Is the distribution of stellar masses universal?

16/03/2015
The initial mass function (IMF) dictates the distribution of stellar masses for any single star formation event in a galaxy. Traditionally it has been assumed that the IMF is universal, i.e. the same for all galaxies since the origin of the universe. Recent studies of nearby galaxies suggest changes in the IMF. However, the IMF of distant galaxies has been studied only indirectly. A study led by researchers from the IAC / ULL and the Universidad Complutense de Madrid has analyzed for the first time the IMF of massive quiescent galaxies at half the age of the Universe from spectro-photometric data obtained with the Hubble telescope and GTC. The results of this study suggest that the most massive galaxies are populated by a larger number of low-mass stars than expected, and that the IMF has remained unchanged over the last 8,000 million years for these galaxies. The work, which was published in ApJ Letters, is the result of stay of Pablo Pérez González, researcher at the UCM, in the IAC within the Severo Ochoa senior visitors programme.