331 research outputs found
Evidence for Intrinsic Redshifts in Normal Spiral Galaxies
The Tully-Fisher Relationship (TFR) is utilized to identify anomalous
redshifts in normal spiral galaxies. Three redshift anomalies are identified in
this analysis: (1) Several clusters of galaxies are examined in which late type
spirals have significant excess redshifts relative to early type spirals in the
same clusters, (2) Galaxies of morphology similar to ScI galaxies are found to
have a systematic excess redshift relative to the redshifts expected if the
Hubble Constant is 72 km s-1 Mpc-1, (3) individual galaxies, pairs, and groups
are identified which strongly deviate from the predictions of a smooth Hubble
flow. These redshift deviations are significantly larger than can be explained
by peculiar motions and TFR errors. It is concluded that the redshift anomalies
identified in this analysis are consistent with previous claims for large
non-cosmological (intrinsic) redshifts.Comment: Accepted for publication at Astrophysics&Space Science. 36 pages
including 8 tables and 7 figure
Piecing together the puzzle of NGC 5253: abundances, kinematics and WR stars
We present Gemini-S/GMOS-IFU optical spectroscopy of four regions near the
centre of the nearby (3.8 Mpc) dwarf starburst galaxy NGC 5253. This galaxy is
famous for hosting a radio supernebula containing two deeply embedded massive
super star clusters, surrounded by a region of enhanced nitrogen abundance that
has been linked to the presence of WR stars. We detected 11 distinct sources of
red WR bump (CIV) emission over a 20" (~350 pc) area, each consistent with the
presence of ~1 WCE-type star. WC stars are not found coincident with the
supernebula, although WN stars have previously been detected here. We performed
a multi-component decomposition of the H\alpha\ line across all four fields and
mapped the kinematics of the narrow and broad (FWHM = 100-250 km/s) components.
These maps paint a picture of localised gas flows, as part of multiple
overlapping bubbles and filaments driven by the star clusters throughout the
starburst. We confirm the presence of a strong H\alpha\ velocity gradient over
~4.5" (~80 pc) coincident with the region of N/O enhancement, and high gas
density known from previous study, and interpret this as an accelerating
ionized gas outflow from the supernebula clusters. We measure the ionized gas
abundances in a number of regions in the outer IFU positions and combine these
with measurements from the literature to assess the radial abundance
distribution. We find that the O/H and N/H profiles are consistent with being
flat. Only the central 50 pc exhibits the well-known N/O enhancement, and we
propose that the unusually high densities/pressures in the supernebula region
have acted to impede the escape of metal-enriched hot winds from the star
clusters and allow them to mix with the cooler phases, thus allowing these
freshly processed chemicals to be seen in the optical.Comment: 16 pages, accepted to A&
Intrinsic Redshifts and the Tully-Fisher Distance Scale
The Tully-Fisher relationship (TFR) has been shown to have a relatively small
observed scatter of ~ +/-0.35 mag implying an intrinsic scatter < +/-0.30 mag.
However, when the TFR is calibrated from distances derived from the Hubble
relation for field galaxies scatter is consistently found to be +/-0.64 to
+/-0.84 mag. This significantly larger scatter requires that intrinsic TFR
scatter is actually much larger than +/-0.30 mag, that field galaxies have an
intrinsic TFR scatter much larger than cluster spirals, or that field galaxies
have a velocity dispersion relative to the Hubble flow in excess of 1000 km
s-1. Each of these potential explanations faces difficulties contradicted by
available data and the results of previous studies. An alternative explanation
is that the measured redshifts of galaxies are composed of a cosmological
redshift component predicted from the value of the Hubble Constant and a
superimposed intrinsic redshift component previously identified in other
studies. This intrinsic redshift component may exceed 5000 km s-1 in individual
galaxies. In this alternative scenario a possible value for the Hubble Constant
is 55-60 km s-1 Mpc-1.Comment: 15 pages, Astrophysics&Space Science - Accepted for publicatio
The Ks-band Tully-Fisher Relation - A Determination of the Hubble Parameter from 218 ScI Galaxies and 16 Galaxy Clusters
The value of the Hubble Parameter (H0) is determined using the
morphologically type dependent Ks-band Tully-Fisher Relation (K-TFR). The slope
and zero point are determined using 36 calibrator galaxies with ScI morphology.
Calibration distances are adopted from direct Cepheid distances, and group or
companion distances derived with the Surface Brightness Fluctuation Method or
Type Ia Supernova. Distances are determined to 16 galaxy clusters and 218 ScI
galaxies with minimum distances of 40.0 Mpc. From the 16 galaxy clusters a
weighted mean Hubble Parameter of H0=84.2 +/-6 km s-1 Mpc-1 is found. From the
218 ScI galaxies a Hubble Parameter of H0=83.4 +/-8 km s-1 Mpc-1 is found. When
the zero point of the K-TFR is corrected to account for recent results that
find a Large Magellanic Cloud distance modulus of 18.39 +/-0.05 a Hubble
Parameter of 88.0 +/-6 km s-1 Mpc-1 is found. A comparison with the results of
the Hubble Key Project (Freedman et al 2001) is made and discrepancies between
the K-TFR distances and the HKP I-TFR distances are discussed. Implications for
Lamda-CDM cosmology are considered with H0=84 km s-1 Mpc-1. (Abridged)Comment: 37 pages including 12 tables and 7 figures. Final version accepted
for publication in the Journal of Astrophysics & Astronom
Beyond the standard seesaw: neutrino masses from Kahler operators and broken supersymmetry
We investigate supersymmetric scenarios in which neutrino masses are
generated by effective d=6 operators in the Kahler potential, rather than by
the standard d=5 superpotential operator. First, we discuss some general
features of such effective operators, also including SUSY-breaking insertions,
and compute the relevant renormalization group equations. Contributions to
neutrino masses arise at low energy both at the tree level and through finite
threshold corrections. In the second part we present simple explicit
realizations in which those Kahler operators arise by integrating out heavy
SU(2)_W triplets, as in the type II seesaw. Distinct scenarios emerge,
depending on the mechanism and the scale of SUSY-breaking mediation. In
particular, we propose an appealing and economical picture in which the heavy
seesaw mediators are also messengers of SUSY breaking. In this case, strong
correlations exist among neutrino parameters, sparticle and Higgs masses, as
well as lepton flavour violating processes. Hence, this scenario can be tested
at high-energy colliders, such as the LHC, and at lower energy experiments that
measure neutrino parameters or search for rare lepton decays.Comment: LaTeX, 34 pages; some corrections in Section
Advances in prevention and therapy of neonatal dairy calf diarrhoea : a systematical review with emphasis on colostrum management and fluid therapy
Neonatal calf diarrhoea remains the most common cause of morbidity and mortality in preweaned dairy calves worldwide. This complex disease can be triggered by both infectious and non-infectious causes. The four most important enteropathogens leading to neonatal dairy calf diarrhoea are Escherichia coli, rota-and coronavirus, and Cryptosporidium parvum. Besides treating diarrhoeic neonatal dairy calves, the veterinarian is the most obvious person to advise the dairy farmer on prevention and treatment of this disease. This review deals with prevention and treatment of neonatal dairy calf diarrhoea focusing on the importance of a good colostrum management and a correct fluid therapy
Belle II Technical Design Report
The Belle detector at the KEKB electron-positron collider has collected
almost 1 billion Y(4S) events in its decade of operation. Super-KEKB, an
upgrade of KEKB is under construction, to increase the luminosity by two orders
of magnitude during a three-year shutdown, with an ultimate goal of 8E35 /cm^2
/s luminosity. To exploit the increased luminosity, an upgrade of the Belle
detector has been proposed. A new international collaboration Belle-II, is
being formed. The Technical Design Report presents physics motivation, basic
methods of the accelerator upgrade, as well as key improvements of the
detector.Comment: Edited by: Z. Dole\v{z}al and S. Un
Search for squarks and gluinos in events with isolated leptons, jets and missing transverse momentum at s√=8 TeV with the ATLAS detector
The results of a search for supersymmetry in final states containing at least one isolated lepton (electron or muon), jets and large missing transverse momentum with the ATLAS detector at the Large Hadron Collider are reported. The search is based on proton-proton collision data at a centre-of-mass energy s√=8 TeV collected in 2012, corresponding to an integrated luminosity of 20 fb−1. No significant excess above the Standard Model expectation is observed. Limits are set on supersymmetric particle masses for various supersymmetric models. Depending on the model, the search excludes gluino masses up to 1.32 TeV and squark masses up to 840 GeV. Limits are also set on the parameters of a minimal universal extra dimension model, excluding a compactification radius of 1/R c = 950 GeV for a cut-off scale times radius (ΛR c) of approximately 30
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