Cooling in the X-ray halo of the rotating, massive early-type galaxy NGC 7049
Date Issued
2019
Author(s)
Juráňová, A.
•
Werner, N.
•
•
Lakhchaura, K.
•
Nulsen, P. E. J.
•
Sun, M.
•
Canning, R. E. A.
•
Allen, S. W.
•
Simionescu, A.
•
Oonk, J. B. R.
•
Connor, T.
•
Donahue, M.
Abstract
The relative importance of the physical processes shaping the thermodynamics of the hot gas permeating rotating, massive early-type galaxies is expected to be different from that in non-rotating systems. Here, we report the results of the analysis of XMM-Newton data for the massive, lenticular galaxy NGC 7049. The galaxy harbours a dusty disc of cool gas and is surrounded by an extended hot X-ray emitting gaseous atmosphere with unusually high central entropy. The hot gas in the plane of rotation of the cool dusty disc has a multitemperature structure, consistent with ongoing cooling. We conclude that the rotational support of the hot gas is likely capable of altering the multiphase condensation regardless of the t_cool/t_ff ratio, which is here relatively high, ∼40. However, the measured ratio of cooling time and eddy turnover time around unity (C-ratio ≈ 1) implies significant condensation, and at the same time, the constrained ratio of rotational velocity and the velocity dispersion (turbulent Taylor number) Ta_t > 1 indicates that the condensing gas should follow non-radial orbits forming a disc instead of filaments. This is in agreement with hydrodynamical simulations of massive rotating galaxies predicting a similarly extended multiphase disc.
Volume
484
Issue
2
Start page
2886
Issn Identifier
0035-8711
Ads BibCode
2019MNRAS.484.2886J
Rights
open.access
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