Suppressed effective viscosity in the bulk intergalactic plasma

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216224%3A14310%2F19%3A00111553" target="_blank" >RIV/00216224:14310/19:00111553 - isvavai.cz</a>

Výsledek na webu

<a href="https://www.nature.com/articles/s41550-019-0794-z" target="_blank" >https://www.nature.com/articles/s41550-019-0794-z</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1038/s41550-019-0794-z" target="_blank" >10.1038/s41550-019-0794-z</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Suppressed effective viscosity in the bulk intergalactic plasma

Popis výsledku v původním jazyce

Transport properties, such as viscosity and thermal conduction, of the hot intergalactic plasma in clusters of galaxies are largely unknown. Whereas for laboratory plasmas these characteristics are derived from the gas density and temperature(1), such recipes can be fundamentally different for the intergalactic plasma(2) owing to a low rate of particle collisions and a weak magnetic field(3). In numerical simulations, these unknowns can often be avoided by modelling these plasmas as hydrodynamic fluids(4-6), even though local, non-hydrodynamic features observed in clusters contradict this assumptions(7-)(9). Using deep Chandra observations of the Coma Cluster(10,11), we probe gas fluctuations in intergalactic medium down to spatial scales where the transport processes should prominently manifest themselves-provided that hydrodynamic models(12) with pure Coulomb collision rates are indeed adequate. We do not find evidence of such transport processes, implying that the effective isotropic viscosity is orders of magnitude smaller than naively expected. This indicates either an enhanced collision rate in the plasma due to particle scattering off microfluctuations caused by plasma instabilities(2,13,24) or that the transport processes are anisotropic with respect to the local magnetic field(15). This also means that numerical models with high Reynolds number appear more consistent with observations. Our results demonstrate that observations of turbulence in clusters(16,17) are giving rise to a branch of astrophysics that can sharpen theoretical views on galactic plasmas.

Název v anglickém jazyce

Suppressed effective viscosity in the bulk intergalactic plasma

Popis výsledku anglicky

Transport properties, such as viscosity and thermal conduction, of the hot intergalactic plasma in clusters of galaxies are largely unknown. Whereas for laboratory plasmas these characteristics are derived from the gas density and temperature(1), such recipes can be fundamentally different for the intergalactic plasma(2) owing to a low rate of particle collisions and a weak magnetic field(3). In numerical simulations, these unknowns can often be avoided by modelling these plasmas as hydrodynamic fluids(4-6), even though local, non-hydrodynamic features observed in clusters contradict this assumptions(7-)(9). Using deep Chandra observations of the Coma Cluster(10,11), we probe gas fluctuations in intergalactic medium down to spatial scales where the transport processes should prominently manifest themselves-provided that hydrodynamic models(12) with pure Coulomb collision rates are indeed adequate. We do not find evidence of such transport processes, implying that the effective isotropic viscosity is orders of magnitude smaller than naively expected. This indicates either an enhanced collision rate in the plasma due to particle scattering off microfluctuations caused by plasma instabilities(2,13,24) or that the transport processes are anisotropic with respect to the local magnetic field(15). This also means that numerical models with high Reynolds number appear more consistent with observations. Our results demonstrate that observations of turbulence in clusters(16,17) are giving rise to a branch of astrophysics that can sharpen theoretical views on galactic plasmas.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10308 - Astronomy (including astrophysics,space science)

Projekt

—

Návaznosti

S - Specificky vyzkum na vysokych skolach<br>I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2019

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

NATURE ASTRONOMY

ISSN

2397-3366

e-ISSN

—

Svazek periodika

3

Číslo periodika v rámci svazku

9

Stát vydavatele periodika

GB - Spojené království Velké Británie a Severního Irska

Počet stran výsledku

6

Strana od-do

832-837

Kód UT WoS článku

000485096800014

EID výsledku v databázi Scopus

2-s2.0-85068085056