Illuminating the dark ages: Cosmic backgrounds from accretion onto primordial black hole dark matter

Cold dark matter as the sum of different mass Primordial Black Hole (PBH) could explain a number of mysteries, like the massive seed BH needed for the earliest QSOs, the massive LIGO/VIRGO binary BH, or the putative "Planet X" PBH in our Solar System. The most abundant PBH should be around the Chandrasekhar mass. This may already have been vindicated by the recent OGLE/GAIA population of putative BH of 1-10 Msun. I assume that all dark matter exists in the form of 1.4 Msun PBH and estimate the contribution of baryon accretion onto PBH to the cosmic backgrounds, concentrating on the Cosmic X-ray/Cosmic infrared background fluctuations discovered in deep Chandra and Spitzer surveys. Bondi accretion over cosmic time, assuming appropriate values of baryon density and effective relative velocity, as well as accretion and radiation efficiencies, predict a PBH contribution consistent with the residual X-ray fluctuations, peaking at z~17-30 consistent with other constraints requiring high redshifts for this signal. The PBH contribution to the Cosmic Infrared fluctuations is only about 1%, thus these are likely from star formation processes associated with the PBH. Other phenomena could be affected by the PBH accretion. Magnetic fields are an essential ingredient in the accretion process, and PBH can play an important role in amplifying magnetic seed fields in the early universe. The contribution of PBH to the re-ionization history of the universe does not conflict with the stringent limits from the most recent Planck data. X-ray heating from PBH can contribute to the entropy floor observed in groups of galaxies. The redshifted 21-cm absorption line feature observed by EDGES could be connected to the PBH radio emission. The diffuse X-ray emission in the Galactic Center region is not violated by PBH; some of the discrete sources in the Chandra Galactic Ridge observations could be PBH.