Just as real as the concepts of particles at all. They're just really likely to recombine because they form in pairs of opposite charges and will attract and a

Just as real as the concepts of particles at all. They're just really likely to recombine because they form in pairs of opposite charges and will attract and annihilate. Hawking radiation is adding another force with a gradient (extremely strong gravity near an event horizon) that'll absorb one of the particles of the pair, and then the other flies off into space as the real, bona fide particle it always was.