Lyman continuum leaking AGN in SSA22 field

Two show offsets and likely have stellar LyCin nature or are foreground contaminants. The remaining two LyC candidates are type I AGN.

We argue that the average LyC escape fraction of high-redshift, low-luminosity AGN is not likely to be unity, as often assumed in the literature. From direct measurement we obtain the average LyC-to-UV flux density ratio and ionizing emissivity for a number of AGN classes and find it at least a factor of 2 lower than values obtained assuming f_esc_=1. Comparing to recent Ly{alpha} forest measurements, AGNs at redshift z~3 make up at most ~12 per cent and as little as ~5 per cent of the total ionizing budget.