Any hints of the dark matter?, there is no new physics reported by the LHC since the Higgs bossom, shouldn't this point the research to alternative models to explain the effects on the gravity apart of that "dark matter" (not questioning the Standard Model of course)?
Only indirect hinds. We are still lacking the direct evidence of it. While dark matter has a lot of nice advantage on the cosmology side, other alternative options are still allowed (i.e. modified gravity for instance). For that reasons, you have researchers working on dark matter (for instance myself) and others working on other paradigm. We need to be pragmatic and cover everything,.
For what we know this is the only explanation for the cohesion of the galaxies or could we explain that cohesion for a bad estimation of the weight of the black holes?, never understood how can we be so accurated in that estimation.
I am not sure to get what you mean. Could you please specify? Dark matter is needed to explain the formation of the galaxies in the Standard Model of cosmology. In addition, dark matter could be made of black holes too.
I know I didn't answer the question, but I didn't get it exactly. Feel free to come back to me and I will clarify anything needed.
Sorry maybe I didn't explained myself properly, as I said my knowledge about the subject is very limited, as limited its my english too, so is a double effort to me 🙂.
For what I understood by my previous readings about the dark matter, was needed to add enough mass to the galaxies, and to explain the fact that they don't break up because of the kinetic forces of their own rotative movement. (maybe I misunderstood this)
What I didn't know is that is also needed to explain their formation which is very interesting too. For what I understand from your reply there is no sure measure of the weight of the black holes (because dark matter could be part of them) and therefore I was wrong assuming that the scientists have this problem "solved".
Many times in the scientists articles I use to read they say for example this black hole has 20 times the sun mass and the like, they seem to affirm it with so much conviction that I assumed that they're sure about it, therefore my confusion.
Thank you very much for your kind explanation.
No problem with the double effort. I will be patient, don't worry ^^
Dark matter was initially postulated to explain the motion of the stars in the galaxies, as well as the global motion of the galaxies themselves. Assuming gravity, observations are only reproduced if we add something invisible (that generates some gravitational force): dark matter.
Today, we also know that dark matter is also needed to explain galaxy formation, the cosmic microwave background, gravitational lensing.
In short, many cosmological observations are pointing towards its existence and everything seems to agree with each other. The only missing link is the direct observation of dark matter on Earth.
The mass of a black hole (and not the weight) can be inferred from the motion of the objects lying around it. This is thus another story, different from dark matter. We indeed observe how objects are attracted by the black hole or orbit around it. From there, one can extract the black hole mass.