  What are the mass and galaxy profiles of cosmic voids? In this paper we use
two methods to extract voids in the Dark Energy Survey (DES) Year 1 redMaGiC
galaxy sample to address this question. We use either 2D slices in projection,
or the 3D distribution of galaxies based on photometric redshifts to identify
voids. For the mass profile, we measure the tangential shear profiles of
background galaxies to infer the excess surface mass density. The
signal-to-noise ratio for our lensing measurement ranges between 10.7 and 14.0
for the two void samples. We infer their 3D density profiles by fitting models
based on N-body simulations and find good agreement for void radii in the range
15-85 Mpc. Comparison with their galaxy profiles then allows us to test the
relation between mass and light at the 10%-level, the most stringent test to
date. We find very similar shapes for the two profiles, consistent with a
linear relationship between mass and light both within and outside the void
radius. We validate our analysis with the help of simulated mock catalogues and
estimate the impact of photometric redshift uncertainties on the measurement.
Our methodology can be used for cosmological applications, including tests of
gravity with voids. This is especially promising when the lensing profiles are
combined with spectroscopic measurements of void dynamics via redshift-space
distortions.
