{mosimage}For years, astronomers have been trying to find out what is the fraction of Compton thick AGN out of the entire AGN population. Now, by studying the NH distribution in a complete sample of 88 AGN selected in the 20-40 keV band from INTEGRAL/IBIS observations, IASF-BO researcher {cb_profile=malizia}Angela Malizia{/cb_profile} and her team have been able to provide both an answer and an explanation for the disagreement among previous optical and high energy surveys. Their conclusion, soon to be published in Monthly Notices, is that only in the low redshift bin the entire AGN population is seen, while the Compton thick objects are lost at higher redshifts due to their lower intensity. Thus, the fraction of Compton thick objects in the Local Universe can be estimated to be 1 out of 4 AGNs. Their work has been awarded the august 2009 integral picture of the month. Press coverage: see the local issues of Il Corriere della Sera (with images) and L’Informazione.