An X-ray study of the galactic-scale starburst-driven outflow in NGC 253

Abstract

X-ray properties of hot interstellar gas in a starburst galaxy NGC 253 were investigated to gain a further understanding of starburst-driven outflow activity by XMM-Newton and Suzaku. Spectroscopic analysis for three regions of the galaxy characterized by multiwavelength observations was conducted. The hot gas was represented by two thin thermal plasmas with temperatures of kT ~0.2 and ~0.6 keV. Abundance ratios i.e., O/Fe, Ne/Fe, Mg/Fe and Si/Fe, are consistent between three regions, which suggests the common origin of the hot gas. The abundance patterns are consistent with those of type II supernova ejecta, indicating that the starburst activity in the central region provides metals toward the halo through a galactic-scale starburst-driven outflow. The energetics also can support this indication on condition that 0.01-50 η^0.5 % of the total emission in the nuclear region has flowed to the halo region. To constrain the dynamics of hot interstellar gas, surface brightness and hardness ratio profiles which trace the density and temperature were extracted. Assuming a simple polytropic equation of state of gas, Tρ^(1-γ) = const, we constrained the physical condition. γ is consistent with 5/3 at the hot disk and T is constant (γ = 1) in the halo. It is suggested that the hot gas expands adiabatically from the central region towards the halo region while it moves as free expansion from the inner part of the halo towards the outer part of the halo as the outflow. We constrained the outflow velocity to be >100 km s^-1 from the observed temperature gradient in the halo. In comparison with the escape velocity of ~220 km s^-1 for NGC 253, it is indicated that the hot interstellar gas can escape from the gravitational potential of NGC 253 by combining the outflow velocity and the thermal velocity.

10 figures, accepted by PASJ

References in corpus (5)

• The ACS Nearby Galaxy Survey Treasury
• Probing the Dark Matter and Gas Fraction in Relaxed Galaxy Groups with X-ray observations from Chandra and XMM
• The Sub-parsec Scale Radio Properties of Southern Starburst Galaxies. I. Supernova Remnants, the Supernova Rate, and the Ionised Medium in the NGC 253 Starburst
• XMM-Newton observations of the diffuse X-ray emission in the starburst galaxy NGC 253
• High-resolution X-ray spectroscopy and imaging of the nuclear outflow of the starburst galaxy NGC 253

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• HIFI Spectroscopy of ${\mathrm{H}}_2\mathrm{O}$ submm Lines in Nuclei of Actively Star Forming Galaxies
• X-ray Properties of NGC 253's Starburst-Driven Outflow
• NuSTAR and Chandra Insight into the Nature of the 3-40 keV Nuclear Emission in NGC 253
• A study of X-ray emission of galaxies hosting molecular outflows (MOX sample)
• Revisiting the abundance pattern and charge-exchange emission in the M82 centre
• Disentangling the X-ray variability in the Lyman continuum emitter Haro 11
• Physical Conditions of the Ionized Superwind in NGC 253 with VLT/MUSE
• Exploring Hot Gas at Junctions of Galaxy Filaments with Suzaku
• The Nuclear Source of the Galactic Wind in NGC 253
• Outflows from starburst galaxies with various driving mechanisms and their X-ray properties