315 research outputs found
Search for hidden turbulent gas through interstellar scintillation
Stars twinkle because their light propagates through the atmosphere. The same
phenomenon is expected when the light of remote stars crosses a Galactic - disk
or halo - refractive medium such as a molecular cloud. We present the promising
results of a test performed with the ESO-NTT and the perspectives of detection.Comment: Structure and dynamics of disk galaxies, Petit Jean Mountain : United
States (2013). arXiv admin note: substantial text overlap with
arXiv:1208.637
Applying MOG to lensing: Einstein rings, Abell 520 and the Bullet Cluster
We investigate gravitational lensing in the context of the MOG modified
theory of gravity. Using a formulation of the theory with no adjustable or
fitted parameters, we present the MOG equations of motion for slow,
nonrelativistic test particles and for ultrarelativistic test particles, such
as rays of light. We demonstrate how the MOG prediction for the bending of
light can be applied to astronomical observations. Our investigation first
focuses on a small set of strong lensing observations where the properties of
the lensing objects are found to be consistent with the predictions of the
theory. We also present an analysis of the colliding clusters 1E0657-558 (known
also as the Bullet Cluster) and Abell 520; in both cases, the predictions of
the MOG theory are in good agreement with observation.Comment: 14 pages, 2 figures; final proof before publicatio
Study of a Strategy for Parallax Microlensing Detection Towards the Magellanic Clouds
In this article, we have investigated the possibility to distinguish between
different galactic models through the microlensing parallax studies. We show
that a systematic search for parallax effects can be done using the currently
running alert systems and complementary photometric telescopes, to distinguish
between different lens distance distributions. We have considered two galactic
dark compact objects distributions, with total optical depths corresponding to
the EROS current upper limits. These models correspond to two extreme
hypothesis on a three component galactic structure made of a thin disc, a thick
disc, and a spherically symmetric halo. Our study shows that for sub-solar mass
lenses, an exposure of staryr toward LMC should allow to
distinguish between these two extreme models. In addition the self-lensing
hypothesis (lensing by LMC objects) can efficiently be tested through the
method proposed here.Comment: 10 pages, 12 eps figures. To be published in A&A (accepted version).
Minor changes: - Discussion added on the differential velocity of the thick
galactic disk with respect to the thin disk. - Quality and lisibility of
figures improved. - Typo errors correcte
Search for Turbulent Gas through Interstellar Scintillation
Stars twinkle because their light propagates through the atmosphere. The same
phenomenon is expected when the light of remote stars crosses a Galactic - disk
or halo - refractive medium such as a molecular cloud.We present the promising
results of a test performed with the ESO-NTT and the perspectives.Comment: Tenth Symposium on Sources and Detection of Dark Matter and Dark
Energy in the Universe, Los-Angeles : \'Etats-Unis (2012
- …