Is Planet 9 Actually A Primordial Black Hole? - Forbes

[+] hypothesized black hole in the outer solar system.

Conventional theory has it that Planet 9 —- our outer solar system’s hypothetical 9th planet —- is merely a heretofore undetected planet, likely captured by our solar system at some point over its 4.6 billion year history. .

But Harvard University astronomers now raise the possibility that orbital evidence for Planet 9 could possibly be the result of a missing link in the decades-long puzzle of dark matter. That is, a hypothetical primordial black hole (PBH) with a horizon size no larger than a grapefruit, and with a mass 5 to 10 times that of Earth.

Our paper shows that if Planet 9 is a black hole, then comets residing in the outskirts of the Solar system (in the "Oort cloud") would impact it, Avi Loeb, Chair of Harvard University’s Dept.

We calculated that the flares from the accretion of a small body onto a Planet 9 black hole would be brightest near the optical band, where LSST operates, he says?

 And they expect to be able to rule out or confirm Planet 9 as a primordial black hole within the first two years of the LSST’s operation?

Why would our own solar system harbor such an exotic primordial black hole.

 The authors estimate that it might be somewhat likely that our solar system gravitationally-captured at least once such primordial black hole over the eons.

If Planet 9 is a primordial black hole, are there likely to be others within the galaxy.