Since 2019 it is proposed that the hypothetical Planet IX may in fact be a primordial black hole. Black holes are being looked after differently than planets. You can look for a gravitational lens or for an accretion disc. However, the black hole theory doesn't seem to be taken serious by many.
Is there any ongoing search for such black hole rather than a planet, or are there any plans to look after a primordial black hole if the planet theory would get disproved?
Maybe, Harvard scientists have proposed a way to determine, once and for all, whether Planet Nine actually could be a black hole. Specifically, the new method would scour the outer solar system for evidence of telltale flares that are emitted when a black hole devours a comet or other distant object. Such flares, they say, should be detectable by the upcoming Vera C. Rubin Observatory in Chile, which is expected to begin a 10-year survey of the southern sky within the next few years.
I suppose if funding is available for this it will be done when the telescope comes on-line. This may solve the problem of if it's a black hole but a large planet could still be possible but unknown.
