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Title: X-Ray Properties of NGC 253's Starburst-driven Outflow
Abstract

We analyze image and spectral data from ≈365 ks of observations from the Chandra X-ray Observatory of the nearby, edge-on starburst galaxy NGC 253 to constrain properties of the hot phase of the outflow. We focus our analysis on the −1.1 to +0.63 kpc region of the outflow and define several regions for spectral extraction where we determine best-fit temperatures and metal abundances. We find that the temperatures and electron densities peak in the central ∼250 pc region of the outflow and decrease with distance. These temperature and density profiles are in disagreement with an adiabatic spherically expanding starburst wind model and suggest the presence of additional physics such as mass loading and nonspherical outflow geometry. Our derived temperatures and densities yield cooling times in the nuclear region of a few million years, which may imply that the hot gas can undergo bulk radiative cooling as it escapes along the minor axis. Our metal abundances of O, Ne, Mg, Si, S, and Fe all peak in the central region and decrease with distance along the outflow, with the exception of Ne, which maintains a flat distribution. The metal abundances indicate significant dilution outside of the starburst region. We also find estimates of the mass outflow rates, which are 2.8Myr−1in the northern outflow and 3.2Myr−1in the southern outflow. Additionally, we detect emission from charge exchange and find it makes a significant contribution (20%–42%) to the total broadband (0.5–7 keV) X-ray emission in the central and southern regions of the outflow.

 
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Award ID(s):
2108140
NSF-PAR ID:
10470309
Author(s) / Creator(s):
; ; ; ; ; ; ;
Publisher / Repository:
The Astrophysical Journal
Date Published:
Journal Name:
The Astrophysical Journal
Volume:
942
Issue:
2
ISSN:
0004-637X
Page Range / eLocation ID:
108
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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