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Category: cosmology – Page 287

The Ophiuchus star-forming complex offers an analog for the formation of the solar system, including the sources of elements found in primitive meteorites.

A region of active star formation in the constellation Ophiuchus is giving astronomers new insights into the conditions in which our own solar system was born. In particular, a new study of the Ophiuchus star-forming complex shows how our solar system may have become enriched with short-lived radioactive elements.

Evidence of this enrichment process has been around since the 1970s, when scientists studying certain mineral inclusions in meteorites concluded that they were pristine remnants of the infant solar system and contained the decay products of short-lived radionuclides. These radioactive elements could have been blown onto the nascent solar system by a nearby exploding star (a supernova) or by the strong stellar winds from a type of massive star known as a Wolf-Rayet star.

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But a team of physicists is proposing a radical idea: Instead of forming black holes through the usual death-of-a-massive-start route, giant dark matter halos directly collapsed, forming the seeds of the first great black holes.

Supermassive black holes (SMBHs) appear early in the history of the universe, as little as a few hundred million years after the Big Bang. That rapid appearance poses a challenge to conventional models of SMBH birth and growth because it doesn’t look like there can be enough time for them to grow so massive so quickly.

“Physicists are puzzled why SMBHs in the early universe, which are located in the central regions of dark matter halos, grow so massively in a short time,” said Hai-Bo Yu, an associate professor of physics and astronomy at UC Riverside, who led a study of SMBH formation that appeared in Astrophysical Journal Letters.

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About 2,000 light-years away from Earth, there is a star catapulting toward the edge of the Milky Way. This particular star, known as LP 40–365, is one of a unique breed of fast-moving stars—remnant pieces of massive white dwarf stars—that have survived in chunks after a gigantic stellar explosion.

“This star is moving so fast that it’s almost certainly leaving the galaxy…[it’s] moving almost two million miles an hour,” says JJ Hermes, Boston University College of Arts & Sciences assistant professor of astronomy. But why is this flying object speeding out of the Milky Way? Because it’s a piece of shrapnel from a past explosion—a cosmic event known as a supernova—that’s still being propelled forward.

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Physicists at the National Institute of Standards and Technology (NIST) have linked together, or “entangled,” the mechanical motion and electronic properties of a tiny blue crystal, giving it a quantum edge in measuring electric fields with record sensitivity that may enhance understanding of the universe.

The quantum sensor consists of 150 beryllium ions (electrically charged atoms) confined in a magnetic field, so they self-arrange into a flat 2D crystal just 200 millionths of a meter in diameter. Quantum sensors such as this have the potential to detect signals from dark matter — a mysterious substance that might turn out to be, among other theories, subatomic particles that interact with normal matter through a weak electromagnetic field. The presence of dark matter could cause the crystal to wiggle in telltale ways, revealed by collective changes among the crystal’s ions in one of their electronic properties, known as spin.

As described in the August 6, 2021, issue of Science, researchers can measure the vibrational excitation of the crystal — the flat plane moving up and down like the head of a drum — by monitoring changes in the collective spin. Measuring the spin indicates the extent of the vibrational excitation, referred to as displacement.

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Astronomers have seen light from BEHIND a black hole for the first time. I explained the discovery and results to my editor, Levi. Congrats to D. Wilkins and the astronomy team!

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Mathematicians have proved that a geometric object called the Fargues-Fontaine curve can connect arithmetic and geometry. The work is a major advance in one of the most ambitious projects in mathematics.

The grandest project in mathematics has received a rare gift, in the form of a mammoth 350-page paper posted in February that will change the way researchers around the world investigate some of the field’s deepest questions. The work fashions a new geometric object that fulfills a bold, once fanciful dream about the relationship between geometry and numbers.

“This truly opens up a tremendous amount of possibilities. Their methods and constructions are so new they’re just waiting to be explored,” said Tasho Kaletha of the University of Michigan.

The work is a collaboration between Laurent Fargues of the Institute of Mathematics of Jussieu in Paris and Peter Scholze of the University of Bonn. It opens a new front in the long-running “Langlands program,” which seeks to link disparate branches of mathematics — like calculus and geometry — to answer some of the most fundamental questions about numbers.

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Like a shaggy dog in springtime, some black holes have to shed. New computer simulations reveal how black holes might discard their magnetic fields.

Unlike dogs with their varied fur coats, isolated black holes are mostly identical. They are characterized by only their mass, spin and electric charge. According to a rule known as the no-hair theorem, any other distinguishing characteristics, or “hair,” are quickly cast off. That includes magnetic fields.

The rule applies to black holes in a vacuum, where magnetic fields can simply slip away. But, says astrophysicist Ashley Bransgrove of Columbia University, “what we were thinking about is what happens in a more realistic scenario.” A magnetized black hole would typically be surrounded by electrically charged matter called plasma, and scientists didn’t know how — or even if — such black holes would undergo hair loss.

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