Why don’t all galaxies form stars at the same rate?

Project area/S

• Physics of the Diffuse Universe and The Evolving Universe

Project Details

A massive burst of star formation in a disc galaxy.

It is now well established that star-forming galaxies follow a well-defined relation in the star formation rate (SFR) vs. stellar mass plane, referred to as star-forming main sequence (SFMS). Put simply, bigger galaxies form more stars per year.
All this does sound reasonable but, when we look at this relation in the details, things start looking less “obvious”. The scatter in the relation is not the same across all masses. Instead, it is very high at low and high stellar masses, while reaching a minimum value at masses typical of the mass of the Milky Way.

Why is that?

Many works suggest that this is due to two different physical processes: short burst of star formation at low masses, and the onset of feedback from supermassive black-holes at high masses. But, is it really the case?

In this project, the student will develop a simple analytical model to investigate the potential origin for the dependence of scatter on stellar mass. Specifically, they will determine whether “exotic” scenarios like bursts and/or black-holes are really needed, or if what we are seeing is just a more simple consequence of the secular star formation history of galaxies. Sometimes, we might be overlooking the most simple explanation for complex problems.

Student Attributes

Academic Background

Basic knowledge of astronomy.

Computing Skills

Basic python knowledge (e.g., ability to read and write files and to make basic plots).

Training Requirement

Ability to handle astronomical data and to understand basics of astronomy observational techniques.

Project Timeline