Information says that the gravitational waves, recently detected by LIGO, correspond (according to Einstein theory equations) to the effect of two black holes merging (with the masses of both black holes being estimated).
Does the above method (detection of gravitational waves) constitute proven scientific fact of astronomical discovery with regards that the source of those waves was indeed the merger of two black holes, or is it still at best currently a possible implied assumption (should there be at least two independent of each other methods to claim the establishment of the astronomical discovery?)?
Note that I am not questioning the fact of establishing gravitational waves existence via their detection; I am questioning whether this detection constitutes established scientific fact of the merger of two black holes (versus any other cause, for which current state of the science possibly has no knowledge of).
So is it an established scientific astronomical (cosmological) fact or just a best possible implied assumption?
From what I have read before, typically black holes are located in the center of galaxies and that "supermassive black holes contain ~0.5% of the stellar mass of their host galaxies".
With regards to those two colliding black holes, which created gravitational waves recently detected by LIGO, - what happened with their host galaxies (did they merge?)?
PS - back to question 1)
After I was educated by the answers, which cleared my black holes classification confusion :-) - my apologies for lack of prior knowledge on that, it appears to me that it will be looking more like a definite proof of validity of gravitational wave generational artifacts, following from the Einstein General Relativity theory, when additionally gravitational waves, caused by the merge of the supermassive black holes (those which ARE indeed located in the centers of the merging galactics) will be detected, since merges of galactics could be observed by the methods independent of gravitational waves such as registering the fact of the quasar appearance ...
Could someone offer me the historical ASTRONOMY precedent when the second degree of inference (from the mathematical model, being associated with the theory of Physics) was accepted as the discovery of the astronomical object?
Could someone give a reference to trustable scientific publication, with the subject of study being discussion of requirements satisfying claim of astronomical discovery of an astronomical object?
Have independent scientific sources (outside of members of the LIGO team) analyzed methodology and results of the LIGO signal detection, and published their conclusions with regards of what was actually discovered?