817 research outputs found
Importance of AcidâBase Equilibrium in Electrocatalytic Oxidation of Formic Acid on Platinum
This work was supported by Japanese Society for the Promotion of Science (JSPS) KAKENHI Grants Nos. 24550143 and 24750117 and MEXT Project of Integrated Research on Chemical Synthesis. M.T.M.K. gratefully acknowledges the award of Long-Term Fellowship of JSPS (No. L-11527) and Visiting Professorship of Hokkaido University. T.U. acknowledges Grants-in-Aid for Regional R&D Proposal-Based Program from Northern Advancement Center for Science & Technology of Hokkaido, Japan. J.J. acknowledges scholarship of Asian Graduate School, Hokkaido University.Peer reviewedPostprin
Decreased Specific Star Formation Rates in AGN Host Galaxies
We investigate the location of an ultra-hard X-ray selected sample of AGN
from the Swift Burst Alert Telescope (BAT) catalog with respect to the main
sequence (MS) of star-forming galaxies using Herschel-based measurements of the
star formation rate (SFR) and stellar mass (\mstar) from Sloan Digital Sky
Survey (SDSS) photometry where the AGN contribution has been carefully removed.
We construct the MS with galaxies from the Herschel Reference Survey and
Herschel Stripe 82 Survey using the exact same methods to measure the SFR and
\mstar{} as the Swift/BAT AGN. We find a large fraction of the Swift/BAT AGN
lie below the MS indicating decreased specific SFR (sSFR) compared to non-AGN
galaxies. The Swift/BAT AGN are then compared to a high-mass galaxy sample
(COLD GASS), where we find a similarity between the AGN in COLD GASS and the
Swift/BAT AGN. Both samples of AGN lie firmly between star-forming galaxies on
the MS and quiescent galaxies far below the MS. However, we find no
relationship between the X-ray luminosity and distance from the MS. While the
morphological distribution of the BAT AGN is more similar to star-forming
galaxies, the sSFR of each morphology is more similar to the COLD GASS AGN. The
merger fraction in the BAT AGN is much higher than the COLD GASS AGN and
star-forming galaxies and is related to distance from the MS. These results
support a model in which bright AGN tend to be in high mass star-forming
galaxies in the process of quenching which eventually starves the supermassive
black hole itself.Comment: 23 pages, 14 figures, Accepted for publication in MNRAS 2015 June 23.
In original form 2015 January 2
The Auxiliary Field Method in Quantum Mechanical Four-Fermi Models -- A Study Toward Chiral Condensation in QED
A study for checking validity of the auxiliary field method (AFM) is made in
quantum mechanical four-fermi models which act as a prototype of models for
chiral symmetry breaking in Quantum Electrodynamics. It has been shown that
AFM, defined by an insertion of Gaussian identity to path integral formulas and
by the loop expansion, becomes more accurate when taking higher order terms
into account under the bosonic model with a quartic coupling in 0- and
1-dimensions as well as the model with a four-fermi interaction in 0-dimension.
The case is also confirmed in terms of two models with the four-fermi
interaction among species in 1-dimension (the quantum mechanical four-fermi
models): higher order corrections lead us toward the exact energy of the ground
state. It is found that the second model belongs to a WKB-exact class that has
no higher order corrections other than the lowest correction. Discussions are
also made for unreliability on the continuous time representation of path
integration and for a new model of QED as a suitable probe for chiral symmetry
breaking.Comment: 30 pages, 12 figure
Strong-coupling Analysis of Parity Phase Structure in Staggered-Wilson Fermions
We study strong-coupling lattice QCD with staggered-Wilson fermions, with
emphasis on discrete symmetries and possibility of their spontaneous breaking.
We perform hopping parameter expansion and effective potential analyses in the
strong-coupling limit. From gap equations we find nonzero pion condensate in
some range of a mass parameter, which indicates existence of the parity-broken
phase in lattice QCD with staggered-Wilson fermions. We also find massless
pions and PCAC relations around second-order phase boundary. These results
suggest that we can take a chiral limit by tuning a mass parameter in lattice
QCD with staggered-Wilson fermions as with the Wilson fermion.Comment: 37 pages, 9 figure
QCD phase diagram with 2-flavor lattice fermion formulations
We propose a new framework for investigating two-flavor lattice QCD with
finite temperature and density. We consider the Karsten-Wilczek fermion
formulation, in which a species-dependent imaginary chemical potential term can
reduce the number of species to two without losing chiral symmetry. This
lattice discretization is useful for study on finite-(,) QCD since its
discrete symmetries are appropriate for the case. To show its applicability, we
study strong-coupling lattice QCD with temperature and chemical potential. We
derive the effective potential of the scalar meson field and obtain a critical
line of the chiral phase transition, which is qualitatively consistent with the
phenomenologically expected phase diagram. We also discuss that
renormalization of imaginary chemical potential can be controlled by adjusting
a parameter of a dimension-3 counterterm.Comment: 21 pages, 11 figure
Infalling Faint [OII] Emitters in Abell 851. I. Spectroscopic Confirmation of Narrowband-Selected Objects
We report on a spectroscopic confirmation of narrowband-selected [OII]
emitters in Abell 851 catalogued by Martin et al. (2000). The optical spectra
obtained from the Keck I Low Resolution Imaging Spectrometer (LRIS) and Keck II
Deep Imaging Multi-Object Spectrograph (DEIMOS) have confirmed [OII]3727
emission in narrowband-selected cluster [OII] candidates at a 85% success rate
for faint (i <~ 25) blue (g-i < 1) galaxies. The rate for the successful
detection of [OII] emission is a strong function of galaxy color, generally
proving the efficacy of narrowband [OII] search supplemented with broadband
colors in selecting faint cluster galaxies with recent star formation. Balmer
decrement-derived reddening measurements show a high degree of reddening
[E(B-V) >~ 0.5] in a significant fraction of this population. Even after
correcting for dust extinction, the [OII]/Ha line flux ratio for the
high-E(B-V) galaxies remains generally lower by a factor of ~2 than the mean
[OII]/Ha ratios reported by the studies of nearby galaxies. The strength of
[OII] equivalent width shows a negative trend with galaxy luminosity while the
Ha equivalent width does not appear to depend as strongly on luminosity. This
in part is due to the high amount of reddening observed in luminous galaxies.
Furthermore, emission line ratio diagnostics show that AGN-like galaxies are
abundant in the high luminosity end of the cluster [OII]-emitting sample, with
only moderately strong [OII] equivalent widths, consistent with a scenario of
galaxy evolution connecting AGNs and suppression of star-forming activity in
massive galaxies.Comment: 11 pages (LaTeX emulateapj), 8 figures, to appear in ApJ. A version
with high resolution figures available from the lead autho
Gravitational Waves from Sub-lunar Mass Primordial Black Hole Binaries - A New Probe of Extradimensions
In many braneworld models, gravity is largely modified at the electro-weak
scale ~ 1TeV. In such models, primordial black holes (PBHs) with lunar mass M ~
10^{-7}M_sun might have been produced when the temperature of the universe was
at ~ 1TeV. If a significant fraction of the dark halo of our galaxy consists of
these lunar mass PBHs, a huge number of BH binaries will exist in our
neighborhood. Third generation detectors such as EURO can detect gravitational
waves from these binaries, and can also determine their chirp mass. With a new
detector designed to be sensitive at high frequency bands greater than 1 kHz,
the existence of extradimensions could be confirmed.Comment: 4 pages, 1 figure, typos correcte
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