The two that merged were 1.6 and 1.1 times as massive as our sun, but each was no wider than Washington, D.C”
Washington, D.C. is very dense.
Wash DC is a black hole sucking in our money.....
In astrophysics there is a number called the
Tolman–Oppenheimer–Volkoff limit, which specifies how much mass must exist for a neutron star to collapse to the stage past that, which would be a singularity. This is about three stellar masses (a stellar mass is the mass of our own local star, Sol). Since the combined mass of these two objects was less than that, the answer would be no. Plus mass would be lost during the collision in the form of energy, which would reduce the combined mass even more.
However, if one of these objects was less than 1.4 stellar masses, then it would be a white dwarf, not a neutron star at all. This is called the Chandrasekhar Limit. Still quite dense, but not on the order of a neutron star.
Please bear in mind that I'm not a rocket scientist nor do I play one on TV. $:-)