Outflows from starburst galaxies with various driving mechanisms and their X-ray properties

TL;DR

This study uses hydrodynamic simulations to explore outflows in starburst galaxies driven by thermal energy, cosmic rays, or both, analyzing their X-ray spectral signatures and potential for remote diagnostics.

Contribution

It presents the first detailed simulation-based analysis of X-ray properties of starburst galaxy outflows driven by different mechanisms, including synthetic spectra and broadband diagnostics.

Findings

Outflows reach a stationary state with profiles matching semi-analytical models.

Distinct X-ray spectral signatures differentiate thermal and cosmic-ray-driven outflows.

Broadband X-ray color analysis can identify outflow driving mechanisms in distant galaxies.

Abstract

Outflows in starburst galaxies driven by thermal-mechanical energy, cosmic rays and their mix are investigated with 1D and 2D hydrodynamic simulations. We show that these outflows could reach a stationary state, after which their hydrodynamic profiles asymptotically approach previous results obtained semi-analytically for stationary outflow configurations. The X-rays from the simulated outflows are computed, and high-resolution synthetic spectra and broadband light curves are constructed. The simulated outflows driven by thermal mechanical pressure and CRs have distinguishable spectral signatures, in particular, in the sequence of the keV K$\alpha$ lines of various ions and in the L-shell Fe emission complex. We demonstrate that broadband colour analysis in X-rays is a possible alternative means to probe outflow driving mechanisms for distant galaxies, where observations may not be able to provide sufficient photons for high-resolution spectroscopic analyses.