{"paper":{"title":"Reconstructing the Last Major Merger of the Milky Way with the H3 Survey","license":"http://creativecommons.org/licenses/by/4.0/","headline":"","cross_cats":[],"primary_cat":"astro-ph.GA","authors_text":"Ana Bonaca, Charlie Conroy, Dennis Zaritsky, Jiwon Jesse Han, Joshua S. Speagle, Nelson Caldwell, Phillip A. Cargile, Rainer Weinberger, Rohan P. Naidu, Sandro Tacchella, Yuan-Sen Ting","submitted_at":"2021-03-04T19:00:00Z","abstract_excerpt":"Several lines of evidence suggest the Milky Way underwent a major merger at z~2 with a galaxy known as Gaia-Sausage-Enceladus (GSE). Here we use H3 Survey data to argue that GSE entered the Galaxy on a retrograde orbit based on a population of highly retrograde stars with chemistry similar to the largely radial GSE debris. We present the first tailored, high-resolution N-body simulations of the merger. From a grid of ~500 simulations we find a GSE with $M_{*}=5\\times10^{8}\\ M_{\\odot}, M_{\\rm{DM}}=2\\times10^{11} M_{\\odot}$ (a 2.5:1 total mass merger) best matches the H3 data. This simulation sh"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"2103.03251","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/2103.03251/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"}