NOAO > Observing Info > Approved Programs > 2012B-0230
|
NOAO > Observing Info > Approved Programs > 2012B-0230 |
|
PI: Alessandro Sonnenfeld, UC Santa Barbara, sonnen@physics.ucsb.edu
Address: Department of Physics, Broida Hall, Building 572, Santa Barbara, CA, 93106-9530, USA
CoI: Sherry Suyu, UC Santa Barbara
CoI: Geraint Lewis, University of Sydney
CoI: Vasily Belokurov, University of Cambridge
CoI: Matthew Auger, University of Cambridge
CoI: Yashar Hezaveh, McGill University
CoI: Brendon Brewer, UC Santa Barbara
CoI: Simona Vegetti, Massachusetts Institute of Technology (Astrophysics)
CoI: Nicholas Bate, University of Sydney
Title: Probing dark matter in the Cosmic Horseshoe
Abstract:
Numerical simulations predict dark matter halos to have steep inner density
profiles. While for massive elliptical galaxies this prediction is consistent
with observations, measurements in galaxy clusters revealed significantly
shallower inner dark matter slopes than predicted, setting a problem for the
standard cold dark matter paradigm. The shape of the dark matter distribution
depends both on the properties of dark matter itself and on the baryonic
physics that takes place during the formation and evolution of luminous
structures. New and better observations are needed, particularly at mass
scales intermediate between galaxies and clusters, to distinguish between the
wealth of possible models.
The gravitational lens system SDSSJ1148+1930 (the “cosmic horseshoe”) offers
a unique opportunity to measure the inner slope of a group-scale dark matter
halo. We recently discovered a radial arc in the system. The radial arc
provides strong constraints on the shape of the mass distribution of the lens
galaxy, once its redshift is known. Therefore, we request time to measure the
redshift of the object associated with the radial arc. This would provide the
first robust measurement of the inner slope of the dark matter halo of a
group-scale system, which can then be used as a benchmark for simulations.
National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360
|
NOAO > Observing Info > Approved Programs > 2012B-0230 |
|