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It is said that the gravitational waves (GW), recently detected by LIGO, correspond (according to Einstein General Relativity theory equations) to the effect of two black holes merging (with the masses of both colliding black holes and the mass of the black hole, which resulted due to that merger, being estimated).

Does the above method (detection of gravitational waves) constitute acceptable scientific method of proving with regards that the source of those waves was indeed the merger of two black holes (as definitely existing astronomical objects), or is it still at best currently possible implied assumption?

Since in the given case, existence of black holes is derived using two steps of inference from the General Relativity Theory mathematical model, should there be at least two independent of each other methods to claim the discovery of those two black holes as astronomical objects?

As an alternative, could LIGO signature detected GW possibly have been produced by collision/merge/annihilation of some matter and antimatter objects (this one is highly hypothetical assumptive question and I am asking it just to illustrate my point that the collision of two BHs, implied as the cause of LIGO detected GW, perhaps should be considered as just highly probable but not absolutely established astronomical fact)?

Could this issue (specifically with regards to detection of two black holes merge and existence of resulted from that merge single black hole) be compared (in the sense that both relied on indirect evidence analogy) with the issue of existence of Planet 9 (per California Institute of Technology astronomers Konstantin Batygin, a theoretician, and Mike Brown), which is considered at this point as just a hypothesis (with all evidence of its existence being indirect and relying on the calculational model)?

http://www.cbsnews.com/news/researchers-find-evidence-for-yet-unseen-planet-nine/

P.S. It is interesting (see below link)

https://www.theguardian.com/science/2016/feb/11/gravitational-waves-discovery-i-was-right-says-stephen-hawking

that at the beginning of above article the word "discovery" was only applied by Stephen Hawking to the detection of gravitational waves as such, but further the term "discovery" was extended as:

"This discovery is the first detection of a black hole binary system and the first observation of black holes merging.”

Further on

"Asked what more could be discovered if scientists scanned for gravitational waves, he said: “Apart from testing general relativity, we could hope to see black holes throughout the history of the universe. We may even see relics of the very early universe during the big bang at the most extreme energies possible.”"

This question is a refinement of the previously asked by me question

Do the LIGO observations constitute proof of a black hole merger, and what happened to the black holes?,

which was diluted (Mia culpa) by another issue (related to classification of black holes).

I would like to see here an answer, which would more in general cover the subject of methodologies, with regards what constitutes discovery in PHYSICS (such as the phenomena of gravitational waves) versus discovery in ASTRONOMY (such as discovery of black holes, as astronomical objects). With regards to LIGO detection, I think that it amounts to discovery (in the field of Physics) of gravitational waves (as physical phenomena), but I do question whether LIGO detection constitutes a discovery (in the field of Astronomy) of specific black holes (as astronomical objects) - the latter one, IMHO, should be characterized as highly plausible very probable hypothesis ...

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?

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Alex
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    "This is highly hypothetical question..." It's not even that. Physicists don't make a habit of wild outright guesses. They may start with a guess but then they ask themselves if that guess can be made to line up with what is known. The signal oscillates and exhibited increasing frequency in time. What is it about a matter-anti matter interaction that you think would produce either of those features of the signal? – dmckee --- ex-moderator kitten Feb 17 '16 at 18:19
  • @dmckee What would you think Newton would say if being asked (at his times) about effects of General Relativity - I guess that his answer would be in line with your comment ... :-) – Alex Feb 17 '16 at 18:24
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    @Alex: Nothing is absolutely established... – Martin Feb 17 '16 at 18:38
  • This isn't terribly different from your other query – Kyle Kanos Feb 17 '16 at 18:42
  • @Martin - granted, but the hype created around this LIGO GW detection with regards to its cause tends to claim the opposite. So since you have just admitted the relativity of scientific findings, why don't we (with regards to LIGO) assign different probabilities: one value to GW existence and yet another to its probable cause - the merge of two BHs? – Alex Feb 17 '16 at 18:57
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    @Alex you cannot separate them because it is the coincidence of the temporal shape of the signal to two black hole mergers that allows to identify it wiht the GR . There would be no gravitational wave of such magnitude from two matter antimatter collisions . All the energy would go to gammas and other particles and much more than 5% of the masses. – anna v Feb 17 '16 at 19:03
  • @annav At least on cognitional semantics level those two things are separable - one is direct, another is implied. – Alex Feb 17 '16 at 19:17
  • @DavidZ This question is a refinement of the previously asked by me question http://physics.stackexchange.com/questions/236107, which was diluted (Mia culpa) by another issue (related to classification of black holes). I would like to see here an answer, which would more in general cover the subject of methodologies, with regards what constitutes discovery in PHYSICS (such as the phenomena of gravitational waves) versus discovery in ASTRONOMY (such as discovery of black holes, as astronomical objects). – Alex Feb 28 '16 at 19:08
  • @DavidZ - in my previous message addressed to you - did I give convincing explanation why I consider two my questions to be different? – Alex Feb 29 '16 at 17:05
  • No, you didn't. I don't see how these questions are sufficiently different not to be considered duplicates. – David Z Feb 29 '16 at 17:42

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The LIGO signature was matched to a waveform of a colliding black hole binary system. If the colliding bodies had had mass and extent, then you would have deformations of the objects as they collided and combined (and this would likely have been followed by gravitational collapse), which would have changed the signature, and produced a different waveform.

In particular, if the two colliding objects were made of matter and antimatter, you would expect annhilation, heating, and therefore, an explosion at the initial point of contact. This would push the objects apart, before (perhaps) another inspiral, which would spread out the GW wave release. Whether you get multiple peaks or something like that is obviously dependent on the details, but you wouldn't get the nice sharp plunge you get with a binary BH merger.

Zo the Relativist
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    Also two large masses annihilating would give a lot radiation in gamma rays which would give a strong signal , gamma ray burst. There was a small one http://motls.blogspot.gr/2016/02/fermi-saw-gamma-rays-04-seconds-after.html – anna v Feb 17 '16 at 18:47
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    the paper trying to explain it http://arxiv.org/abs/1602.04735 – anna v Feb 17 '16 at 18:58