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| Format: | Preprint |
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2026
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| Online Access: | https://arxiv.org/abs/2602.12325 |
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| author | Fei, Qinyue Fujimoto, Seiji Brammer, Gabriel Li, Ruancun Ho, Luis C. Bromm, Volker Álvarez-Márquez, Javier Asada, Yoshihisa Barro, Guillermo Colina, Luis Dayal, Pratika Finkelstein, Steven L. Fynbo, Johan P. U. Ginolfi, Michele Inayoshi, Kohei Kokorev, Vasily Leung, Gene C. K. Matthee, Jorryt Meyer, Romain A. Naidu, Rohan P. Onoue, Masafusa Pérez-González, Pablo G. Steinhardt, Charles L. Valentino, Francesco Walter, Fabian Xiao, Mengyuan Zhang, Haowen |
| author_facet | Fei, Qinyue Fujimoto, Seiji Brammer, Gabriel Li, Ruancun Ho, Luis C. Bromm, Volker Álvarez-Márquez, Javier Asada, Yoshihisa Barro, Guillermo Colina, Luis Dayal, Pratika Finkelstein, Steven L. Fynbo, Johan P. U. Ginolfi, Michele Inayoshi, Kohei Kokorev, Vasily Leung, Gene C. K. Matthee, Jorryt Meyer, Romain A. Naidu, Rohan P. Onoue, Masafusa Pérez-González, Pablo G. Steinhardt, Charles L. Valentino, Francesco Walter, Fabian Xiao, Mengyuan Zhang, Haowen |
| contents | We present a panchromatic optical-mm characterization of GNz7q, a recently identified X-ray weak, rapidly growing red quasar embedded within a dusty starburst galaxy at $z=7.1899$, using the full suite of JWST/NIRCam, NIRSpec, MIRI, and archival NOEMA observations. Our deep NIRSpec/G395M spectroscopy reveals unambiguous broad Balmer emission (FWHM $=2221\pm20$kms$^{-1}$), confirming a super-Eddington accreting black hole ($λ_{\rm Edd}=2.7\pm0.4$) with a mass of $\log(M_{\rm BH}/M_{\odot})=7.55\pm0.34$, using accretion-rate corrected BH mass estimators. After subtracting the point source, we robustly detect stellar emission from the host galaxy across multiple NIRCam and MIRI filters. Out joint morphological-spectral analysis yields a stellar mass of $\log (M_*/M_\odot)=10.5\pm0.4$ and an intense star formation rate of ${\rm SFR}=330\pm97\,M_\odot\,\rm yr^{-1}$, confirming the host as a massive, dusty starburst galaxy. We find that GNz7q lies on the local $M_{\rm BH}$-$M_*$ relation ($M_{\rm BH}/M_*\simeq 0.001$) and is well positioned to evolve into the locus of massive SDSS quasars with $\log (M_{\rm BH}/M_\odot)\approx 9$ and $M_*\approx 10^{11}\,M_\odot$ at $z\sim 6$, owing to its remarkably rapid growth in both the black hole and its host galaxy. This stands in stark contrast to many recently reported JWST AGN populations at similar redshifts, including the little red dots (LRDs), whose weak or undetected star formation makes it difficult for them to grow into the massive galaxies hosting SDSS-like quasars. These results suggest that GNz7q marks as a rare, pivotal phase of early BH-galaxy co-eolution, plausibly providing a crucial direct pathway to the supermassive black hole systems within the first billion years of the Universe. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2602_12325 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Direct pathway to the Early Supermassive Black Holes: A Red Super-Eddington Quasar in a Massive Starburst Host at $z=7.2$ Fei, Qinyue Fujimoto, Seiji Brammer, Gabriel Li, Ruancun Ho, Luis C. Bromm, Volker Álvarez-Márquez, Javier Asada, Yoshihisa Barro, Guillermo Colina, Luis Dayal, Pratika Finkelstein, Steven L. Fynbo, Johan P. U. Ginolfi, Michele Inayoshi, Kohei Kokorev, Vasily Leung, Gene C. K. Matthee, Jorryt Meyer, Romain A. Naidu, Rohan P. Onoue, Masafusa Pérez-González, Pablo G. Steinhardt, Charles L. Valentino, Francesco Walter, Fabian Xiao, Mengyuan Zhang, Haowen Astrophysics of Galaxies We present a panchromatic optical-mm characterization of GNz7q, a recently identified X-ray weak, rapidly growing red quasar embedded within a dusty starburst galaxy at $z=7.1899$, using the full suite of JWST/NIRCam, NIRSpec, MIRI, and archival NOEMA observations. Our deep NIRSpec/G395M spectroscopy reveals unambiguous broad Balmer emission (FWHM $=2221\pm20$kms$^{-1}$), confirming a super-Eddington accreting black hole ($λ_{\rm Edd}=2.7\pm0.4$) with a mass of $\log(M_{\rm BH}/M_{\odot})=7.55\pm0.34$, using accretion-rate corrected BH mass estimators. After subtracting the point source, we robustly detect stellar emission from the host galaxy across multiple NIRCam and MIRI filters. Out joint morphological-spectral analysis yields a stellar mass of $\log (M_*/M_\odot)=10.5\pm0.4$ and an intense star formation rate of ${\rm SFR}=330\pm97\,M_\odot\,\rm yr^{-1}$, confirming the host as a massive, dusty starburst galaxy. We find that GNz7q lies on the local $M_{\rm BH}$-$M_*$ relation ($M_{\rm BH}/M_*\simeq 0.001$) and is well positioned to evolve into the locus of massive SDSS quasars with $\log (M_{\rm BH}/M_\odot)\approx 9$ and $M_*\approx 10^{11}\,M_\odot$ at $z\sim 6$, owing to its remarkably rapid growth in both the black hole and its host galaxy. This stands in stark contrast to many recently reported JWST AGN populations at similar redshifts, including the little red dots (LRDs), whose weak or undetected star formation makes it difficult for them to grow into the massive galaxies hosting SDSS-like quasars. These results suggest that GNz7q marks as a rare, pivotal phase of early BH-galaxy co-eolution, plausibly providing a crucial direct pathway to the supermassive black hole systems within the first billion years of the Universe. |
| title | Direct pathway to the Early Supermassive Black Holes: A Red Super-Eddington Quasar in a Massive Starburst Host at $z=7.2$ |
| topic | Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2602.12325 |