{"doi":"10.1086/422167","OA_place":"repository","status":"public","year":"2004","publication_identifier":{"issn":["0004-637X"],"eissn":["1538-4357"]},"day":"01","publisher":"American Astronomical Society","article_processing_charge":"No","date_updated":"2024-11-12T10:16:58Z","quality_controlled":"1","extern":"1","author":[{"full_name":"Dijkstra, Mark","first_name":"Mark","last_name":"Dijkstra"},{"full_name":"Haiman, Zoltán","first_name":"Zoltán","orcid":"0000-0003-3633-5403","last_name":"Haiman","id":"7c006e8c-cc0d-11ee-8322-cb904ef76f36"},{"first_name":"Abraham","full_name":"Loeb, Abraham","last_name":"Loeb"}],"abstract":[{"lang":"eng","text":"A population of black holes (BHs) at high redshifts (z ≳ 6) that contributes significantly to the ionization of the intergalactic medium (IGM) would be accompanied by the copious production of hard (≳10 keV) X-ray photons. The resulting hard X-ray background would redshift and be observed as a present-day soft X-ray background (SXB). Under the hypothesis that BHs are the main producers of reionizing photons in the high-redshift universe, we calculate their contribution to the present-day SXB. We find that accreting BHs with a hard spectrum (be it luminous quasars or their lower mass \"miniquasar\" counterparts) could not fully reionize the universe without saturating the unresolved component of the 0.5-2 keV SXB at the ≥2 σ level. Distant miniquasars that produce enough X-rays to only partially ionize the IGM to a level of at most xe ~ 50% saturate the unresolved SXB by ≲1 σ. Improved determinations of the unresolved component of the SXB can provide a powerful constraint on the contribution of accreting BHs to partial or full reionization."}],"type":"journal_article","arxiv":1,"issue":"2","external_id":{"arxiv":["astro-ph/0403078"]},"title":"A limit from the X‐ray background on the contribution of quasars to reionization","intvolume":"       613","_id":"17806","page":"646-654","oa_version":"Preprint","main_file_link":[{"open_access":"1","url":"https://doi.org/10.48550/arXiv.astro-ph/0403078"}],"oa":1,"language":[{"iso":"eng"}],"publication":"The Astrophysical Journal","article_type":"original","scopus_import":"1","citation":{"mla":"Dijkstra, Mark, et al. “A Limit from the X‐ray Background on the Contribution of Quasars to Reionization.” <i>The Astrophysical Journal</i>, vol. 613, no. 2, American Astronomical Society, 2004, pp. 646–54, doi:<a href=\"https://doi.org/10.1086/422167\">10.1086/422167</a>.","short":"M. Dijkstra, Z. Haiman, A. Loeb, The Astrophysical Journal 613 (2004) 646–654.","apa":"Dijkstra, M., Haiman, Z., &#38; Loeb, A. (2004). A limit from the X‐ray background on the contribution of quasars to reionization. <i>The Astrophysical Journal</i>. American Astronomical Society. <a href=\"https://doi.org/10.1086/422167\">https://doi.org/10.1086/422167</a>","ama":"Dijkstra M, Haiman Z, Loeb A. A limit from the X‐ray background on the contribution of quasars to reionization. <i>The Astrophysical Journal</i>. 2004;613(2):646-654. doi:<a href=\"https://doi.org/10.1086/422167\">10.1086/422167</a>","chicago":"Dijkstra, Mark, Zoltán Haiman, and Abraham Loeb. “A Limit from the X‐ray Background on the Contribution of Quasars to Reionization.” <i>The Astrophysical Journal</i>. American Astronomical Society, 2004. <a href=\"https://doi.org/10.1086/422167\">https://doi.org/10.1086/422167</a>.","ieee":"M. Dijkstra, Z. Haiman, and A. Loeb, “A limit from the X‐ray background on the contribution of quasars to reionization,” <i>The Astrophysical Journal</i>, vol. 613, no. 2. American Astronomical Society, pp. 646–654, 2004.","ista":"Dijkstra M, Haiman Z, Loeb A. 2004. A limit from the X‐ray background on the contribution of quasars to reionization. The Astrophysical Journal. 613(2), 646–654."},"publication_status":"published","date_created":"2024-09-06T11:34:30Z","OA_type":"free access","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","month":"10","volume":613,"date_published":"2004-10-01T00:00:00Z"}