1,490 research outputs found
ROSAT PSPC observations of nearby spiral galaxies - II. Statistical properties
We present a statistical analysis of the largest X-ray survey of nearby
spiral galaxies in which diffuse emission has been separated from discrete
source contributions. Regression and rank-order correlation analyses are used
to compare X-ray properties such as total, source and diffuse luminosities, and
diffuse emission temperature, with a variety of physical and multi-wavelength
properties, such as galaxy mass, type and activity, and optical and infrared
luminosity. The results are discussed in terms of the way in which hot gas and
discrete X-ray sources scale with the mass and activity of galaxies, and with
the star formation rate. We find that the X-ray properties of starburst
galaxies are dependent primarily on their star-forming activity, whilst for
more quiescent galaxies, galaxy mass is the more important parameter. One of
the most intriguing results is the tight linear scaling between far-infrared
and diffuse X-ray luminosity across the sample, even though the hot gas changes
from a hydrostatic corona to a free wind across the activity range sampled
here.Comment: 13 pages, latex file, 18 postscript figures, to appear in MNRA
Spectral properties of the one-dimensional two-channel Kondo lattice model
We have studied the energy spectrum of a one-dimensional Kondo lattice, where
the localized magnetic moments have SU(N) symmetry and two channels of
conduction electrons are present. At half filling, the system is shown to exist
in two phases: one dominated by RKKY-exchange interaction effects, and the
other by Kondo screening. A quantum phase transition point separates these two
regimes at temperature . The Kondo-dominated phase is shown to possess
soft modes, with spectral gaps much smaller than the Kondo temperature.Comment: 4 pages + 2 figures. Submitted for publicatio
High-resolution UV spectrum of the benzeneâN2 van der Waals complex
The rotationally resolved spectrum of the 610 band of the S1 â S0 electronic transition of the benzeneâN2 van der Waals complex has been recorded and 119 transitions assigned. The C6H6·N2 complex, produced in a pulsed molecular beam, was detected by mass-selected two-photon two-colour ionization employing a high-resolution (ÎÎœUV = 100 MHz, fwhm) pulsed-amplified cw laser for the resonant intermediate excitation. The observed rotational structure is that of a rigid symmetric top with weaker additional rotational transitions most likely arising from the free internal rotation of the N2 in the plane parallel to the benzene ring. The N2 is located parallel to the benzene ring at a distance of 3.50 Ă
; this decreases by 45 mĂ
in the excited electronic state
The XMM-Newton Slew view of IGRJ17361-4441: a transient in the globular cluster NGC 6388
IGRJ17361-4441 is a hard transient recently observed by the INTEGRAL
satellite. The source, close to the center of gravity of the globular cluster
NGC 6388, quickly became the target of follow-up observations conducted by the
Chandra, Swift/XRT and RXTE observatories. Here, we concentrate in particular
on a set of observations conducted by the XMM-Newton satellite during two
slews, in order to get the spectral information of the source and search for
spectral variations. The spectral parameters determined by the recent
XMM-Newton slew observations were compared to the previously known results. The
maximum unabsorbed -ray flux in the 0.5-10 keV band as detected by the
XMM-Newton slew observations is erg cm
s, i.e. consistent with that observed by the Swift/XRT satellite 15 days
earlier. The spectrum seems to be marginally consistent () with that derived from the previous high energy observation.Comment: Accepted for publication on New Astronomy, 2012. A sentence about the
globular cluster 47 Tuc was partially rewritten to avoid confusio
Lusztig limit of quantum sl(2) at root of unity and fusion of (1,p) Virasoro logarithmic minimal models
We introduce a Kazhdan--Lusztig-dual quantum group for (1,p) Virasoro
logarithmic minimal models as the Lusztig limit of the quantum sl(2) at pth
root of unity and show that this limit is a Hopf algebra. We calculate tensor
products of irreducible and projective representations of the quantum group and
show that these tensor products coincide with the fusion of irreducible and
logarithmic modules in the (1,p) Virasoro logarithmic minimal models.Comment: 19 page
Bimodule structure in the periodic gl(1|1) spin chain
This paper is second in a series devoted to the study of periodic super-spin
chains. In our first paper at 2011, we have studied the symmetry algebra of the
periodic gl(1|1) spin chain. In technical terms, this spin chain is built out
of the alternating product of the gl(1|1) fundamental representation and its
dual. The local energy densities - the nearest neighbor Heisenberg-like
couplings - provide a representation of the Jones Temperley Lieb (JTL) algebra.
The symmetry algebra is then the centralizer of JTL, and turns out to be
smaller than for the open chain, since it is now only a subalgebra of U_q sl(2)
at q=i, dubbed U_q^{odd} sl(2). A crucial step in our associative algebraic
approach to bulk logarithmic conformal field theory (LCFT) is then the analysis
of the spin chain as a bimodule over U_q^{odd} sl(2) and JTL. While our
ultimate goal is to use this bimodule to deduce properties of the LCFT in the
continuum limit, its derivation is sufficiently involved to be the sole subject
of this paper. We describe representation theory of the centralizer and then
use it to find a decomposition of the periodic gl(1|1) spin chain over JTL for
any even number N of tensorands and ultimately a corresponding bimodule
structure. Applications of our results to the analysis of the bulk LCFT will
then be discussed in the third part of this series.Comment: latex, 42 pp., 13 figures + 5 figures in color, many comments adde
Design of linear block copolymers and ABC star terpolymers that produce two length scales at phase separation
The dataset contains the data for generating the figures in the paper. There are two models: a linear block copolymer (with three variants) and an ABC star terpolymer. For the linear chains, we give the height or heights of the maxima in the structure function, and the ratio of the wavenumbers where there are two maxima. For the ABC star model, we give csv files containing the (x,y) coordinates of the lines in figure 8, for each specified ratio of wavenumbers and N chi values
Analytical results for the Coqblin-Schrieffer model with generalized magnetic fields
Using the approach alternative to the traditional Thermodynamic Bethe Ansatz,
we derive analytical expressions for the free energy of Coqblin-Schrieffer
model with arbitrary magnetic and crystal fields. In Appendix we discuss two
concrete examples including the field generated crossover from the SU(4) to the
SU(2) symmetry in the SU(4)-symmetric model.Comment: 5 page
Andreev reflection at QGP/CFL interface
In this letter we address the question of the phenomena of Andreev reflection
between the cold quark-gluon plasma phase and CFL color superconductor. We show
that there are two different types of reflections connected to the structure of
the CFL phase. We also calculate the probability current at the interface and
we show that it vanishes for energy of scattering quarks below the
superconducting gap.Comment: 6 pages, 1 figure. Minor changes in the "Conclusions
Chiral Dynamics and Fermion Mass Generation in Three Dimensional Gauge Theory
We examine the possibility of fermion mass generation in 2+1- dimensional
gauge theory from the current algebra point of view.In our approach the
critical behavior is governed by the fluctuations of pions which are the
Goldstone bosons for chiral symmetry breaking. Our analysis supports the
existence of an upper critical number of Fermion flavors and exhibits the
explicit form of the gap equation as well as the form of the critical exponent
for the inverse correlation lenght of the order parameterComment: Latex,10 pages,DFUPG 70/9
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