This is because a dusty, doughnut-shaped torus of gas and dust (the "obscuring torus" from AGN unification models) surrounds the equatorial plane of the black hole. In Mrk 231, we are viewing the system at an angle where the line of sight passes through the edge of this torus, dimming and reddening the blue quasar light, while polarized light scattered from above the torus remains blue.
For amateur astronomers, Mrk 231 is a challenging target. It is not visible in small telescopes. markarian 231
Discovered on photographic plates by the Armenian astrophysicist in 1969 as part of his survey of galaxies with excessive ultraviolet radiation, Mrk 231 has since become a cosmic laboratory for understanding galactic collisions, supermassive black hole growth, and the dramatic termination of star formation. This is because a dusty, doughnut-shaped torus of
A smaller black hole, weighing about 4 million solar masses, orbiting the primary. It is not visible in small telescopes