2,800 research outputs found
Infinite Volume and Continuum Limits of the Landau-Gauge Gluon Propagator
We extend a previous improved action study of the Landau gauge gluon
propagator, by using a variety of lattices with spacings from to
0.41 fm, to more fully explore finite volume and discretization effects. We
also extend a previously used technique for minimizing lattice artifacts, the
appropriate choice of momentum variable or ``kinematic correction'', by
considering it more generally as a ``tree-level correction''. We demonstrate
that by using tree-level correction, determined by the tree-level behavior of
the action being considered, it is possible to obtain scaling behavior over a
very wide range of momenta and lattice spacings. This makes it possible to
explore the infinite volume and continuum limits of the Landau-gauge gluon
propagator.Comment: 24 pages RevTex, 18 figures; Responses to referee comments, minor
change
The M81 Group Dwarf Irregular Galaxy DDO 165. II. Connecting Recent Star Formation with ISM Structures and Kinematics
We compare the stellar populations and complex neutral gas dynamics of the
M81 group dIrr galaxy DDO 165 using data from the HST and the VLA. Paper I
identified two kinematically distinct HI components, multiple localized high
velocity gas features, and eight HI holes and shells (the largest of which
spans ~2.2x1.1 kpc). Using the spatial and temporal information from the
stellar populations in DDO 165, we compare the patterns of star formation over
the past 500 Myr with the HI dynamics. We extract localized star formation
histories within 6 of the 8 HI holes identified in Paper I, as well as 23 other
regions that sample a range of stellar densities and neutral gas properties.
From population synthesis modeling, we derive the energy outputs (from stellar
winds and supernovae) of the stellar populations within these regions over the
last 100 Myr, and compare with refined estimates of the energies required to
create the HI holes. In all cases, we find that "feedback" is energetically
capable of creating the observed structures in the ISM. Numerous regions with
significant energy inputs from feedback lack coherent HI structures but show
prominent localized high velocity gas features; this feedback signature is a
natural product of temporally and spatially distributed star formation. In DDO
165, the extended period of heightened star formation activity (lasting more
than 1 Gyr) is energetically capable of creating the observed holes and high
velocity gas features in the neutral ISM.Comment: The Astrophysical Journal, in press. Full-resolution version
available on request from the first autho
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