20,188 research outputs found
Obscuring Material around Seyfert Nuclei with Starbursts
The structure of obscuring matter in the environment of active galactic
nuclei with associated nuclear starbursts is investigated using 3-D
hydrodynamical simulations. Simple analytical estimates suggest that the
obscuring matter with energy feedback from supernovae has a torus-like
structure with a radius of several tens of parsecs and a scale height of about
10 pc. These estimates are confirmed by the fully non-linear numerical
simulations, in which the multi-phase inhomogeneous interstellar matter and its
interaction with the supernovae are consistently followed. The globally stable,
torus-like structure is highly inhomogeneous and turbulent. To achieve the high
column densities (> 10^{24} cm^{-2}) as suggested by observations of some
Seyfert 2 galaxies with nuclear starbursts, the viewing angle should be larger
than about 70 degree from the pole-on for a 10^8 solar mass massive black hole.
Due to the inhomogeneous internal structure of the torus, the observed column
density is sensitive to the line-of-sight, and it fluctuates by a factor of
order 100. The covering fraction for N > 10^{23} cm^{-2} is about 0.4. The
average accretion rate toward R < 1 pc is 0.4 solar mass/yr, which is boosted
to twice that in the model without the energy feedback.Comment: ApJL in press (4 pages, 3 figures) A gziped ps file with high
resolution figures is available at http://th.nao.ac.jp/~wada/AGN
Superlens made of a metamaterial with extreme effective parameters
We propose a superlens formed by an ultra-dense array of crossed metallic
wires. It is demonstrated that due to the anomalous interaction between crossed
wires, the structured substrate is characterized by an anomalously high index
of refraction and supports strongly confined guided modes with very short
propagation wavelengths. It is theoretically proven that a planar slab of such
structured material makes a superlens that may compensate for the attenuation
introduced by free-space propagation and restore the subwavelength details of
the source. The bandwidth of the proposed device can be quite significant since
the response of the structured substrate is non-resonant. The theoretical
results are fully supported by numerical simulations.Comment: Accepted for publication in Phys. Rev. B (in press
The extended minimal geometric deformation of SU() dark glueball condensates
The extended minimal geometric deformation (EMGD) procedure, in the
holographic membrane paradigm, is employed to model stellar distributions that
arise upon self-interacting scalar glueball dark matter condensation. Such
scalar glueballs are SU() Yang-Mills hidden sectors beyond the Standard
Model. Then, corrections to the gravitational wave radiation, emitted by
SU() EMGD dark glueball stars mergers, are derived, and their respective
spectra are studied in the EMGD framework, due to a phenomenological brane
tension with finite value. The bulk Weyl fluid that drives the EMGD is then
proposed to be experimentally detected by enhanced windows at the eLISA and
LIGO.Comment: 9 pages, 7 figure
Extended quantum portrait of MGD black holes and information entropy
The extended minimal geometric deformation (EMGD) is employed on the fluid
membrane paradigm, to describe compact stellar objects as Bose--Einstein
condensates (BEC) consisting of gravitons. The black hole quantum portrait,
besides deriving a preciser phenomenological bound for the fluid brane tension,
is then scrutinized from the point of view of the configurational entropy. It
yields a range for the critical density of the EMGD BEC, whose configurational
entropy has global minima suggesting the configurational stability of the EMGD
BEC.Comment: 9 pages, 7 figures, matches the published versio
Nonequilibrium scaling explorations on a 2D Z(5)-symmetric model
We have investigated the dynamic critical behavior of the two-dimensional
Z(5)-symmetric spin model by using short-time Monte Carlo (MC) simulations. We
have obtained estimates of some critical points in its rich phase diagram and
included, among the usual critical lines the study of first-order (weak)
transition by looking into the order-disorder phase transition. Besides, we
also investigated the soft-disorder phase transition by considering empiric
methods. A study of the behavior of along the self-dual critical
line has been performed and special attention has been devoted to the critical
bifurcation point, or FZ (Fateev-Zamolodchikov) point. Firstly, by using a
refinement method and taking into account simulations out-of-equilibrium, we
were able to localize parameters of this point. In a second part of our study,
we turned our attention to the behavior of the model at the early stage of its
time evolution in order to find the dynamic critical exponent z as well as the
static critical exponents and of the FZ-point on square
lattices. The values of the static critical exponents and parameters are in
good agreement with the exact results, and the dynamic critical exponent
very close of the 4-state Potts model ().Comment: 11 pages, 7 figure
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