Is the sun home to a black hole? No, but this is why researchers are wondering

Astrophysicist Matt Caplan revealed the publication of a new study with the unusual title “Is there a black hole at the heart of the Sun?” just before the year 2023 came to a close. When I asked for the quick response, he responded, predictably, with “probably not.” However, the narrative doesn’t finish there.

The new study, which is presently accessible on arxiv, is not yet peer-reviewed, but it is published alongside a piece in The Astrophysical Journal Letters that skirts the same weird subject in order to reach an intriguing conclusion.

The purpose of all this is to set up an epic hypothesis about the existence of dark matter, which is a mysterious and elusive object that is maybe the greatest cosmic enigma of our time. Together with its equally perplexing counterpart, dark energy, this material makes up more than 95% of the cosmos. However, the two are still concealed from view. Scientists have proposed a number of theories over the years to explain the dark universe, from the possibility that our arithmetic is flawed to the possibility of bizarre new particles. There has been no success.

Towards that end, Caplan is a member of a team that suggests the dark matter component of the dark universe may consist of a vast number of atom-sized black holes created during the early universe, each of which is roughly as massive as an asteroid in our solar system, rather than particles as we would imagine. Caplan, an associate professor of physics at Illinois State University, told Space.com that “I think all dark matter theories are just a little bit wacky.” “Primitive black holes are treated seriously, and some conjectures are better than others. I’ll even venture to suggest that they may be well-liked.”

That leads us to this new black hole-sun debate: in order for scientists to prove the concept, he claims, they must actually locate one of these tiny old gaps. In their publications, Caplan and his co-authors speculate that some of those extremely tiny black holes may have become entangled in dust clouds during the process of star formation. It’s possible that they found themselves actually stuck in those shimmering oceans of plasma in the end. They may perhaps still be there.

Therefore, the answer to the question is probably negative, although it is possible that other stars traveling through space have black holes in fact lodged in their centers.

The phone conversation that began it all

It seems sense that astronomy faced several challenges during the COVID-19 epidemic, which resulted in numerous delays but also in a great deal of ingenuity.

“Astroseismologist Earl Ballenger and I became friends,” Caplan stated. “We were simply having a typical research conversation, exchanging pleasantries about stars. And he made this kind of casual, thrownaway comment just now. “I always thought it would be interesting to center these simulations on a black hole and see what would happen,” he said.

Additionally, Caplan remembers contradicting Ballenger as he concluded his remarks with “But there’s no need to do that,” saying, “No, really, this is a testable dark matter candidate.”

Caplan stated that he had already been thinking about testing the atom-sized primordial black hole hypothesis in the solar system, particularly since if these theoretical phenomena are real, they would probably exist in large numbers because of their low mass. One may anticipate that some of these black holes will sometimes pass through our region of space. In fact, he has already produced a study article describing the possible outcomes of one of these black holes colliding with Earth or the moon.

Caplan countered that it was evident he understood it would be crazy if the sun caught one. Furthermore, he thinks the likelihood of an atom-sized black hole ever becoming trapped within any star in the Milky Way is extremely remote. “Everything travels quicker in a more massive galaxy or environment; higher gravity indicates faster motion,” the speaker stated.

This implies that dark matter would move very swiftly in extremely huge systems, like the Milky Way, which are known to contain a lot of it. Thus, if the suggested micro black holes make up dark matter, they would need to be travelling at a very high speed in unison. This would make it unlikely that anything would be able to catch them. However, dark matter flows far more slowly on average in other settings, such as less massive globular clusters or dwarf galaxies.

A star-forming cloud may occasionally catch a few particles of dark matter, or in this case, a primordial black hole, which would then become gravitationally connected to the cloud and eventually sink to the star’s core as it grows, he added. It is precisely these stars in dwarf galaxies that may show signs of having a black hole inside them that the scientists say they will be looking for next.

Because Stephen Hawking authored the groundbreaking work on primordial black holes, he and Ballinger refer to these as “Hawking stars.” Amazingly, Hawking had proposed that the early cosmos was probably crowded and chaotic enough to produce a large number of these strange things in its very first moments. Furthermore, Hawking noted that these black holes might have almost any mass, which is significant for the new theory.

Hawking even says that stars may swallow up an asteroid mass’ worth of these black holes, consuming them from the inside out. We chose to name it after him because, as Caplan said, “he sort of recommended it in the original article and it’s sort of in the footnotes that most people overlook when they’re doing this work.”

Here’s the latest map, at last, to locate one of these old pinprick spaces.

Looking for hypothetical giants

No, a star with a black hole anchor would not appear to be some kind of time-warping, fiery space oddity, even though it would make an amazing “Interstellar: Part 2.” In fact, it would appear very typical.

Caplan said, “Your gut tells you that the celebrity is going to get swallowed up like in a CGI scenario.” Nevertheless, according to science and accurate estimates, it may take billions of years for black holes to consume the star because of how luminous they are and how much radiation they create that pushes back against their surrounds.

What then would we search for if not an insane star? For another succinct response, Caplan adds that looking for puffier, fainter red giants (in smaller galaxies, of course) is the key.

He explained, “A star may have a pretty odd giant phase when a black hole brightens. This phase differs from regular red giant phases and might make them stand out if you seek for them.”

Star power and feasts from black holes

In general, there are three primary parts to the anatomy of a black hole, regardless of its size. The singularity, the invisible point at a black hole’s precise center where all matter is squeezed, is the first thing to consider. This explains how a black hole may have such a large mass and a little physical size. The second concept is the event horizon, which is the boundary between our universe and whatever is within and looks like a ring around the singularity. Beyond the event horizon, light cannot pass. It’s all really enigmatic.

The accretion disk is the third component and crucial to the new research. That is the gas- and dust-filled loop of stuff that is rotating around the entire body.

On the other side, stellar fusion describes the process by which stars are energized. By converting light hydrogen atoms into heavy helium atoms through an inherent nuclear fusion process, stars provide an outward push that counteracts the inward pull of their own gravity. This process, which persists until a star dies and transforms into a red giant, also adds to their brilliance. The fusion events eventually come to an end, and the star’s gravity prevails. The next stage in the life cycle of massive stars is a supernova explosion, which can produce a neutron star or a black hole of “normal size.” (Neutron stars are extremely dense and intriguing in and of themselves, but that’s an other topic.)

Well, we know about typical red giants, but Caplan suggests that a fascinating thing may happen if a star with an intrinsic black hole reached the red giant phase. “The enormous phase is accretion-powered, not fusion-powered,” he stated. “At that point, the fusion really stops and turns into this massive, puffy cloud whirling around this little black hole, which is roughly the mass of the Earth.”

That would mean that the confined black hole would have a mass of just a millionth of the mass of the Hawking star that holds it, but its surrounding material would still be equivalent to a solar mass. According to Caplan, “this radically transforms the star’s interior structure.”

“The star can survive for the whole duration of the universe thus far without alteration if the black hole is tiny enough and has a low enough mass,” he continued. “Well, huge black holes have broader event horizons, so if it’s a more enormous black hole.”

Stated differently, the enormous black holes would have the capacity to develop and accrete quicker. Therefore, scientists predict that larger black holes might destroy their stars in a matter of billions of years.

As to why an accretion-powered red giant would be dimmer than a normal red giant, this is simply because fusion power leads to more brightness than accretion power does in stars. “This is part of that story about ultra faint dwarf galaxies,” he said. “Why are these dwarf galaxies so dim? And why do they seem to have so much dark matter?”

That does not imply, however, that accretion power has no significance. It’s maybe even more amazing since a star’s brilliance might be raised to a point where it approaches extreme fusion-powered brightness by an accreting black hole that was once the size of an atom!

Regarding the red dwarf targets, Caplan stated, “Earl looked through various surveys, and he found that there’s roughly 500 of them that would be ideal targets for observation.” “In the coming year, we hope to examine a few hundred possibilities in further depth using asteroseismology.”

And if you are wondering how successful this next search for red-giant-disguised stars wandering the cosmos with black holes the size of atoms in their centers may be, well, I would think about two things.

First off, there isn’t much debate regarding the idea that cosmic things can absorb dark matter. For instance, researchers collaborating with the IceCube facility at the South Pole are looking for proof that signals from dark matter originate on Earth. Secondly, the hunt for dark matter is essentially a blind guess.

The reality might very well be nothing more than a plethora of voids scattered around the cosmos that become trapped inside stars.

“It’s not surprising if they don’t exist, but it’s also not surprising if they do,” Caplan said.

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