LAUSR

We have studied numerically the shadows of a non-Kerr rotating compact object which belongs to Manko-Novikov family. The non-integrable photon motion caused by quadrupole mass moment affects sharply the shadow of the compact object. As the quadrupole mass moment parameter is negative, the shadow of compact object is prolate and there are two disconnected main shadows with eyebrows located symmetrically on both sides of the equatorial plane. As the quadrupole mass moment parameter is positive, the shadow becomes oblate and the main shadow is joined together in the equatorial plane. Moreover, in this positive cases, there is a disorder region in the left of shadow which increases with the quadrupole mass moment parameter. Interestingly, we also find that Einstein ring is broken as the deviation from Kerr metric is larger than a certain critical value. This critical value decreases with the rotation parameter of black hole. Especially, the observer on the direction of rotation axis will find some concentric bright rings in the black disc. Our result show that the presence of quadrupole mass moment brings richer patterns for the shadow of a non-Kerr rotating compact object.