Observational appearance of the spherically symmetric black hole in PFDM

We investigate the observational appearance of spherically symmetric black holes in perfect fluid dark matter (PFDM), with the celestial sphere and an accretion disk being light sources. For the celestial sphere model, we show the variations in black holes' appearance from different angles. And for an optically thin accretion disk, the intensity observed can be characterized by the redshift factor and the transfer functions. Then we investigate the angular dependencies for a resting and rotating accretion disk, respectively. It is found that as the observation angle increases, the blue-shift effect of black holes in rotating accretion disks becomes more pronounced. Our study may provide new insights into the physical characteristics of PFDM black holes and their surrounding environment.