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The Origin of the Local 1/4-KeV X-Ray Flux in Both Charge Exhange and a Hot BubbleThe solar neighbourhood is the closest and most easily studied sample of the Galactic interstellar medium, an understanding of which is essential for models of star formation and galaxy evolution. Observations of an unexpectedly intense diffuse flux of easily absorbed 1/4-kiloelectronvolt X-rays coupled with the discovery that interstellar space within about a hundred parsecs of the Sun is almost completely devoid of cool absorbing gas, led to a picture of a 'local cavity' filled with X-ray-emitting hot gas, dubbed the local hot bubble. This model was recently challenged by suggestions that the emission could instead be readily produced within the Solar System by heavy solar-wind ions exchanging electrons with neutral H and He in interplanetary space, potentially removing the major piece of evidence for the local existence of million-degree gas within the Galactic disk. Here we report observations showing that the total solar wind charge-exchange contribution is approximately 40 percent of the 1/4-keV flux in the Galactic plane. The fact that the measured flux is not dominated by charge exchange supports the notion of a million-degree hot bubble extending about a hundred parsecs from the Sun.
Document ID
20150019916
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Galeazzi, M.
(Miami Univ. Miami, FL, United States)
Chiao, M.
(Maryland Univ. Baltimore County Baltimore, MD, United States)
Collier, M. R.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Cravens, T.
(Kansas Univ. Lawrence, KS, United States)
Koutroumpa, D.
(Universite de Versailles Saint-Quentin-en-Yvelines Versailles, France)
Kuntz, K. D.
(Johns Hopkins Univ. Baltimore, MD, United States)
Lallement, R.
(Observatoire de Paris-Meudon France)
Lepri, S. T.
(Michigan Univ. Ann Arbor, MI, United States)
McCammon, D.
(Wisconsin Univ. Madison, WI, United States)
Morgan, K.
(Wisconsin Univ. Madison, WI, United States)
Porter, F. S.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Robertson, I. P.
(Kansas Univ. Lawrence, KS, United States)
Snowden, S. L.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Thomas, N. E.
(Maryland Univ. Baltimore County Baltimore, MD, United States)
Uprety, Y.
(Miami Univ. Miami, FL, United States)
Ursino, E.
(Miami Univ. Miami, FL, United States)
Walsh, B. M.
(California Univ. Berkeley, CA, United States)
Date Acquired
October 29, 2015
Publication Date
July 27, 2014
Publication Information
Publication: Nature
Publisher: Macmillan Publishers Limited
Volume: 512
Issue: 7513
Subject Category
Solar Physics
Report/Patent Number
GSFC-E-DAA-TN24159
Funding Number(s)
CONTRACT_GRANT: NNG06EO90A
CONTRACT_GRANT: NNX14AB76A
Distribution Limits
Public
Copyright
Other
Keywords
Charge exhange and a hot bubble
The origin of the local 1/4-keV X-ray flux in both

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