The Nature and Origin of Large Scale Diffuse X -Ray Emission in the Large Magellanic Cloud
Points, Sean Daniel
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https://hdl.handle.net/2142/85169
Description
Title
The Nature and Origin of Large Scale Diffuse X -Ray Emission in the Large Magellanic Cloud
Author(s)
Points, Sean Daniel
Issue Date
2001
Doctoral Committee Chair(s)
Chu, You-Hua
Department of Study
Astronomy
Discipline
Astronomy
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Physics, Astronomy and Astrophysics
Language
eng
Abstract
X-ray mosaics of the Large Magellanic Cloud (LMC) taken with the ROSAT Position Sensitive Proportional Counter (PSPC) have revealed extensive diffuse X-ray emission, indicative of hot ≳ 106 K gas associated with this irregular galaxy on scales from ∼10 pc to ≥1000 pc. Here we examine the nature and origin of the large scale diffuse X-ray emission from the LMC. We first examine the large scale spatial distribution and physical conditions of hot gas in the LMC. We find that although the large scale diffuse X-ray emission with the highest X-ray surface brightness is usually associated with supergiant shells in the LMC, the bulk of the large scale diffuse X-ray emission is associated with field gas. To better understand the production of ≳ 106 K gas in the LMC, we examine the physical structure of the multi-phase interstellar medium (ISM) of supergiant shells in the LMC using LMC2 as a detailed case study because it has the highest X-ray surface brightness of all supergiant shells in the LMC. Neither Halpha nor H I 21-cm line observations of LMC2 show an unambiguous signature of a coherent expanding shell. These data allow us to better interpret observations of supergiant shells in more distant (≥4 Mpc) galaxies. X-ray spectra show the plasma temperature of the hot gas interior to LMC2 to be kT ∼ 0.1--0.7 keV. The derived electron densities for the hot gas inside LMC2 is higher than the electron densities for other supergiant shells in the LMC, but are comparable to or lower than those of superbubbles and supernova remnants in the LMC. Finally, we have investigated the production of the ≳ 106 K gas by the underlying stellar population of LMC2. We find tentative evidence that the hot ≳ 106 K gas content of LMC2 can be produced by its underlying massive stellar population. This is the first time detailed observations of the multiphase ISM of a supergiant shell has been examined in conjuction with the resolved massive stellar population.
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