Dynamics of hot galactic winds launched from spherically-stratified starburst cores. Issue 1 (16th November 2022)

• Record Type: Journal Article
• Authors: Nguyen, Dustin D; Thompson, Todd A; Schneider, Evan E; Lopez, Sebastian; Lopez, Laura A
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 518:Issue 1(2022)
• Page Start: L87
• Page End: L91
• Publication Date: 2022-11-16
• Subjects: hydrodynamics -- galaxies: starburst -- galaxies: nuclei -- X-rays: galaxies; Astronomy -- Research -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnrasl/slac141
• Languages: English
• ISSNs: 1745-3933

Abstract

ABSTRACT: The analytic galactic wind model derived by Chevalier and Clegg in 1985 (CC85) assumes uniform energy and mass-injection within the starburst galaxy nucleus. However, the structure of nuclear star clusters, bulges, and star-forming knots are non-uniform. We generalize to cases with spherically-symmetric energy/mass injection that scale as r −Δ within the starburst volume R, providing solutions for Δ = 0, 1/2, 1, 3/2, and 2. In marked contrast with the CC85 model (Δ = 0), which predicts zero velocity at the centre, for a singular isothermal sphere profile (Δ = 2), we find that the flow maintains a constant Mach number of $\mathcal {M}=\sqrt{3/5} \simeq 0.77$ throughout the volume. The fast interior flow can be written as $v_{r \lt R} = (\dot{E}_T/3\dot{M}_T)^{1/2} \simeq 0.41 \, v_\infty$, where v ∞ is the asymptotic velocity, and $\dot{E}_T$ and $\dot{M}_T$ are the total energy and mass injection rates. For $v_\infty \simeq 2000 \, \mathrm{km \, s^{-1}}$, $v_{r\lt R} \simeq 820 \, \mathrm{km\, s^{-1}}$ throughout the wind-driving region. The temperature and density profiles of the non-uniform models may be important for interpreting spatially-resolved maps of starburst nuclei. We compute velocity resolved spectra to contrast the Δ = 0 (CC85) and Δ = 2 models. Next generation X-ray space telescopes such as XRISM may assess these kinematic predictions.