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    The Active Fraction of Massive Black Holes in Dwarf Galaxies

    Pacucci, Fabio and Mezcua, Mar and Regan, John (2021) The Active Fraction of Massive Black Holes in Dwarf Galaxies. The Astrophysical Journal, 920 (2). p. 134. ISSN 0004-637X

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    The population of massive black holes (MBHs) in dwarf galaxies is elusive, but fundamentally important to understand the coevolution of black holes with their hosts and the formation of the first collapsed objects in the universe. While some progress was made in determining the X-ray detected fraction of MBHs in dwarfs, with typical values ranging from 0%–6%, their overall active fraction, , is still largely unconstrained. Here, we develop a theoretical model to predict the multiwavelength active fraction of MBHs in dwarf galaxies starting from first principles and based on the physical properties of the host, namely, its stellar mass and angular momentum content. We find multiwavelength active fractions for MBHs, accreting at typically low rates, ranging from 5%–22%, and increasing with the stellar mass of the host as  ~ log10 M 4.5 ( ) . If dwarfs are characterized by low-metallicity environments, the active fraction may reach ∼30% for the most massive hosts. For galaxies with stellar mass in the range of 107 < Må[ Me] < 1010, our predictions are in agreement with occupation fractions derived from simulations and semi-analytical models. Additionally, we provide a fitting formula to predict the probability of finding an active MBH in a dwarf galaxy from observationally derived data. This model will be instrumental to guide future observational efforts to find MBHs in dwarfs. The James Webb Space Telescope, in particular, will play a crucial role in detecting MBHs in dwarfs, possibly uncovering active fractions ∼3 times larger than current X-ray surveys.

    Item Type: Article
    Keywords: Active Fraction; Massive Black Holes; Dwarf Galaxies;
    Academic Unit: Faculty of Science and Engineering > Research Institutes > Hamilton Institute
    Faculty of Science and Engineering > Theoretical Physics
    Item ID: 18411
    Identification Number:
    Depositing User: John Regan
    Date Deposited: 18 Apr 2024 15:30
    Journal or Publication Title: The Astrophysical Journal
    Publisher: American Astronomical Society
    Refereed: Yes
    Use Licence: This item is available under a Creative Commons Attribution Non Commercial Share Alike Licence (CC BY-NC-SA). Details of this licence are available here

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