The Lx-M relation of clusters of galaxies

E. S. Rykoff, A. E. Evrard, T. A. McKay, M. R. Becker, D. E. Johnston, B. P. Koester, B. Nord, E. Rozo, E. S. Sheldon, R. Stanek, R. H. Wechsler

Research output: Contribution to journalLetterpeer-review

95 Scopus citations


We present a new measurement of the scaling relation between X-ray luminosity and total mass for 17 000 galaxy clusters in the maxBCG cluster sample. Stacking subsamples within fixed ranges of optical richness, N200, we measure the mean 0.1-2.4 keV X-ray luminosity, (Lx), from the ROSAT All-Sky Survey. The mean mass, (M200), is measured from weak gravitational lensing of SDSS background galaxies. For 9 ≤ N200 < 200, the data are well fitted by a power law, (Lx)/1042h-2ergs-1 = [12.6+1.4-1.3 (stat) ± 1.6(sys)](M200)/1014/h-1 M)1.65±0.13. The slope agrees to within 10 per cent with previous estimates based on X-ray selected catalogues, implying that the covariance in Lx and A/200 at a fixed halo mass is not large. The luminosity intercept is 30 per cent, or 2σ, lower than that determined from the X-ray flux-limited sample of Reiprich & Böhringer, assuming hydrostatic equilibrium. This slight difference could arise from a combination of Malmquist bias and/or systematic error in hydrostatic mass estimates, both of which are expected. The intercept agrees with that derived by Stanek et al. using a model for the statistical correspondence between clusters and haloes in a WMAP3 cosmology with power spectrum normalization σ8 = 0.85. Similar exercises applied to future data sets will allow constraints on the covariance among optical and hot gas properties of clusters at a fixed mass.

Original languageEnglish (US)
Pages (from-to)L28-L32
JournalMonthly Notices of the Royal Astronomical Society: Letters
Issue number1
StatePublished - Jun 2008


  • Galaxies: clusters: general
  • X-rays: galaxies: clusters

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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