Searching for a Black Hole in the Outer Solar System
Abstract
There are hints of a novel object ("Planet 9") with a mass 5-10 M in the outer Solar System, at a distance of order 500 AU. If it is a relatively conventional planet, it can be found in telescopic searches. Alternatively, it has been suggested that this body might be a primordial black hole (PBH). In that case, conventional searches will fail. A possible alternative is to probe the gravitational field of this object using small, laser-launched spacecraft, like the ones envisioned in the Breakthrough Starshot project. With a velocity of order .001~c, such spacecraft can reach Planet 9 roughly a decade after launch and can discover it if they can report timing measurements accurate to 10-5 seconds back to Earth.
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