3,996 research outputs found
Scalar Field Dark Matter: head-on interaction between two structures
In this manuscript we track the evolution of a system consisting of two
self-gravitating virialized objects made of a scalar field in the newtonian
limit. The Schr\"odinger-Poisson system contains a potential with
self-interaction of the Gross-Pitaevskii type for Bose Condensates. Our results
indicate that solitonic behavior is allowed in the scalar field dark matter
model when the total energy of the system is positive, that is, the two blobs
pass through each other as should happen for solitons; on the other hand, there
is a true collision of the two blobs when the total energy is negative.Comment: 8 revtex pages, 11 eps figures. v2 matches the published version.
v2=v1+ref+minor_change
Spectroscopy of quadrupole and octupole states in rare-earth nuclei from a Gogny force
Collective quadrupole and octupole states are described in a series of Sm and
Gd isotopes within the framework of the interacting boson model (IBM), whose
Hamiltonian parameters are deduced from mean field calculations with the Gogny
energy density functional. The link between both frameworks is the
() potential energy surface computed within the
Hartree-Fock-Bogoliubov framework in the case of the Gogny force. The
diagonalization of the IBM Hamiltonian provides excitation energies and
transition strengths of an assorted set of states including both positive and
negative parity states. The resultant spectroscopic properties are compared
with the available experimental data and also with the results of the
configuration mixing calculations with the Gogny force within the generator
coordinate method (GCM). The structure of excited states and its
connection with double octupole phonons is also addressed. The model is shown
to describe the empirical trend of the low-energy quadrupole and octupole
collective structure fairly well, and turns out to be consistent with GCM
results obtained with the Gogny force.Comment: 17 pages, 12 figures, 4 table
Structural evolution in germanium and selenium nuclei within the mapped interacting boson model based on the Gogny energy density functional
The shape transitions and shape coexistence in the Ge and Se isotopes are
studied within the interacting boson model (IBM) with the microscopic input
from the self-consistent mean-field calculation based on the Gogny-D1M energy
density functional. The mean-field energy surface as a function of the
quadrupole shape variables and , obtained from the constrained
Hartree-Fock-Bogoliubov method, is mapped onto the expectation value of the IBM
Hamiltonian with configuration mixing in the boson condensate state. The
resultant Hamiltonian is used to compute excitation energies and
electromagnetic properties of the selected nuclei Ge and
Se. Our calculation suggests that many nuclei exhibit
softness. Coexistence between prolate and oblate, as well as between spherical
and -soft, shapes is also observed. The method provides a reasonable
description of the observed systematics of the excitation energy of the
low-lying energy levels and transition strengths for nuclei below the neutron
shell closure , and provides predictions on the spectroscopy of
neutron-rich Ge and Se isotopes with , where data are scarce
or not available.Comment: 16 pages, 20 figure
Unveiling the origin of shape coexistence in lead isotopes
The shape coexistence in the nuclei Pb is analyzed within the
Hartree-Fock-Bogoliubov approach with the effective Gogny force. A good
agreement with the experimental energies is found for the coexisting spherical,
oblate and prolate states. Contrary to the established interpretation, it is
found that the low-lying prolate and oblate states observed in this mass
region are predominantly characterized by neutron correlations whereas the
protons behave as spectators rather than playing an active role.Comment: 5 pages, 6 postscript figure
Structure of krypton isotopes within the interacting boson model derived from the Gogny energy density functional
The evolution and coexistence of the nuclear shapes as well as the
corresponding low-lying collective states and electromagnetic transition rates
are investigated along the Krypton isotopic chain within the framework of the
interacting boson model (IBM). The IBM Hamiltonian is determined through
mean-field calculations based on the several parametrizations of the Gogny
energy density functional and the relativistic mean-field Lagrangian. The
mean-field energy surfaces, as functions of the axial and triaxial
quadrupole deformations, are mapped onto the expectation value of the
interacting-boson Hamiltonian that explicitly includes the particle-hole
excitations. The resulting boson Hamiltonian is then used to compute low-energy
excitation spectra as well as E2 and E0 transition probabilities for
Kr. Our results point to a number of examples of the prolate-oblate
shape transitions and coexistence both on the neutron-deficient and
neutron-rich sides. A reasonable agreement with the available experimental data
is obtained for the considered nuclear properties.Comment: 13 pages, 9 figures, 2 table
Internal Kinematics of Luminous Compact Blue Galaxies
We describe the dynamical properties which may be inferred from HST/STIS
spectroscopic observations of luminous compact blue galaxies (LCBGs) between
0.1<z<0.7. While the sample is homogeneous in blue rest-frame color, small size
and line-width, and high surface-brightness, their detailed morphology is
eclectic. Here we determine the amplitude of rotation versus random, or
disturbed motions of the ionized gas. This information affirms the accuracy of
dynamical mass and M/L estimates from Keck integrated line-widths, and hence
also the predictions of the photometric fading of these unusual galaxies. The
resolved kinematics indicates this small subset of LCBGs are dynamically hot,
and unlikely to be embedded in disk systems.Comment: To appear in "Starbursts: from 30 Doradus to Lyman Break Galaxies"
2005, eds. R. de Grijs and R. M. Gonzalez Delgado (Kluwer
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