Abstract
The relation between early type galaxy size, surface brightness and velocity dispersion, "the fundamental plane", has long been understood as resulting from equilibrium in their largely pressure supported stellar dynamics. The dissipation and feedback involved in reaching such an equilibrium through merger formation of these galaxies over cosmic time can be responsible for the orientation of the plane. We see a correlation between surface brightness enhancement and youth in the 6dF Galaxy Survey. Correlations of this `tilt' with stellar mass, age, concentration, shape and metallicity now point the direction for further work on the resolved kinematics and structure of these nearby galaxies and on their initial mass function and dark matter component. On the face of it, the Tully Fisher relation is a simpler one dimensional scaling relation. However, as late type galaxies have bulges as well as disks, and, as the surface density of disks is only standard for the more massive galaxies, additional parameters are involved.
Highlights
The fundamental plane (FP) of early type galaxies is fairly aptly named, because in the 3-space of velocity dispersion (σ ), surface brightness and effective radius is expressed the dynamical equilibrium that a galaxy has reached, but not how it got there
4A particular choice of f(σ ) and g, for example, yields the Faber and Jackson (1976) power law relation. 5http://www.icg.port.ac.uk/maraston/Claudia%27s_Stellar_Population_Model. html. Based on these mass-to-light ratios, Figure 2 is the deviation from the virial plane as a function of stellar mass
The difficulty of measuring their velocity dispersions means that few have been placed in the FP
Summary
The fundamental plane (FP) of early type galaxies is fairly aptly named, because in the 3-space of velocity dispersion (σ ), surface brightness and effective radius is expressed the dynamical equilibrium that a galaxy has reached, but not (the interesting part) how it got there. It has long been understood that the virial theorem will place quiescent galaxies with a well-defined mass to light ratio in a plane in this space. The observed tilt of the plane differs from the expectation, and the deviation can be patched using the halo occupation distribution formalism (e.g., Moster et al, 2010; Mould, 2014, 2017). That formalism is not physics: it is a mapping between the dark matter universe and the observed one. The reason for the copout, is the difficulty of modeling baryonic processes, such as star formation with their challenging demands for spatial resolution
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
