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“Fossils” of galaxies reveal the formation and evolution of massive galaxies

| Science

An international team led by researchers at Swiss Federal Institute of Technology in Zurich observed massive dead galaxies in the universe 4 billion years after the Big Bang with the Subaru Telescope’s Multi-Object InfraRed Camera and Spectrograph (MOIRCS). They discovered that the stellar content of these galaxies is strikingly similar to that of massive elliptical galaxies seen locally. Furthermore, they identified progenitors of these dead galaxies when they were forming stars at an earlier cosmic epoch, unveiling the formation and evolution of massive galaxies across 11 billion years of cosmic time.

Composite spectrum of 24 massive dead galaxies in the universe 4 billion years after the Big Bang.
Figure. Composite spectrum of 24 massive dead galaxies in the universe 4 billion years after the Big Bang. The spectra is equivalent to 200 hours of Subaru Telescope's observing time. Rectangles on the spectrum indicate spectral features, which are used to calculate the ages, the amount of heavy elements and the α-element abundance in the stellar populations of these galaxies.

This research was published on 1st August 2015 in The Astrophysical Journal (Onodera et al. 2015 “The Ages, Metallicities, and Element Abundance Ratios of Massive Quenched Galaxies at z~1.6”).

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