17,936 research outputs found
Role of low- component in deformed wave functions near the continuum threshold
The structure of deformed single-particle wave functions in the vicinity of
zero energy limit is studied using a schematic model with a quadrupole deformed
finite square-well potential. For this purpose, we expand the single-particle
wave functions in multipoles and seek for the bound state and the Gamow
resonance solutions. We find that, for the states, where is
the -component of the orbital angular momentum, the probability of each
multipole components in the deformed wave function is connected between the
negative energy and the positive energy regions asymptotically, although it has
a discontinuity around the threshold. This implies that the
resonant level exists physically unless the component is inherently large
when extrapolated to the well bound region. The dependence of the multipole
components on deformation is also discussed
Relativistic Compact Objects in Isotropic Coordinates
We present a matrix method for obtaining new classes of exact solutions for
Einstein's equations representing static perfect fluid spheres. By means of a
matrix transformation, we reduce Einstein's equations to two independent
Riccati type differential equations for which three classes of solutions are
obtained. One class of the solutions corresponding to the linear barotropic
type fluid with an equation of state is discussed in detail.Comment: 9 pages, no figures, accepted for publication in Pramana-Journal of
Physic
Rotational Bands and Electromagnetic Transitions of some even-even Neodymium Nuclei in J-Projected Hartree-Fock Model
Rotational structures of even-even Nd nuclei are studied with the
self-consistent deformed Hartree-Fock (HF) and angular momentum (J) projection
model. Spectra of ground band, recently observed , and a few
more excited, positive and negative parity bands have been studied upto high
spin values. Apart from these detailed electromagnetic properties (like E2, M1
matrix elements) of all the bands have been obtained. There is substantial
agreement between our model calculations and available experimental data.
Predictions are made about the band structures and electromagnetic properties
of these nuclei. Some 4-qasiparticle K-isomeric bands and their electromagnetic
properties are predicted.Comment: 20 page
The nature of z ~ 2.3 Lyman-alpha emitters
We study the multi-wavelength properties of a set of 171 Ly-alpha emitting
candidates at redshift z = 2.25 found in the COSMOS field, with the aim of
understanding the underlying stellar populations in the galaxies. We especially
seek to understand what the dust contents, ages and stellar masses of the
galaxies are, and how they relate to similar properties of Ly-alpha emitters at
other redshifts. The candidates here are shown to have different properties
from those of Ly-alpha emitters found at higher redshift, by fitting the
spectral energy distributions (SEDs) using a Monte-Carlo Markov-Chain technique
and including nebular emission in the spectra. The stellar masses, and possibly
the dust contents, are higher, with stellar masses in the range log M_* = 8.5 -
11.0 M_sun and A_V = 0.0 - 2.5 mag. Young population ages are well constrained,
but the ages of older populations are typically unconstrained. In 15% of the
galaxies only a single, young population of stars is observed. We show that the
Ly-alpha fluxes of the best fit galaxies are correlated with their dust
properties, with higher dust extinction in Ly-alpha faint galaxies. Testing for
whether results derived from a light-weighted stack of objects correlate to
those found when fitting individual objects we see that stellar masses are
robust to stacking, but ages and especially dust extinctions are derived
incorrectly from stacks. We conclude that the stellar properties of Ly-alpha
emitters at z = 2.25 are different from those at higher redshift and that they
are diverse. Ly-alpha selection appears to be tracing systematically different
galaxies at different redshifts.Comment: 15 pages, 11 figures, 8 tables, accepted in A&A. Table 6 available in
full from the author
Electronic compressibility of a graphene bilayer
We calculate the electronic compressibility arising from electron-electron
interactions for a graphene bilayer within the Hartree-Fock approximation. We
show that, due to the chiral nature of the particles in this system, the
compressibility is rather different from those of either the two-dimensional
electron gas or ordinary semiconductors. We find that an inherent competition
between the contributions coming from intra-band exchange interactions
(dominant at low densities) and inter-band interactions (dominant at moderate
densities) leads to a non-monotonic behavior of the compressibility as a
function of carrier density.Comment: 4 pages, 4 figures. Final versio
Triaxial projected shell model approach
The projected shell model analysis is carried out using the triaxial
Nilsson+BCS basis. It is demonstrated that, for an accurate description of the
moments of inertia in the transitional region, it is necessary to take the
triaxiality into account and perform the three-dimensional angular-momentum
projection from the triaxial Nilsson+BCS intrinsic wavefunction.Comment: 9 pages, 2 figure
Multiwavelength observation from radio through very-high-energy Gamma-ray of OJ 287 during the 12-year cycle flare in 2007
We performed simultaneous multiwavelength observations of OJ 287 with the
Nobeyama Millimeter Array for radio, the KANATA telescope and the KVA telescope
for optical, the Suzaku satellite for X-ray and the MAGIC telescope for very
high energy (VHE) gamma-ray in 2007. The observations were conducted for a
quiescent state in April and in a flaring state in November-December. We
clearly observed increase of fluxes from radio to X-ray bands during the
flaring state while MAGIC could not detect significant VHE gamma-ray emission
from the source. We could derive an upper limit (95% confidence level) of 1.7%
of the Crab Nebula flux above 150 GeV from about 41.2 hours of the MAGIC
observation. A simple SSC model suggests that the observed flaring activity
could be caused by evolutions in the distribution of the electron population
rather than changes of the magnetic field strength or Doppler beaming factor in
the jet.Comment: Contribution to the 31st ICRC, Lodz, Poland, July 200
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