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Medientyp:
E-Artikel
Titel:
Gas Perturbations in the Cool Cores of Galaxy Clusters: Effective Equation of State, Velocity Power Spectra, and Turbulent Heating
Beteiligte:
Zhuravleva, Irina;
Allen, Steven W.;
Mantz, Adam;
Werner, Norbert
Erschienen:
American Astronomical Society, 2018
Erschienen in:The Astrophysical Journal
Sprache:
Nicht zu entscheiden
DOI:
10.3847/1538-4357/aadae3
ISSN:
0004-637X;
1538-4357
Entstehung:
Anmerkungen:
Beschreibung:
<jats:title>Abstract</jats:title>
<jats:p>We present the statistical analysis of X-ray surface brightness and gas density fluctuations in the cool cores of 10 nearby, X-ray-bright galaxy clusters that have deep <jats:italic>Chandra</jats:italic> observations and show observational indications of radio-mechanical active galactic nucleus (AGN) feedback. Within the central parts of the cool cores, the total variance of fluctuations is dominated by isobaric and/or isothermal fluctuations on spatial scales ∼10–60 kpc, which are likely associated with slow gas motions and bubbles of relativistic plasma. Adiabatic fluctuations, associated with weak shocks and/or sonic turbulence, constitute less than 10% of the total variance in all clusters. The typical amplitude of density fluctuations is small, ∼10% or less on scales of ∼10–15 kpc. The observed subdominant contribution of adiabatic fluctuations and the small amplitude of density fluctuations support a model of gentle AGN feedback. The measured one-component velocities of gas motions are typically below 100–150 km s<jats:sup>−1</jats:sup> on scales <50 kpc and can be up to ∼300 km s<jats:sup>−1</jats:sup> on ∼100 kpc scales. The nonthermal energy is <12% of the thermal energy. Regardless of the source that drives these motions, the dissipation of the energy in such motions provides heat that is sufficient to balance radiative cooling on average, albeit with significant uncertainties. The results presented here support previous conclusions based on the analysis of the Virgo and Perseus Clusters and agree with the <jats:italic>Hitomi</jats:italic> measurements. With next-generation observatories like <jats:italic>Athena</jats:italic> and <jats:italic>Lynx</jats:italic>, these techniques will be yet more powerful.</jats:p>