Cluster morphologies and model-independent Y_SZ estimates from Bolocam
  Sunyaev-Zel'dovich images
  We present initial results from our ongoing program to image the
Sunyaev-Zel'dovich (SZ) effect in galaxy clusters at 143 GHz using Bolocam;
five clusters and one blank field are described in this manuscript. The images
have a resolution of 58 arcsec and a radius of 6-7 arcmin, which is
approximately r500 - 2r500 for these clusters. The beam-smoothed RMS is ~10
uK_CMB in these images; with this sensitivity we are able to detect SZ signal
to beyond r500 in binned radial profiles. We have fit our images to beta and
Nagai models, fixing spherical symmetry or allowing for ellipticity in the
plane of the sky, and we find that the best-fit parameter values are in general
consistent with those obtained from other X-ray and SZ data. Our data show no
clear preference for the Nagai model or the beta model due to the limited
spatial dynamic range of our images. However, our data show a definitive
preference for elliptical models over spherical models. The weighted mean
ellipticity of the five clusters is 0.27 +- 0.03, consistent with results from
X-ray data. Additionally, we obtain model-independent estimates of Y500, the
integrated SZ y-parameter over the cluster face to a radius of r500, with
systematics-dominated uncertainties of ~10%. Our Y500 values, which are free
from the biases associated with model-derived Y500 values, scale with cluster
mass in a way that is consistent with both self-similar predictions and
expectations of a 10% intrinsic scatter.
