Title: Investigating early-type galaxy evolution with a multiwavelength approach. II. The UV structure of 11 galaxies with Swift-UVOT,
Abstract: GALEX detected a significant fraction of early-type galaxies showing Far-UV
bright structures. These features suggest the occurrence of recent star
formation episodes. We aim at understanding their evolutionary path[s] and the
mechanisms at the origin of their UV-bright structures. We investigate with a
multi-lambda approach 11 early-types selected because of their nearly passive
stage of evolution in the nuclear region. The paper, second of a series,
focuses on the comparison between UV features detected by Swift-UVOT, tracing
recent star formation, and the galaxy optical structure mapping older stellar
populations. We performed their UV surface photometry and used BVRI photometry
from other sources. Our integrated magnitudes have been analyzed and compared
with corresponding values in the literature. We characterize the overall galaxy
structure best fitting the UV and optical luminosity profiles using a single
Sersic law. NGC 1366, NGC 1426, NGC 3818, NGC 3962 and NGC 7192 show
featureless luminosity profiles. Excluding NGC 1366 which has a clear edge-on
disk , n~1-2, and NGC 3818, the remaining three have Sersic's indices n~3-4 in
optical and a lower index in the UV. Bright ring/arm-like structures are
revealed by UV images and luminosity profiles of NGC 1415, NGC 1533, NGC 1543,
NGC 2685, NGC 2974 and IC 2006. The ring/arm-like structures are different from
galaxy to galaxy. Sersic indices of UV profiles for those galaxies are in the
range n=1.5-3 both in S0s and in Es. In our sample optical Sersic indices are
usually larger than the UV ones. (M2-V) color profiles are bluer in
ring/arm-like structures with respect to the galaxy body. The lower values of
Sersic's indices in the UV bands with respect to optical ones, suggesting the
presence of a disk, point out that the role of the dissipation cannot be
neglected in recent evolutionary phases of these early-type galaxies.