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 temperature1, such recipes can be fundamentally different for the intergalactic plasma2 owing to a low rate of particle collisions and a weak magnetic field3. In numerical simulations, these unknowns can often be avoided by modelling these plasmas as hydrodynamic fluids4,5,6, even though local, non-hydrodynamic features observed in clusters contradict this assumption7,8,9. Using deep Chandra observations of the Coma Cluster10,11, we probe gas fluctuations in intergalactic medium down to spatial scales where the transport processes should prominently manifest themselves—provided that hydrodynamic models12 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 instabilities2,13,14 or that the transport processes are anisotropic with respect to the local magnetic field15. This also means that numerical models with high Reynolds number appear more consistent with observations. Our results demonstrate that observations of turbulence in clusters16,17 are giving rise to a branch of astrophysics that can sharpen theoretical views on galactic plasmas.
This is a preview of subscription content, access via your institution
Subscribe to Nature+
Get immediate online access to Nature and 55 other Nature journal
Subscribe to Journal
Get full journal access for 1 year
only $9.92 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Tax calculation will be finalised during checkout.
Get time limited or full article access on ReadCube.
All prices are NET prices.
The observational data analysed in this study are available in NASA’s HEASARC repository (https://heasarc.gsfc.nasa.gov). The analysed and plotted data of this study are available from the corresponding author upon reasonable request.
Spitzer, L. & Härm, R. Transport phenomena in a completely ionized gas. Phys. Rev. 89, 977–981 (1953).
Schekochihin, A. A. & Cowley, S. C. Turbulence, magnetic fields and plasma physics in clusters of galaxies. Phys. Plasmas 13, 056501 (2006).
Schekochihin, A. A., Cowley, S. C., Rincon, F. & Rosin, M. S. Magnetofluid dynamics of magnetized cosmic plasma: firehose and gyrothermal instabilities. Mon. Not. R. Astron. Soc. 405, 291–300 (2010).
Bryan, G. L. & Norman, M. L. Statistical properties of X-ray clusters: analytic and numerical comparisons. Astrophys. J. 495, 80–99 (1998).
Kravtsov, A. V., Klypin, A. & Hoffman, Y. Constrained simulations of the real universe. II. Observational signatures of intergalactic gas in the local supercluster region. Astrophys. J. 571, 563–575 (2002).
Dolag, K., Vazza, F., Brunetti, G. & Tormen, G. Turbulent gas motions in galaxy cluster simulations: the role of smoothed particle hydrodynamics viscosity. Mon. Not. R. Astron. Soc. 364, 753–772 (2005).
Markevitch, M. & Vikhlinin, A. Shocks and cold fronts in galaxy clusters. Phys. Rep. 443, 1–53 (2007).
Fabian, A. C., Johnstone, R. M. & Sanders, J. S. Magnetic support of the optical emission line filaments in NGC 1275. Nature 454, 968–970 (2008).
Roediger, E. et al. Stripped elliptical galaxies as probes of ICM physics. I. Tails, wakes, and flow patterns in and around stripped ellipticals. Astrophys. J. 806, 103–121 (2015).
Churazov, E. et al. X-ray surface brightness and gas density fluctuations in the Coma cluster. Mon. Not. R. Astron. Soc. 421, 1123–1135 (2012).
Sanders, J. S. et al. Linear structures in the core of the Coma cluster of galaxies. Science 341, 1365–1368 (2013).
Ishihara, T., Morishita, K., Yokokawa, M., Uno, A. & Kaneda, Y. Energy spectrum in high-resolution direct numerical simulations of turbulence. Phys. Rev. Fluids 1, 082403 (2016).
Melville, S., Schekochihin, A. A. & Kunz, M. W. Pressure-anisotropy-driven microturbulence and magnetic-field evolution in shearing, collisionless plasma. Mon. Not. R. Astron. Soc. 459, 2701–2720 (2016).
Kunz, M. W., Schekochihin, A. A. & Stone, J. M. Firehose and mirror instabilities in a collisionless shearing plasma. Phys. Rev. Lett. 112, 205003 (2014).
Squire, J., Schekochihin, A. A., Quataert, E. & Kunz, M. W. Magneto-immutable turbulence in weakly collisional plasmas. J. Plasma Phys. 85, 905850114 (2019).
Zhuravleva, I. et al. Turbulent heating in galaxy clusters brightest in X-rays. Nature 515, 85–87 (2014).
Hitomi Collaboration. The quiescent intracluster medium in the core of the Perseus cluster. Nature 535, 117–121 (2016).
Vikhlinin, A., Forman, W. & Jones, C. Another collision for the Coma cluster. Astrophys. J. 474, L4–L10 (1997).
Schuecker, P., Finoguenov, A., Miniati, F., Böhringer, H. & Briel, U. G. Probing turbulence in the Coma galaxy cluster. Astron. Astrophys. 426, 387–397 (2004).
Bonafede, A. et al. The Coma cluster magnetic field from Faraday rotation measures. Astron. Astrophys. 513, A30 (2010).
Arévalo, P., Churazov, E., Zhuravleva, I., Hernández-Monteagudo, C. & Revnivtsev, M. A Mexican hat with holes: calculating low-resolution power spectra from data with gaps. Mon. Not. R. Astron. Soc. 426, 1793–1807 (2012).
Zhuravleva, I. et al. The relation between gas density and velocity power spectra in galaxy clusters: qualitative treatment and cosmological simulations. Astrophys. J. 788, L13–L18 (2014).
Gaspari, M. & Churazov, E. Constraining turbulence and conduction in the hot ICM through density perturbations. Astron. Astrophys. 559, A78–A96 (2013).
Gauding, M., Wick, A., Pitsch, H. & Peters, N. Generalized scale-by-scale energy-budget equations and large-eddy simulations of anisotropic scalar turbulence at various Schmidt numbers. J. Turbul. 15, 857–882 (2014).
Sarazin, C. L X-ray Emissions from Clusters of Galaxies (Cambridge Astrophysics Series, Cambridge Univ. Press, 1988).
Zhuravleva, I., Allen, S. W., Mantz, A. & Werner, N. Gas perturbations in the cool cores of galaxy clusters: effective equation of state, velocity power spectra, and turbulent heating. Astrophys. J. 865, 53–68 (2018).
Riquelme, M. A., Quataert, E. & Verscharen, D. PIC simulations of the effect of velocity space instabilities on electron viscosity and thermal conduction. Astrophys. J. 824, 123–134 (2016).
Komarov, S., Schekochihin, A. A., Churazov, E. & Spitkovsky, A. Self-inhibiting thermal conduction in a high-β, whistler-unstable plasma. J. Plasma Phys. 84, 905840305 (2018).
Braginskii, S. I. Transport processes in a plasma. Rev. Plasma Phys. 1, 205 (1965).
Vikhlinin, A., Forman, W. & Jones, C. Mass concentrations associated with extended X-ray sources in the core of the Coma cluster. Astrophys. J. 435, 162–170 (1994).
Batchelor, G. K. Small-scale variation of convected quantities like temperature in turbulent fluid. Part 1. General discussion and the case of small conductivity. J. Fluid Mech. 5, 113–133 (1959).
Finoguenov, A. et al. The X-ray luminosity function of galaxies in the Coma cluster. Astron. Astrophys. 419, 47–61 (2004).
Yagi, M., Koda, J., Komiyama, Y. & Yamanoi, H. Catalog of ultra-diffuse galaxies in the Coma clusters from Subaru imaging data. Astrophys. J. Suppl. Ser. 225, 11–34 (2016).
Vikhlinin, A., Markevitch, M., Forman, W. & Jones, C. Zooming in on the Coma cluster with Chandra: compressed warm gas in the brightest cluster galaxies. Astrophys. J. 555, L87–L90 (2001).
Planck Collaboration. Planck intermediate results. X. Physics of the hot gas in the Coma cluster. Astron. Astrophys. 554, 1–19 (2013).
Zhuravleva, I. et al. Gas density fluctuations in the Perseus cluster: clumping factor and velocity power spectrum. Mon. Not. R. Astron. Soc. 450, 4184–4197 (2015).
Support for this work was provided by NASA through Chandra Award Number GO6-17123×, issued by the Chandra X-ray Observatory Center, which is operated by the Smithsonian Astrophysical Observatory for and on behalf of NASA under contract NAS8-03060. E.C. acknowledges partial support by the Russian Science Foundation grant 19-12-00369. A.A.S. acknowledges partial support by grants from UK STFC and EPSRC and by the Simons Foundation via a Visiting Professorship at NBIA. N.W. is supported by the Lendület LP2016-11 grant awarded by the Hungarian Academy of Sciences.
The authors declare no competing interests.
Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
About this article
Cite this article
Zhuravleva, I., Churazov, E., Schekochihin, A.A. et al. Suppressed effective viscosity in the bulk intergalactic plasma. Nat Astron 3, 832–837 (2019). https://doi.org/10.1038/s41550-019-0794-z
This article is cited by
Nature Astronomy (2020)
Nature Astronomy (2019)