LAUSR

Dark matter could comprise, at least in part, primordial black holes (PBH). To test this hypothesis, we present an approach to constrain the PBH mass (MPBH) and mass fraction (fPBH) from the flux ratios of quadruply imaged quasars. Our approach uses an approximate Bayesian computation (ABC) forward modeling technique to directly sample the posterior distribution of MPBH and fPBH, while marginalizing over the subhalo mass function amplitude, spatial distribution, and the size of the lensed source. We apply our method to 11 quadruply-imaged quasars and derive a new constraint on the intermediate-mass area of PBH parameter space 104M⊙ < MPBH < 106M⊙. We obtain an upper limit fPBH < 0.17 (95  per cent C.L.). This constraint is independent of all other previously published limits.