Image of the Schwarzschild black hole pierced by a cosmic string with a thin accretion disk

We study the optical appearance of a thin accretion disk around a Schwarzschild black hole pierced by a cosmic string with a semi-analytic method of Luminet [Astron. Astrophys. 75 (1979) 228]. Direct and secondary images with different parameters observed by a distant observer are plotted. The cosmic string parameter s can modify the shape and size of the thin disk image. We calculate and plot the distribution of both redshift and observed flux as seen by distant observers at different inclination angles. Those distributions are dependent on the inclination angle of the observer and cosmic string parameter s.