English

Revealing Hidden Substructures in the $M_{BH}$-$\sigma$ Diagram, and Refining the Bend in the $L$-$\sigma$ Relation

Astrophysics of Galaxies 2019-12-11 v3

Abstract

Using 145 early- and late-type galaxies (ETGs and LTGs) with directly-measured super-massive black hole masses, MBHM_{BH}, we build upon our previous discoveries that: (i) LTGs, most of which have been alleged to contain a pseudobulge, follow the relation MBHM,sph2.16±0.32M_{BH}\propto\,M_{*,sph}^{2.16\pm0.32}; and (ii) the ETG relation MBHM,sph1.27±0.07M_{BH}\propto\,M_{*,sph}^{1.27\pm0.07} is an artifact of ETGs with/without disks following parallel MBHM,sph1.9±0.2M_{BH}\propto\,M_{*,sph}^{1.9\pm0.2} relations which are offset by an order of magnitude in the MBHM_{BH}-direction. Here, we searched for substructure in the MBHM_{BH}--(central velocity dispersion, σ\sigma) diagram using our recently published, multi-component, galaxy decompositions; 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 S\'ersic and core-S\'ersic galaxies define two distinct relations: MBHσ5.75±0.34M_{BH}\propto\sigma^{5.75\pm0.34} and MBHσ8.64±1.10M_{BH}\propto\sigma^{8.64\pm1.10}, with ΔrmsBH=0.55\Delta_{rms|BH}=0.55 and 0.460.46~dex, respectively. We also report on the consistency with the slopes and bends in the galaxy luminosity (LL)--σ\sigma relation due to S\'ersic and core-S\'ersic ETGs, and LTGs which all have S\'ersic light-profiles. Two distinct relations (superficially) reappear in the MBHM_{BH}--σ\sigma 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 MBHM_{BH} samples. Our new, (morphological type)-dependent, MBHM_{BH}--σ\sigma relations more precisely estimate MBHM_{BH} in other galaxies, and hold implications for galaxy/black hole co-evolution theories, and simulations. (Abridged)

Keywords

Cite

@article{arxiv.1908.06838,
  title  = {Revealing Hidden Substructures in the $M_{BH}$-$\sigma$ Diagram, and Refining the Bend in the $L$-$\sigma$ Relation},
  author = {Nandini Sahu and Alister W. Graham and Benjamin L. Davis},
  journal= {arXiv preprint arXiv:1908.06838},
  year   = {2019}
}

Comments

33 pages, 15 figures, 5 tables; Accepted for publication in Astrophysical Journal on 22 October 2019