Higgs Hour with Sergey Koposov: 'Hyper-velocity stars as probes of the super-massive black hole in the Galactic centre'

Hyper-velocity stars are interesting objects that were first theoretically proposed by Richard Hills as products of interaction of a binary star and a supermassive black hole, that leads to the star being ejected out the galaxy with the speed of hundreds and thousands of km/s. About 15 years ago, a first hyper-velocity star that could have been produced by Hills mechanism have been identified in the Milky Way outskirts moving at the speed of ~ 800 km/s, that is larger than the escape speed of the Galaxy. Since then a few more possible stars like this have been identified. Last year however while analysing data from the survey that measured radial velocities of tens of thousands of stars from disrupted galaxies around the Milky Way we have identified the fastest hyper-velocity star that we can unambiguously trace back to the black hole in the Galactic center. The ejection happened ~ 5 Myr ago and that age curiously coincides with the ages of several other structures next to the Galactic centre. In the talk I'll discuss some history of the discoveries of hyper-velocity stars, some recent results as well as what they can tell us in the future.

Note, passcode for Zoom can be found in email invitation or contact Ines (ines.foidl [at] ed.ac.uk)

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