Space Science Reviews

, Volume 177, Issue 1, pp 155–194

The Three-Dimensional Shapes of Galaxy Clusters

  • Marceau Limousin
  • Andrea Morandi
  • Mauro Sereno
  • Massimo Meneghetti
  • Stefano Ettori
  • Matthias Bartelmann
  • Tomas Verdugo
Article

DOI: 10.1007/s11214-013-9980-y

Cite this article as:
Limousin, M., Morandi, A., Sereno, M. et al. Space Sci Rev (2013) 177: 155. doi:10.1007/s11214-013-9980-y

Abstract

While clusters of galaxies are considered one of the most important cosmological probes, the standard spherical modelling of the dark matter and the intracluster medium is only a rough approximation. Indeed, it is well established both theoretically and observationally that galaxy clusters are much better approximated as triaxial objects. However, investigating the asphericity of galaxy clusters is still in its infancy. We review here this topic which is currently gathering a growing interest from the cluster community. We begin by introducing the triaxial geometry. Then we discuss the topic of deprojection and demonstrate the need for combining different probes of the cluster’s potential. We discuss the different works that have been addressing these issues. We present a general parametric framework intended to simultaneously fit complementary data sets (X-ray, Sunyaev Zel’dovich and lensing data). We discuss in details the case of Abell 1689 to show how different models/data sets lead to different haloe parameters. We present the results obtained from fitting a 3D NFW model to X-ray, SZ, and lensing data for 4 strong lensing clusters. We argue that a triaxial model generally allows to lower the inferred value of the concentration parameter compared to a spherical analysis. This may alleviate tensions regarding, e.g. the over-concentration problem. However, we stress that predictions from numerical simulations rely on a spherical analysis of triaxial halos. Given that triaxial analysis will have a growing importance in the observational side, we advocate the need for simulations to be analysed in the very same way, allowing reliable and meaningful comparisons. Besides, methods intended to derive the three dimensional shape of galaxy clusters should be extensively tested on simulated multi-wavelength observations.

Keywords

Cosmology Galaxy clusters Triaxiality Gravitational lensing X-Rays Sunyaev Zel’dovich 

Copyright information

© Springer Science+Business Media Dordrecht 2013

Authors and Affiliations

  • Marceau Limousin
    • 1
    • 2
  • Andrea Morandi
    • 3
  • Mauro Sereno
    • 4
    • 5
  • Massimo Meneghetti
    • 6
    • 7
  • Stefano Ettori
    • 6
    • 7
  • Matthias Bartelmann
    • 8
  • Tomas Verdugo
    • 9
  1. 1.LAM (Laboratoire d’Astrophysique de Marseille)Aix Marseille Université, CNRS, UMR 7326MarseilleFrance
  2. 2.Dark Cosmology Centre, Niels Bohr InstituteUniversity of CopenhagenCopenhagenDenmark
  3. 3.Raymond and Beverly Sackler School of Physics and AstronomyTel Aviv UniversityTel AvivIsrael
  4. 4.Dipartimento di FisicaPolitecnico di TorinoTorinoItaly
  5. 5.Sezione di TorinoINFNTorinoItaly
  6. 6.Osservatorio Astronomico di BolognaINAFBolognaItaly
  7. 7.Sezione di BolognaINFNBolognaItaly
  8. 8.Institut für Theoretische AstrophysikZentrum für AstronomieHeidelbergGermany
  9. 9.Centro de Investigaciones de Astronomía (CIDA)MéridaVenezuela

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