{"paper":{"title":"High-$z$ radio Quasars in RACS I: Selection, identification, and multi-wavelength properties","license":"http://creativecommons.org/licenses/by/4.0/","headline":"","cross_cats":["astro-ph.HE"],"primary_cat":"astro-ph.GA","authors_text":"A. Caccianiga, A. L\\'opez-S\\'anchez, A. Moretti, A. Rossi, B. Arsioli, C. Reynolds, C. Spingola, C. Vignali, D. Dallacasa, F. Rigamonti, F. Tavecchio, I. Matute, J. Afonso, J. K. Leung, J. W. Broderick, L. Ighina, N. Seymour, P. Severgnini, R. Della Ceca, S. Bisogni, T. An, T. Connor, Y. Liu, Z. Wang","submitted_at":"2025-04-14T18:00:00Z","abstract_excerpt":"Radio-bright, jetted quasars at $z>5$ serve as unique laboratories for studying supermassive black hole activity in the early Universe. In this work, we present a sample of high-$z$ jetted quasars selected from the combination of the radio Rapid ASKAP Continuum Survey (RACS) with deep wide-area optical/near-infrared surveys. From this cross-match we selected 45 new high-$z$ radio quasar candidates with S$_{888MHz}>1$ mJy and mag$z<21.3$ over an area of 16000deg$^2$. Using spectroscopic observations, we confirmed the high-$z$ nature of 24 new quasars, 13 at $4.5<z<5$ and 11 at $z>5$. If we also"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"2504.10573","kind":"arxiv","version":1},"verdict":{"id":null,"model_set":{},"created_at":null,"strongest_claim":"","one_line_summary":"","pipeline_version":null,"weakest_assumption":"","pith_extraction_headline":""},"integrity":{"clean":true,"summary":{"advisory":0,"critical":0,"by_detector":{},"informational":0},"endpoint":"/pith/2504.10573/integrity.json","findings":[],"available":true,"detectors_run":[],"snapshot_sha256":"c28c3603d3b5d939e8dc4c7e95fa8dfce3d595e45f758748cecf8e644a296938"},"references":{"count":0,"sample":[],"resolved_work":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","internal_anchors":0},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"}