Evidence for tidal stripping of dark matter halos in massive cluster-lenses

Priyamvada Natarajan; Jean-Paul Kneib; Ian Smail

doi:10.1086/345399

paper

Evidence for tidal stripping of dark matter halos in massive cluster-lenses

arXiv:astro-ph/0207049 · doi:10.1086/345399

Abstract

In this letter, we present the results of our study of galaxy-galaxy lensing in massive cluster-lenses spanning $z = 0.17$ to 0.58, utilizing high-quality archival {\it Hubble Space Telescope} ({\it HST}) data. Local anisotropies in the shear maps are assumed to arise from dark matter substructure within these clusters. Associating the substructure with bright early-type cluster galaxies, we quantify the properties of typical $L^{*}$ cluster members in a statistical fashion. The fraction of total mass associated with individual galaxies within the inner regions of these clusters ranges from 10--20% implying that the bulk of the dark matter in massive lensing clusters is smoothly distributed. Looking at the properties of the cluster galaxies, we find strong evidence ( $> 3$ - $σ$ significance) that a fiducial early-type $L^{*}$ galaxy in these clusters has a mass distribution that is tidally truncated compared to equivalent luminosity galaxies in the field. In fact, we exclude field galaxy scale dark halos for these cluster early-types at $> 10$ - $σ$ significance. We compare the tidal radii obtained from this lensing analysis with the central density of the cluster potentials and find a correlation which is in excellent agreement with theoretical expectations of tidal truncation: $lo g [r_{t} *] \propto (- 0.6 \pm 0.2) lo g [ρ_{0}]$ .

minor revisions, ApJ Letters in press, matches print version

Evidence for tidal stripping of dark matter halos in massive cluster-lenses

Abstract

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