The Influence of Disk Composition on the Evolution of Stars in the Disks of Active Galactic Nuclei
Disks of gas accreting onto supermassive black holes, powering active galactic nuclei (AGN), can capture stars from nuclear star clusters or form stars in situ via gravitational instability. The density and thermal conditions of these disks can result in rapid accretion onto embedded stars, dramatic...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
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IOP Publishing
2023-01-01
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| Series: | The Astrophysical Journal |
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| Online Access: | https://doi.org/10.3847/1538-4357/acacf2 |
| _version_ | 1797702096387047424 |
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| author | Alexander J. Dittmann Adam S. Jermyn Matteo Cantiello |
| author_facet | Alexander J. Dittmann Adam S. Jermyn Matteo Cantiello |
| author_sort | Alexander J. Dittmann |
| collection | DOAJ |
| description | Disks of gas accreting onto supermassive black holes, powering active galactic nuclei (AGN), can capture stars from nuclear star clusters or form stars in situ via gravitational instability. The density and thermal conditions of these disks can result in rapid accretion onto embedded stars, dramatically altering their evolution in comparison to stars in the interstellar medium. Theoretical models predict that, when subjected to sufficiently rapid accretion, fresh gas replenishes hydrogen in the cores of these stars as quickly as it is burned into helium, reaching a quasi-steady state. Such massive, long-lived (“immortal”) stars may be capable of dramatically enriching AGN disks with helium, and would increase the helium abundance in AGN broad-line regions relative to that in the corresponding narrow-line regions and hosts. We investigate how the helium abundance of AGN disks alters the evolution of stars embedded therein. We find, in agreement with analytical arguments, that stars at a given mass are more luminous at higher helium mass fractions, and so undergo more radiation-driven mass loss. We further find that embedded stars tend to be less massive in disks with higher helium mass fractions, and that immortal stars are less common in such disks. Thus, disk composition can alter the rates of electromagnetic and gravitational wave transients as well as further chemical enrichment by embedded stars. |
| first_indexed | 2024-03-12T04:45:13Z |
| format | Article |
| id | doaj.art-9cfc13f0346d469b9d25e0d3619b5d7e |
| institution | Directory Open Access Journal |
| issn | 1538-4357 |
| language | English |
| last_indexed | 2024-03-12T04:45:13Z |
| publishDate | 2023-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal |
| spelling | doaj.art-9cfc13f0346d469b9d25e0d3619b5d7e2023-09-03T09:29:28ZengIOP PublishingThe Astrophysical Journal1538-43572023-01-0194615610.3847/1538-4357/acacf2The Influence of Disk Composition on the Evolution of Stars in the Disks of Active Galactic NucleiAlexander J. Dittmann0https://orcid.org/0000-0001-6157-6722Adam S. Jermyn1https://orcid.org/0000-0001-5048-9973Matteo Cantiello2https://orcid.org/0000-0002-8171-8596Department of Astronomy and Joint Space-Science Institute, University of Maryland , College Park, MD 20742-2421, USA ; dittmann@astro.umd.edu; Theoretical Division, Los Alamos National Laboratory , Los Alamos, NM 87545, USACenter for Computational Astrophysics, Flatiron Institute , 162 5th Avenue, New York, NY 10010, USACenter for Computational Astrophysics, Flatiron Institute , 162 5th Avenue, New York, NY 10010, USA; Department of Astrophysical Sciences, Princeton University , Princeton, NJ 08544, USADisks of gas accreting onto supermassive black holes, powering active galactic nuclei (AGN), can capture stars from nuclear star clusters or form stars in situ via gravitational instability. The density and thermal conditions of these disks can result in rapid accretion onto embedded stars, dramatically altering their evolution in comparison to stars in the interstellar medium. Theoretical models predict that, when subjected to sufficiently rapid accretion, fresh gas replenishes hydrogen in the cores of these stars as quickly as it is burned into helium, reaching a quasi-steady state. Such massive, long-lived (“immortal”) stars may be capable of dramatically enriching AGN disks with helium, and would increase the helium abundance in AGN broad-line regions relative to that in the corresponding narrow-line regions and hosts. We investigate how the helium abundance of AGN disks alters the evolution of stars embedded therein. We find, in agreement with analytical arguments, that stars at a given mass are more luminous at higher helium mass fractions, and so undergo more radiation-driven mass loss. We further find that embedded stars tend to be less massive in disks with higher helium mass fractions, and that immortal stars are less common in such disks. Thus, disk composition can alter the rates of electromagnetic and gravitational wave transients as well as further chemical enrichment by embedded stars.https://doi.org/10.3847/1538-4357/acacf2Stellar physicsStellar evolutionary modelsMassive starsQuasarsGalactic center |
| spellingShingle | Alexander J. Dittmann Adam S. Jermyn Matteo Cantiello The Influence of Disk Composition on the Evolution of Stars in the Disks of Active Galactic Nuclei The Astrophysical Journal Stellar physics Stellar evolutionary models Massive stars Quasars Galactic center |
| title | The Influence of Disk Composition on the Evolution of Stars in the Disks of Active Galactic Nuclei |
| title_full | The Influence of Disk Composition on the Evolution of Stars in the Disks of Active Galactic Nuclei |
| title_fullStr | The Influence of Disk Composition on the Evolution of Stars in the Disks of Active Galactic Nuclei |
| title_full_unstemmed | The Influence of Disk Composition on the Evolution of Stars in the Disks of Active Galactic Nuclei |
| title_short | The Influence of Disk Composition on the Evolution of Stars in the Disks of Active Galactic Nuclei |
| title_sort | influence of disk composition on the evolution of stars in the disks of active galactic nuclei |
| topic | Stellar physics Stellar evolutionary models Massive stars Quasars Galactic center |
| url | https://doi.org/10.3847/1538-4357/acacf2 |
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