Feasibility of Primordial Black Hole Remnants as Dark Matter in View of Hawking Radiation Recoil

Abstract: It has recently been suggested that black hole remnants of primordial origin are not a viable dark matter candidate since they would have far too large a velocity due to the recoil of Hawking radiation. We re-examined this interesting claim in more details and found that it does not rule out such a possibility. On the contrary, for models based on non-commutativity of spacetime near the Planck scale, essentially the same argument can be used to estimate the scale at which non-commutativity effect becomes important. If dark matter "particles" are non-commutative black holes that have passed the maximum temperature, this implies that the non-commutative scale is about 100 times the Planck length. The same analysis applies to other black hole remnants whose temperature reaches a maximum before cooling off, for example, black holes in asymptotically safe gravity.