Showing 2002Show all
2 papers · 1 filter
astro-ph2002
A New Mass Degeneracy in Gravitational Lenses: Is there a crisis between a large and the time delay by a large lens halo?
HongSheng Zhao, Bo Qin
Isothermal models and other simple smooth models of dark matter halos of gravitational lenses often predict a dimensionless time delay much too small to be comfortable with…
astro-ph2002
Probing Galaxy Formation with High Energy Gamma-Rays
Joel R. Primack
I discuss how measurements of the absorption of -rays from GeV to TeV energies via pair production on the extragalactic background light (EBL) can probe important issues in gala…