Transonic solutions of isothermal galactic winds in a cold dark matter halo

Abstract

We study fundamental properties of steady, spherically symmetric, isothermal galactic outflow in appropriate gravitational potential models. We aim at constructing a universal scale free theory not only for galactic winds, but also for winds from clusters/groups of galaxies. In particular, we consider effects of mass-density distribution on the formation of transonic galactic outflows under several models of the density distribution profile predicted by cosmological simulations of structure formation based on the cold dark matter (CDM) scenario. In this study, we have clarified that there exists two types of transonic solutions: outflows from the central region and from distant region with a finite radius, depending upon the density distribution of the system. The system with sufficiently steep density gradient at the center is allowed to have the transonic outflows from the center. The resultant criterion intriguingly indicates that the density gradient at the center must be steeper than that of the prediction of conventional CDM model including Navarro, Frenk & White (1997) and Moore et al. (1999). This result suggests that an additional steeper density distribution originated by baryonic systems such as the stellar component and/or the central massive black hole is required to realize transonic outflow from the central region. On the other hand, we predict the outflow, which is started at the outskirts of the galactic center and is slowly-accelerated without any drastic energy injection like starburst events. These transonic outflows may contribute secularly to the metal enrichment of the intergalactic medium.

10 pages, 6 figures and an appendix, accepted for publication in MNRAS

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• Ubiquitous outflows in DEEP2 spectra of star-forming galaxies at z=1.4
• The Hot Interstellar Medium in Normal Elliptical Galaxies III: The Thermal Structure of the Gas
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Cited by in corpus (4)

• Re-examining the Too-Big-To-Fail Problem for Dark Matter Haloes with Central Density Cores
• Transonic galactic outflows in a dark matter halo with a central black hole and its application to the Sombrero galaxy
• Galactic breeze origin for the Fermi bubbles emission
• Supermassive black hole in NGC 4649 (M60) with a dark matter halo: Impact on shadow measurements and thermodynamic properties