{"doi":"10.1093/mnras/stag1839","title":"Heavy black hole seed survivors in dwarf galaxies: A case study of Leo I","year":"2026","date_updated":"2026-10-19T07:05:55Z","status":"public","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","has_accepted_license":"1","quality_controlled":"1","_id":"23150","intvolume":"       552","publisher":"Oxford University Press","author":[{"last_name":"Scoggins","full_name":"Scoggins, Matthew T.","first_name":"Matthew T."},{"id":"7c006e8c-cc0d-11ee-8322-cb904ef76f36","first_name":"Zoltán","orcid":"0000-0003-3633-5403","last_name":"Haiman","full_name":"Haiman, Zoltán"},{"last_name":"Pacucci","full_name":"Pacucci, Fabio","first_name":"Fabio"}],"oa":1,"das_tickbox":"1","fulldoi":"https://doi.org/10.1093/mnras/stag1839","type":"journal_article","date_published":"2026-11-01T00:00:00Z","DOAJ_listed":"1","arxiv":1,"date_created":"2026-10-18T22:01:51Z","article_number":"stag1839","external_id":{"arxiv":["2511.04736"]},"dataavailabilitystatement":"The code used to analyse the merger trees and generate figures for this manuscript is available at this GitHub repository. All other data will be shared upon reasonable request to the corresponding author.","department":[{"_id":"ZoHa"}],"OA_type":"gold","article_processing_charge":"Yes","OA_place":"publisher","month":"11","publication_status":"published","supplementarymaterial":"no","volume":552,"abstract":[{"text":"High-redshift supermassive black holes (SMBHs) have challenged our understanding of black hole formation and growth. The ‘heavy-seed’ pathway eases the problem with the progenitors of these SMBHs having birth masses up to∼105 M\u0003. Here, we investigate the possibility that a local dwarf galaxy, Leo I, harbours a heavy-seed descendant. Using Monte Carlo merger trees to generate the merger histories of 1000 dark matter haloes similar to the Milky Way (MW), we search for Leo- like satellite haloes and investigate the probability that the progenitors of these satellites formed a heavy seed. We derive the likelihood of such ‘heavy-seed survivors’ (HSSs) across various formation and survival criteria as well as Leo-similarity criteria. We find that the virial temperature for the onset of atomic cooling and rapid gas infall that yields heavy seeds, Tact , has the largest impact on HSS frequency. We find HSSs in a fraction 0.7 per cent, 18.1 per cent, and 96.5 per cent of MW-like haloes when Tact is set to 9000, 7000, and 5000 K, respectively. For the canonical atomic-cooling threshold ( Tact \u0002 8000 K), the HSS fraction is\u0003 1per cent , indicating that Leo I hosting a heavy-seed descendant is unlikely under well-motivated physical assumptions. Higher HSS fractions occur only under optimistic and currently unsubstantiated assumptions on Tact . Nevertheless, these results motivate future work that clarifies the possibility of heavy-seed BH formation in pristine haloes with nominal virial temperatures below 8000 K. This may motivate Leo I as a target for disentangling heavy seeds from other SMBH formation mechanisms.","lang":"eng"}],"article_type":"original","day":"01","scopus_import":"1","researchdata_availability":"yes","ddc":["520"],"publication":"Monthly Notices of the Royal Astronomical Society","language":[{"iso":"eng"}],"issue":"3","acknowledgement":"We thank the anonymous reviewer for feedback that helped clarify this manuscript. ZH acknowledges support from NSF grant AST-2006176. FP acknowledges support from the Black Hole Initiative at Harvard University, which is funded by grants from the John Templeton Foundation and the Gordon and Betty Moore Foundation. Merger tree generation and analysis were performed with NSF’s ACCESS allocations AST-120046 and AST-140041 on the Stampede3 resource. The freely available plotting library matplotlib (J. D. Hunter 2007) was used to construct the plots in this paper.","tmp":{"short":"CC BY (4.0)","legal_code_url":"https://creativecommons.org/licenses/by/4.0/legalcode","name":"Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)","image":"/images/cc_by.png"},"oa_version":"Published Version","citation":{"chicago":"Scoggins, Matthew T., Zoltán Haiman, and Fabio Pacucci. “Heavy Black Hole Seed Survivors in Dwarf Galaxies: A Case Study of Leo I.” <i>Monthly Notices of the Royal Astronomical Society</i>. Oxford University Press, 2026. <a href=\"https://doi.org/10.1093/mnras/stag1839\">https://doi.org/10.1093/mnras/stag1839</a>.","ieee":"M. T. Scoggins, Z. Haiman, and F. Pacucci, “Heavy black hole seed survivors in dwarf galaxies: A case study of Leo I,” <i>Monthly Notices of the Royal Astronomical Society</i>, vol. 552, no. 3. Oxford University Press, 2026.","apa":"Scoggins, M. T., Haiman, Z., &#38; Pacucci, F. (2026). Heavy black hole seed survivors in dwarf galaxies: A case study of Leo I. <i>Monthly Notices of the Royal Astronomical Society</i>. Oxford University Press. <a href=\"https://doi.org/10.1093/mnras/stag1839\">https://doi.org/10.1093/mnras/stag1839</a>","short":"M.T. Scoggins, Z. Haiman, F. Pacucci, Monthly Notices of the Royal Astronomical Society 552 (2026).","ista":"Scoggins MT, Haiman Z, Pacucci F. 2026. Heavy black hole seed survivors in dwarf galaxies: A case study of Leo I. Monthly Notices of the Royal Astronomical Society. 552(3), stag1839.","mla":"Scoggins, Matthew T., et al. “Heavy Black Hole Seed Survivors in Dwarf Galaxies: A Case Study of Leo I.” <i>Monthly Notices of the Royal Astronomical Society</i>, vol. 552, no. 3, stag1839, Oxford University Press, 2026, doi:<a href=\"https://doi.org/10.1093/mnras/stag1839\">10.1093/mnras/stag1839</a>.","ama":"Scoggins MT, Haiman Z, Pacucci F. Heavy black hole seed survivors in dwarf galaxies: A case study of Leo I. <i>Monthly Notices of the Royal Astronomical Society</i>. 2026;552(3). doi:<a href=\"https://doi.org/10.1093/mnras/stag1839\">10.1093/mnras/stag1839</a>"},"publication_identifier":{"eissn":["1365-2966"],"issn":["0035-8711"]},"file":[{"date_updated":"2026-10-19T07:05:43Z","access_level":"open_access","success":1,"creator":"dernst","file_size":1450204,"file_id":"23164","relation":"main_file","date_created":"2026-10-19T07:05:43Z","file_name":"2026_MonthNoticesRAS_Scoggins.pdf","checksum":"99a35f1305b7f1ed3813bcd51ba16724","content_type":"application/pdf"}],"file_date_updated":"2026-10-19T07:05:43Z"}