686 research outputs found
On the geometry of Siegel-Jacobi domains
We study the holomorphic unitary representations of the Jacobi group based on
Siegel-Jacobi domains. Explicit polynomial orthonormal bases of the Fock spaces
based on the Siegel-Jacobi disk are obtained. The scalar holomorphic discrete
series of the Jacobi group for the Siegel-Jacobi disk is constructed and
polynomial orthonormal bases of the representation spaces are given.Comment: 15 pages, Latex, AMS fonts, paper presented at the the International
Conference "Differential Geometry and Dynamical Systems", August 25-28, 2010,
University Politehnica of Bucharest, Romani
The HI and Ionized Gas Disk of the Seyfert Galaxy NGC 1144 = Arp 118: A Violently Interacting Galaxy with Peculiar Kinematics
We present observations of the distribution and kinematics of neutral and
ionized gas in NGC 1144, a galaxy that forms part of the Arp 118 system.
Ionized gas is present over a huge spread in velocity (1100 km/s) in the disk
of NGC 1144, but HI emission is detected over only 1/3 of this velocity range,
in an area that corresponds to the NW half of the disk. In the nuclear region
of NGC 1144, a jump in velocity in the ionized gas component of 600 km/s is
observed. Faint, narrow HI absorption lines are also detected against radio
sources in the SE part of the disk of NGC 1144, which includes regions of
massive star formation and a Seyfert nucleus. The peculiar HI distribution,
which is concentrated in the NW disk, seems to be the inverse of the molecular
distribution which is concentrated in the SE disk. Although this may partly be
the result of the destruction of HI clouds in the SE disk, there is
circumstantial evidence that the entire HI emission spectrum of NGC 1144 is
affected by a deep nuclear absorption line covering a range of 600 km/s, and is
likely blueshifted with respect to the nucleus. In this picture, a high
column-density HI stream is associated with the nuclear ionized gas velocity
discontinuity, and the absorption effectively masks any HI emission that would
be present in the SE disk of NGC 1144.Comment: manuscript, arp118.ps: 28 pages; 1 Table: arp118.tab1.ps; 16 Figures:
arp118.fig1-16.ps; Accepted to Ap
IC 225: a dwarf elliptical galaxy with a peculiar blue core
We present the discovery of a peculiar blue core in the elliptical galaxy IC
225 by using images and spectrum from the Sloan Digital Sky Survey (SDSS). The
outer parts of the surface brightness profiles of u-, g-, r-, i- and z-band
SDSS images for IC 225 are well fitted with an exponential function. The
fitting results show that IC 225 follows the same relations between the
magnitude, scale length and central surface brightness for dwarf elliptical
galaxies. Its absolute blue magnitude (M_B) is -17.14 mag, all of which suggest
that IC 225 is a typical dwarf elliptical galaxy. The g-r color profile
indicates a very blue core with a radius of 2 arcseconds, which is also clearly
seen in the RGB image made of g-, r- and i-band SDSS images. The SDSS optical
spectrum exhibits strong and very narrow nebular emission lines. The metal
abundances derived by the standard methods, which are 12+log(O/H) = 8.98,
log(N/O) = -0.77 and 12+log(S+/H+) = 6.76, turn out to be significantly higher
than that predicted by the well-known luminosity-metallicity relation. After
carefully inspecting the central region of IC 225, we find that there are two
distinct nuclei, separated by 1.4 arcseconds, the off-nucleated one is even
bluer than the nucleus of IC 225. The asymmetric line profiles of higher-order
Balmer lines indicate that the emission lines are bluer shifted relative to the
absorption lines, suggesting that the line emission arises from the off-center
core, whose nature is a metal-rich Hii region. To the best of our knowledge, it
is the first high-metallicity Hii region detected in a dwarf elliptical galaxy.Comment: 7 figures, accepted for publication in A
Anomalous Metal-Insulator Transition in Filled Skutterudite CeOsSb
Anomalous metal-insulator transition observed in filled skutterudite
CeOsSb is investigated by constructing the effective tight-binding
model with the Coulomb repulsion between f electrons. By using the mean field
approximation, magnetic susceptibilities are calculated and the phase diagram
is obtained. When the band structure has a semimetallic character with small
electron and hole pockets at and H points, a spin density wave
transition with the ordering vector occurs due to the
nesting property of the Fermi surfaces. Magnetic field enhances this phase in
accord with the experiments.Comment: 4 pages, 4 figure
Electron correlation in FeSe superconductor studied by bulk-sensitive photoemission spectroscopy
We have investigated the electronic structures of recently discovered
superconductor FeSe by soft-x-ray and hard-x-ray photoemission spectroscopy
with high bulk sensitivity. The large Fe 3d spectral weight is located in the
vicinity of the Fermi level (EF), which is demonstrated to be a coherent
quasi-particle peak. Compared with the results of the band structure
calculation with local-density approximation, Fe 3d band narrowing and the
energy shift of the band toward EF are found, suggesting an importance of the
electron correlation effect in FeSe. The self energy correction provides the
larger mass enhancement value (Z^-1=3.6) than in Fe-As superconductors and
enables us to separate a incoherent part from the spectrum. These features are
quite consistent with the results of recent dynamical mean-field calculations,
in which the incoherent part is attributed to the lower Hubbard band.Comment: 8 pages, 5 figures, 1 talbl
Possible unconventional superconductivity in iron-based layered compound LaFePO: Study of heat capacity
Heat capacity measurements were performed on recently discovered iron based
layered superconductors, non doped LaFePO and fluorine doped LaFePO. A
relatively large electronic heat capacity coefficient and a small normalized
heat capacity jump at Tc = 3.3 K were observed in LaFePO. LaFePO0.94F0.06 had a
smaller electronic heat capacity coefficient and a larger normalized heat
capacity jump at Tc = 5.8 K. These values indicate that these compounds have
strong electron electron correlation and magnetic spin fluctuation, which are
the signatures of unconventional superconductivity mediated by spin
fluctuation.Comment: 15 Pages, 3 Figure
The Structure of Rapidly Rotating Late-Type Spiral Galaxies: I. Photometry, HI and Optical Kinematics
We present I-band photometry, long-slit optical spectroscopy, and new
aperture synthesis HI observations for eight late-type spirals with rotation
velocities in the range 243 km/s < V_{rot} < 308 km/s. The sample will be used
to study the structure and angular momentum of disks at the high-mass end of
the spiral galaxy population; here we discuss the basic properties of these
``fast rotators'', and derive hybrid optical/HI rotation curves for each.
Despite the presence of HI warps and low-mass companions in many systems, their
kinematics are regular and there is excellent agreement between optical and HI
tracers near the optical radius r_{opt}. At high inclinations at which
projection effects are negligible, the sample galaxies exhibit flat,
featureless rotation curves out to their last measured points at
1.7r_{opt}--3.5 r_{opt}. The intermediate inclination systems are also
consistent with a constant rotation amplitude for r > 0.5 r_{opt}. We therefore
find no evidence for declining rotation curves at the high-mass end of the
late-type spiral galaxy population. Combining our data with the compilation of
spirals with reliable outer HI kinematics from the work of Casertano & van
Gorkom, we find no convincing trends between logarithmic outer rotation curve
slopes and rotation amplitudes or surface brightnesses for galaxies with
V_{rot} > 220 km/s. Correlations between these slopes and morphological types
or disk scale lengths are also marginal in this regime.Comment: v2: minor changes to match proofs. 23 pages, 15 figures, AJ in press.
For version with high resolution figures, see
http://www.physics.rutgers.edu/~spekkens/papers/fast1.pd
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