ﻻ يوجد ملخص باللغة العربية
We model the mass distribution in the recently discovered Einstein ring LBG J213512.73-010143 (the `Cosmic Eye) using archival Hubble Space Telescope imaging. We reconstruct the mass density profile of the z=0.73 lens and the surface brightness distribution of the z=3.07 source and find that the observed ring is best fit with a dual-component lens model consisting of a baryonic Sersic component nested within a dark matter halo. The dark matter halo has an inner slope of 1.42+/-0.23, consistent with CDM simulations after allowing for baryon contraction. The baryonic component has a B-band mass-to-light ratio of 1.71+0.28-0.38 (solar units) which when evolved to the present day is in agreement with local ellipticals. Within the Einstein radius of 0.77 (5.6 kpc), the baryons account for (46+/-11)% of the total lens mass. External shear from a nearby foreground cluster is accurately predicted by the model. The reconstructed surface brightness distribution in the source plane clearly shows two peaks. Through a generalisation of our lens inversion method, we conclude that the redshifts of both peaks are consistent with each other, suggesting that we are seeing structure within a single galaxy.
The non-detection of dark matter (DM) particles in increasingly stringent laboratory searches has encouraged alternative gravity theories where gravity is sourced only from visible matter. Here, we consider whether such theories can pass a two-dimens
We introduce the Illustris Project, a series of large-scale hydrodynamical simulations of galaxy formation. The highest resolution simulation, Illustris-1, covers a volume of $(106.5,{rm Mpc})^3$, has a dark mass resolution of ${6.26 times 10^{6},{rm
We show that proton storage ring experiments designed to search for proton electric dipole moments can also be used to look for the nearly dc spin precession induced by dark energy and ultra-light dark matter. These experiments are sensitive to both
In the present paper we derive the density distribution of dark matter (DM) in a well-observed nearby disc galaxy, the Andromeda galaxy. From photometrical and chemical evolution models constructed in the first part of the study (Tamm, Tempel & Tenje
We construct a structural model of the Andromeda Galaxy, simultaneously corresponding to observed photometrical and kinematical data and chemical abundances. In this paper we present the observed surface brightness, colour and metallicity distributio