Wind-fed Supermassive Black Hole Accretion by the Nuclear Star Cluster: The Case of M31*
The central supermassive black hole (SMBH) of the Andromeda galaxy, known as M31*, exhibits dim electromagnetic emission and is inferred to have an extremely low accretion rate for its remarkable mass (∼10 ^8 M _⊙ ). In this work, we use three-dimensional hydrodynamical simulations to explore a prev...
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2025-01-01
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| author | Zhao Su Zhiyuan Li Zongnan Li |
| author_facet | Zhao Su Zhiyuan Li Zongnan Li |
| author_sort | Zhao Su |
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| description | The central supermassive black hole (SMBH) of the Andromeda galaxy, known as M31*, exhibits dim electromagnetic emission and is inferred to have an extremely low accretion rate for its remarkable mass (∼10 ^8 M _⊙ ). In this work, we use three-dimensional hydrodynamical simulations to explore a previously untested scenario, in which M31* is fed by the collective stellar mass loss from its surrounding nuclear star cluster, manifested as a famous eccentric disk of predominantly old stellar populations. The stellar mass loss is assumed to be dominated by the slow and cold winds from 100 asymptotic giant-branch stars, which follow well-constrained Keplerian orbits around M31* and together provide a mass injection rate of ∼4 × 10 ^−5 M _⊙ yr ^−1 . The simulations achieve a quasi-steady state on a megayear timescale, at which point a quasi-Keplerian, cool ( T ∼ 10 ^3 –10 ^4 K) gas disk extending several parsecs is established. This disk is continuously supplied by the stellar winds and itself feeds the central SMBH. At the end of the simulations at 2 Myr, an accretion rate of ∼2 × 10 ^−5 M _⊙ yr ^−1 is found but could vary by a factor of a few depending on whether the subdominant gravity of the NSC or a moderate global inflow is included. The predicted X-ray luminosity of ∼10 ^36 erg s ^−1 , dominated by the hot ( T ∼ 10 ^7 –10 ^8 K) plasma within 0.2 pc of the SMBH, is consistent with Chandra observations. We conclude that the feeding mechanism of M31* is successfully identified, which has important implications for the working of dormant SMBHs prevalent in the local Universe. |
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| institution | Kabale University |
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| spelling | doaj-art-69dec3b2b34443d0bfb64f481200604d2025-08-20T03:25:19ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-0198816810.3847/1538-4357/ade1d5Wind-fed Supermassive Black Hole Accretion by the Nuclear Star Cluster: The Case of M31*Zhao Su0https://orcid.org/0000-0002-6738-3259Zhiyuan Li1https://orcid.org/0000-0003-0355-6437Zongnan Li2https://orcid.org/0000-0002-7172-6306School of Astronomy and Space Science, Nanjing University , Nanjing 210046, People’s Republic of China ; suzhao@smail.nju.edu.cn, lizy@nju.edu.cn; Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University) , Ministry of Education, Nanjing 210046, People’s Republic of ChinaSchool of Astronomy and Space Science, Nanjing University , Nanjing 210046, People’s Republic of China ; suzhao@smail.nju.edu.cn, lizy@nju.edu.cn; Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University) , Ministry of Education, Nanjing 210046, People’s Republic of China; Institute of Science and Technology for Deep Space Exploration, Suzhou Campus, Nanjing University , Suzhou 215163, People’s Republic of ChinaNational Astronomical Observatory of Japan , 2-21-1 Osawa, Mitaka, Tokyo, 181-8588, Japan ; zongnan.li@astro.nao.ac.jpThe central supermassive black hole (SMBH) of the Andromeda galaxy, known as M31*, exhibits dim electromagnetic emission and is inferred to have an extremely low accretion rate for its remarkable mass (∼10 ^8 M _⊙ ). In this work, we use three-dimensional hydrodynamical simulations to explore a previously untested scenario, in which M31* is fed by the collective stellar mass loss from its surrounding nuclear star cluster, manifested as a famous eccentric disk of predominantly old stellar populations. The stellar mass loss is assumed to be dominated by the slow and cold winds from 100 asymptotic giant-branch stars, which follow well-constrained Keplerian orbits around M31* and together provide a mass injection rate of ∼4 × 10 ^−5 M _⊙ yr ^−1 . The simulations achieve a quasi-steady state on a megayear timescale, at which point a quasi-Keplerian, cool ( T ∼ 10 ^3 –10 ^4 K) gas disk extending several parsecs is established. This disk is continuously supplied by the stellar winds and itself feeds the central SMBH. At the end of the simulations at 2 Myr, an accretion rate of ∼2 × 10 ^−5 M _⊙ yr ^−1 is found but could vary by a factor of a few depending on whether the subdominant gravity of the NSC or a moderate global inflow is included. The predicted X-ray luminosity of ∼10 ^36 erg s ^−1 , dominated by the hot ( T ∼ 10 ^7 –10 ^8 K) plasma within 0.2 pc of the SMBH, is consistent with Chandra observations. We conclude that the feeding mechanism of M31* is successfully identified, which has important implications for the working of dormant SMBHs prevalent in the local Universe.https://doi.org/10.3847/1538-4357/ade1d5Andromeda galaxySupermassive black holesHydrodynamical simulationsAccretionStar clustersStellar winds |
| spellingShingle | Zhao Su Zhiyuan Li Zongnan Li Wind-fed Supermassive Black Hole Accretion by the Nuclear Star Cluster: The Case of M31* The Astrophysical Journal Andromeda galaxy Supermassive black holes Hydrodynamical simulations Accretion Star clusters Stellar winds |
| title | Wind-fed Supermassive Black Hole Accretion by the Nuclear Star Cluster: The Case of M31* |
| title_full | Wind-fed Supermassive Black Hole Accretion by the Nuclear Star Cluster: The Case of M31* |
| title_fullStr | Wind-fed Supermassive Black Hole Accretion by the Nuclear Star Cluster: The Case of M31* |
| title_full_unstemmed | Wind-fed Supermassive Black Hole Accretion by the Nuclear Star Cluster: The Case of M31* |
| title_short | Wind-fed Supermassive Black Hole Accretion by the Nuclear Star Cluster: The Case of M31* |
| title_sort | wind fed supermassive black hole accretion by the nuclear star cluster the case of m31 |
| topic | Andromeda galaxy Supermassive black holes Hydrodynamical simulations Accretion Star clusters Stellar winds |
| url | https://doi.org/10.3847/1538-4357/ade1d5 |
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