摘要:
   We develop an analytic mass model for lensing galaxies, based  on a broken power-law (BPL) density profile, which is a power-law  profile with a mass deficit or surplus in the central region. Under the  assumption of an elliptically symmetric surface mass distribution, the  deflection angle and magnification can be evaluated analytically for  this new model. We compute the theoretical prediction for various  quantities, including the volume and surface mass density profiles of  the galaxies, and the aperture and luminosity-weighted line-of-sight  velocity dispersions, and compare them to those measured from the  Illustris simulation. We find an excellent agreement between our model  prediction and the simulation, which validates our modeling. The high  efficiency and accuracy of our model manifests itself as a promising  tool for studying properties of galaxies with strong lensing.