5,786 research outputs found
Multi-wavelength properties of IGR J05007-7047 (LXP 38.55) and identification as a Be X-ray binary pulsar in the LMC
We report on the results of a 40 d multi-wavelength monitoring of the
Be X-ray binary system IGR J05007-7047 (LXP 38.55). During that period the
system was monitored in the X-rays using the Swift telescope and in the optical
with multiple instruments. When the X-ray luminosity exceeded erg/s
we triggered an XMM-Newton ToO observation. Timing analysis of the photon
events collected during the XMM-Newton observation reveals coherent X-ray
pulsations with a period of 38.551(3) s (1 {\sigma}), making it the 17
known high-mass X-ray binary pulsar in the LMC. During the outburst, the X-ray
spectrum is fitted best with a model composed of an absorbed power law () plus a high-temperature black-body (kT 2 keV) component. By
analysing 12 yr of available OGLE optical data we derived a 30.776(5) d
optical period, confirming the previously reported X-ray period of the system
as its orbital period. During our X-ray monitoring the system showed limited
optical variability while its IR flux varied in phase with the X-ray
luminosity, which implies the presence of a disk-like component adding cooler
light to the spectral energy distribution of the system.Comment: 11 pages, 11 figures, Accepted for publication in MNRA
Subtropical Real Root Finding
We describe a new incomplete but terminating method for real root finding for
large multivariate polynomials. We take an abstract view of the polynomial as
the set of exponent vectors associated with sign information on the
coefficients. Then we employ linear programming to heuristically find roots.
There is a specialized variant for roots with exclusively positive coordinates,
which is of considerable interest for applications in chemistry and systems
biology. An implementation of our method combining the computer algebra system
Reduce with the linear programming solver Gurobi has been successfully applied
to input data originating from established mathematical models used in these
areas. We have solved several hundred problems with up to more than 800000
monomials in up to 10 variables with degrees up to 12. Our method has failed
due to its incompleteness in less than 8 percent of the cases
On the Invariant Theory of Weingarten Surfaces in Euclidean Space
We prove that any strongly regular Weingarten surface in Euclidean space
carries locally geometric principal parameters. The basic theorem states that
any strongly regular Weingarten surface is determined up to a motion by its
structural functions and the normal curvature function satisfying a geometric
differential equation. We apply these results to the special Weingarten
surfaces: minimal surfaces, surfaces of constant mean curvature and surfaces of
constant Gauss curvature.Comment: 16 page
Analysis, Visualization, and Transformation of Audio Signals Using Dictionary-based Methods
date-added: 2014-01-07 09:15:58 +0000 date-modified: 2014-01-07 09:15:58 +0000date-added: 2014-01-07 09:15:58 +0000 date-modified: 2014-01-07 09:15:58 +000
Matching factors for Delta S=1 four-quark operators in RI/SMOM schemes
The non-perturbative renormalization of four-quark operators plays a
significant role in lattice studies of flavor physics. For this purpose, we
define regularization-independent symmetric momentum-subtraction (RI/SMOM)
schemes for Delta S=1 flavor-changing four-quark operators and provide one-loop
matching factors to the MS-bar scheme in naive dimensional regularization. The
mixing of two-quark operators is discussed in terms of two different classes of
schemes. We provide a compact expression for the finite one-loop amplitudes
which allows for a straightforward definition of further RI/SMOM schemes.Comment: 22 pages, 5 figure
Very extended cold gas, star formation and outflows in the halo of a bright QSO at z>6
Past observations of QSO host galaxies at z >6 have found cold gas and star
formation on compact scales of a few kiloparsecs. We present new high
sensitivity IRAM PdBI follow-up observations of the [CII] 158micron emission
line and FIR continuum in the host galaxy of SDSS J1148+5152, a luminous QSO at
redshift 6.4189. We find that a large fraction of the gas traced by [CII] is at
high velocities, up to ~1400 km/s relative to the systemic velocity, confirming
the presence of a major quasar-driven outflow indicated by previous
observations. The outflow has a complex morphology and reaches a maximum
projected radius of ~30 kpc. The extreme spatial extent of the outflow allows
us, for the first time in an external galaxy, to estimate mass-loss rate,
kinetic power and momentum rate of the outflow as a function of the projected
distance from the nucleus and the dynamical time-scale. These trends reveal
multiple outflow events during the past 100 Myr, although the bulk of the mass,
energy and momentum appear to have been released more recently, within the past
~20 Myr. Surprisingly, we discover that also the quiescent gas at systemic
velocity is extremely extended. More specifically, we find that, while 30% of
the [CII] within v\in(-200, 200) km/s traces a compact component that is not
resolved by our observations, 70% of the [CII] emission in this velocity range
is extended, with a projected FWHM size of 17.4+-1.4 kpc. We detect FIR
continuum emission associated with both the compact and the extended [CII]
components, although the extended FIR emission has a FWHM of 11+-3 kpc, thus
smaller than the extended [CII] source. Overall, our results indicate that the
cold gas traced by [CII] is distributed up to r~30 kpc. A large fraction of
extended [CII] is likely associated with star formation on large scales, but
the [CII] source extends well beyond the FIR continuum.Comment: Accepted for publication in A&A, 21 pages, 18 figures, 3 tables (v2:
accepted version, discussion expanded in Sect. 3, 4 and in the Appendices,
minor changes elsewhere
Study of the Distillability of Werner States Using Entanglement Witnesses and Robust Semidefinite Programs
We use Robust Semidefinite Programs and Entanglement Witnesses to study the
distillability of Werner states. We perform exact numerical calculations which
show 2-undistillability in a region of the state space which was previously
conjectured to be undistillable. We also introduce bases which yield
interesting expressions for the {\em distillability witnesses} and for a tensor
product of Werner states with arbitrary number of copies.Comment: 16 pages, 2 figure
Infrared Spectroscopy of the Diffuse Ionized Halo of NGC 891
We present infrared spectroscopy from the Spitzer Space Telescope at one disk
position and two positions at a height of 1 kpc from the disk in the edge-on
spiral NGC 891, with the primary goal of studying halo ionization. Our main
result is that the [Ne III]/[Ne II] ratio, which provides a measure of the
hardness of the ionizing spectrum free from the major problems plaguing optical
line ratios, is enhanced in the extraplanar pointings relative to the disk
pointing. Using a 2D Monte Carlo-based photo-ionization code which accounts for
the effects of radiation field hardening, we find that this trend cannot be
reproduced by any plausible photo-ionization model, and that a secondary source
of ionization must therefore operate in gaseous halos. We also present the
first spectroscopic detections of extraplanar PAH features in an external
normal galaxy. If they are in an exponential layer, very rough emission
scale-heights of 330-530 pc are implied for the various features. Extinction
may be non-negligible in the midplane and reduce these scale-heights
significantly. There is little significant variation in the relative emission
from the various features between disk and extraplanar environment. Only the
17.4 micron feature is significantly enhanced in the extraplanar gas compared
to the other features, possibly indicating a preference for larger PAHs in the
halo.Comment: 35 pages in ApJ preprint format, 8 figures, accepted for publication
in ApJ. Minor change to Introduction to give appropriate credit to earlier,
related wor
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