Remarks on Dark Matter Constituents with Many Solar Masses

Abstract

Dark matter constituents of many solar masses will accrete normal matter which emits X-rays that can be downgraded to microwaves which may distort the precisely-measured black-body spectrum of the Cosmic Microwave Background. However, it is known from elsewhere that spherical models of accretion vastly overestimate the amount accreted and consequently the emitted X-rays. Therefore, exclusion plots based on spherical accretion for the allowed fraction of the dark matter versus the MACHO mass give upper limits on intermediate-mass MACHOs which are too severe, sometimes by orders of magnitude.