Cosmic explosions, life in the Universe and the Cosmological Constant
  Galactic Gamma-Ray Bursts (GRBs) are copious sources of gamma-rays that can
pose a threat to complex life. Using recent determinations of their rate and
the probability of GRBs causing massive extinction, we explore what type of
universes are most likely to harbour advanced forms of life. For this purpose
we use cosmological N-body simulations to determine at what time and for what
value of the cosmological constant ($\Lambda$) the chances of life being
unaffected by cosmic explosions are maximised. We find that $\Lambda-$dominated
universes favour the survival of life against GRBs. Within a $\Lambda$CDM
cosmology, the parameters that govern the likelihood of life survival to GRBs
are dictated by the value of $\Lambda$ and the age of the Universe. We find
that we seem to live in a favorable point in this parameter phase space which
minimises the exposure to cosmic explosions, yet maximises the number of main
sequence (hydrogen-burning) stars around which advanced life forms can exist.
