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We present the infrared (IR) and X-ray properties of a sample of 33 mid-IRluminous quasars ($\nu$L(6 micron)>6x10$^{44}$ erg/s) at redshift z~1-3,identified through detailed spectral energy distribution analyses of distantstar-forming galaxies, using the deepest IR data from Spitzer and Herschel inthe GOODS-Herschel fields. The aim is to constrain the fraction of obscured,and Compton-thick (CT, N$_H$>1.5x10$^{24}$ cm$^{-2}$) quasars at the peak eraof nuclear and star-formation activities. Despite being very bright in themid-IR band, ~30% of these quasars are not detected in the extremely deep 2 Msand 4 Ms Chandra X-ray data available in these fields. X-ray spectral analysisof the detected sources reveals that the majority (~67%) are obscured by columndensities N$_H$>10$^{22}$ cm$^{-2}$; this fraction reaches ~80% when includingthe X-ray undetected sources (9 out of 33), which are likely to be the mostheavily-obscured, CT quasars. We constrain the fraction of CT quasars in oursample to be ~24-48%, and their space density to be$\Phi$=(6.7$\pm$2.2)x10$^{-6}$ Mpc$^{-3}$. From the investigation of the quasarhost galaxies in terms of star-formation rates (SFRs) and morphologicaldistortions, as a sign of galaxy mergers/interactions, we do not find anydirect relation between SFRs and quasar luminosity or X-ray obscuration. On theother hand, there is tentative evidence that the most heavily-obscured quasarshave, on average, more disturbed morphologies than theunobscured/moderately-obscured quasar hosts, which preferentially live inundisturbed systems. However, the fraction of quasars with disturbed morphologyamongst the whole sample is ~40%, suggesting that galaxy mergers are not themain fuelling mechanism of quasars at z~2.

Mid-infrared luminous quasars in the GOODS-Herschel fields: a large population of heavily-obscured, Compton-thick quasars at z~2