Reionization of the early Universe by electromagnetic cascades from microquasars

DOUNA, VANESA M.; MIRABEL, I. FÉLIX; PELLIZZA, LEONARDO J.; LAURENT, PHILIPPE

Porquerolles

Workshop; From Quiescence to Outburst: when microquasares go wild; 2017

CNRS

Reionization is one of the main cosmological phase transitions of the Universe. Observational evidence shows that ~1Gyr after the Big Bang, the intergalactic medium was ionized, although it had become neutral much before, when the Cosmic Microwave Background was released ~0.3 Myr after the Big Bang. Despite the increasing knowledge of the Epoch of Reionization in light of the new observational skills, the sources of reionization are still being debated. UV photons from massive stars seem to be the main reionization agents, although X-rays from accreting black-hole populations and cosmic rays have also been considered. At this age, massive black holes should be in majority in the accreting black hole populations, and thus microquasars should have contributed, as they display jets in which electrons are accelerated to multi-TeV energies and ionize the surrounding medium. With the aim of studying the kinetic feedback of microquasars, we simulated by means of a Monte Carlo scheme, the propagation of the electrons injected by these sources. In this work, we explore the contribution of the electromagnetic cascades they initiate to the ionization and heating of the intergalactic medium at cosmic dawn.