A lower bound on the maximum mass if the secondary in GW190814 was once a rapidly spinning neutron star

The recent detection of GW190814 featured the merger of a binary with a primary having a mass of similar to 23 M-circle dot and a secondary with a mass of similar to 2.6 M-circle dot. While the primary was most likely a black hole, the secondary could be interpreted as either the lightest black hole or the most massive neutron star ever observed, but also as the indication of a novel class of exotic compact objects. We here argue that although the secondary in GW190814 is most likely a black hole at merger, it needs not be an ab-initio black hole nor an exotic object. Rather, based on our current understanding of the nuclear-matter equation of state, it can be a rapidly rotating neutron star that collapsed to a rotating black hole at some point before merger. Using universal relations connecting the masses and spins of uniformly rotating neutron stars, we estimate the spin, 0.49(-0.05)(+0.08) less than or similar to chi less than or similar to 0.68(-0.05)(+0.11), of the secondary - a quantity not constrained so far by the detection - and a novel strict lower bound on the maximum mass, M-TOV > 2.08(-0.04)(+0.04) M-circle dot and an optimal bound of M-TOV > 2.15(-0.04)(+0.04) M-circle dot, of non-rotating neutron stars, consistent with recent observations of a very massive pulsar. The new lower bound also remains valid even in the less likely scenario in which the secondary neutron star never collapsed to a black hole.