dc.description.abstract | We present a study of the Coma cluster using ultraviolet (UV) imaging obtained using
the Ultraviolet Imaging Telescope. We discuss methods for measuring sizes and morphology
of galaxies in the UV. Several cluster galaxies in our sample exhibit small UV sizes relative
to their optical sizes, while we find that galaxies in a field sample have similar sizes in UV
and optical bands. Further, we have shown that when cluster and field galaxies are matched
up one-to-one based on colour and absolute i-band magnitude, the cluster galaxies tend
to have smaller UV sizes than their field counterparts. We have used an NUV − i colour
magnitude relation to identify a red sequence and blue cloud of galaxies in our sample.
There is a trend whereby redder disk galaxies exhibit even smaller UV sizes, relative to
field counterparts, than galaxies at the bluer end of the spectrum. Since this result is
consistent with environmentally driven gas stripping, we have identified from our sample
six known stripping candidates, and further identified one new candidate. Additionally,
we find that this sample of galaxies exhibits redder UV-optical colours in the outer regions
of the galaxy, a result consistent with an outside-in quenching mechanism affecting the
galaxy. Beyond the blue cloud, we find a substantial population of red disks/spirals in
our sample; as high as 38% of galaxies using an NUV − i = 4.0 cut to separate blue
and red galaxies. This result is highly dependent on the definition of the red sequence,
however. The existence of red spirals has been discussed in the literature as a possible
indication of starvation lowering the rates of star formation in previously blue spirals
while not disturbing the overall morphological structure of the galaxy. We have discussed
these results in context as potential indicators of various environmentally driven quenching
mechanisms underway in the Coma cluster, and discussed future surveys that will allow a
more robust quantification of the prevalence of these mechanisms. | en |