Contents

• GRB show mass-dependent obscuration
• Predicted by simulations
• Metallicity-effects
• Host galaxy obscuration for AGN population
• Caveats: SF distribution, metallicity, host mass
• Galaxy gas+dust can explain much of the AGN obscuration at NH = 1022 – 1023 cm-2
• Consistent with simulations
• Nuclear obscurer model for Torus modellers & simulations
• Covering factors is dependent on
• Black hole mass
• Accretion rate (X-ray luminosity)
• Host galaxy mass

Consistent with Swift/BAT survey

Consistent with IR covering fractions