Primordial black holes having gravitomagnetic monopole

A primordial black hole (PBH) is thought to be made of the regular matter or ordinary mass (M) only, and hence could have already been decayed due to the Hawking radiation if its initial ordinary mass were ≲5×1011 kg. Here, we study the role of a gravitomagnetic monopole for the evaporation of PBHs, and propose that the lower-energy PBHs (equivalent to ordinary mass M≪5×1011 kg) could still exist in our present Universe, if it has a gravitomagnetic monopole. If a PBH was initially made of both regular matter and a gravitomagnetic monopole, the regular matter could decay away due to the Hawking radiation. The remnant gravitomagnetic monopole might not entirely decay, which could still be found as a PBH in the form of the 'pseudomass-energy'. If a PBH with M5×1011 kg is detected, one may not be able to conclude if it has gravitomagnetic monopole, but, a plausible detection of a relatively low-energy (equivalent to 2.176×10-8 kg<M5×1011 kg) PBH in future may imply the existence of a gravitomagnetic monopole PBH, which may or may not contain the ordinary mass.