Strong gravitational lensing of Bardeen black hole in cloud of strings

In strong gravitational lensing (SGL) photons complete many turns around photon sphere of gravitating objects Lens(Lens). We investigate SGL of regular Bardeen black hole (RBH) in the presence of clouds of strings (CoS) b. We found that angular radius of relativistic, Einstein ring (RER) increases in CoS and decreases with magnetic charge parameter g. Using angular radius of RER, we determined shadow size of BH in CoS. Finally using EHT observation, we constrained CoS for shadows of BH within 1- confidence level. Therefore, it may be possible to detect CoS and magnetic charge of primordial BH in the early Universe with advanced detectors in future.