The Star Formation History of the Universe

(Note: all figures from Madau and Dickenson, ARAA 2014)

How do we measure the star formation history of the universe?

Galaxy luminosity functions in the rest frame ultraviolet (left) and far-infrared (right):

How to convert these to star formation rates?

Estimating extinction correction by comparing (uncorrected) UV and FIR star formation rates.

Left: Star formation rate, Right: Inferred extinction (magnitudes)

Combined datasets, after extinction correction (blue/green points = UV, red/purple points = FIR)

Remember, this is NOT the SFR history of individual galaxies, it's the integrated SFR history of the universe.

Consistency checks

1) Integrating the star formation history over time should give the stellar mass of the universe.

Stellar mass function of galaxies: Total stellar mass (data points) compared to integrated SFR (solid line):

2) Type II (massive star) core-collapse supernovae rate as a function of redshift (data points), compared to derived SFR (solid line):

3) Combine SFR fit with metallicity evolution model to predict average metallicity of the universe.

Zb = rho(metals)/rho(baryon)