Extra-planar X-ray emission from disc-wide outflows in spiral galaxies

Abstract

We study the effects of mass and energy injection due to OB associations spread across the rotating disc of a Milky Way-type galaxy, with the help of 3D hydrodynamic simulations. We compare the resulting X-ray emission with that produced from the injection of mass and energy from a central region. We find that the predicted X-ray image shows a filamentary structure that arises even in the absence of disc gas inhomogeneity. This structure stems from warm clumps made of disc material being lifted by the injected gas. We show that as much as half of the total X-ray emission comes from regions surrounding warm clumps that are made of a mix of disk and injected gas. This scenario has the potential to explain the origin of the observed extra-planar X-ray emission around star forming galaxies and can be used to understand the observed sublinear relation between the $L_X$ and SFR. We quantify the mass contained in these `bow-shock' regions. We also show that the top-most region of the outer shock above the central area emits harder X-rays than the rest. Further, we find that the mass distribution in different temperature ranges is bimodal, peaking at $10^4-10^5$ K (in warm clumps) and $10^6-10^7$ K (X-ray emitting gas). The mass loading factor is found to decrease with increasing SFR, consistent with previous theoretical estimates and simulations.

18 pages, 18 figures- Accepted in MNRAS. Comments and suggestions welcomed

References in corpus (6)

• PLUTO: a Numerical Code for Computational Astrophysics
• Cosmological Simulations of Intergalactic Medium Enrichment from Galactic Outflows
• Interactions of a Light Hypersonic Jet with a Non-Uniform Interstellar Medium
• Iron line and diffuse hard X-ray emission from the starburst galaxy M82
• Long way to go: how outflows from large galaxies propagate through the hot halo gas
• Suzaku X-ray Observations of the Fermi Bubbles: Northernmost Cap and Southeast Claw Discovered with MAXI-SSC

Cited by in corpus (18)

• The Physical Nature of Starburst-Driven Galactic Outflows
• The Structure of Multiphase Galactic Winds
• Growth and structure of multiphase gas in the cloud-crushing problem with cooling
• The Survival of Multiphase Dusty Clouds in Hot Winds
• Introducing CGOLS: The Cholla Galactic OutfLow Simulation Suite
• Kinematics and Dynamics of Multiphase Outflows in Simulations of the Star-Forming Galactic ISM
• A Graphical Interpretation of Circumgalactic Precipitation
• X-ray Spectra of Circumgalactic Medium Around Star-Forming Galaxies: Connecting Simulations to Observations
• Self-ionizing galactic winds
• Cooling flows around cold clouds in the circumgalactic medium: steady-state models & comparison with TNG50
• Launching of hot gas outflow by disc-wide supernova explosions
• Radio halos of star forming galaxies
• On the origin of the $10^7$ K hot emitting gas in the Circumgalactic medium of the Milky Way
• Fading in the Flow: Suppression of cold gas growth in expanding galactic outflows
• Radio Halo of NGC 4631: Comparing Observations and Simulations
• Plasma processes at the scales of galaxies and clusters of galaxies
• Quokka-based understanding of outflows (QED) -- II. X-ray metallicity gradients as a signature of galactic wind metal loading
• Modeling Multiphase Galactic Outflows: A Multifluid Moving Mesh Approach