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AKARI reveals cosmic star formation history

Many results from the AKARI data are appeared in a special issue by "Astronomy and Astrophysics" published in May 2010 . Here we introduce a research revealing cosmic star formation history featured in Goto et al. (2010).

When were stars born? Understanding cosmic star formation history is one of the major goals of modern astronomy. Observing star formation in the infrared is especially important, since much intense star formation activity is obscured by dust. However, the starting point of this history, the local star formation rate at the current epoch, is still based on the 25-year-old IRAS data, which covered only up to 100um. Taking advantage of AKARI's six-band all sky survey---which covers the key far-infrared wavelengths across the peak of the cool dust emission up to 160um---we measured the local star formation density more precisely than previous work. By comparing this to results from the distant Universe (also measured by the AKARI deep survey), we obtain the cosmic star formation history as shown in the figure.

The figure shows cosmic star formation history measured by AKARI. The AKARI all sky survey measured local star formation density at z=0 (present epoch) much more precisely than previous work. Data at z>0 (distant Universe, in the past) are from the AKARI deep survey. Orange and blue squares are for ultra-luminous infrared galaxies (ULIRG) and luminous infrared galaxies (LIRG), respectively.

It shows a steep increase from now back to 10.6 billion years ago, when the star formation density was 20 times higher. Also ultra-luminous infrared galaxies contributed 10 times more than in the present Universe.

Tomotsugu Goto (University of Hawaii), June, 2010