Revealing Hidden Substructures in the M BH-σ Diagram, and Refining the Bend in the L-σ Relation

Nandini Sahu, Alister W. Graham, Benjamin L. Davis

    Research output: Contribution to journalArticlepeer-review


    Using 145 early- and late-type galaxies (ETGs and LTGs) with directly measured supermassive black hole masses, M BH, we build upon our previous discoveries that: (i) LTGs, most of which have been alleged to contain a pseudobulge, follow the relation MBH ∝ M∗,sph 2.16±0.32 and (ii) the ETG relation MBH ∝ M∗,sph 1.27±0.07 is an artifact of ETGs with/without disks following parallel MBH ∝ M∗,sph 1.9±0.2 relations that are offset by an order of magnitude in the M BH direction. Here, we searched for substructure in the diagram of M BH versus central velocity dispersion σ, using our recently published multi-component galaxy decompositions, by investigating divisions based on the presence of a depleted stellar core (major dry merger), a disk (minor wet/dry merger, gas accretion), or a bar (evolved unstable disk). The Sérsic and core-Sérsic galaxies define two distinct relations: MBH ∝ σ5.75±0.34 and MBH ∝ σ8.64±1.10, with Δrms|BH and 0.46 dex, respectively. We also report on the consistency with the slopes and bends in the galaxy luminosity (L)-σ relation due to Sérsic and core-Sérsic ETGs, and LTGs that all have Sérsic light profiles. Two distinct relations (superficially) reappear in the M BH-σ diagram upon separating galaxies with/without a disk (primarily for the ETG sample), while we find no significant offset between barred and non-barred galaxies, nor between galaxies with/without active galactic nuclei. We also address selection biases purported to affect the scaling relations for dynamically measured M BH samples. Our new M BH-σ relations, dependent on morphological type, more precisely estimate M BH in other galaxies, and hold implications for galaxy/black hole coevolution theories, simulations, feedback, the pursuit of a black-hole fundamental plane, and calibration of virial f-factors for reverberation mapping.

    Original languageEnglish (US)
    Article number10
    JournalAstrophysical Journal
    Issue number1
    StatePublished - Dec 10 2019

    ASJC Scopus subject areas

    • Astronomy and Astrophysics
    • Space and Planetary Science


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