Gravitational Lensing and Elliptical Galaxies
نویسندگان
چکیده
The probability that high-redshift quasars are gravitationally-lensed by intervening galaxies increases rapidly with the cosmological constant, ΩΛ0 (whilst being only weakly dependent on the density parameter, Ωm0), and the low number of lenses observed implies that ΩΛ0 ∼< 0.7 (e.g. Kochanek 1996). One of many uncertainties has been the (small) core radii of elliptical galaxies, which, at least naively, reduce their lensing cross-section. However, if ellipticals are normalised relative to their observed line-of-sight velocity dispersion, σ||, then increasing the core radius must result in an increased mass normalisation (specified by the assymptotic velocity dispersion, σ∞).
منابع مشابه
Looking at the Fundamental Plane through a gravitational lens
We consider the Fundamental Plane of elliptical galaxies lensed by the gravitational field of a massive deflector (typically, a cluster of galaxies). We show that the Fundamental Plane relation provides a straightforward measurement of the projected mass distribution of the lens with a typical accuracy of ≈ 0.15 in the dimensionless column density κ. The proposed technique breaks the mass-sheet...
متن کاملWeek 7: Gravitational Lensing
According to general relativity, the trajectories of light rays can be bent by gravitational fields. Massive objects can therefore gravitationally “lens” the images of objects behind them. A cosmological examples of gravitational lensing is lensing of galaxies or quasars at redshifts z ∼ 1 by elliptical galaxies or galaxy clusters along the line of sight. If the lensing is “strong,” then there ...
متن کاملCold Dark Matter and Strong Gravitational Lensing: Concord or Conflict?
Using the number and sizes of observed gravitational lenses, I derive upper limits on the dark matter content of elliptical galaxies. On average, dark matter can account for no more than 33% of the total mass within one effective radius (Re) of elliptical galaxies, or 40% of the mass within 2Re (95% confidence upper limits). I show that galaxies built from Cold Dark Matter (CDM) mass distributi...
متن کاملBayesian analysis of joint strong gravitational lensing and dynamic galactic mass in SLACS: evidence of line-of-sight contamination
We readdress the calculation of the mass of early-type galaxies using strong gravitational lensing and stellar dynamics. Our sample comprises 27 galaxies in the Sloan Lens ACS (SLACS) Survey. Comparing the mass estimates from these two independent methods in a Bayesian framework, we find evidence of significant line-of-sight mass contamination. Assuming a powerlaw mass distribution, the best fi...
متن کاملGravitational Lensing in Low-redshift Clusters of Galaxies: the Arc-like Object in Abell 3408 and Its Lensing Interpretation
We analyze the seldomly discussed lensing effects expected in low-z clusters (z = 0.05-0.15), using as an example the bright arc (z = 0.073) discovered by Campusano and Hardy(1996) near the central elliptical galaxy of the cluster Abell 3408 (z = 0.042). The photometric and spectroscopic observations for both the central elliptical and the arc are presented. The mass distribution in A3408 is mo...
متن کاملWhat Are the Environments of Lens Galaxies?
Using measured tangential shear profiles and number counts of massive elliptical galaxies, the halo occupation distribution of strong lensing galaxies is constrained. The resulting HOD is then used to populate an N-body simulation with lens galaxies, in order to assess the importance of environment for strong lensing systems. Typical estimated values for the convergence and shear produced by ne...
متن کامل