Galactic habitability re-examined: indications of bimodality

The problem of the extent of habitable zones in different kinds of galaxies is one of the outstanding challenges for contemporary astrobiology. In the present study, we investigate habitability in a large sample of simulated galaxies from the illustris Project in order to at least roughly quantify the hospitality to life of different galactic types. The pioneering study of Dayal et al. is critically examined and some of its results are amended. In particular, we find a tentative evidence for a second mode of galactic habitability comprising metal-rich dwarfs similar to IC 225, LMC, or M32. The role of the galactic environment and the observation-selection effects is briefly discussed and prospects for further research on the topic outlined.