3,912 research outputs found
THE ROLE OF VITAMIN B 6 IN THE TOXICITY OF HYDRAZINES *
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73785/1/j.1749-6632.1969.tb54264.x.pd
Co-accelerated particles in the C-metric
With appropriately chosen parameters, the C-metric represents two uniformly
accelerated black holes moving in the opposite directions on the axis of the
axial symmetry (the z-axis). The acceleration is caused by nodal singularities
located on the z-axis.
In the~present paper, geodesics in the~C-metric are examined. In general
there exist three types of timelike or null geodesics in the C-metric:
geodesics describing particles 1) falling under the black hole horizon;
2)crossing the acceleration horizon; and 3) orbiting around the z-axis and
co-accelerating with the black holes.
Using an effective potential, it can be shown that there exist stable
timelike geodesics of the third type if the product of the parameters of the
C-metric, mA, is smaller than a certain critical value. Null geodesics of the
third type are always unstable. Special timelike and null geodesics of the
third type are also found in an analytical form.Comment: 10 pages, 12 EPS figures, changes mainly in abstract & introductio
On the possibility for constraining cosmic topology from the celestial distribution of astronomical objects
We present a method to constrain cosmic topology from the distribution of
astronomical objects projected on the celestial sphere. This is an extension of
the 3D method introduced in Fujii & Yoshii (2011) that is to search for a pair
of pairs of observed objects (quadruplet) linked by a holonomy, i.e., the
method we present here is to search for a pair of celestial sphere -tuplets
for . We find, however, that this method is impractical to apply in
realistic situations due to the small signal to noise ratio. We conclude
therefore that it is unrealistic to constrain the topology of the Universe from
the celestial distribution, and the 3D catalogs are necessary for the purpose.Comment: 4 pages, 1 figure, accepted for publication in A&A (2011
Chaotic Scattering and Capture of Strings by Black Hole
We consider scattering and capture of circular cosmic strings by a
Schwarzschild black hole. Although being a priori a very simple axially
symmetric two-body problem, it shows all the features of chaotic scattering. In
particular, it contains a fractal set of unstable periodic solutions; a
so-called strange repellor. We study the different types of trajectories and
obtain the fractal dimension of the basin-boundary separating the space of
initial conditions according to the different asymptotic outcomes. We also
consider the fractal dimension as a function of energy, and discuss the
transition from order to chaos.Comment: RevTeX 3.1, 9 pages, 5 figure
Reconstructing the global topology of the universe from the cosmic microwave background
If the universe is multiply-connected and sufficiently small, then the last
scattering surface wraps around the universe and intersects itself. Each circle
of intersection appears as two distinct circles on the microwave sky. The
present article shows how to use the matched circles to explicitly reconstruct
the global topology of space.Comment: 6 pages, 2 figures, IOP format. To be published in the proceedings of
the Cleveland Cosmology and Topology Workshop 17-19 Oct 1997. Submitted to
Class. Quant. Gra
Characterizing the Galactic Gravitational Wave Background with LISA
We present a Monte Carlo simulation for the response of the Laser
Interferometer Space Antenna (LISA) to the galactic gravitational wave
background. The simulated data streams are used to estimate the number and type
of binary systems that will be individually resolved in a 1-year power
spectrum. We find that the background is highly non-Gaussian due to the
presence of individual bright sources, but once these sources are identified
and removed, the remaining signal is Gaussian. We also present a new estimate
of the confusion noise caused by unresolved sources that improves on earlier
estimates.Comment: 32 pages, 14 figures. Version to appear in PR
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