Cooling in the X-ray halo of the rotating, massive early-type galaxy NGC 7049
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 tcool/tff 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) Tat > 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.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- April 2019
- DOI:
- 10.1093/mnras/stz185
- arXiv:
- arXiv:1808.05761
- Bibcode:
- 2019MNRAS.484.2886J
- Keywords:
-
- galaxies: active;
- galaxies: elliptical and lenticular;
- cD;
- X-rays: galaxies;
- Astrophysics - Astrophysics of Galaxies;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- 11 pages, 12 figures, accepted for publication in MNRAS