14 research outputs found
Solutions to Cosmological Problems with Energy Conservation and Varying c, G and Lambda
The flatness and cosmological constant problems are solved with varying speed
of light c, gravitational coupling strength G and cosmological parameter
Lambda, by explicitly assuming energy conservation of observed matter. The
present solution to the flatness problem is the same as the previous solution
in which energy conservation was absent.Comment: 5 pages, Replaced with LaTex file with minor change
Tunneling conductance of Luttinger liquids: resonances
We have calculated the two-probe Landauer conductance of a one-channel quantum wire containing a Luttinger liquid and connected to two noninteracting leads through tunnel barriers. The tunneling conductance shows broad resonances as a function of the bias voltage, this being a manifestation of the spin-charge separation. In the limit of zero bias and zero barrier, the tunneling conductance reduces to the ballistic contact value e2/h per channel
Brane World Dynamics and Adiabatic Matter creation
We have treated the adiabatic matter creation process in various three-brane
models by applying thermodynamics of open systems. The matter creation rate is
found to affect the evolution of scale factor and energy density of the
universe. We find modification at early stages of cosmic dynamics. In GB and RS
brane worlds, by chosing appropriate parameters we obtain standard scenario,
while the warped DGP model has different Friedmann equations. During later
stages, since the matter creation is negligible the evolution reduces to FRW
expansion, in RS and GB models.Comment: Replaced with TEX file,No figures, Corrected References and typos.
Accepted in IJMP
PyMorph: Automated Galaxy Structural Parameter Estimation using Python
We present a new software pipeline -- PyMorph -- for automated estimation of
structural parameters of galaxies. Both parametric fits through a two
dimensional bulge disk decomposition as well as structural parameter
measurements like concentration, asymmetry etc. are supported. The pipeline is
designed to be easy to use yet flexible; individual software modules can be
replaced with ease. A find-and-fit mode is available so that all galaxies in a
image can be measured with a simple command. A parallel version of the Pymorph
pipeline runs on computer clusters and a Virtual Observatory compatible web
enabled interface is under development.Comment: 15 pages, 12 figures, 1 table, accepted for publication in MNRA
Super-reflection of light from a random amplifying medium with disorder in the complex refractive index : Statistics of fluctuations
The probability distribution of the reflection coefficient for light
reflected from a one-dimensional random amplifying medium with {\it
cross-correlated} spatial disorder in the real and the imaginary parts of the
refractive index is derived using the method of invariant imbedding. The
statistics of fluctuations have been obtained for both the correlated telegraph
noise and the Gaussian white-noise models for the disorder. In both cases, an
enhanced backscattering (super-reflection with reflection coefficient greater
than unity) results because of coherent feedback due to Anderson localization
and coherent amplification in the medium. The results show that the effect of
randomness in the imaginary part of the refractive index on localization and
super-reflection is qualitatively different.Comment: RevTex 6 pages, 3 figures in ps file
Quantitative measure of evolution of bright cluster galaxies at moderate redshifts
Using archival data from the Hubble Space Telescope, we study the
quantitative morphological evolution of spectroscopically confirmed bright
galaxies in the core regions of nine clusters ranging in redshift from to . We use morphological parameters derived from two
dimensional bulge-disk decomposition to study the evolution. We find an
increase in the mean bulge-to-total luminosity ratio as the Universe
evolves. We also find a corresponding increase in the fraction of early type
galaxies and in the mean S\'ersic index. We discuss these results and their
implications to physical mechanisms for evolution of galaxy morphology.Comment: 5 pages, 3 figures, Accepted for publication in MNRAS: Letter