The Star Formation History of the Universe

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

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

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

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 (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 compared to integrated SFR:

2) Type II (massive star) core-collapse supernovae rate as a function of redshift, compared to SFR

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

Zb = rho(metals)/rho(baryon)