The distance between a black hole and us may not be as far as you think
The artist imagines the comet being destroyed by a black hole. New research suggests that we can detect the existence of this hypothetical black hole. Image credit: M. Weiss
You've probably heard of Planet Nine, a hypothetical planet thought to exist on the outer reaches of the solar system. Maybe it's not a planet at all, but a small black hole. New research has revealed the possibility of detecting this hypothetical black hole, which could begin as early as next year.
Harvard astronomers Ive Loeb and Amir Sjean proposed in a paper that there is a new method that could be used to detect grapefruit-sized black holes outside the solar system, which has been accepted for publication in the Astrophysical Journal Letters. Astronomers can observe black holes using the Verarubin Observatory under construction in Chile: detecting them indirectly by observing the phenomenon of the black hole's engulfment.
The reason why it is thought that black holes may be lurking on the outer periphery of the solar system is related to a set of unexplained astronomical observations. Something — we don't know what it is — seems to be affecting objects outside Neptune's orbit. One possible explanation is that there is an undetected planet there, which astronomers call Planet Nine, with a mass between 5 and 10 Earth masses, located in an elongated orbit between 400 and 800 AU from the Sun, where 1 AU is the average distance from Earth to the Sun. Recently, scientists have come up with another explanation: It could be a primordial black hole of similar mass.
There may be an ancient black hole within our solar system that isn't as scary as it sounds. As Loeb explained to Gemmu Modi, scientists believe black holes could be responsible for the presence of dark matter in the universe. If that's the case, there should be a lot of black holes out there, so the idea of having one trapped in the solar system isn't stupid.
"This would obviously be very exciting because we've been searching for the nature of dark matter for nearly half a century," Loeb wrote in an email to Gezi Modi. "If a black hole is dark matter, then there should be 50 trillion similar matter in the Milky Way alone to make up the mass of the entire Milky Way, equivalent to a trillion solar masses."
By the way, the quadrillion is 1 after 15 0 Oh.
Finding an object with a grapefruit-sized event horizon may sound daunting, but these large and heavy objects can wreak havoc on the surrounding environment. This is exactly what Loeb and Sjean point out, because the hypothetical black hole should absorb the occasional Oort cloud object, the comet.
In the clutches of a black hole, the comet gradually accepts its doom, and it begins to melt as it interacts with the hot gas that has accumulated in the region. This process is supposed to produce a detectable radiation signature from Earth, which scientists call accretion flares.
"Our paper suggests that if Planet Nine were a black hole, the comet that inhabits the outer solar system — the so-called Oort cloud — would hit it, be destroyed by its powerful gravitational tides, and rapidly produce flares as the black hole accretion, a series of effects that will be done quickly in less than a second." Loeb told Gerz Modi.
If the comet is large enough, it should be detectable through the Space-Time Heritage Project (LSST), which will be implemented at the Rubin Observatory next year. Due to its unusually large field of view, this telescope is ideally suited for this task. Astronomers have only a very rough idea of where they should look for Planet Nine, or a black hole, but LSST will cover half of the sky and make 824 repeat visits to each location over a 10-year period.
"If Planet 9 is a black hole, we expect to see at least some flares about a year after LSST started observing the sky," Loeb said.
This isn't the first proposal to propose a potential black hole. Earlier this year, Edward Witten, a physicist at the Institute for Advanced Study, proposed that hundreds of spacecraft could be sent to the outer solar system. Changes in their sensitive clocks will indicate the presence of a strong gravitational field produced by tiny black holes. It sounds cool, but Loeb and Sjean's new proposal is more practical.
Jacob Scholz, a postdoc at durham University's Institute of Phenomenology of Particle Physics in the UK, told Gerz Modi: "If it turns out to be a reasonable strategy, then the idea loeb and Sjean came up with is really great." "For Planet Nine, as a primordial black hole, it would be a game-changer."
Scholz and his colleague James Aonwy of the University of Illinois at Chicago published a paper last year arguing that Planet Nine could actually be a black hole. He said our solar system has about a 50 percent chance of catching a black hole, so if the authors can test this, "we should continue to do that." ”
Either way, the LSST project will produce meaningful results, as the lack of evidence for black holes may point to other possibilities, such as that Planet Nine is actually a planet. Incredibly, we know very little about our solar system.
by: george dvorsky
fy: Dong Meihui
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