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A direct search of $\gamma$-ray emission centered on multi-frequency selectedcandidates is a valuable complementary approach to the standard search adoptedin current $\gamma$-ray Fermi-LAT catalogs. Our candidates are part of the2WHSP sample, that was assembled with the aim of providing targets for ImagingAtmospheric Cherenkov Telescopes (IACT), and is currently the largest set ofhigh synchrotron peaked (HSP) blazars. We perform a likelihood analysis withthe Fermi Science Tools using positions from 400 2WHSP blazars as seeds oftentative $\gamma$-ray sources. This enabled us to detect 150 $\gamma$-rayexcess signals that have not yet been reported in previous $\gamma$-raycatalogs (1FGL, 2FGL, and 3FGL). By identifying new sources, we solve afraction of the extragalactic isotropic $\gamma$-ray background (IGRB)composition, improving the description of the $\gamma$-ray sky. Our analysisconsiders the 0.3-500 GeV energy band, integrating over 7.2 yrs of Fermi-LATobservation and making use of the Pass 8 data release. Within the 150 2WHSPsthat showed excess $\gamma$-ray signature: 85 are high-significance detectionswith test statistic (TS)$>$25, and 65 are lower-significance detections with TSbetween 10 to 25. We study the $\gamma$-ray photon spectral index distribution,the likelihood of detection according to the synchrotron peak brightness, andplot the measured $\gamma$-ray LogN-LogS of HSP blazars, also discussing theportion of the IGRB that has been resolved by this work. We report on fourcases where we could resolve source confusion and find counterparts forunassociated 3FGL sources with the help of high-energy TS maps together withmulti-frequency data. The 150 new $\gamma$-ray sources are named with theacronym 1BIGB for the first version of the Brazil ICRANet Gamma-ray Blazarcatalog, in reference to the cooperation agreement supporting this work.

Searching for $\gamma$-ray signature in WHSP blazars: Fermi-LAT detection of 150 excess signal in the 0.3-500 GeV band