scholarly journals Gravitational lensing of quasar 0957+561 and the determination of H0

1995 ◽  
Author(s):  
George Rhee ◽  
Gary Bernstein ◽  
Tony Tyson ◽  
Phil Fischer
Keyword(s):  
Gravitational Lensing

scholarly journals Zeldovich and the Missing Baryons, Results from Gravitational Lensing

2014 ◽  
Vol 11 (S308) ◽  
pp. 380-381
Author(s):  
Rudolph E. Schild
Keyword(s):  
Dark Matter ◽  
Distribution Function ◽  
Gravitational Lensing ◽  
Mass Function ◽  
Gravitational Theory ◽  
Magellanic Clouds ◽  
Planetary Mass ◽  
Mass Distribution Function ◽  
Baryonic Dark Matter

AbstractCentral to Zeldovich's attempts to understand the origin of cosmological structure was his exploration of the fluid dynamical effects in the primordial gas, and how the baryonic dark matter formed. Unfortunately microlensing searches for condensed objects in the foreground of the Magellanic Clouds were flawed by the assumption that the objects would be uniformly (Gaussian) distributed, and because the cadence of daily observations strongly disfavored detection of planet mass microlenses. But quasar microlensing showed them to exist at planetary mass at the same time that a hydro-gravitational theory predicted the planet-mass population as fossils of turbulence at the time of recombination (z = 1100; Gibson 1996, 2001). Where the population has now been detected from MACHO searches to the LMC (Sumi et al. 2011) we compare the quasar microlensing results to the recent determination of the mass distribution function measured for the planetary mass function, and show that the population can account for the baryonic dark matter.

scholarly journals Strong gravitational lensing: relativity in action

2009 ◽  
Vol 5 (S261) ◽  
pp. 249-259
Author(s):  
Joachim Wambsganss
Keyword(s):  
Gravitational Lensing ◽  
Extrasolar Planets ◽  
Hubble Constant ◽  
Stellar Atmospheres ◽  
Gravitational Lens ◽  
Cosmological Distance Scale ◽  
Galaxy Halos ◽  
Guided Tour ◽  
Observational Science

AbstractDeflection of light by gravity was predicted by Einstein's Theory of General Relativity and observationally confirmed in 1919. In the following decades, various aspects of the gravitational lens effect were explored theoretically, among them measuring the Hubble constant from multiple images of a background source, making use of the magnifying effect as a gravitational telescope, or the possibility of a “relativistic eclipse” as a perfect test of GR. Only in 1979, gravitational lensing became an observational science when the first doubly imaged quasar was discovered. Today lensing is a booming part of astrophysics and cosmology. A whole suite of strong lensing phenomena have been investigated: multiple quasars, giant luminous arcs, Einstein rings, quasar microlensing, and galactic microlensing. The most recent lensing application is the detection of extrasolar planets. Lensing has contributed significant new results in areas as different as the cosmological distance scale, mass determination of galaxy clusters, physics of quasars, searches for dark matter in galaxy halos, structure of the Milky Way, stellar atmospheres and exoplanets. A guided tour through some of these applications will illustrate how gravitational lensing has established itself as a very useful universal astrophysical tool.

scholarly journals Gravitational Lensing in the Clumpy Universe

1999 ◽  
Vol 183 ◽  
pp. 241-241
Author(s):  
Hideki Asada
Keyword(s):  
Time Delay ◽  
Gravitational Lensing ◽  
Cosmological Parameters ◽  
Cosmological Parameter ◽  
Accurate Estimation ◽  
Image Separation ◽  
Cosmological Tests ◽  
The Universe

Most of methods to determine the cosmological parameters by using the gravitational lensing are based on the following three typical observations; (1) the image separation, (2) the lensing statistics and (3) the time delay. For the accurate estimation of the cosmological parameter, it is of great importance to clarify the relation between the observation in the realistic universe and the determination of the cosmological parameters. In particular, it has been discussed by many authors that inhomogeneities of the universe may affect the cosmological tests.

scholarly journals Dark-Matter in Galaxies from Gravitational Lensing and Stellar Dynamics Studies

2009 ◽  
Vol 5 (H15) ◽  
pp. 74-74
Author(s):  
L. V. E. Koopmans
Keyword(s):  
Dark Matter ◽  
Mass Distribution ◽  
Density Profile ◽  
Gravitational Lensing ◽  
Total Mass ◽  
Stellar Dynamics ◽  
Early Type ◽  
Complementary Methods ◽  
Strong Gravitational Lensing

AbstractStrong gravitational lensing and stellar dynamics provide two complementary methods in the study of the mass distribution of dark matter in galaxies out to redshift of unity. They are particularly powerful in the determination of the total mass and the density profile of mass early-type galaxies on kpc to tens of kpc scales, and also reveal the presence of mass-substructure on sub-kpc scale. I will shortly discuss these topics in this review.

scholarly journals Cosmological Applications of Gravitational Lensing

1996 ◽  
Vol 168 ◽  
pp. 209-217
Author(s):  
Peter Schneider
Keyword(s):  
Gravitational Lensing ◽  
High Redshift ◽  
Cosmological Parameters ◽  
Gravitational Lens ◽  
Mass Determination ◽  
Gravitational Lenses ◽  
Distant Object ◽  
The Many ◽  
The Universe

It was recognized very early that the gravitational lens effect can be used as an efficient cosmological tool. Of the many researchers who foresaw the use of lensing, F. Zwicky and S. Refsdal should be explicitly mentioned. The perhaps most accurate predictions and foresights by these two authors are as follows: Zwicky estimated the probability that a distant object is multiply imaged to be about 1/400, and thus that the observation of this effect is “a certainty” [73] – his value, which was obtained by a very crude reasoning, is in fact very close to current estimates of the lensing probability of high-redshift QSOs. He predicted that the magnification caused by gravitational light deflection will allow a “deeper look” into the universe –in fact, the spectroscopy of very faint galaxies which are imaged into giant luminous arcs have yielded spectral information which would be very difficult to obtain without these ‘natural telescopes’. And third, Zwicky saw that gravitational lenses may be used to determine the mass of distant extragalactic objects[72] – in fact, the mass determination of clusters masses from giant luminous arcs is as least as accurate as other methods, but does not rely on special assumptions (like spherical symmetry, virial or thermal equilibrium) inherent in other methods, and the determination of the mass within the inner 0.9 arcseconds of the lensing galaxy in the quadruple QSO 2237+0305 to within 2% [52] is the most accurate extragalactic mass determination known. Refsdal predicted the use of gravitational lenses for determining cosmological parameters and for testing cosmological theories [48][49] – we shall return to these issues below.

OBSERVATIONS OF DARK SIDE OF THE UNIVERSE BY GRAVITATIONAL LENSING

2002 ◽  
Vol 17 (20) ◽  
pp. 2677-2687 ◽  
Author(s):  
TOSHIFUMI FUTAMASE
Keyword(s):  
Dark Energy ◽  
Gravitational Lensing ◽  
Mass Concentration ◽  
Recent Observation ◽  
Dark Side ◽  
Observational Cosmology ◽  
Recent Analysis ◽  
Strong Gravitational Lensing ◽  
The Universe

It is now widely recognized that strong and weak gravitational lensing both play important roles in the observational cosmology. We shall here report our proposal and recent observation on the determination of the dark energy using strong gravitational lensing, and our recent analysis of weak shear field around Cl1604+4304 where we found mass concentration with no optical counterparts. Our recent weak shear observation by Subaru/S-Cam is also briefly mentioned.

scholarly journals Gravitational Lensing Of Quasar 0957+561 And The Determination Of H0

1996 ◽  
Vol 173 ◽  
pp. 49-50 ◽  
Author(s):  
George Rhee ◽  
Gary Bernstein ◽  
Tony Tyson ◽  
Phil Fischer
Keyword(s):  
Gravitational Lensing ◽  
Galaxy Cluster ◽  
Cluster Center ◽  
Center Location ◽  
Multiple Imaging ◽  
Unique Model ◽  
The Galaxy

The double quasar 0957+561 was the first discovered instance of multiple imaging via gravitational lensing. The galaxy cluster is an important deflector as well as the first ranked galaxy. This has so far precluded construction of a unique model of the lens, reducing the accuracy of the derived H0 value. We have obtained deep images of the system at CFHT. The cluster is sufficiently massive to cause distortions on distant background galaxy images. We have used a mass map derived from lensing distortions to improve the accuracy of the cluster center location and place new limits on H0.

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