Probing the Low-Mass End of the Black Hole Mass Function via a Study of Faint Local Spiral Galaxies

Michael S. Fusco, Benjamin L. Davis, Julia Kennefick, Daniel Kennefick, Marc S. Seigar

    Research output: Contribution to journalArticlepeer-review


    We present an analysis of the pitch angle distribution function (PADF) for nearby galaxies and its resulting black hole mass function (BHMF) via the well-known relationship between pitch angle and black hole mass. Our sample consists of a subset of 74 spiral galaxies from the Carnegie-Irvine Galaxy Survey with absolute B-band magnitude (Formula presented.) mag and luminosity distance (Formula presented.) Mpc, which is an extension of a complementary set of 140 more luminous ((Formula presented.) mag) late-type galaxies. We find the PADFs of the two samples are, somewhat surprisingly, not strongly dissimilar; a result that may hold important implications for spiral formation theories. Our data show a distinct bimodal population manifest in the pitch angles of the Sa–Sc types and separately the Scd–Sm types, with Sa–Sc types having tighter spiral arms on average. Importantly, we uncover a distinct bifurcation of the BHMF, such that the Sa–Sc galaxies typically host so-called “supermassive” black holes ((Formula presented.)), whereas Scd–Sm galaxies accordingly harbor black holes that are “less-than-supermassive” ((Formula presented.)). It is amongst this latter population of galaxies where we expect fruitful bounties of elusive intermediate-mass black holes (IMBHs), through which a better understanding will help form more precise benchmarks for future generations of gravitational wave detectors.

    Original languageEnglish (US)
    Article number649
    Issue number12
    StatePublished - Dec 2022


    • black hole physics
    • galaxies: spiral
    • galaxies: statistics
    • galaxies: structure

    ASJC Scopus subject areas

    • General Physics and Astronomy


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