M. AckermannM. AjelloL. BaldiniJ. BalletG. BarbielliniD. BastieriJ. Becerra GonzalezR. BellazziniE. BissaldiR. D. BlandfordE. D. BloomR. BoninoE. BottaciniJ. BregeonP. BruelR. BuehlerS. BusonR. A. CameronM. CaragiuloP. A. CaraveoE. CavazzutiC. CecchiC. C. CheungJ. ChiangG. ChiaroS. CipriniJ. ConradD. CostantinF. CostanzaS. CutiniF. D'AmmandoF. De PalmaR. DesianteS. W. DigelN. Di LallaM. Di MauroL. Di VenereA. DomínguezP. S. DrellC. FavuzziS. J. FeganE. C. FerraraJ. FinkeW. B. FockeY. FukazawaS. FunkP. FuscoF. GarganoD. GasparriniN. GigliettoF. GiordanoM. GirolettiD. GreenI. A. GrenierL. GuillemotS. GuiriecD. H. HartmannE. HaysD. HoranT. JoglerG. JóhannessonA. S. JohnsonM. KussG. La MuraS. LarssonL. LatronicoJ. LiF. LongoF. LoparcoM. N. LovelletteP. LubranoJ. D. MagillS. MalderaA. ManfredaL. MarcotulliM. N. MazziottaDeutsche Elektronen-SynchrotronClemson UniversityUniversità di PisaUniversite Paris 7- Denis DiderotIstituto Nazionale di Fisica Nucleare, RomaUniversità degli Studi di TriesteIstituto Nazionale Di Fisica Nucleare, Sezione di PadovaUniversità degli Studi di PadovaNASA Goddard Space Flight CenterUniversity of MarylandIstituto Nazionale Di Fisica Nucleare, Sezione di PisaKavli Institute for Particle Astrophysics and CosmologyUniversità degli Studi di TorinoLaboratoire Univers et Particules de MontpellierLaboratoire Leprince-RinguetUniversità degli Studi di BariINAF Istituto di Astrofisica Spaziale e Fisica Cosmica, MilanAgenzia Spaziale ItalianaUniversità degli Studi di PerugiaNaval Research LaboratoryStockholms universitetOskar Klein Centre for Cosmoparticle PhysicsINAF Istituto di Astrofisica Spaziale e Fisica Cosmica, BolognaAlma Mater Studiorum Università di BolognaUniversità degli Studi di Napoli Federico IIUniversità degli Studi di UdineHiroshima UniversityErlangen Centre for Astroparticle PhysicsUniversite d'OrleansInstitut National des Sciences de l'UniversFriedrich-Alexander-Universität Erlangen-NürnbergUniversity Science Institute ReykjavikThe Royal Institute of Technology (KTH)Universitat Autònoma de BarcelonaMahidol UniversityUniversity of DenverMax Planck Institut für Physik (Werner-Heisenberg-Institut)Osservatorio Astronomico di Trieste2018-12-212019-03-142018-12-212019-03-142017-03-01Astrophysical Journal Letters. Vol.837, No.1 (2017)20418213204182052-s2.0-85015148943https://repository.li.mahidol.ac.th/handle/20.500.14594/42507© 2017. The American Astronomical Society. All rights reserved. The detection of high-redshift (z > 3) blazars enables the study of the evolution of the most luminous relativistic jets over cosmic time. More importantly, high-redshift blazars tend to host massive black holes and can be used to constrain the space density of heavy black holes in the early universe. Here, we report the first detection with the Fermi-Large Area Telescope of five γ-ray-emitting blazars beyond z = 3.1, more distant than any blazars previously detected in γ-rays. Among these five objects, NVSS J151002+570243 is now the most distant known γ-ray-emitting blazar at z = 4.31. These objects have steeply falling γ-ray spectral energy distributions (SEDs), and those that have been observed in X-rays have a very hard X-ray spectrum, both typical of powerful blazars. Their Compton dominance (ratio of the inverse Compton to synchrotron peak luminosities) is also very large (>20). All of these properties place these objects among the most extreme members of the blazar population. Their optical spectra and the modeling of their optical-UV SEDs confirm that these objects harbor massive black holes (MBH ∼ 10 8-10 Mo ). We find that, at z ≈ 4, the space density of >109 Mo black holes hosted in radio-loud and radio-quiet active galactic nuclei are similar, implying that radio-loudness may play a key role in rapid black hole growth in the early universe.Mahidol UniversityEarth and Planetary SciencesArticleSCOPUS10.3847/2041-8213/aa5fff