524 research outputs found
The X-ray Fundamental Plane and Relation of Clusters of Galaxies
We analyze the relations among central gas density, core radius, and
temperature of X-ray clusters by plotting the observational data in the
three-dimensional (, , and ) space and find that
the data lie on a 'fundamental plane'. Its existence implies that the clusters
form a two-parameter family. The data on the plane still has a correlation and
form a band on the plane. The observed relation turns
out to be the cross section of the band perpendicular to the major axis, while
the major axis is found to describe the virial density. We discuss implications
of this two-parameter family nature of X-ray clusters.Comment: 7 pages, 2 figures. To be published in ApJ Letter
Orbital approach to microstate free entropy
Motivated by Voiculescu's liberation theory, we introduce the orbital free
entropy for non-commutative self-adjoint random variables (also for
"hyperfinite random multi-variables"). Besides its basic properties the
relation of with the usual free entropy is shown. Moreover,
the dimension counterpart of is discussed, and we
obtain the relation of with the original free entropy
dimension with applications to itself.Comment: 38 pages; Section 5 was largely improved and Section 6 was adde
The X-ray Jet in Centaurus A: Clues on the Jet Structure and Particle Acceleration
We report detailed studies of the X-ray emission from the kpc scale jet in
the nearest active galaxy, Cen A. 41 compact sources were found within the jet,
13 of which were newly identified. We construct the luminosity function for the
detected jet-knots and argue that the remaining emission is most likely to be
truly diffuse, rather than resulting from the pile-up of unresolved faint
knots. The transverse jet profile reveals that the extended emission has the
intensity peak at the jet boundaries. We note that limb-brightened jet
morphologies have been observed previously at radio frequencies in some jet
sources, but never so clearly at higher photon energies. Our result therefore
supports a stratified jet model, consisting of a relativistic outflow including
a boundary layer with a velocity shear. In addition, we found that the X-ray
spectrum of the diffuse component is almost uniform across and along the jet.
We discuss this spectral behavior within a framework of shock and stochastic
particle acceleration processes. We note some evidence for a possible spectral
hardening at the outer sheath of the jet. Due to the limited photon statistics
of the present data, further deep observations of Cen A are required to
determine the reality of this finding, however we note that the existence of
the hard X-ray features at outer jet boundaries would provide an important
challenge to theories for the evolution of ultra-relativistic particles within
the jets.Comment: 27page, 8 figures, ver2, accepted for publication in the Ap
IODP Advances in the Understanding of Subseafloor Life
The most recent decadal phase of scientific ocean drilling through the International Ocean Discovery Program (IODP) has resulted in paradigm-shifting understanding of life below the seafloor. Enabled by new drilling and coring approaches, cutting-edge methodologies, and novel observatory science, IODP expeditions have significantly advanced understanding of the amount and diversity of subseafloor life, the metabolic strategies that this life uses to survive under extreme energy limitation, and consequences of this life for the Earth system. Here, we summarize highlights from recent IODP expeditions focused on life beneath the seafloor and emphasize remaining major science challenges in investigating the form and function of life in this environment
Site-site memory equation approach in study of density/pressure dependence of translational diffusion coefficient and rotational relaxation time of polar molecular solutions: acetonitrile in water, methanol in water, and methanol in acetonitrile
We present results of theoretical study and numerical calculation of the
dynamics of molecular liquids based on combination of the memory equation
formalism and the reference interaction site model - RISM. Memory equations for
the site-site intermediate scattering functions are studied in the
mode-coupling approximation for the first order memory kernels, while
equilibrium properties such as site-site static structure factors are deduced
from RISM. The results include the temperature-density(pressure) dependence of
translational diffusion coefficients D and orientational relaxation times t for
acetonitrile in water, methanol in water and methanol in acetonitrile, all in
the limit of infinite dilution. Calculations are performed over the range of
temperatures and densities employing the SPC/E model for water and optimized
site-site potentials for acetonitrile and methanol. The theory is able to
reproduce qualitatively all main features of temperature and density
dependences of D and t observed in real and computer experiments. In
particular, anomalous behavior, i.e. the increase in mobility with density, is
observed for D and t of methanol in water, while acetonitrile in water and
methanol in acetonitrile do not show deviations from the ordinary behavior. The
variety exhibited by the different solute-solvent systems in the density
dependence of the mobility is interpreted in terms of the two competing origins
of friction, which interplay with each other as density increases: the
collisional and dielectric frictions which, respectively, increase and decrease
with increasing density.Comment: 13 pages, 8 eps-figures, 3 tables, RevTeX4-forma
Radiation Yield and Radicals Produced in Irradiated Poly (Butylene Succinate)
The main chemical effects of ionizing irradiation on polymers are crosslinking and chain scission. Both processes occur simultaneously and their yields determine the final results of processing. The radiation yield of crosslinking could be determined by several methods depending on the characteristics of the material and properties of the gel. Radiation parameters of gelation, such as gelation dose and ratio of scission yield to crosslinking yield, as well as their values were estimated. In this study, those parameters depend on the amount of Trimethallyl isocyanurate (TMAIC) in Poly(butylene succinate) (PBS), molecular weight of PBS, and irradiation condition. In the absence of TMAIC, higher molecular weight of PBS required less energy to start gelation process compare to lower molecular weight of PBS. While in the presence of TMAIC all of the PBS samples require similar energy to start gelation process. The existence of macroradicals were observed by Electron Spin Resonance measurements. The result showed that the spectra consisted of signals derived from radicals on carbon nearby carbonyl, and signals derived from radicals on carbon reside between two similar carbon on polymer, both of radicals lead to crosslinking
Lieb-Thirring Bound for Schr\"odinger Operators with Bernstein Functions of the Laplacian
A Lieb-Thirring bound for Schr\"odinger operators with Bernstein functions of
the Laplacian is shown by functional integration techniques. Several specific
cases are discussed in detail.Comment: We revised the first versio
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