20 research outputs found
Detection of compact objects by means of gravitational lensing in binary systems
We consider the gravitational magnification of light for binary systems
containing two compact objects: white dwarfs, a white dwarf and a neutron star
or a white dwarf and a black hole. Light curves of the flares of the white
dwarf caused by this effect were built in analytical approximations and by
means of numerical calculations. We estimate the probability of the detection
of these events in our Galaxy for different types of binaries and show that
gravitational lensing provides a tool for detecting such systems. We propose to
use the facilities of the Sloan Digital Sky Survey (SDSS) to search for these
flares. It is possible to detect several dozens compact object pairs in such a
programme over 5 years. This programme is apparently the best way to detect
stellar mass black holes with open event horizons.Comment: 15 pages, 11 figures; Accepted for publication in Astronomy &
Astrophysic
Notes on Hidden Mirror World
A few remarks on Dark Matter (DM) models are presented. An example is Mirror
Matter which is the oldest but still viable DM candidate, perhaps not in the
purest form. It can serve as a test-bench for other analogous DM models, since
the properties of macroscopic objects are quite firmly fixed for Mirror Matter.
A pedagogical derivation of virial theorem is given and it is pointed out that
concepts of virial velocity or virial temperature are misleading for some
cases. It is shown that the limits on self-interaction cross-sections derived
from observations of colliding clusters of galaxies are not real limits for
individual particles if they form macroscopic bodies. The effect of the heating
of interstellar medium by Mirror Matter compact stars is very weak but may be
observable. The effect of neutron star heating by accretion of M-baryons may be
negligible. Problems of MACHOs as Mirror Matter stars are touched upon.Comment: Latex, revtex, 24 pages, 1 figure, references updated and adde