  We report on a study of 9 nearby star-forming, very low-metallicity galaxies
observed by Hubble's COS far-UV spectrograph that can serve as templates of
high-z galaxies to be observed by JWST. We find that the nebular spectra of
these primitive galaxies show evidence of irradiation by X-ray emitters.
Following Thuan et al. (2004), we identify the sources of X-ray emission as
massive X-ray binaries containing a massive accreting stellar black hole. We
further find that the lower the metallicity, the higher the probability of
strong X-irradiation. Following Heger et al. (2003), we suggest that these
accreting black holes are produced by direct collapse of stars having initial
masses greater than $\sim50\, M_\odot$. Our models of young star clusters with
an embedded stellar black hole produce effects on the surrounding gaseous
medium that are consistent with the observed spectra. We conclude that
primitive galaxies are qualitatively different from more metal-rich galaxies in
showing evidence of hard radiation that can best be explained by the presence
of one or more embedded stellar black holes.
