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Luminous and Dark Matter Profiles from Galaxies to Clusters: Bridging the Gap with Group-scale Lenses

Newman, Andrew B. and Ellis, Richard S. and Treu, Tommaso (2015) Luminous and Dark Matter Profiles from Galaxies to Clusters: Bridging the Gap with Group-scale Lenses. Astrophysical Journal, 814 (1). Art. No. 26. ISSN 0004-637X.

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Observations of strong gravitational lensing, stellar kinematics, and larger-scale tracers enable accurate measures of the distribution of dark matter (DM) and baryons in massive early-type galaxies (ETGs). While such techniques have been applied to galaxy-scale and cluster-scale lenses, the paucity of intermediate-mass systems with high-quality data has precluded a uniform analysis of mass-dependent trends. With the aim of bridging this gap, we present new observations and analyses of 10 group-scale lenses at 〈z 〉= 0.36 characterized by Einstein radii θ_(Ein) = 2".5 − 5".1 and a mean halo mass of M_(200) = 10^(14.0)M_⊙. For these groups, we find a mean halo concentration c_(200) = 5.0 ± 0.8 consistent with unmodified cold dark matter halos. By combining our data with other lens samples, we analyze the mass structure of ETGs in halos spanning the mass range 10^(13) M_⊙ − 10^(15)M_⊙ halos using homogeneous techniques. We show that the slope of the total density profile γtot within the effective radius depends on the stellar surface density, as demonstrated previously, but also on the halo mass. We analyze these trends using halo occupation models and resolved stellar kinematics with the goal of testing the universality of the DM profile. Whereas the central galaxies of clusters require a shallow inner DM density profile, group-scale lenses are consistent with a Navarro–Frenk–White profile or one that is slightly contracted. The largest uncertainties arise from the sample size and likely radial gradients in stellar populations. We conclude that the net effect of baryons on the DM distribution may not be universal, but more likely varies with halo mass due to underlying trends in star formation efficiency and assembly history.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Newman, Andrew B.0000-0001-7769-8660
Ellis, Richard S.0000-0001-7782-7071
Treu, Tommaso0000-0002-8460-0390
Additional Information:© 2015. The American Astronomical Society. Received 2015 March 17. Accepted 2015 October 5. Published 2015 November 13. The authors recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. T.T. acknowledges support by the Packard Foundation in the form of a Packard Fellowship. T.T. thanks the Observatory of Monteporzio Catone and the American Academy in Rome for their gracious hospitality during the writing of this manuscript.
Funding AgencyGrant Number
David and Lucile Packard FoundationUNSPECIFIED
Non-Subject Keywords:dark matter — galaxies: elliptical and lenticular, cD — gravitational lensing: strong
Issue or Number:1
Record Number:CaltechAUTHORS:20150323-161148630
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Official Citation:Andrew B. Newman et al 2015 ApJ 814 26
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:55995
Deposited By: Joy Painter
Deposited On:24 Mar 2015 16:16
Last Modified:03 Oct 2019 08:10

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