{"paper":{"title":"Improved upper limits on the 21-cm signal power spectrum of neutral hydrogen at $\\boldsymbol{z \\approx 9.1}$ from LOFAR","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":[],"primary_cat":"astro-ph.CO","authors_text":"A. Ghosh, A. M. Sardarabadi, A. R. Offringa, B. Ciardi, B. K. Gehlot, E. Chapman, F. G. Mertens, G. Mellema, H. Gan, H. K. Vedantham, I. T. Iliev, J. Schaye, K. M. B. Asad, L.V.E Koopmans, M. A. Brentjens, M. B. Silva, M. Mevius, R. Ghara, R. Kooistra, R. Mondal, S. Gazagnes, S. K. Giri, S. Yatawatta, S. Zaroubi, V. Jeli\\'c, V. N. Pandey","submitted_at":"2020-02-17T19:00:10Z","abstract_excerpt":"A new upper limit on the 21-cm signal power spectrum at a redshift of $z \\approx 9.1$ is presented, based on 141 hours of data obtained with the Low-Frequency Array (LOFAR). The analysis includes significant improvements in spectrally-smooth gain-calibration, Gaussian Process Regression (GPR) foreground mitigation and optimally-weighted power spectrum inference. Previously seen `excess power' due to spectral structure in the gain solutions has markedly reduced but some excess power still remains with a spectral correlation distinct from thermal noise. This excess has a spectral coherence scale"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"2002.07196","kind":"arxiv","version":2},"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/2002.07196/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"}