The authors argue that if Oumuamua were just a random interstellar rock, we should have seen more objects like it. Oumuamua baffled scientists previous year due to its unique speed and trajectory: as it passed through our solar system, Oumuamua accelerated.
That shape would allow solar radiation to push the vessel along and explains the object's unusual acceleration.
Whether Oumuamua is a light sail from a spacecraft of artificial origin floating aimlessly through solar systems or an operational probe sent intentionally to Earth, the researchers said its likely origin will only be determined by searching for other objects like it in the future.
The researchers aren't claiming outright that aliens sent Oumuamua. But after a thorough mathematical analysis of how interstellar object accelerated as it flew past the Sun, they say Omwamwi can be a space ship.
Their paper was accepted for publication in the Astrophysical Journal Letters and will appear on November 12. The word Oumuamua in Hawaiian language means "a messenger reaching out from the distant past".
Oumuamua's unusual trajectory and high speed sets it aside from other space objects such as asteroids and comets.
Another study suggested other objects similar to Oumuamua will eventually enter our solar system, with some of them carrying the building blocks of life. "Namely that it's a comet or asteroid from afar".
It was moving at 59,030mph when it was first tracked by scientists. "So we wrote this paper suggesting this explanation", Loeb told the Boston Globe.
According to NASA, this interstellar object was a "metallic or rocky object" about 400 metres long and 40 metres wide.
"Any functional spacecraft would nearly certainly retract its solar sail once in interstellar space to prevent damage", Jackson said. Instead of the normal mechanic used by comets to accelerate (called "outgassing"), the authors suggest solar radiation pressure could explain 'Oumuamua's behavior. Studies re-examining the light signals more carefully suggest that Oumuamua could be very elongated cigar-shaped to pancake-shaped."What is clear is that it can't have a shape that is almost spherical - like normal rocks we know", he said.Loeb said the mystery of Oumuamua's origin remains.
"Aliens would only come into all of this if you accept their assumption (and that's what it is; it doesn't come from the data) that "Oumuamua is sail-like, and also assume nothing like that can be natural", Bailer-Jones wrote in an email".
The truth may be hard to establish, as Oumuamua has left the solar system and is no longer visible even with telescopes.