62,160 research outputs found
Density-equalizing maps for simply-connected open surfaces
In this paper, we are concerned with the problem of creating flattening maps
of simply-connected open surfaces in . Using a natural principle
of density diffusion in physics, we propose an effective algorithm for
computing density-equalizing flattening maps with any prescribed density
distribution. By varying the initial density distribution, a large variety of
mappings with different properties can be achieved. For instance,
area-preserving parameterizations of simply-connected open surfaces can be
easily computed. Experimental results are presented to demonstrate the
effectiveness of our proposed method. Applications to data visualization and
surface remeshing are explored
Acoustic Spectroscopy of Superfluid 3He in Aerogel
We have designed an experiment to study the role of global anisotropic
quasiparticle scattering on the dirty aerogel superfluid 3He system. We observe
significant regions of two stable phases at temperatures below the superfluid
transition at a pressure of 25 bar for a 98% aerogel.Comment: 2 pages, 2 figures, accepted for publication in proceedings of Low
Temperature Conference 2
Specific Heat of Disordered He
Porous aerogel is a source of elastic scattering in superfluid 3He and
modifies the properties of the superfluid, suppressing the transition
temperature and order parameter. The specific heat jumps for the B-phase of
superfluid 3He in aerogel have been measured as a function of pressure and
interpreted using the homogeneous and inhomogeneous isotropic scattering
models. The specific heat jumps for other p-wave states are estimated for
comparison.Comment: Manuscript prepared for LT 2
Consequences of Mechanical and Radiative Feedback from Black Holes in Disc Galaxy Mergers
We study the effect of AGN mechanical and radiation feedback on the formation
of bulge dominated galaxies via mergers of disc galaxies. The merging galaxies
have mass-ratios of 1:1 to 6:1 and include pre-existing hot gaseous halos to
properly account for the global impact of AGN feedback. Using smoothed particle
hydrodynamics simulation code (GADGET-3) we compare three models with different
AGN feedback models: (1) no black hole and no AGN feedback; (2) thermal AGN
feedback; and (3) mechanical and radiative AGN feedback. The last model is
motivated by observations of broad line quasars which show winds with initial
velocities of 10,000 km/s and also heating associated with the
central AGN X-ray radiation. The primary changes in gas properties due to
mechanical AGN feedback are lower thermal X-ray luminosity from the final
galaxy - in better agreement with observations - and galactic outflows with
higher velocity km/s similar to recent direct observations of
nearby merger remnants. The kinetic energy of the outflowing gas is a factor of
20 higher than in the thermal feedback case. All merger remnants with
momentum-based AGN feedback with km/s and , independent of their progenitor mass-ratios, reproduce the
observed relations between stellar velocity dispersion and black hole mass
() as well as X-ray luminosity () with
erg/s erg/s for
velocity dispersions in the range of 120 km/s 190
km/s. In addition, the mechanical feedback produces a much greater AGN
variability. We also show that gas is more rapidly and impulsively stripped
from the galactic centres driving a moderate increase in galaxy size and
decrease in central density with the mechanical AGN feedback model.Comment: 16 pages, 10 figures, resubmitted to MNRA
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