{"work":{"id":"17119633-e3c8-4915-a6cc-48f7a07e8901","openalex_id":null,"doi":null,"arxiv_id":"2601.10573","raw_key":null,"title":"Origins of the UV continuum and Balmer emission lines in Little Red Dots: observational validation of dense gas envelope models enshrouding the AGN","authors":null,"authors_text":"Asada, Y","year":2026,"venue":"astro-ph.GA","abstract":"We present a statistical study on the origins of the UV continuum and narrow/broad emission lines in little red dots (LRDs), presumably involving active galactic nuclei (AGNs). Leveraging all archived JWST/NIRSpec data, we build a sample of 27 spectroscopically-confirmed LRDs at $5<z_{\\rm spec}<7.2$, by requiring broad H$\\alpha$ emission, blue UV colors, V-shaped continua, and compact morphology. We define a control sample of 7 blue, compact, broad-line AGNs without red optical continua (hereafter little blue dots; LBDs), and examine correlations between rest UV and the narrow/broad H$\\alpha$ luminosities in these populations. In LRDs, both narrow and broad H$\\alpha$ components are tightly correlated with the UV continuum, and the luminosity ratios are consistent with those in young starburst galaxies. In contrast, the UV to broad H$\\alpha$ ratios in LBDs closely match local unobscured AGNs and are statistically different from LRDs. The Ly$\\alpha$ occurrence rates and strengths do not differ between LRDs and LBDs and are comparable to normal star-forming galaxies. These results are consistent with a scenario where the central BH in LRDs is enshrouded by a dense opaque gas envelope -- in this model, the UV continuum as well as narrow and even broad H$\\alpha$ emissions are not powered by AGNs but predominantly by young massive stars surrounding the envelope, while the envelope radiates as a $\\sim 5000$ K blackbody. As the envelope dissipates, direct AGN emission can emerge, potentially transforming LRDs into LBDs and marking the end of a short-lived phase of rapid black hole growth.","external_url":"https://arxiv.org/abs/2601.10573","cited_by_count":null,"metadata_source":"pith","metadata_fetched_at":"2026-07-01T12:15:43.792677+00:00","pith_arxiv_id":"2601.10573","created_at":"2026-05-09T07:24:09.943303+00:00","updated_at":"2026-07-01T12:15:43.792677+00:00","title_quality_ok":true,"display_title":"Origins of the UV continuum and Balmer emission lines in Little Red Dots: observational validation of dense gas envelope models enshrouding the AGN","render_title":"Origins of the UV continuum and Balmer emission lines in Little Red Dots: observational validation of dense gas envelope models enshrouding the AGN"},"hub":{"state":{"work_id":"17119633-e3c8-4915-a6cc-48f7a07e8901","tier":"hub","tier_reason":"10+ Pith inbound or 1,000+ external citations","pith_inbound_count":17,"external_cited_by_count":null,"distinct_field_count":2,"first_pith_cited_at":"2025-08-25T18:00:05+00:00","last_pith_cited_at":"2026-06-29T18:00:00+00:00","author_build_status":"not_needed","summary_status":"needed","contexts_status":"needed","graph_status":"needed","ask_index_status":"not_needed","reader_status":"not_needed","recognition_status":"not_needed","updated_at":"2026-07-01T17:41:24.557690+00:00","tier_text":"hub"},"tier":"hub","role_counts":[{"context_role":"background","n":1},{"context_role":"method","n":1}],"polarity_counts":[{"context_polarity":"background","n":1},{"context_polarity":"use_method","n":1}],"runs":{},"summary":{},"graph":{},"authors":[]}}