# New perspectives on galactic angular momentum, galaxy formation, and the Hubble Sequence

## TL;DR

This paper investigates the relationship between specific angular momentum and stellar mass in galaxies, proposing a model that explains the observed scaling relations and their dependence on galaxy bulge fraction.

## Contribution

It introduces a simple superposition model combining disk and bulge components with distinct scaling relations to explain galaxy angular momentum properties.

## Key findings

- Observations are consistent with a linear superposition model.
- Galaxies follow a curved surface in the space of angular momentum, mass, and bulge fraction.
- Disks and bulges follow separate scaling relations with similar exponents.

## Abstract

This paper provides a summary of our recent work on the scaling relations between the specific angular momentum j_* and mass M_* of the stellar parts of normal galaxies of different bulge fraction beta_*. We find that the observations are consistent with a simple model based on a linear superposition of disks and bulges that follow separate scaling relations of the form j_*d ~ M_*d^alpha and j_*b ~ M_*b^alpha with alpha = 0.67 +/- 0.07 but offset from each other by a factor of 8 +/- 2 over the mass range 8.9 <= log (M_*/M_Sun) <= 11.8. This model correctly predicts that galaxies follow a curved 2D surface in the 3D space of log j_*, log M_*, and beta_*.