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John Kormendy investigates the structure of galaxies and their central supermassive black holes. His 2013 review with Luis C. Ho examines black hole mass measurements inferred from spatially resolved motion and their correlations with different components of the host galaxy.

An important distinction is between a galactic bulge, a galactic disk and a pseudobulge: the authors find that the same simple coevolution story does not describe all three. A correlation such as the M-sigma relation is therefore evidence to interpret in its structural context, rather than a universal description of every galaxy.^[ref]

Luis C. Ho investigates supermassive black holes and their connections to host galaxies. His review with John Kormendy organized dynamically measured black hole masses by host structure, including classical bulges, galactic disks and pseudobulges.

The distinction changes the physical interpretation of a scaling relation. Strong correlations with some bulge properties do not establish equally close coupling to every component of a galaxy. The review argued that weak relations for galactic disks and pseudobulges require a richer account of black hole growth than a single universal coevolution rule.^[ref]

A pseudobulge is a central stellar concentration in a disk galaxy whose structure and dynamics indicate growth through internal disk evolution rather than only rapid merger-driven assembly. A central brightness excess alone does not establish this origin.

Disk-like flattening, appreciable ordered rotation, nuclear spiral arms, galactic bars and ongoing star formation provide complementary diagnostics. A bar can torque gas and move it inward, feeding central star formation over a long timescale. Individual diagnostics are imperfect, so classifications combine imaging and kinematics instead of equating every low-index brightness profile with a unique history.^[ref]