Not sure what happened here, how the hell did I end up writing a paper with actual radio data that needed to be reduced… Call me an ambulance.

The guy here is 3C186 which is not a postcode but a quasar. A funny one because it’s not centered on the galaxy (it’s a bit off) and it’s also going at another velocity (ciao ciao). One of the leading explanations is that 3C186 is a recoiling black hole, the remnant of black-hole merger is being kicked away (yeah these things can happen). 3C186 also has a radio jet, and that should point in the direction of the black-hole spin. The funny thing is that spin and the kick appear perpendicular to each other, and this is fun because theory says they should actually be parallel. We looked into this a bit carefully and discovered it’s all a lie! The spin and the kick both point along the line of sight and appear perpendicular only because of a super strong projection effect. If this is true, the radio jet should also point straight to us! We then tried to test this with whatever ratio data we could grab (where is that ambulance) and found that… mmh, well, it’s a maybe.

Matteo Boschini, Davide Gerosa, Om Sharan Salafia, Massimo Dotti.
Astronomy & Astrophysics 686 (2024) A245.
arXiv:2402.08740 [astro-ph.GA].