Does CMB Distortion Disfavour Intermediate Mass Dark Matter?

Abstract

We investigate the published constraints on MACHOs in the mass region $10^2 - 10^5 M_{\odot}$ and their possible contribution to dark matter. We focus on constraints which rely on the accretion of matter which emits X-rays that can lead, after downgrading to microwaves, to distortion of the CMB spectrum and isotropy. The most questionable step in this chain of arguments is the use of overly simplified accretion models. We compare how the same accretion models apply to X-ray observations from supermassive black holes SMBHs, M87 and Sgr A*. The comparison of these two SMBHs with intermediate mass MACHOs suggests that the latter could, after all, provide the constituents of all the dark matter. We discuss the status of other constraints on IM-MACHOs.