New theory suggests heavy elements created when primordial black holes eat neutron stars from within

August 24, 2017 by Bob Yirka report
Fuller et al. propose a model for the synthesis of heavy elements in which a rapidly rotating neutron star is swallowed from the inside by a tiny black hole. The centrifugally deformed star, shown in cross-section, sheds considerable mass at its equator as it spins up and angular momentum is transferred outward. Heavy atomic nuclei, including gold and platinum, can form via the r-process in the neutron-rich matter that’s expelled from the imploding star. Credit: APS/Alan Stonebraker, via Physics

(Phys.org)—A team of researchers at the University of California has come up with a new theory to explain how heavy elements such as metals came to exist. The group explains their theory in a paper published in the journal Physical Review Letters—it involves the idea of primordial black holes (PBHs) infesting the centers of neutron stars and eating them from the inside out.

Space scientists are confident that they have found explanations for the origins of light and medium elements, but are still puzzling over how the came to exist. Current theories suggest they most likely emerged during what researchers call an r-process—as in rapid. As part of the process, of neutrons would come under high densities, resulting in capture by atomic nuclei—clearly, an extreme environment. The most likely candidate for creating such an environment is a supernova, but there seem to be too few of them to account for the amounts of that exist. In this new effort, the researchers offer a new idea. They believe it is possible that PBHs occasionally collide with neutron stars, and when that happens, the PBH becomes stuck in the center of the star. Once there, it begins pulling in material from the star's center.

PBHs are still just theory, of course. They are believed to have developed shortly after the Big Bang. They are also believed to roam through the galaxies and might be tied to . In this new theory, if a PBH happened to bump into a neutron star, it would take up residence in its center and commence pulling in neutrons and other material. That would cause the star to spin rapidly, which in turn would fling material from its outermost layer into space. The hurled material, the researchers suggest, would be subjected to an environment that would meet the requirements for an r-process, leading to the creation of heavy metals.

The theory assumes a certain number of such collisions could and did occur, and also that at least some small amount of dark matter is made up of black holes, as well. But it also offers a means for gathering real-world evidence that it is correct—by analyzing mysterious bursts of radio waves that could be imploding after internal consumption by a PBH.

Explore further: Primordial black holes may have helped to forge heavy elements

More information: George M. Fuller et al. Primordial Black Holes and r-Process Nucleosynthesis, Physical Review Letters (2017). DOI: 10.1103/PhysRevLett.119.061101

ABSTRACT
We show that some or all of the inventory of r-process nucleosynthesis can be produced in interactions of primordial black holes (PBHs) with neutron stars (NSs) if PBHs with masses 10−14 M⊙ < M PBH < 10−8 M⊙ make up a few percent or more of dark matter. A PBH captured by a NS sinks to the center of the NS and consumes it from the inside. When this occurs in a rotating millisecond-period NS, the resulting spin-up ejects ∼0.1 M⊙–0.5 M⊙ of relatively cold neutron-rich material. This ejection process and the accompanying decompression and decay of nuclear matter can produce electromagnetic transients, such as a kilonova-type afterglow and fast radio bursts. These transients are not accompanied by significant gravitational radiation or neutrinos, allowing such events to be differentiated from compact object mergers occurring within the distance sensitivity limits of gravitational-wave observatories. The PBH-NS destruction scenario is consistent with pulsar and NS statistics, the dark-matter content, and spatial distributions in the Galaxy and ultrafaint dwarfs, as well as with the r-process content and evolution histories in these sites. Ejected matter is heated by beta decay, which leads to emission of positrons in an amount consistent with the observed 511-keV line from the Galactic center.

Related Stories

Neutron stars could be our GPS for deep space travel

June 30, 2017

NASA's Neutron Star Interior Composition Explorer, or NICER, is an X-ray telescope launched on a SpaceX Falcon 9 rocket in early June 2017. Installed on the International Space Station, by mid-July it will commence its scientific ...

Tiny, ancient galaxy preserves record of catastrophic event

March 21, 2016

The lightest few elements in the periodic table formed minutes after the Big Bang. Heavier chemical elements are created by stars, either from nuclear fusion in their interiors or in catastrophic explosions. However, scientists ...

Recommended for you

16 comments

Adjust slider to filter visible comments by rank

Display comments: newest first

rrwillsj
2 / 5 (4) Aug 24, 2017
Factual Headline:
"No One Answer!"
"Chasing The GUT, is a an act of self-delusion."

Seems to me that all these developing experiments are 'proving'? The possibility, that over billions of years, there were/are several or more processes producing the heavier elements.
tblakely1357
5 / 5 (6) Aug 24, 2017
I'm not going to believe that black holes exist until I see one...... ba du bump.
Steelwolf
not rated yet Aug 24, 2017
I have also considered, by seeing various papers on neutron stars, 'quark' stars and 'strange' stars and feel that if a neutron star should continue to accrete mass (which there is no reason why they should not) then at some point in their existence they would create within themselves one or more of the tiny, pseudo-primordial Black Holes. This would happen more readily in a Neutron star-other star close binary where the neutron star feeds on the larger star much as a white dwarf would.

Point collapse at the center of the neutron star due to pressure should lead to a tiny black hole rather than the whole mass dropping at once to form a greater black hole. Certainly there should be energetic releases showing this type of actions.

Essentially this article is pointing out one of the possible end states for a neutron star. Others include 2 neutron stars colliding, a neutron star encountering a larger black hole and shredding itself in the gravitational gradients as well as others.
Benni
2.2 / 5 (10) Aug 24, 2017
I'm not going to believe that black holes exist until I see one...... ba du bump.


Yeah, me too, still waiting for the first pic.
richk
1 / 5 (3) Aug 24, 2017
what/are/they/assuming/the/mass/of/the/primordial/black/holes/is?
Da Schneib
5 / 5 (4) Aug 24, 2017
Interesting hypothesis. The biggest problems with it are the abundance (or rather lack thereof) of black holes, and the lack of a good hypothesis for where the primordial black holes come from.
nikola_milovic_378
Aug 25, 2017
This comment has been removed by a moderator.
rrwillsj
2.3 / 5 (3) Aug 25, 2017
Hey DS, I gotta an answer for your question "Where do the primordial black holes come from?"

The Originating Creator Mechanism (I'm guessing a REALLY big xerox!) is a golfer.

Just playing through.
rrwillsj
3 / 5 (2) Aug 25, 2017
Hey DS, I gotta an answer for your question "Where do the primordial black holes come from?"

The Originating Creator Mechanism (I'm guessing a REALLY big xerox!) is a golfer.

Just playing through.
Da Schneib
not rated yet Aug 25, 2017
@rrwillsj, was looking for something a little more scientific, but it's OK to play. ;)
Ojorf
not rated yet Aug 27, 2017
A primordial black hole is a hypothetical type of black hole formed during the high-density, inhomogeneous phase of the Big Bang due to the gravitational collapse of important density fluctuations. The concept was first proposed in 1971 by Stephen Hawking.


https://en.wikipe...ack_hole
Ojorf
not rated yet Aug 27, 2017
Primordial black holes could have formed in the very early Universe (less than one second after the Big-Bang), during the so-called radiation dominated era. The essential ingredient for a primordial black hole to form is a fluctuation in the density of the Universe, inducing its gravitational collapse. One typically requires density contrasts δ ρ / ρ ∼ 0.1 (where ρ is the density of the Universe) to form a black hole. There are several mechanisms able to produce such inhomogeneities in the context of cosmic inflation (in hybrid inflation models, for example axion inflation, ...), reheating, or cosmological phase transitions.
koitsu
1 / 5 (2) Aug 27, 2017
This is supposed to be a science site. Why is this being reported as a theory? It's a hypothesis.
Da Schneib
not rated yet Aug 27, 2017
@Ojorf, I am aware of the conjectures regarding primordial black holes. None of them rises to the level of a hypothesis, much less a theory. As @koitsu correctly points out.

Without a disqualifying prediction, and a proposed test of that prediction, a conjecture cannot become a hypothesis. Show me a disqualifying prediction.
doogsnova
1 / 5 (1) Aug 27, 2017
Anybody know the total number of elements? Billy Meier does. billymeier dot wordpress dot com. It's 280, for the lazy ones.
Molecular hydrogen
1 / 5 (1) Sep 11, 2017
I am wondering if a tiny neutron star is the singularity.. bending space time to create the illusion of a black hole .. the xray jets cam be just as and even greater than recorded emissions from a black hole suspect.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.