If you don't know have a look at this even if you do know this probably brings things up to date.
Any views on what they could be.
My bet is stuff falling into a black hole as that is perhaps the only thing I can think of to provide the energy and have opportunity to occur so often..perhaps too often but remember there are a lot of galaxies etc etc..but 10,000 a year was news to me
https://youtu.be/cjOKdVsUwLw
Alex