Correlation (or not) between the Spin Directions of Supermassive Black Holes and their Host Galaxies

Yen-Ting Lin^1*

¹Institute of Astronomy and Astrophysics, Academia Sinica, Taipei, Taiwan

* Presenter:Yen-Ting Lin, email:ytl@asiaa.sinica.edu.tw

The existence of various correlations between properties of supermassive black holes (SMBHs) and their host galaxies has implied critical roles SMBHs play in the formation and evolution of massive galaxies. In this work, we attempt to examine whether there is any correlation between the spin directions of SMBHs and their host galaxies.  Using the final galaxy from SDSS-IV MaNGA survey, we have assembled a sample of 130 galaxies with prominent jets, which enable us to infer the (projected) spin direction of their SMBHs.  The kinematics of the galaxies are measured from MaNGA stellar velocity maps.  We have developed an analytic framework that enables us to infer the correlation of the spin directions in 3D, given the ensemble distribution of the 2D, observed angle differences of the jet and galaxy kinematic position angles.  Considering the huge difference in the scales, a naive expectation is a null detection of any correlation.  Surprisingly, we have found that, for elliptical galaxies with younger ages (lower values of 4000 Angstrom break), there exists strong correlations, particularly for those with lower velocity dispersion.  A possible explanation of the correlation is that mergers that create lower mass, young elliptical galaxies, which presumably are wet mergers involving disk galaxies, likely retain the "memory" of the spin alignment of the progenitors.

Keywords: Supermassive black holes, Radio galaxies, Galaxy kinematics, Elliptical galaxies