Abstract

Polarization data for Mrk 421 and 501 in several spectral bands from 0.36 to 0.84 micron, are presented. Wavelength dependence of the linear polarization is found for both objects. A model consisting of a mini-BL Lacertae object embedded in the nucleus of an elliptical galaxy is developed. The spectral index of the power-law energy distribution of the mini-BL Lacertae object and the relative contribution to the total flux in the B band are found to be 0.92 and 88% for Mrk 421, and 0.83 and 68% for Mrk 501. Potential application of the technique to other BL Lacertae objects is discussed.