Big Galaxies and Big Black Holes: The Massive Ends of the Local Stellar and Black Hole Mass Functions and the Implications for Nanohertz Gravitational Waves

Understand

We construct the $z=0$ galaxy stellar mass function (GSMF) by combining the GSMF at stellar masses $M_* \lesssim 10^{11.3} M_\odot$ from the census study of Leja et al.

• (2020) and the GSMF of massive galaxies at $M_* \gtrsim 10^{11.5} M_\odot$ from the volume-limited MASSIVE galaxy survey.
• To obtain a robust estimate of $M_*$ for local massive galaxies, we use MASSIVE galaxies with $M_*$ measured from detailed dynamical modeling or stellar population synthesis modeling (incorporating a bottom-heavy initial mass function) with high-quality spatially-resolved spectroscopy.
• These two independent sets of $M_*$ agree to within ${\sim}7$%.