Evolution of the dust emission of massive galaxies up to z=4 and constraints on their dominant mode of star formation

Understand

We aim to measure the average dust and molecular gas content of massive star-forming galaxies ($\rm > 3 \times 10^{10}\,M_\odot$) up to z=4 in the COSMOS field to determine if the intense star formation observed at high redshift is induced by major mergers or caused by large gas reservoirs.

• Firstly, we measured the evolution of the average spectral energy distributions as a function of redshift using a stacking analysis of Spitzer, Herschel, LABOCA, and AzTEC data for two samples of galaxies: normal star-forming objects and strong starbursts, as defined by their distance to the main sequence.
• We found that the mean intensity of the radiation field $< U >$ heating the dust (strongly correlated with dust temperature) increases with increasing redshift up to z$\sim$4 in main-sequence galaxies.
• We can reproduce this evolution with simple models that account for the decrease of the gas metallicity with redshift.