L. V. E. Koopmans

The initial mass function of early-type galaxies (2009)

Treu, T., Auger, M. W., Koopmans, L. V. E., Gavazzi, R., Marshall, P. J., Bolton, A. S.

We determine an absolute calibration of the initial mass function (IMF) of early-type galaxies, by studying a sample of 56 gravitational lenses identified by the SLACS Survey. Under the assumption of...

The Sloan Lens ACS Survey. IX. Colors, Lensing and Stellar Masses of Early-type Galaxies (2009)

Auger, M. W., Treu, T., Bolton, A. S., Gavazzi, R., Koopmans, L. V. E., Marshall, P. J., ...

We present the current photometric dataset for the Sloan Lens ACS (SLACS) Survey, including HST photometry from ACS, WFPC2, and NICMOS. These data have enabled the confirmation of an additional 15...

Dissecting the Gravitational Lens B1608+656. II. Precision Measurements of the Hubble Constant, Spatial Curvature, and the Dark Energy Equation of State (2009)

Suyu, S. H., Marshall, P. J., Auger, M. W., Hilbert, S., Blandford, R. D., Koopmans, L. V. E., ...

Strong gravitational lens systems with measured time delays between the multiple images provide a method for measuring the ``time-delay distance'' to the lens, and thus the Hubble constant. We...

Radio counterpart of the lensed sub-mm emission in the cluster MS0451.6-0305: new evidence for the merger scenario (2009)

Alba, A. Berciano, Koopmans, L. V. E., Garrett, M. A., Wucknitz, O., Limousin, M.

SMM J04542-0301 is an extended (~1 arcmin) sub-mm source located near the core of the cluster MS0451.6-0305. It has been suggested that part of its emission arises from the interaction between a LBG...

The mass distribution of a moderate redshift galaxy group and brightest group galaxy from gravitational lensing and kinematics (2009)

McKean, J. P., Auger, M. W., Koopmans, L. V. E., Vegetti, S., Czoske, O., Fassnacht, C. D., ...

The gravitational lens system CLASS B2108+213 has two radio-loud lensed images separated by 4.56 arcsec. The relatively large image separation implies that the lensing is caused by a group of...

Detection of a Dark Substructure through Gravitational Imaging (2009)

Vegetti, S., Koopmans, L. V. E., Bolton, A., Treu, T., Gavazzi, R.

We report the detection of a dark substructure through direct gravitational imaging - undetected in the HST-ACS F814W image - in the gravitational lens galaxy of SLACS SDSSJ0946+1006 (the "Double...

Galaxy Number Counts and Implications for Strong Lensing (2009)

Fassnacht, C. D., Koopmans, L. V. E., Wong, K. C.

We compare galaxy number counts in Advanced Camera for Surveys (ACS) fields containing moderate-redshift (0.2

The Structure & Dynamics of Massive Early-type Galaxies: On Homology, Isothermality and Isotropy inside one Effective Radius (2009)

Koopmans, L. V. E., Bolton, A., Treu, T., Czoske, O., Auger, M. W., Barnabe, M., ...

Based on 58 SLACS strong-lens early-type galaxies with direct total-mass and stellar-velocity dispersion measurements, we find that inside one effective radius massive elliptical galaxies with M_eff...

Foregrounds for observations of the cosmological 21 cm line: I. First Westerbork measurements of Galactic emission at 150 MHz in a low latitude field (2009)

Bernardi, G., De Bruyn, A. G., Brentjens, M. A., Ciardi, B., Harker, G., Jelic, V., ...

We present the first results from a series of observations conducted with the Westerbork telescope in the 140--160 MHz range with a 2 arcmin resolution aimed at characterizing the properties of the...

Statistics of mass substructure from strong gravitational lensing: quantifying the mass fraction and mass function (2009)

Vegetti, S., Koopmans, L. V. E.

A Bayesian statistical formalism is developed to quantify the level at which the mass function slope (alpha) and the projected cumulative mass fraction (f) of (CDM) substructure in strong...

Foregrounds for observations of the cosmological 21 cm line - I. First Westerbork measurements of galactic emission at 150 MHz in a low latitude field (2009)

Bernardi, G., De Bruyn, A. G., Brentjens, M. A., Ciardi, B., Harker, G., Jelic, V., ...