4,367 research outputs found
Ongoing Mass Transfer in the Interacting Galaxy Pair NGC 1409/10
I present two-band HST STIS imaging, and WIYN spectral mapping, of ongoing
mass transfer in the interacting galaxy pair NGC 1409/10 (where NGC 1410 is the
Seyfert galaxy also catalogued as III Zw 55). Archival snapshot WFPC2 imaging
from the survey by Malkan et al. showed a dust feature stretching between the
galaxies, apparently being captured by NGC 1409. The new images allow estimates
of the mass being transferred and rate of transfer. An absorption lane
typically 0.25" (100 pc) wide with a representative optical depth tau_B = 0.2
cuts across the spiral structure of NGC 1410, crosses the 7-kpc projected space
between the nuclei, wraps in front of and, at the limits of detection, behind
NGC 1409, and becomes a denser (tau_B = 0.4) polar feature around the core of
NGC 1409. Combination of extinction data in two passbands allows a crude
three-dimensional recovery of the dust structure, supporting the front/back
geometry derived from colors and extinction estimates. The whole feature
contains of order solar masses in dust, implying about 2x10^7 solar
masses of gas, requiring a mass transfer rate averaging ~1 solar mass per year
unless we are particularly unlucky in viewing angle. Curiously, this
demonstrable case of mass transfer seems to be independent of the occurrence of
a Seyfert nucleus, since the Seyfert galaxy in this pair is the donor of the
material. Likewise, the recipient shows no signs of recent star formation from
incoming gas, although NGC 1410 has numerous luminous young star clusters and
widespread H-alpha emission.Comment: 27 pages, 9 figures. Accepted for the Astronomical Journal, March
200
Vacuum polarization by topological defects in de Sitter spacetime
In this paper we investigate the vacuum polarization effects associated with
a massive quantum scalar field in de Sitter spacetime in the presence of
gravitational topological defects. Specifically we calculate the vacuum
expectation value of the field square, . Because this investigation
has been developed in a pure de Sitter space, here we are mainly interested on
the effects induced by the presence of the defects.Comment: Talk presented at the 1st. Mediterranean Conference on Classical and
Quantum Gravity (MCCQG
Nonplanar integrability at two loops
In this article we compute the action of the two loop dilatation operator on
restricted Schur polynomials that belong to the su(2) sector, in the displaced
corners approximation. In this non-planar large N limit, operators that
diagonalize the one loop dilatation operator are not corrected at two loops.
The resulting spectrum of anomalous dimensions is related to a set of decoupled
harmonic oscillators, indicating integrability in this sector of the theory at
two loops. The anomalous dimensions are a non-trivial function of the 't Hooft
coupling, with a spectrum that is continuous and starting at zero at large N,
but discrete at finite N.Comment: version to appear in JHE
The influence of polymer purification on the efficiency of poly(3-hexylthiophene):fullerene organic solar cells
Electronic Phase Separation Transition as the Origin of the Superconductivity and the Pseudogap Phase of Cuprates
We propose a new phase of matter, an electronic phase separation transition
that starts near the upper pseudogap and segregates the holes into high and low
density domains. The Cahn-Hilliard approach is used to follow quantitatively
this second order transition. The resulting grain boundary potential confines
the charge in domains and favors the development of intragrain superconducting
amplitudes. The zero resistivity transition arises only when the intergrain
Josephson coupling is of the order of the thermal energy and phase
locking among the superconducting grains takes place. We show that this
approach explains the pseudogap and superconducting phases in a natural way and
reproduces some recent scanning tunneling microscopy dataComment: 4 pages and 5 eps fig
A double coset ansatz for integrability in AdS/CFT
We give a proof that the expected counting of strings attached to giant
graviton branes in AdS_5 x S^5, as constrained by the Gauss Law, matches the
dimension spanned by the expected dual operators in the gauge theory. The
counting of string-brane configurations is formulated as a graph counting
problem, which can be expressed as the number of points on a double coset
involving permutation groups. Fourier transformation on the double coset
suggests an ansatz for the diagonalization of the one-loop dilatation operator
in this sector of strings attached to giant graviton branes. The ansatz agrees
with and extends recent results which have found the dynamics of open string
excitations of giants to be given by harmonic oscillators. We prove that it
provides the conjectured diagonalization leading to harmonic oscillators.Comment: 33 pages, 3 figures; v2: references adde
Solving Four Dimensional Field Theories with the Dirichlet Fivebrane
The realization of four dimensional super Yang-Mills theories in
terms of a single Dirichlet fivebrane in type IIB string theory is considered.
A classical brane computation reproduces the full quantum low energy effective
action. This result has a simple explanation in terms of mirror symmetry.Comment: Final version to appear in Phys. Rev.
Spin-1 Particles with Light-Front Approach
For the vector sector, i.e, mesons with spin-1, the electromagnetic form
factors and anothers observables are calculated with the light-front approach.
However, the light-front quantum field theory have some problems, for example,
the rotational symmetry breaking. We solve that problem added the zero modes
contribuition to the matrix elements of the electromagnetic current, besides
the valence contribuition. We found that among the four independent matrix
elements of the plus component in the light-front helicity basis only the one carries zero mode contributions.Comment: 5 pages. 3 Figures, use latex and EPJ styl
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