13,083 research outputs found
High Resolution BIMA Observations of CO, HCN, and 13CO in NGC 1068
We present high-resolution CO, HCN, and 13CO maps of the inner arcminute of
NGC 1068 made with the BIMA interferometer. Several features appear in the CO
map which have not previously been observed: (1) a firm detection of CO line
emission from a compact region centered on the nucleus of the galaxy; (2) the
detection of a triplet velocity structure characteristic of kinematically
independent regions shown on the spectrum of the unresolved nuclear emission ;
and (3) the detection of a molecular bar, the extent and position angle of
which are in good agreement with the 2 m stellar bar. The most intense CO
emission is nonnuclear; the structure and kinematics of this emission imply
that this gas is distributed along the inner spiral arms and not in a ring. The
bar's kinematic influence on the molecular gas in the spiral arms is modest,
with typical ordered noncircular motions of \la\ 30 \kms\ in the plane of the
galaxy. Interior to the spiral arms, the bar's influence is more dramatic, as
reflected by the twisted isovelocity contours in the CO and HCN velocity
fields. The surface density of molecular gas within the central 100 pc radius
of NGC 1068 is the same as that in the central 200 pc radius in the Milky Way
to within the uncertainties. There is evidence for an kinematic mode in
NGC 1068; we find the kinematic center of rotation to be displaced from the
radio continuum center by about 2.9", or 200 pc. The HCN image, in contrast to
the CO map, shows a strong concentration of emission centered on the nucleus.
The ratio of integrated intensities of the HCN emission to that of CO is about
0.6 and is the highest ratio measured in the central region of any galaxy.Comment: 35 pages of uuencoded, compressed postscript, 20 postscript figures
not included but available from [email protected] or from
ftp://astro.astro.umd.edu/pub/thelfer/n1068_figs.ps.Z To appear in The
Astrophysical Journal, V. 450, Sept. 199
Quaternionic eigenvalue problem
We discuss the (right) eigenvalue equation for , and
linear quaternionic operators. The possibility to introduce an
isomorphism between these operators and real/complex matrices allows to
translate the quaternionic problem into an {\em equivalent} real or complex
counterpart. Interesting applications are found in solving differential
equations within quaternionic formulations of quantum mechanics.Comment: 13 pages, AMS-Te
Quantum decoupling transition in a one-dimensional Feshbach-resonant superfluid
We study a one-dimensional gas of fermionic atoms interacting via an s-wave
molecular Feshbach resonance. At low energies the system is characterized by
two Josephson-coupled Luttinger liquids, corresponding to paired atomic and
molecular superfluids. We show that, in contrast to higher dimensions, the
system exhibits a quantum phase transition from a phase in which the two
superfluids are locked together to one in which, at low energies, quantum
fluctuations suppress the Feshbach resonance (Josephson) coupling, effectively
decoupling the molecular and atomic superfluids. Experimental signatures of
this quantum transition include the appearance of an out-of-phase gapless mode
(in addition to the standard gapless in-phase mode) in the spectrum of the
decoupled superfluid phase and a discontinuous change in the molecular momentum
distribution function.Comment: 4 RevTeX pages, 1 figure, submitted to PR
Dense Gas in the Milky Way
We present a study of dense gas emission in the Milky Way in order to serve
as a basis for comparison with extragalactic results. This study combines new
observations of HCN, CS, and CO in individual GMCs and in the Milky Way plane
with published studies of emission from these molecules in the inner 500 pc of
the Milky Way. We find a strong trend in the fraction of emission from dense
gas tracers as a function of location in the Milky Way: in the bulge,
I_{HCN}/I_{CO} = 0.081 \pm 0.004, in the plane, I_{HCN}/I_{CO} = 0.026 \pm
0.008 on average, and over the full extent of nearby GMCs, I_{HCN}/I_{CO} =
0.014 \pm 0.020. Similar trends are seen in I_{CS}/I_{CO}. The low intensities
of the HCN and CS emission in the plane suggests that these lines are produced
by gas at moderate densities; they are thus not like the emission produced by
the dense, pc-scale star forming cores in nearby GMCs. The contrast between the
bulge and disk ratios in the Milky Way is likely to be caused by a combination
of higher kinetic temperatures as well as a higher dense gas fraction in the
bulge of the Milky Way.Comment: 34 pages LaTeX, AASTEX macros, includes 11 postscript figures. To
appear in ApJ 478, March 199
The octonionic eigenvalue problem
By using a real matrix translation, we propose a coupled eigenvalue problem
for octonionic operators. In view of possible applications in quantum
mechanics, we also discuss the hermiticity of such operators. Previous
difficulties in formulating a consistent octonionic Hilbert space are solved by
using the new coupled eigenvalue problem and introducing an appropriate scalar
product for the probability amplitudes.Comment: 21 page
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