{"quality_controlled":"1","acknowledgement":"This work is based in part on observations made with the NASA/ESA/CSA James Webb Space Telescope. The data were obtained from the Mikulski Archive for Space Telescopes at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-03127 for JWST. The specific observations analyzed can be accessed via DOI: 10.17909/0esg-h949. All of the data products presented herein were retrieved from the Dawn JWST Archive (DJA). DJA is an initiative of the Cosmic Dawn Center, which is funded by the Danish National Research Foundation under grant No. 140. We express gratitude toward the members of the GTO, GO, and DDT teams, whose public data we utilized in this work.\r\n\r\nSupport for this work was provided by The Brinson Foundation through a Brinson Prize Fellowship grant. Support for program No. 4233 was provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-03127. This research was supported by the International Space Science Institute (ISSI) in Bern, through ISSI International Team project No. 562. D.S. acknowledges helpful conversations with Xiaohui Fan and Jared Siegel that contributed to the quality of this work, in addition to aesthetic sign-off from Stephanie Permut on the colors of figures. T.B.M. was supported by a CIERA fellowship. The work of CCW is supported by NOIRLab, which is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation.","file_date_updated":"2026-02-09T06:39:23Z","status":"public","date_published":"2025-12-09T00:00:00Z","OA_place":"publisher","OA_type":"gold","abstract":[{"lang":"eng","text":"Among the most puzzling early discoveries of JWST are “little red dots” (LRDs), compact red sources that host broad Balmer emission lines, and in many cases exhibit a “V-shaped” change in slope in the rest-optical. The physical properties of LRDs currently have order-of-magnitude uncertainties, because models to explain the continuum of these sources differ immensely. Here, we leverage the complete selection of red sources in the RUBIES program, supplemented with public PRISM spectra, to study the origin of this V shape. By fitting a broken power law with a flexible inflection point, we find that a large fraction of red Hα emitters at 2 < z < 6 exhibit a strong change in slope, and that all strong inflections appear associated with the Balmer limit (0.3645 μm). Using a simple model of a reddened active galactic nucleus (AGN) with an unobscured scattered-light component, we demonstrate that the observed V shape in LRDs is unlikely to occur at any specific wavelength if the entire continuum is dominated by light from a power-law AGN continuum. In contrast, models with an intrinsic feature at the Balmer limit, such as those that are dominated by an evolved stellar population, can produce the observed spectral shapes, provided that a reddened component picks up sufficiently redward of the break. While no model can comfortably explain the full LRD spectral energy distribution, the common inflection location suggests that a single component consistently dominates the rest-frame UV optical in LRDs, and that this component is associated with T ∼ 10^4 K hydrogen."}],"language":[{"iso":"eng"}],"license":"https://creativecommons.org/licenses/by/4.0/","month":"12","title":"Little Red Dots at an inflection point: Ubiquitous v-shaped turnover consistently occurs at the Balmer limit","oa":1,"ddc":["520"],"arxiv":1,"_id":"21057","file":[{"success":1,"access_level":"open_access","creator":"dernst","file_name":"2025_AstrophysicalJournal_Setton.pdf","date_updated":"2026-02-09T06:39:23Z","file_id":"21163","content_type":"application/pdf","date_created":"2026-02-09T06:39:23Z","file_size":1989640,"relation":"main_file","checksum":"2a424eb43748a6370ff058c98adb15c6"}],"article_number":"118","issue":"1","citation":{"ieee":"D. J. Setton <i>et al.</i>, “Little Red Dots at an inflection point: Ubiquitous v-shaped turnover consistently occurs at the Balmer limit,” <i>The Astrophysical Journal</i>, vol. 995, no. 1. IOP Publishing, 2025.","ista":"Setton DJ, Greene JE, de Graaff A, Ma Y逸伦, Leja J, Matthee JJ, Bezanson R, Boogaard LA, Cleri NJ, Katz H, Labbe I, Maseda MV, McConachie I, Miller TB, Price SH, Suess KA, van Dokkum P, Wang 王 B冰洁, Weibel A, Whitaker KE, Williams CC. 2025. Little Red Dots at an inflection point: Ubiquitous v-shaped turnover consistently occurs at the Balmer limit. The Astrophysical Journal. 995(1), 118.","apa":"Setton, D. J., Greene, J. E., de Graaff, A., Ma, Y. 逸伦, Leja, J., Matthee, J. J., … Williams, C. C. (2025). Little Red Dots at an inflection point: Ubiquitous v-shaped turnover consistently occurs at the Balmer limit. <i>The Astrophysical Journal</i>. IOP Publishing. <a href=\"https://doi.org/10.3847/1538-4357/ae1500\">https://doi.org/10.3847/1538-4357/ae1500</a>","mla":"Setton, David J., et al. “Little Red Dots at an Inflection Point: Ubiquitous v-Shaped Turnover Consistently Occurs at the Balmer Limit.” <i>The Astrophysical Journal</i>, vol. 995, no. 1, 118, IOP Publishing, 2025, doi:<a href=\"https://doi.org/10.3847/1538-4357/ae1500\">10.3847/1538-4357/ae1500</a>.","short":"D.J. Setton, J.E. Greene, A. de Graaff, Y.逸伦 Ma, J. Leja, J.J. Matthee, R. Bezanson, L.A. Boogaard, N.J. Cleri, H. Katz, I. Labbe, M.V. Maseda, I. McConachie, T.B. Miller, S.H. Price, K.A. Suess, P. van Dokkum, B.冰洁 Wang 王, A. Weibel, K.E. Whitaker, C.C. Williams, The Astrophysical Journal 995 (2025).","chicago":"Setton, David J., Jenny E. Greene, Anna de Graaff, Yilun 逸伦 Ma, Joel Leja, Jorryt J Matthee, Rachel Bezanson, et al. “Little Red Dots at an Inflection Point: Ubiquitous v-Shaped Turnover Consistently Occurs at the Balmer Limit.” <i>The Astrophysical Journal</i>. IOP Publishing, 2025. <a href=\"https://doi.org/10.3847/1538-4357/ae1500\">https://doi.org/10.3847/1538-4357/ae1500</a>.","ama":"Setton DJ, Greene JE, de Graaff A, et al. Little Red Dots at an inflection point: Ubiquitous v-shaped turnover consistently occurs at the Balmer limit. <i>The Astrophysical Journal</i>. 2025;995(1). doi:<a href=\"https://doi.org/10.3847/1538-4357/ae1500\">10.3847/1538-4357/ae1500</a>"},"tmp":{"name":"Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)","image":"/images/cc_by.png","short":"CC BY (4.0)","legal_code_url":"https://creativecommons.org/licenses/by/4.0/legalcode"},"DOAJ_listed":"1","PlanS_conform":"1","external_id":{"arxiv":["2411.03424"]},"year":"2025","has_accepted_license":"1","publisher":"IOP Publishing","oa_version":"Published Version","intvolume":"       995","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","author":[{"last_name":"Setton","first_name":"David J.","full_name":"Setton, David J."},{"full_name":"Greene, Jenny E.","first_name":"Jenny E.","last_name":"Greene"},{"full_name":"de Graaff, Anna","first_name":"Anna","last_name":"de Graaff"},{"full_name":"Ma, Yilun 逸伦","last_name":"Ma","first_name":"Yilun 逸伦"},{"last_name":"Leja","first_name":"Joel","full_name":"Leja, Joel"},{"last_name":"Matthee","first_name":"Jorryt J","orcid":"0000-0003-2871-127X","id":"7439a258-f3c0-11ec-9501-9df22fe06720","full_name":"Matthee, Jorryt J"},{"last_name":"Bezanson","first_name":"Rachel","full_name":"Bezanson, Rachel"},{"full_name":"Boogaard, Leindert A.","first_name":"Leindert A.","last_name":"Boogaard"},{"last_name":"Cleri","first_name":"Nikko J.","full_name":"Cleri, Nikko J."},{"first_name":"Harley","last_name":"Katz","full_name":"Katz, Harley"},{"full_name":"Labbe, Ivo","first_name":"Ivo","last_name":"Labbe"},{"full_name":"Maseda, Michael V.","first_name":"Michael V.","last_name":"Maseda"},{"full_name":"McConachie, Ian","last_name":"McConachie","first_name":"Ian"},{"last_name":"Miller","first_name":"Tim B.","full_name":"Miller, Tim B."},{"full_name":"Price, Sedona H.","last_name":"Price","first_name":"Sedona H."},{"full_name":"Suess, Katherine A.","last_name":"Suess","first_name":"Katherine A."},{"first_name":"Pieter","last_name":"van Dokkum","full_name":"van Dokkum, Pieter"},{"full_name":"Wang 王, Bingjie 冰洁","last_name":"Wang 王","first_name":"Bingjie 冰洁"},{"full_name":"Weibel, Andrea","first_name":"Andrea","last_name":"Weibel"},{"full_name":"Whitaker, Katherine E.","first_name":"Katherine E.","last_name":"Whitaker"},{"last_name":"Williams","first_name":"Christina C.","full_name":"Williams, Christina C."}],"day":"09","publication":"The Astrophysical Journal","type":"journal_article","doi":"10.3847/1538-4357/ae1500","article_processing_charge":"Yes","date_created":"2026-01-28T15:21:47Z","department":[{"_id":"JoMa"}],"volume":995,"date_updated":"2026-02-09T06:41:48Z","publication_status":"published","article_type":"original","scopus_import":"1","publication_identifier":{"issn":["0004-637X"],"eissn":["1538-4357"]}}