Stars, supernovae, black holes and stellar remnants

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Two Telescopes Investigate the Oldest Black Hole Ever Discovered
by Doris Elin Urrutia
November 7, 2023

Conclusion:

(Inverse) In 2017, Yale University astrophysicist Priyamvada Natarajan, who is a co-author of the new study describing the findings, proposed a theoretical model. In it, supermassive black holes in the early universe form when a huge cloud of gas collapses, resulting in what Natarajan calls an “Outsize Black Hole.”

We think that this is the first detection of an ‘Outsize Black Hole’ and the best evidence yet obtained that some black holes form from massive clouds of gas,” Natarajan said in NASA’s statement. “For the first time we are seeing a brief stage where a supermassive black hole weighs about as much as the stars in its galaxy.”

A paper with a deeper investigation into this galaxy and the Outsize Black Hole premise is forthcoming, according to NASA. But the new revelation from Chandra and JWST show that the science of the ancient universe is coming into reach.

Read more here: https://www.inverse.com/science/ancie ... discovery

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Five new pulsars discovered with FAST
https://phys.org/news/2023-11-pulsars-fast.html
by Tomasz Nowakowski , Phys.org

Using the Five-hundred Aperture Spherical Telescope (FAST), astronomers from China and Australia have discovered five new pulsars, two of which turned out to have ultra-short spin periods. The finding was reported in a research paper published November 1 on the preprint server arXiv.

Pulsars are highly magnetized, rotating neutron stars emitting a beam of electromagnetic radiation from their magnetic poles. This radiation can only be observed when the beam of emission is pointing toward the Earth.

The most rapidly rotating pulsars, with rotation periods below 30 milliseconds, are known as millisecond pulsars (MSPs). It is assumed that they are formed in binary systems when the initially more massive component turns into a neutron star that is then spun up due to accretion of matter from the secondary star.

Now, a team of astronomers led by Qi-Jun Zhi of the Guizhou Normal University in Guiyang, China, reports the detection of five new pulsars with FAST as part of a pilot survey at intermediate Galactic latitudes.

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TESS detects new cataclysmic variable system of a rare type

https://phys.org/news/2023-11-tess-cata ... -rare.html

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Please note that while the first citation (see below) is highly technical, the second citation is somewhat more accessible in understanding from a layman’s perspective.

Physicists Simulate a Black Hole in The Lab.

Abstract:

(Physical Review Research) Synthetic horizons in models for quantum matter provide an alternative route to explore fundamental questions of modern gravitational theory. Here we apply these concepts to the problem of emergence of thermal quantum states in the presence of a horizon, by studying ground-state thermalization due to instantaneous horizon creation in a gravitational setting and its condensed matter analog. By a sudden quench to position-dependent hopping amplitudes in a one-dimensional lattice model, we establish the emergence of a thermal state accompanying the formation of a synthetic horizon. The resulting temperature for long chains is shown to be identical to the corresponding Unruh temperature, provided that the postquench Hamiltonian matches the entanglement Hamiltonian of the prequench system. Based on detailed analysis of the outgoing radiation we formulate the conditions required for the synthetic horizon to behave as a purely thermal source, paving a way to explore this interplay of quantum-mechanical and gravitational aspects experimentally.

Source: https://journals.aps.org/prresearch/ab ... .043084


To unpack and help explain what that means:

(Science Alert) Using a chain of atoms in single-file to simulate the event horizon of a black hole, a team of physicists in 2022 observed the equivalent of what we call Hawking radiation – particles born from disturbances in the quantum fluctuations caused by the black hole's break in spacetime.

This, they say, could help resolve the tension between two currently irreconcilable frameworks for describing the Universe: the general theory of relativity, which describes the behavior of gravity as a continuous field known as spacetime; and quantum mechanics, which describes the behavior of discrete particles using the mathematics of probability.

A one-dimensional chain of atoms served as a path for electrons to 'hop' from one position to another. By tuning the ease with which this hopping can occur, the physicists could cause certain properties to vanish, effectively creating a kind of event horizon that interfered with the wave-like nature of the electrons.

The effect of this fake event horizon produced a rise in temperature that matched theoretical expectations of an equivalent black hole system, the team said, but only when part of the chain extended beyond the event horizon.

This could mean the entanglement of particles that straddle the event horizon is instrumental in generating Hawking radiation.

Read more here: https://www.sciencealert.com/physicists ... -glow

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Astronomers Find a Brilliant Explosion That Just Keeps Exploding
by Monica Young
November 21, 2023

Introduction:

(Sky & Telescope) On September 7, 2022, an automatic telescope picked up a blazing dot of blue light some 1,000 times brighter than a typical supernova. The brilliant blue flare lasted only days before it faded away, but not before an automated system had put astronomers on alert.

The system designated the event AT2022tsd, but it some came to be called the “Tasmanian Devil.” It joined the short list of a special class of objects discovered in 2018 known as luminous fast blue optical transients (LFBOTs). Astronomers think these explosive flares are a special kind of supernova, but they could also be stars ripped apart in the intense gravitational field surrounding a neutron star or black hole. The devil, as they say, is in the details.

But while the Tasmanian Devil’s discovery was a welcome surprise, the real bombshell came 100 days later. In December that year, Anna Ho (Cornell University) and colleagues were reviewing routine images that had monitored the fading flare when, to their bewilderment, they found a red-colored burst almost as bright as the original blue one, and in the same position on the sky.

Scouring for more data, both in the archive and then with new observations, the astronomers found another outburst — and then another, and another. The energy of each one of these outbursts is equivalent to that released from an exploding star. Overall, at least 14 flares followed the first one, Ho and colleagues report in Nature, and it’s likely there were many more they missed.

“An event like this has never been witnessed before,” says team member Jeff Cooke (Swinburne University of Technology and the ARC Centre of Excellence in Gravitational Wave Discovery, Australia).

Read more here: https://skyandtelescope.org/astronomy ... xploding/

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12-billion-year-old body of water discovered floating in space

https://www.indy100.com/science-tech/gi ... g-in-space

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Further evidence for quark-matter cores in massive neutron stars
https://phys.org/news/2023-12-evidence- ... utron.html
by Johanna Pellinen, University of Helsinki

Neutron-star cores contain matter at the highest densities reached in our present-day universe, with as much as two solar masses of matter compressed inside a sphere of 25 km in diameter. These astrophysical objects can indeed be thought of as giant atomic nuclei, with gravity compressing their cores to densities exceeding those of individual protons and neutrons many-fold.

These densities make neutron stars interesting astrophysical objects from the point of view of particle and nuclear physics. A longstanding open problem is whether the immense central pressure of neutron stars can compress protons and neutrons into a new phase of matter, known as cold quark matter. In this exotic state of matter, individual protons and neutrons no longer exist.

"Their constituent quarks and gluons are instead liberated from their typical color confinement and are allowed to move almost freely," explains Aleksi Vuorinen, professor of theoretical particle physics at the University of Helsinki.

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In a Huge First, Scientists Have Observed the 'Missing Link' Between Stars and Black Holes
by Michelle Starr
January11, 2024

Introduction:

(Science Alert) In a magnificent first, we finally have direct observational evidence of the stellar process that produces neutron stars and black holes.

From a supernova that exploded in a nearby galaxy, astronomers observed the emergence of something with the hallmarks of such compact objects. It's not clear which kind, neutron star or black hole, but the finding finally confirms that the core collapse of massive stars produces the densest objects in the Universe, in a spectacular explosion of stellar material.

Stellar-mass black holes and neutron stars are thought to be the result of similar processes.

Towards the end of its lifespan, a star runs out of the fuel required to sustain fusion, the process that keeps it burning. There's a somewhat complicated series of events, but ultimately, the star will eject its outer material; the core, no longer supported by the outward pressure of fusion, collapses under gravity to become a super-dense object (for most stars, anyway).

The nature of that object depends on its mass. Stars smaller than eight Suns produce a white dwarf, the eventual predicted fate of the Sun itself.

Read more here: https://www.sciencealert.com/in-a-huge ... k-holes

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The first 3D map of magnetic fields in our galaxy explains star-forming regions
https://phys.org/news/2024-01-3d-magnet ... -star.html
by University of Tokyo

A team of astronomers including those from the University of Tokyo have created the first-ever map of magnetic field structures within a spiral arm of our Milky Way galaxy. Previous studies on galactic magnetic fields only gave a very general picture, but the new study reveals that magnetic fields in the spiral arms of our galaxy break away from this general picture significantly and are tilted away from the galactic average by a high degree.

The findings, appearing in The Astrophysical Journal, suggest magnetic fields strongly impact star-forming regions which means they played a part in the creation of our own solar system.

It might come as a surprise to some that magnetic fields can exist on scales larger than a planet. Most of our daily experience with magnetic fields involves either sticking things to our refrigerator, or perhaps using a compass to point north. The latter shows the existence of magnetic fields generated by our planet.

Our sun also creates a vast magnetic field, and this can affect phenomena like solar flares. But magnetic fields that span the galaxy are almost too large to comprehend, and yet they likely have a role in the formation of stars and planets.

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Cosmic dawn observational progress with NenuFAR
https://phys.org/news/2024-01-cosmic-dawn-nenufar.html
by Paris Observatory

The NenuFAR Cosmic Dawn project has taken an important step in the exploration of the Cosmic Dawn, this key period in our universe marked by the formation of the first stars. An upper limit on the amplitude of the neutral hydrogen fluctuations at 21 cm from this distant time was established using the NenuFAR radio telescope. This advance represents a crucial step in our efforts to unravel the mysteries of the first stars formation.

The recent study, published in the journal Astronomy & Astrophysics, analyzes one night of observation of the North Celestial Pole deep field with the NenuFAR radio telescope, providing new limits on the fluctuations of the transition line at 21 cm from neutral hydrogen. These observations will help to study the conditions of formation of the first stars, approximately 180 million years after the Big Bang, a key epoch in the evolution of the universe.

NenuFAR, a low-frequency radio interferometer located at the Nançay Radioastronomy Observatory in France, is distinguished by its large collecting surface, making it exceptionally sensitive for observing the 21 cm signal from the Cosmic Dawn. Observing this signal is complex due to signal interferences from our galaxy and other celestial sources, which overshadow the weak signal from the Cosmic Dawn. The team implemented advanced techniques to try to isolate this signal.

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ALMA observations show how double, triple, quadruple and quintuple star systems form simultaneously in a molecular cloud
https://phys.org/news/2024-01-alma-trip ... -star.html
by Max Planck Society

For humans, the chance of giving birth to multiples is less than 2%. The situation is different with stars, especially with particularly heavy stars. Astronomers observe stars that are many times heavier than the sun in more than 80% of cases in double or multiple systems. The key question is whether they were also born as multiples, or whether stars are born alone and approach each other over time.

Multiple births have long been the norm for massive stars. At least on the computer, because in theoretical simulations huge clouds of gas and dust tend to collapse and form multiple systems of massive stars. These simulations depict a hierarchical process in which larger cloud portions contract to form denser cores, and where smaller regions within those "parent cores" collapse to form the separate stars: massive stars, but also numerous less massive stars.

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At the Dawn of Time, Astronomers Discover the Earliest Black Hole Ever Seen
Michelle Starr
January 18, 2024

Introduction:

(Science Alert) A glimmer flickering from across the gulf of time and space is the earliest black hole we've ever seen.

The light detected by a team led by astrophysicist Roberto Maiolino of the University of Cambridge is the blaze emitted by the black hole's host galaxy as it swirls inexorably towards the event horizon. Appearing as it was just 400 million years after the Big Bang, the black hole is already massive – some 1.6 million times the mass of the Sun.

It's a discovery that seems to confirm the direct collapse model of supermassive black hole formation in the early Universe, rather than the long, slow process of accretion from something the mass of a large star.

Read more here: https://www.sciencealert.com/at-the-da ... etected

Edit: On that same topic: https://www.inverse.com/science/oldest- ... ingly-big

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Webb data suggest many early galaxies were long and thin, not disk-like or spherical
https://phys.org/news/2024-01-webb-earl ... -disk.html
by Columbia University

Columbia researchers analyzing images from NASA's James Webb Space Telescope have found that galaxies in the early universe are often flat and elongated, like breadsticks—and are rarely round, like balls of pizza dough.

"Roughly 50 to 80% of the galaxies we studied appear to be flattened in two dimensions," explained Viraj Pandya, a NASA Hubble Fellow at Columbia University and the lead author of a new paper slated to appear in The Astrophysical Journal that outlines the findings. The paper is currently published on the arXiv preprint server.

"Galaxies that look like long, thin breadsticks seem to be very common in the early universe, which is surprising since they are uncommon among galaxies in the present-day universe."

The team focused on a vast field of near-infrared images delivered by Webb, known as the Cosmic Evolution Early Release Science (CEERS) Survey, plucking out galaxies that are estimated to have existed when the universe was 600 million to 6 billion years old.

While most distant galaxies look like breadsticks, others are shaped like pizza pies and balls of pizza dough. The "balls of pizza dough," or sphere-shaped galaxies, appear to be the smallest type of galaxy and were also the least frequently identified. The pizza pie-shaped galaxies were found to be as large as breadstick-shaped galaxies along their longest axis. "They are more common in the nearby universe, which, due to the universe's ongoing expansion, is made up of older, more mature galaxies."

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Milky Way: Manchester astronomers find mysterious object

2 hours ago

A new object in the Milky Way that is heavier than the heaviest neutron stars known to scientists, and yet lighter than the lightest known black holes, has been found by astronomers.

Researchers in Manchester and Germany found it orbiting a millisecond pulsar 40,000 light years away.

Millisecond pulsars spin very rapidly - hundreds of times per second.

Project lead Ben Stappers, professor of astrophysics at the University of Manchester, said it was "exciting".

Researchers from the University of Manchester and the Max Planck Institute for Radio Astronomy in Munich, believe it could be the first discovery of a radio pulsar-black hole binary - a pairing that could allow new tests of Einstein's general relativity and open doors to the study of black holes.

Professor Stappers added: "A pulsar-black hole system will be an important target for testing theories of gravity and a heavy neutron star will provide new insights in nuclear physics at very high densities."

https://www.bbc.co.uk/news/uk-england-m ... r-68028464

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Sharpest-Ever Image of a Black Hole Released
A follow-up on the Event Horizon Telescope’s iconic 2019 M87* image depicts the 'fiery donut' in all its glowing glory.
By Adrianna Nine January 19, 2024

The Event Horizon Telescope has outdone itself once again. Five years after releasing the world’s first-ever image of a black hole, the international network of radio observatories has published a more detailed depiction of M87*, a black hole at the center of galaxy M87. Not only does the “new” snapshot offer astronomers and amateur skygazers the opportunity to visualize an incredibly elusive phenomenon, but it also expands the scope of possibility for the world’s most powerful ground observatories.

The EHT Collaboration published its original M87* image in 2019, but the observations that image was built upon were conducted in April 2017. Back then, the EHT consisted of eight sites around the world. Using an atomic clock to synchronize each site’s telescope within a fraction of a millimeter, these sites spent four days collecting 5 petabytes of data from M87*. It’s this data that resulted in the composite set of images published in April 2019. Before then, astronomers had only “seen” black holes indirectly via peripheral data, so even a relatively blurry “fiery donut” was enough to wow the scientific community and the general public.

https://www.extremetech.com/science/sha ... e-released

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"Old Smokers": Astronomers discover previously unknown type of star
By Michael Irving
January 29, 2024
https://newatlas.com/space/old-smokers-unknown-star/

“Astronomers discover a completely unknown object floating around in space” is a common news theme, but it’s fun every time. The latest is a brand new type of star – ancient red giants the team has nicknamed “Old Smokers.”

Ironically, the researchers set out to study newborn stars. To do so, they analyzed 10 years of data from the Visible and Infrared Survey Telescope (VISTA) in Chile, which watches a large patch of sky for objects that changed brightness over time. They narrowed it down to 222 objects with the most drastic brightness changes, most of which were easy to identify as known types of events. Then, they analyzed the spectra of the last ones with the Very Large Telescope.

“Our main aim was to find rarely-seen newborn stars, also called protostars, while they are undergoing a great outburst that can last for months, years, or even decades,” said Dr. Zhen Guo, an author of the study. “These outbursts happen in the slowly spinning disc of matter that is forming a new solar system. They help the newborn star in the middle to grow, but make it harder for planets to form. We don't yet understand why the discs become unstable like this.”

But during the study, the team spotted 21 strange stars near the center of our galaxy that were changing brightness in weird ways. One, for instance, was clearly visible in images taken in 2010, but by 2015 it had vanished entirely. Just three years later, it was back, albeit dimmer than before.

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Dracula's Chivito: New protoplanetary disk discovered with Pan-STARRS
https://phys.org/news/2024-02-dracula-c ... k-pan.html
by Tomasz Nowakowski , Phys.org

By analyzing the images obtained with the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS), astronomers have serendipitously discovered a new protoplanetary disk located some 800 light years away. The finding was reported in a paper published February 1 on the pre-print server arXiv.

A protoplanetary disk is a disk of dense gas and dust, orbiting a newly formed star. It is assumed that planets are born by the gradual accumulation of material in such a structure, therefore discoveries and studies of protoplanetary disks are essential for improving our understanding of planetary formation processes.

Now, a team of astronomers led by Ciprian T. Berghea of the U.S. Naval Observatory (USNO) in Washington, DC, has discovered a new disk of this type that is associated with an infrared source known as IRAS 23077+6707. The finding was made by inspecting the Pan-STARRS data while working on a variability study of active galactic nuclei (AGN) candidates.

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Cosmic Surprise: Black Holes May Have Existed at Universe’s Birth
February 6, 2024

Introduction:

(Futurity) Black holes not only existed at the dawn of time, they birthed new stars and supercharged galaxy formation, new research suggests.

The insights upend theories of how black holes shape the cosmos, challenging classical understanding that they formed after the first stars and galaxies emerged.

Instead, black holes might have dramatically accelerated the birth of new stars during the first 50 million years of the universe, a fleeting period within its 13.8 billion-year history.

“We know these monster black holes exist at the center of galaxies near our Milky Way, but the big surprise now is that they were present at the beginning of the universe as well and were almost like building blocks or seeds for early galaxies,” says lead author Joseph Silk, a professor in the physics and astronomy department at Johns Hopkins University and at the Institute of Astrophysics, Paris, Sorbonne University.

“They really boosted everything, like gigantic amplifiers of star formation, which is a whole turnaround of what we thought possible before—so much so that this could completely shake up our understanding of how galaxies form.”

Read more here: https://www.futurity.org/black-holes-d ... -3176012/