Constraining the galaxy mass content in the core of A383 using velocity dispersion measurements for individual cluster members
We use velocity dispersion measurements of 21 individual cluster members in the core of Abell 383, obtained with Multiple Mirror Telescope Hectospec, to separate the galaxy and the smooth dark halo (DH) lensing contributions. While lensing usually constrains the overall, projected mass density, the innovative use of velocity dispersion measurements as a proxy for masses of individual cluster members breaks inherent degeneracies and allows us to (a) refine the constraints on single galaxy masses and on the galaxy mass-to-light scaling relation and, as a result, (b) refine the constraints on the DM-only map, a high-end goal of lens modelling. The knowledge of cluster member velocity dispersions improves the fit by 17 per cent in terms of the image reproduction χ^2, or 20 per cent in terms of the rms. The constraints on the mass parameters improve by ∼10 per cent for the DH, while for the galaxy component, they are refined correspondingly by ∼50 per cent, including the galaxy halo truncation radius. For an L^* galaxy with M^∗_B=−20.96, for example, we obtain best-fitting truncation radius r^∗_(tr)=20.5^(+9.6)_(−6.7) kpc and velocity dispersion σ_* = 324 ± 17 km s^(−1). Moreover, by performing the surface brightness reconstruction of the southern giant arc, we improve the constraints on r_(tr) of two nearby cluster members, which have measured velocity dispersions, by more than ∼30 per cent. We estimate the stripped mass for these two galaxies, getting results that are consistent with numerical simulations. In the future, we plan to apply this analysis to other galaxy clusters for which velocity dispersions of member galaxies are available.
© 2014 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2014 November 28. Received 2014 November 27; in original form 2014 October 29. First published online December 22, 2014. Thiswork is supported by the Transregional Collaborative Research Centre TRR 33 – The Dark Universe and the DFG cluster of excellence 'Origin and Structure of the Universe. The CLASH Multi-Cycle Treasury Program (GO-12065) is based on observations made with the NASA/ESA Hubble Space Telescope. The Space Telescope Science Institute is operated by the Association of Universities for Research in Astronomy, Inc. under NASA contract NAS 5-26555. The Dark Cosmology Centre is funded by the DNRF. Support for AZ is provided by NASA through Hubble Fellowship grant #HSTHF-51334.01-A awarded by STScI. The Smithsonian Institution supports the research of DGF, MJG, and HSH. We thank Daniel Gruen for his contribution to the improvement of the text.
Submitted - 1412.0023v1.pdf
Published - MNRAS-2015-Monna-1224-41.pdf