The intensity ratio in different wave bands between images of gravitationally lensed quasars as a probe of dark matter

Abstract

We constrain the possible mass range of clumpy constituents of dark matter in galactic halos and in clusters, with the help of presently available observations of intensity ratios in different wave bands between images of gravitationally lensed quasars. It would appear that compact objects with a mass M<SUB>c</SUB> in the range 1 &lt; M<SUB>c</SUB> &lt; 3 × 10<SUP>4</SUP> M<SUB>sun</SUB> are probably unlikely to be the constituents of dark matter in the lens galaxy and cluster of the twin quasar 0957 + 561 and the possible lens galaxy of 1115 + 080. There is some tentative evidence of massive compact objects in the mass range 3 × 10<SUP>4</SUP> &lt; M<SUB>c</SUB> &lt; 3 × 10<SUP>7</SUP> M<SUB>sun</SUB>, making up the halos of the lens galaxies in the case of the multiply imaged system MG 2016 + 112. These objects may be likened to the very massive objects which have been invoked as possible candidates for the dark matter in galaxies. We also emphasize the use of certain aspects of Ricci focusing of light beams in a clumpy lens, which we refer to as "implicit minilensing," as a valuable probe of dark matter.