1,672 research outputs found
Quantum Chaos in the Yang-Mills-Higgs System at Finite Temperature
The quantum chaos in the finite-temperature Yang-Mills-Higgs system is
studied. The energy spectrum of a spatially homogeneous SU(2) Yang-Mills-Higgs
is calculated within thermofield dynamics. Level statistics of the spectra is
studied by plotting nearest-level spacing distribution histograms. It is found
that finite temperature effects lead to a strengthening of chaotic effects,
i.e. spectrum which has Poissonian distribution at zero temperature has
Gaussian distribution at finite-temperature.Comment: 6 pages, 5 figures, Revte
VLBI study of water maser emission in the Seyfert 2 galaxy NGC5793. I: Imaging blueshifted emission and the parsec-scale jet
We present the first result of VLBI observations of the blueshifted water
maser emission from the type 2 Seyfert galaxy NGC5793, which we combine with
new and previous VLBI observations of continuum emission at 1.7, 5.0, 8.4, 15,
and 22 GHz. Maser emission was detected earlier in single-dish observations and
found to have both red- and blueshifted features relative to the systemic
velocity. We could image only the blueshifted emission, which is located 3.6 pc
southwest of the 22 GHz continuum peak. The blueshifted emission was found to
originate in two clusters that are separated by 0.7 milliarcsecond (0.16 pc).
No compact continuum emission was found within 3.6 pc of the maser spot. A
compact continuum source showing a marginally inverted spectrum between 1.7 and
5.0 GHz was found 4.2 pc southwest of the maser position. The spectral turnover
might be due to synchrotron self-absorption caused by a shock in the jet owing
to collision with dense gas, or it might be due to free-free absorption in an
ionized screen possibly the inner part of a disk, foreground to the jet.
The water maser may be part of a maser disk. If so, it would be rotating in
the opposite sense to the highly inclined galactic disk observed in CO
emission. We estimate a binding mass within 1 pc of the presumed nucleus to be
on the order of 10^7 Msun. Alternatively, the maser emission could result from
the amplification of a radio jet by foreground circumnuclear molecular gas. In
this case, the high blueshift of the maser emission might mean that the masing
region is moving outward away from the molecular gas surrounding an active
nucleus.Comment: 20 pages, 6 figures, to appear in ApJ, Oct. 200
Arc-like distribution of high CO(J=3-2)/CO(J=1-0) ratio gas surrounding the central star cluster of the supergiant HII region NGC 604
We report the discovery of a high CO(J=3-2)/CO(J=1-0) ratio gas with an
arc-like distribution (``high-ratio gas arc'') surrounding the central star
cluster of the supergiant HII region NGC 604 in the nearby spiral galaxy M 33,
based on multi-J CO observations of a 5' 5' region of NGC 604
conducted using the ASTE 10-m and NRO 45-m telescopes. The discovered
``high-ratio gas arc'' extends to the south-east to north-west direction with a
size of 200 pc. The western part of the high-ratio gas arc closely
coincides well with the shells of the HII regions traced by H and radio
continuum peaks. The CO(J=3-2)/CO(J=1-0) ratio, R_{3-2/1-0}, ranges between 0.3
and 1.2 in the observed region, and the R_{3-2/1-0} values of the high-ratio
gas arc are around or higher than unity, indicating very warm (T_kin > 60 K)
and dense (n(H_2) > 10^{3-4} cm^{-3}) conditions of the high-ratio gas arc. We
suggest that the dense gas formation and second-generation star formation occur
in the surrounding gas compressed by the stellar wind and/or supernova of the
first-generation stars of NGC 604, i.e., the central star cluster of NGC 604.Comment: 4 pages, 4 figures. The Astrophysical Journal Letters, in pres
Formation of a Massive Black Hole at the Center of the Superbubble in M82
We performed 12CO(1-0), 13CO(1-0), and HCN(1-0) interferometric observations
of the central region (about 450 pc in radius) of M82 with the Nobeyama
Millimeter Array, and have successfully imaged a molecular superbubble and
spurs. The center of the superbubble is clearly shifted from the nucleus by 140
pc. This position is close to that of the massive black hole (BH) of >460 Mo
and the 2.2 micron secondary peak (a luminous supergiant dominated cluster),
which strongly suggests that these objects may be related to the formation of
the superbubble. Consideration of star formation in the cluster based on the
infrared data indicates that (1) energy release from supernovae can account for
the kinetic energy of the superbubble, (2) the total mass of stellar-mass BHs
available for building-up the massive BH may be much higher than 460 Mo, and
(3) it is possible to form the middle-mass BH of 100-1000 Mo within the
timescale of the superbubble. We suggest that the massive BH was produced and
is growing in the intense starburst region.Comment: 9 pages, 3 figures, to appear in ApJ Lette
Information-Geometric Indicators of Chaos in Gaussian Models on Statistical Manifolds of Negative Ricci Curvature
A new information-geometric approach to chaotic dynamics on curved
statistical manifolds based on Entropic Dynamics (ED) is proposed. It is shown
that the hyperbolicity of a non-maximally symmetric 6N-dimensional statistical
manifold M_{s} underlying an ED Gaussian model describing an arbitrary system
of 3N degrees of freedom leads to linear information-geometric entropy growth
and to exponential divergence of the Jacobi vector field intensity, quantum and
classical features of chaos respectively.Comment: 8 pages, final version accepted for publicatio
VLA Observations of H2O Masers in the Class 0 Protostar S106 FIR: Evidence for a 10 AU-Scale Accelerating Jet-like Flow
We conducted VLA observations at 0".06 resolution of the 22 GHz water masers
toward the Class 0 source S106 FIR (d=600 pc; 15" west of S106-IRS4) on two
epochs separated by ~3 months. Two compact clusters of the maser spots were
found in the center of the submillimeter core of S106 FIR. The separation of
the clusters was ~80 mas (48 AU) along P. A. = 70 degrees and the size of each
cluster was ~20 mas x 10 mas. The western cluster, which had three maser
components, was 7.0 km/s redshifted with respect to the ambient cloud velocity.
Each component was composed of a few spatially localized maser spots and was
aligned on a line connecting the clusters. We found relative proper motions of
the components with ~30 mas/yr (18 AU/yr) along the line. In addition, a series
of single-dish observations show that the maser components drifted with a
radial acceleration of ~1 km/s/yr.
These facts indicate that the masers could be excited by a 10 AU-scale
jet-like accelerating flow ejected from an assumed protostar located between
the two clusters. The outflow size traced by the masers was 50 AU x 5 AU after
correction for an inclination angle of 10 degrees which was derived from the
relative proper motions and radial velocities of the maser components. The
three-dimensional outflow velocity ranged from 40 to 70 km/s assuming symmetric
motions for the blue and red components. Since no distinct CO molecular
outflows have been detected so far, we suggest that S106 FIR is an extremely
young protostar observed just after the onset of outflowing activity.Comment: 24 pages, 6 figures, No. 5 color. Accepted, Astrophysical Journa
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