Strong Gravitational Lensing by Bardeen Black Hole in Cloud of Strings

We investigate the gravitational lensing by Bardeen black hole in cloud of strings (CoS) in strong field limit. The effect of CoS parameter $b$ has been outlined in comparison with Bardeen black hole lens. The strong deflection limit coefficients are determined in terms of impact parameter for various values of CoS parameter. We obtain magnification of relativistic images and determine relativistic Einstein rings by using the parameters of two astrophysical black hole lenses $SgrA^{*}$ and $M87^{*}$. We constrain CoS parameter of Bardeen black hole using EHT observations for these black holes.