{"paper":{"title":"Improved recipes for peculiar velocity power spectra using Evolution Mapping","license":"http://creativecommons.org/licenses/by/4.0/","headline":"New fitting functions for peculiar velocity power spectra reach 1-2 percent accuracy by parametrizing non-linear evolution with the clustering amplitude σ12.","cross_cats":[],"primary_cat":"astro-ph.CO","authors_text":"Andr\\'es N. Ruiz, Ariel G. S\\'anchez, Julien Bel, Matteo Esposito","submitted_at":"2026-05-13T18:00:00Z","abstract_excerpt":"We present new fitting functions for the velocity divergence auto- and cross-power spectra, $P_{\\theta\\theta}(k)$ and $P_{\\delta\\theta}(k)$, calibrated on gravity-only $N$-body simulations. By applying the Evolution Mapping framework, we revise existing prescriptions to introduce a physically motivated parametrisation in terms of the clustering amplitude $\\sigma_{12}$, the RMS density fluctuation smoothed at $12\\,\\text{Mpc}$. This approach improves robustness and extends the range of applicability beyond that of previous models. Our fits are calibrated using a suite of multi-resolution simulat"},"claims":{"count":4,"items":[{"kind":"strongest_claim","text":"Validation against independent simulations spanning a broad range of cosmological models confirms an accuracy of 1-2 per cent on scales where the measurements are robust, systematically outperforming existing prescriptions.","source":"verdict.strongest_claim","status":"machine_extracted","claim_id":"C1","attestation":"unclaimed"},{"kind":"weakest_assumption","text":"That neglecting deviations from the exact evolution mapping relation induced by differing growth histories introduces only subdominant errors for most cosmologies of practical interest.","source":"verdict.weakest_assumption","status":"machine_extracted","claim_id":"C2","attestation":"unclaimed"},{"kind":"one_line_summary","text":"Improved fitting functions for P_θθ(k) and P_δθ(k) parametrized by σ12 achieve 1-2% accuracy across cosmologies and outperform existing prescriptions.","source":"verdict.one_line_summary","status":"machine_extracted","claim_id":"C3","attestation":"unclaimed"},{"kind":"headline","text":"New fitting functions for peculiar velocity power spectra reach 1-2 percent accuracy by parametrizing non-linear evolution with the clustering amplitude σ12.","source":"verdict.pith_extraction.headline","status":"machine_extracted","claim_id":"C4","attestation":"unclaimed"}],"snapshot_sha256":"8b4e3a1d2f9933851c481c871269546dd69770a34ef03ae0dcd97d6236e0994d"},"source":{"id":"2605.13948","kind":"arxiv","version":1},"verdict":{"id":"1c201f5c-e2c7-4321-8976-aff3f2267a47","model_set":{"reader":"grok-4.3"},"created_at":"2026-05-15T02:24:26.683336Z","strongest_claim":"Validation against independent simulations spanning a broad range of cosmological models confirms an accuracy of 1-2 per cent on scales where the measurements are robust, systematically outperforming existing prescriptions.","one_line_summary":"Improved fitting functions for P_θθ(k) and P_δθ(k) parametrized by σ12 achieve 1-2% accuracy across cosmologies and outperform existing prescriptions.","pipeline_version":"pith-pipeline@v0.9.0","weakest_assumption":"That neglecting deviations from the exact evolution mapping relation induced by differing growth histories introduces only subdominant errors for most cosmologies of practical interest.","pith_extraction_headline":"New fitting functions for peculiar velocity power spectra reach 1-2 percent accuracy by parametrizing non-linear evolution with the clustering amplitude σ12."},"references":{"count":60,"sample":[{"doi":"10.1093/mnras/stac1656","year":null,"title":"Evolution mapping: a new approach to describe matter clustering in the non-linear regime. , keywords =. doi:10.1093/mnras/stac1656 , archivePrefix =. 2108.12710 , primaryClass =","work_id":"dd16ca4c-5923-4aff-a509-be13fb6c6265","ref_index":1,"cited_arxiv_id":"","is_internal_anchor":false},{"doi":"10.1103/physrevd.102.123511","year":2020,"title":"S\\'anchez, Ariel G. , journal =. Arguments against using. 2020 , month =. doi:10.1103/PhysRevD.102.123511 , url =","work_id":"471cf04b-3b6f-4f2b-bd8a-eeb67b51018a","ref_index":2,"cited_arxiv_id":"","is_internal_anchor":false},{"doi":"10.1142/s0218271801000822","year":null,"title":"Accelerating uni- verses with scaling dark matter","work_id":"7789cbe1-9129-4380-a7e9-282bec1dbc92","ref_index":3,"cited_arxiv_id":"gr-qc/0009008","is_internal_anchor":true},{"doi":"10.1103/physrevlett.90.091301","year":2003,"title":"Exploring the expansion history of the universe","work_id":"21c058c4-5cce-4dfe-a752-363d53aa7f88","ref_index":4,"cited_arxiv_id":"","is_internal_anchor":false},{"doi":"","year":null,"title":"Galaxy Formation and Evolution","work_id":"ace00c7d-38ba-4c2c-89fc-5e2f4fc489d8","ref_index":5,"cited_arxiv_id":"","is_internal_anchor":false}],"resolved_work":60,"snapshot_sha256":"bc217e8ce9e0d5cb2615b6eed723626b8a83834e849d64c276447c1a264f26bc","internal_anchors":11},"formal_canon":{"evidence_count":2,"snapshot_sha256":"cbc1301091cf38445774af00680fcea199ca8499530a52a92b45ea1c471f7bab"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"}