The MASSIVE Survey IX: Photometric Analysis of 35 High Mass Early-Type
  Galaxies with HST WFC3/IR
  We present near-infrared observations of 35 of the most massive early-type
galaxies in the local universe. The observations were made using the infrared
channel of the Hubble Space Telescope Wide Field Camera 3 in the F110W (1.1
$\mu$m) filter. We measured surface brightness profiles and elliptical
isophotal fit parameters from the nuclear regions out to a radius of ~10 kpc in
most cases. We find that 37% (13) of the galaxies in our sample have isophotal
position angle rotations greater than 20 degrees over the radial range imaged
by WFC3/IR, which is often due to the presence of neighbors or multiple nuclei.
Most galaxies in our sample are significantly rounder near the center than in
the outer regions. This sample contains six fast rotators and 28 slow rotators.
We find that all fast rotators are either disky or show no measurable deviation
from purely elliptical isophotes. Among slow rotators, significantly disky and
boxy galaxies occur with nearly equal frequency. The galaxies in our sample
often exhibit changing isophotal shapes, sometimes showing both significantly
disky and boxy isophotes at different radii. The fact that parameters vary
widely between galaxies and within individual galaxies is evidence that these
massive galaxies have complicated formation histories, and some of them have
experienced recent mergers and have not fully relaxed. These data demonstrate
the value of high spatial resolution IR imaging of galaxies and provide
measurements necessary for determining stellar masses, dynamics, and black hole
masses in high mass galaxies.
