How do a dark halo and central black hole determine transonic wind solutions?

A polytropic wind framework explores how gravity and the gas equation of state shape galactic outflows.

Polytropic transonic galactic outflows in a dark matter halo with a central black hole

Polytropic transonic galactic outflows in a dark matter halo with a central black hole. Igarashi, Asuka; Mori, Masao; Nitta, Shin-ya, Monthly Notices of the Royal Astronomical Society, 470, 2225 (2017).

arXiv:1508.01331 Publication · DOI

Approach

Steady, spherical flow solutions are classified by sonic-point topology in combined halo and black-hole potentials, then compared with the Sombrero galaxy.

Main result

The black hole adds a solution branch. Slowly accelerating winds can occur in quiescent systems, and the polytropic model reproduces Sombrero gas profiles with a more plausible mass flux than an isothermal model.

Scientific implications

Hot-gas profiles can be compatible with a gradual wind even without an obvious fast outflow.

Scope and limitations

The framework assumes spherical steady flow and a polytropic prescription; real winds can be asymmetric, variable and multiphase.