Dwarf Galaxies as a Challenge for Star Formation and Galactic Winds
Dwarf Galaxies as a Challenge for Star Formation and Galactic Winds
The Nature of Dwarfs: Gas Rich, Long Depletion Time
tH
Papastergis+ (2012)
Forbes+ (2016)
Baryon Fraction and Mass Loading Both Very Uncertain
Papastergis+ (2012)
Schroetter+ (2015)
Mass Loading Uncertainty and Bathtub Models
Forbes+ (2014)
Simulations with Resolved SNe and Photoelectric Heating Gas Surface Density Jeans Unstable Gas Newly formed stars
Forbes+ (2016)
Turning Physics On and Off No feedback SNe only PE only SNe + PE
Need PE Feedback to Match Data
Wind Properties
Mass Loading
Metal Loading
Figure 6.4: The Metal Mixing Factor. The metal enhancement of the wind. The
Implications •
In dwarfs, the mechanisms that regulate star formation and launch winds are decoupled
•
Star formation in small galaxies is NOT regulated by momentum feedback
•
The bathtub model is not applicable to dwarfs because they do not reach equilibrium in < tH
•
Possible new theoretical definition of dwarf: dwarfs are galaxies that do not reach equilibrium in a Hubble time
•
Major question: what is the range in halo mass / redshift over which galaxies are dwarfs (by this definition)?
The Nature of Dwarfs: Gas Rich, Long Depletion Time
tH
Papastergis+ (2012)
Forbes+ (2016)
Baryon Fraction and Mass Loading Both Very Uncertain
Papastergis+ (2012)
Schroetter+ (2015)
Mass Loading Uncertainty and Bathtub Models
Forbes+ (2014)
Simulations with Resolved SNe and Photoelectric Heating Gas Surface Density Jeans Unstable Gas Newly formed stars
Forbes+ (2016)
Turning Physics On and Off No feedback SNe only PE only SNe + PE
Need PE Feedback to Match Data
Wind Properties
Mass Loading
Metal Loading
Figure 6.4: The Metal Mixing Factor. The metal enhancement of the wind. The
Implications •
In dwarfs, the mechanisms that regulate star formation and launch winds are decoupled
•
Star formation in small galaxies is NOT regulated by momentum feedback
•
The bathtub model is not applicable to dwarfs because they do not reach equilibrium in < tH
•
Possible new theoretical definition of dwarf: dwarfs are galaxies that do not reach equilibrium in a Hubble time
•
Major question: what is the range in halo mass / redshift over which galaxies are dwarfs (by this definition)?
