September 2006 Bogdan Popescu

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SELECTED TOPICS on GRAVITATIONAL LENSES


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Gravitational Lens Timeline
-18th Century - JOHN MICHELL , LAPLACE and
CAVENDISH - deflection of light by a body,
assuming the corpuscular theory of light and
Newtons law of gravitation. -1915 - EINSTEIN -
General Relativity - gravitational deflection of
the light -1919 - OLIVER LODGE - proposal of
gravitational lens -1919 - EDDINGTON - first
experimental proof -1924 - CHWOLSON - Chwolson
Rings (now Einstein Rings) -1936 - EINSTEIN -
confirm existence of Einstein Rings -1937 -
ZWICKY - affirm that is possible to detect the
images -1937-1979 - a lot of theoretical
work -1979 - DENNIS WALSH , R.F.CARSWELL and
R.J.WEYMANN discover first double quasar (0957
561 A, B ) proved as multiple images of the
same object.
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Deflection of the Light
Sir HENRY CAVENDISH (1784)
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Q 0957561 A, B The First Gravitational Lens
September 2006

Bogdan Popescu
Image credit http//antwrp.gsfc.nasa.gov
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Q 0957561 A, B The First Gravitational Lens
The first gravitationally lensed object ever
discovered, Q0957561 is a quasar whose image is
split into two by the gravity of a foreground
galaxy. In this image, the two star like objects
are the split images of the quasar. The fuzzy
object near top quasar image is the foreground
galaxy. The quasar lies at a redshift of 1.41.
The foreground galaxy lies at a redshift of 0.39.
In optical light, Q0957561 appears as two point
images of roughly 17 mag separated by 6.1
arcseconds.
Image credit Walsh, D. and Carswell, R.F.
and Weyman, R.J. 1979, "0957561 A,B twin
quasistellar objects or gravitational lens?"
Nature, 279, 381
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Gravitational Lens Optics
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Images
,, Image credit http//cassfos02.ucsd
.edu/public/tutorial/GLens.html
http//www.iam.ubc.ca/newb
ury/lenses/research.html
http//zebu.uoregon.edu/soper/Mas
s/gravlens.html
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Images
Image credit http//www-ra.phys.utas.edu.au/j
lovell/simlens/
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Images Strong and Weak Lenses 3
Image credit Jetzer, P. Gravitational Lensing
in Modern Cosmology, edited by Bonometto, S. et
al, 2002
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Dark Matter
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Dark Matter
Image credit http//zebu.uoregon.edu/sope
r/Mass/gravlens.html
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Mass Distribution from Gravitational Lenses
This animation shows a galaxy cluster with two
mass concentrations (the pink shading indicates
the projected mass density) lensing a background
field of faint blue galaxies. The magnitude of
this shear pattern can be used to determine the
mass contained within the cluster. Abell 2218 and
CL2244-02 are clusters with tangential arcs.
Image credit http//zebu.uoregon.edu/sop
er/Mass/gravlens.html
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Weak Gravitational Lenses (WL)
Image credit Schneider, P -
astro-ph/0509252
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Weak Gravitational Lenses (WL) (astro-ph/0509252
- P. Schneider)
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Weak Gravitational Lenses (WL) (astro-ph/0509252
- P. Schneider)
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Mass Reconstruction
Three principal methods for determining the mass
of galaxy clusters are in use - Dynamical mass
estimates - Assuming virial equilibrium, the
observed velocity distribution of galaxies in
clusters can be converted into a mass estimate,
employing the virial theorem this method
typically requires assumptions about the
statistical distribution of the anisotropy of the
galaxy orbits. - X-ray mass determination of
clusters - The hot intra-cluster gas, as visible
through its Bremsstrahlung in X-rays, traces the
gravitational potential of the cluster. Under
certain assumptions (relaxed clusters), the mass
profile can be constructed from the X-ray
emission. - Weak and strong gravitational
lensing probes the projected mass profile of
clusters, with strong lensing confined to the
central regions of clusters, whereas weak lensing
can yield mass measurements for larger radii.
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Mass Reconstruction (astro-ph/0509252 - P.
Schneider)
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Mass Reconstruction (astro-ph/0509252 - P.
Schneider)
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Mass Reconstruction (astro-ph/0509252 - P.
Schneider)
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Mass Reconstruction (astro-ph/0509252 - P.
Schneider)
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Mass Reconstruction (astro-ph/0509252 - P.
Schneider)
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Mass Reconstruction Multiple Lens 1,5
Image credit 1 Bernadeau, F Gravitational
Lensing From Micro-Lensing to Cosmic Shear
Experiments in Frontiers of Cosmology, edited
by Blanchard, A. and Signore, M., 2005 5
Schneider, P et all Gravitational Lenses, 1999
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Mass Reconstruction (astro-ph/0509252 - P.
Schneider)
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Mass Reconstruction - Ellipticities
(astro-ph/0509252 - P. Schneider)
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The Galaxy-Galaxy Lensing Signal
(astro-ph/0509252 - P. Schneider)
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Mass Reconstruction (astro-ph/0509252 - P.
Schneider)
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Mass Reconstruction (astro-ph/0509252 - P.
Schneider)
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Mass Reconstruction - Dark Matter
(astro-ph/0608408 Bradac et al)
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Mass Reconstruction - Dark Matter
(astro-ph/0608408 Bradac et al)
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Mass Reconstruction - Dark Matter
(astro-ph/0608408 Bradac et al)
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Mass Reconstruction - Dark Matter
(astro-ph/0608408 Bradac et al)
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References
1. Bernadeau, F Gravitational Lensing From
Micro-Lensing to Cosmic Shear Experiments in
Frontiers of Cosmology, edited by Blanchard, A.
and Signore, M., 2005 2. Bradac, M. et al -
astro-ph/0608408 3. Jetzer, P. Gravitational
Lensing in Modern Cosmology, edited by
Bonometto, S. et al, 2002 4. Schneider, P -
astro-ph/0509252 5. Schneider, P et all
Gravitational Lenses, 1999
Images http//www-ra.phys.utas.edu.au/j
lovell/simlens/ http//cassfos02.ucsd.edu/publi
c/tutorial/GLens.html Walsh, D. and Carswell,
R.F. and Weyman, R.J. 1979, "0957561 A,B twin
quasistellar objects or gravitational lens?"
Nature, 279, 381 http//www.iam.ubc.ca/newb
ury/lenses/research.html http//zebu.uoregon
.edu/soper/Mass/gravlens.html
http//antwrp.gsfc.nasa.gov/
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Link
http//www.physics.uc.edu/popescu/
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September 2006

Bogdan Popescu