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25 April 2024 |
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Evidence for Non-Hydrostatic Gas Motions in the Hot ISM of Centaurus A | | R. P. Kraft
; M. J. Hardcastle
; G. R. Sivakoff
; A. Jordán
; P. E. J. Nulsen
; M. Birkinshaw
; W. R. Forman
; C. Jones
; D. M. Worrall
; J. H. Croston
; D. A. Evans
; S. Raychaudhury
; S. S. Murray
; N. J. Brassington
; J. L. Goodger
; W. E. Harris
; A. M. Juett
; C. L. Sarazin
; K. A. Woodley
; | | Date: |
25 Mar 2008 | | Abstract: | We present preliminary results from a deep (600 ks) {em Chandra} observation
of the hot interstellar medium of the nearby early-type galaxy Centaurus A (Cen
A). We find a surface brightness discontinuity in the gas $sim$3.5 kpc from
the nucleus spanning a 120$^circ$ arc. The temperature of the gas is
0.60$pm$0.05 and 0.68$pm$0.10 keV, interior and exterior to the
discontinuity, respectively. The elemental abundance is poorly constrained by
the spectral fits, but if the abundance is constant across the discontinuity,
there is a factor of 2.3$pm$0.4 pressure jump across the discontinuity. This
would imply that the gas is moving at 470$pm$100 km s$^{-1}$, or Mach
1.0$pm$0.2 (1.2$pm$0.2) relative to the sound speed of the gas external
(internal) to the discontinuity. Alternatively, pressure balance could be
maintained if there is a large (factor of $sim$7) discontinuity in the
elemental abundance. We suggest that the observed discontinuity is the result
of non-hydrostatic motion of the gas core (i.e. sloshing) due to the recent
merger. In this situation, both gas motions and abundance gradients are
important in the visibility of the discontinuity. Cen A is in the late stages
of merging with a small late-type galaxy, and a large discontinuity in density
and abundance across a short distance demonstrates that the gas of the two
galaxies remains poorly mixed even several hundred million years after the
merger. The pressure discontinuity may have had a profound influence on the
temporal evolution of the kpc-scale jet. The jet could have decollimated
crossing the discontinuity and thereby forming the northeast radio lobe. | | Source: | arXiv, 0803.3595 | | Services: | Forum | Review | PDF | Favorites | |
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