Stability of a bound system of electron or proton orbiting a small black hole in cosmic conditions

Mini black holes (BH) of various mass could be left over in space from the early expansion Big Bang phase (so called primordial BHs) and can be a part of dark matter (DM). As a result of interaction of those BHs with the interstellar hydrogen they could form a bound system with an electron or a proton (or both). However, the stability of such system depends on a few factors -- BH mass, limits imposed by both special relativity (SR) and general relativity (GR) on such quantum system, gravitational radiation they could emit, as well as the environmental factors -- ionizing effects of starlight, starwind, cosmic microwave background radiation (CMBR), interstellar magnetic field, etc. We analyze those limitations to find lifetimes of such ``gravitational atoms'' in typical interstellar space conditions