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/17959