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White dwarf mass accretion in AGN accretion disk
* 1, 2 , * 1 , * 1 , * 3, 4 , * 5 , * 3 , * 6
1  Department of Physics, Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR, China
2  Gerald Choa Neuroscience Institute, Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR, China
3  Mullard Space Science Laboratory, University College London, Holmbury St Mary, Surrey RH5 6NT, United Kingdom
4  Kavli Institute for the Physics and Mathematics of the Universe (WPI), UTIAS, The University of Tokyo, Kashiwa, Chiba 277-8583, Japan
5  Department of Physics and Astronomy, University College London, Gower Street, London, WC1E 6BT, United Kingdom
6  Astrophysical Big Bang Laboratory (ABBL), RIKEN Cluster for Pioneering Research, Wakō , Saitama, 351-0198 Japan
Academic Editor: Nicolas Chamel

Abstract:

Many galaxies show strong star formation activity in their central regions. In galaxies that also host an active galactic nucleus (AGN), star formation may occur locally within the AGN accretion disk itself. Low-mass stars constitute the majority of the stellar population, and as they reach the end of their life cycles, they evolve into white dwarfs. We therefore expect to find a population of white dwarfs embedded in and comoving with the AGN accretion disk. The disk provides a dense environment in which white dwarfs can efficiently accrete gas and grow in mass. As their mass approaches the Chandrasekhar limit of 1.4 solar masses, the temperature becomes high enough to trigger runaway nuclear fusion, eventually leading to a Type Ia supernova. Type Ia supernovae are crucial both as standard candles for cosmology and as major contributors to the chemical enrichment of the universe. In this work, we investigate the population of white dwarfs in AGN disks, their mass growth through accretion, and their eventual collapse into Type Ia supernovae. We show that the accretion of white dwarfs in AGN disks is a viable channel for producing type 1a supernovae. We discuss the resulting consequences for the evolution of the AGN and its accretion disk, the chemical enrichment of galactic centers, and the universality of Type Ia supernovae as standard candles.

Keywords: White Dwarfs; AGN disks; Type Ia Supernovae

 
 
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