No LIGO MACHO: Primordial Black Holes, Dark Matter and Gravitational Lensing of Type Ia Supernovae

Abstract

Black hole merger events detected by the Laser Interferometer Gravitational-Wave Observatory (LIGO) have revived dark matter models based on primordial black holes (PBH) or other massive compact halo objects (MACHO). This macroscopic dark matter paradigm can be distinguished from particle physics models through their gravitational lensing predictions: compact objects cause most lines of sight to be demagnified relative to the mean, with a long tail of higher magnifications. We test the PBH model using the lack of lensing signatures on type Ia supernovae (SNe), modeling the effects of large scale structure, allowing for a non-gaussian model for the intrinsic SNe luminosity distribution and addressing potential systematic errors. Using current JLA (Union) SNe data, we derive bounds \(\Omega_{\rm PBH}/\Omega_{\rm M} < 0.346\,(0.405)\) at 95\% confidence, ruling out the hypothesis of MACHO/PBH comprising the totality of the dark matter at \(5.01\sigma (4.28\sigma)\) significance. The finite size of SNe limits the validity of the results to \(M_{\rm PBH} \gtrsim 10^{-2} M_\odot\), fully covering the black hole mergers detected by LIGO and closing that previously open PBH mass range.