{"paper":{"title":"Constraining Cosmic Evolution of Type Ia Supernovae","license":"","headline":"","cross_cats":[],"primary_cat":"astro-ph","authors_text":"A. C. Becker, A. Clocchiatti, A. G. Riess, A. Miceli, A. Rest, A. V. Filippenko, A. Zenteno, B. Leibundgut, B. P. Schmidt, C. Aguilera, C. W. Stubbs, G. Miknaitis, G. Pignata, J. L. Tonry, J. Sollerman, J. Spyromilio, K. Krisciunas, N. B. Suntzeff, P. Challis, P. M. Garnavich, R. Covarrubias, R. C. Smith, R. P. Kirshner, Ryan J. Foley, S. Blondin, S. Jha, T. Matheson, T. M. Davis, W. Li, W. M. Wood-Vasey","submitted_at":"2007-10-11T20:00:34Z","abstract_excerpt":"We present the first large-scale effort of creating composite spectra of high-redshift type Ia supernovae (SNe Ia) and comparing them to low-redshift counterparts. Through the ESSENCE project, we have obtained 107 spectra of 88 high-redshift SNe Ia with excellent light-curve information. In addition, we have obtained 397 spectra of low-redshift SNe through a multiple-decade effort at Lick and Keck Observatories, and we have used 45 UV spectra obtained by HST/IUE. The low-redshift spectra act as a control sample when comparing to the ESSENCE spectra. In all instances, the ESSENCE and Lick compo"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"0710.2338","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":""},"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"}