Journal Article Galactic Centre hypershell model for the North Polar Spurs

Sofue, Y.  ,  Habe, A.  ,  Kataoka, J.  ,  Totani, T.  ,  Inoue, Y.  ,  Nakashima, S.  ,  Matsui, H.  ,  Akita, M.

459 ( 1 )  , pp.108 - 120 , 2016-06-12 , Oxford University Press
The bipolar-hypershell (BHS) model for the North Polar Spurs (NPS-E, -W, and Loop I) and counter southern spurs (SPS-E and -W) is revisited based on numerical hydrodynamical simulations. Propagations of shock waves produced by energetic explosive events in the Galactic Centre are examined. Distributions of soft X-ray brightness on the sky at 0.25, 0.7, and 1.5 keV in the +/- 50 degrees x +/- 50 degrees region around the Galactic Centre are modelled by thermal emission from high-temperature plasma in the shock-compressed shell considering shadowing by the interstellar H I and H-2 gases. The result is compared with the ROSAT wide field X-ray images in R2, 4, and 6 bands. The NPS and southern spurs are well reproduced by the simulation as shadowed dumbbell-shaped shock waves. We discuss the origin and energetics of the event in relation to the starburst and/or active galactic nucleus activities in the Galactic Centre.

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