X-ray coronae in simulations of disc galaxy formation

被引:131
作者
Crain, Robert A. [1 ]
McCarthy, Ian G. [2 ]
Frenk, Carlos S. [3 ]
Theuns, Tom [3 ,4 ]
Schaye, Joop [5 ]
机构
[1] Swinburne Univ Technol, Ctr Astrophys & Supercomp, Hawthorn, Vic 3122, Australia
[2] Univ Cambridge, Kavli Inst Cosmol, Cambridge CB3 0HA, England
[3] Univ Durham, Inst Computat Cosmol, Dept Phys, Durham DH1 3LE, England
[4] Univ Antwerp, Dept Phys, B-2020 Antwerp, Belgium
[5] Leiden Univ, Leiden Observ, NL-2300 RA Leiden, Netherlands
基金
澳大利亚研究理事会;
关键词
methods: numerical; galaxies: formation; galaxies: haloes; X-rays: galaxies; HIGH-VELOCITY CLOUDS; SMOOTHED PARTICLE HYDRODYNAMICS; ROSAT PSPC OBSERVATIONS; HOT GAS HALOS; DARK-MATTER; STAR-FORMATION; COSMOLOGICAL SIMULATIONS; SPECTRAL PROPERTIES; STELLAR POPULATION; NEUTRAL HYDROGEN;
D O I
10.1111/j.1365-2966.2010.16985.x
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
The existence of X-ray luminous gaseous coronae around massive disc galaxies is a long-standing prediction of galaxy formation theory in the cold dark matter cosmogony. This prediction has garnered little observational support, with non-detections commonplace and detections for only a relatively small number of galaxies which are much less luminous than expected. We investigate the coronal properties of a large sample of bright, disc-dominated galaxies extracted from the GIMIC suite of cosmological hydrodynamic simulations recently presented by Crain et al. Remarkably, the simulations reproduce the observed scalings of X-ray luminosity with K-band luminosity and star formation rate (SFR) and, when account is taken of the density structure of the halo, with disc rotation velocity as well. Most of the star formation in the simulated galaxies (which have realistic stellar mass fractions) is fuelled by gas cooling from a quasi-hydrostatic hot corona. However, these coronae are more diffuse, and of a lower luminosity, than predicted by the analytic models of White & Frenk because of a substantial increase in entropy at z similar to 1-3. Both the removal of low entropy gas by star formation and energy injection from supernovae contribute to this increase in entropy, but the latter is dominant for halo masses M-200 less than or similar to 10(12.5) M-circle dot. Only a small fraction of the mass of the hot gas is outflowing as a wind but, because of its high density and metallicity, it contributes disproportionally to the X-ray emission. The bulk of the X-ray emission, however, comes from the diffuse quasi-hydrostatic corona which supplies the fuel for ongoing star formation in discs today. Future deep X-ray observations with high spectral resolution (e. g. with NeXT/ASTRO-H or IXO) should be able to map the velocity structure of the hot gas and test this fundamental prediction of current galaxy formation theory.
引用
收藏
页码:1403 / 1422
页数:20
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