11 research outputs found
On the Spontaneous Identity of Chiral and Super Symmetry Breaking in Pure Super Yang Mills Theories
We show that in supersymmetric pure Yang Mills theories with arbitrary simple
gauge group, the spontaneous breaking of chiral fermionic and bosonic charge by
the associated gaugino and gauge boson condensates implies the spontaneous
breaking of supersymmetry by the condensate of the underlying Lagrangian
density. The explicit breaking of the restricted fermionic charge through the
chiral anomaly is deferred to a secondary stage in the elimination of infrared
singularities or long range forces.Comment: 14 pages, uses amsmath, amssymb, shorter version, references added,
eq. (44) correcte
The Tully-Fisher relation at intermediate redshift
Using the Very Large Telescope in Multi Object Spectroscopy mode, we have
observed a sample of 113 field spiral galaxies in the FORS Deep Field (FDF)
with redshifts in the range 0.1<z<1.0. The galaxies were selected upon apparent
brightness (R<23) and encompass all late spectrophotometric types from Sa to
Sdm/Im. Spatially resolved rotation curves have been extracted for 77 galaxies
and fitted with synthetic velocity fields taking into account all observational
effects from inclination and slit misalignment to seeing and slit width. We
also compared different shapes for the intrinsic rotation curve. To gain robust
values of V_max, our analysis is focussed on galaxies with rotation curves
which extend well into the region of constant rotation velocity at large radii.
If the slope of the local Tully-Fisher relation (TFR) is held fixed, we find
evidence for a mass-dependent luminosity evolution which is as large as up to 2
mag for the lowest-mass galaxies, but is small or even negligible for the
highest-mass systems in our sample. In effect, the TFR slope is shallower at
z~0.5 in comparison to the local sample. We argue for a mass-dependent
evolution of the mass-to-light ratio. An additional population of blue,
low-mass spirals does not seem a very appealing explanation. The flatter tilt
we find for the distant TFR is in contradiction to the predictions of recent
semi-analytic simulations.Comment: 18 pages, 14 figures, A&A, in press. Section on sample completeness
added. Please note that the entire analysis is based on undisturbed, high
quality rotation curves! Potential effects of tidal interactions are also
discusse
The iron abundance of the Magellanic Bridge
High-resolution HST ultra-violet spectra for five B-type stars in the
Magellanic Bridge and in the Large and Small Magellanic Clouds have been
analysed to estimate their iron abundances. Those for the Clouds are lower than
estimates obtained from late-type stars or the optical lines in B-type stars by
approximately 0.5 dex. This may be due to systematic errors possibly arising
from non-LTE effects or from errors in the atomic data as similar low Fe
abundances having previously been reported from the analysis of the
ultra-violet spectra of Galactic early-type stars. The iron abundance estimates
for all three Bridge targets appear to be significantly lower than those found
for the SMC and LMC by approximately -0.5 dex and -0.8 dex respectively and
these differential results should not be affected by any systematic errors
present in the absolute abundance estimates. These differential iron abundance
estimates are consistent with the underabundances for C, N, O, Mg and Si of
approximately -1.1 dex relative to our Galaxy previously found in our Bridge
targets. The implications of these very low metal abundances for the Magellanic
Bridge are discussed in terms of metal deficient material being stripped from
the SMC.Comment: Accepted for publication in MNRA