new cosmology stuff

[GreenBlaze]

billy rubin no I have not heard of that before, but I have heard of the James Webb telescope and the upcoming Vera Rubin and what it might mean for the Big Bang Theory and have you heard of these?

[Recusant]

[billy rubin]

billy rubin no I have not heard of that before, but I have heard of the James Webb telescope and the upcoming Vera Rubin and what it might mean for the Big Bang Theory and have you heard of these?

no idea what the vera rubin is, although i read she was an astronomer.

i dont keep up with as much as i could.

[Icarus]

https://www.youtube.com/watch?v=ipHmcBBpYOA

[Recusant]

This item is intriguing, though I'll say that it's beyond my depth. I can repeat the title of the paper to you and mumble something about "mathematical images or descriptions of theoretical versions of space-time," but don't ask for much more at the moment.

This excerpt from the paper says more than I could. 



"What happened before the Big Bang? Computational method may provide answers" | Phys.org

We're often told it is "unscientific" or "meaningless" to ask what happened before the Big Bang. But a new paper by FQxI cosmologist Eugene Lim, of King's College London, UK, and astrophysicists Katy Clough, of Queen Mary University of London, UK, and Josu Aurrekoetxea, at Oxford University, UK, published in Living Reviews in Relativity, proposes a way forward: using complex computer simulations to numerically (rather than exactly) solve Einstein's equations for gravity in extreme situations.

The team argues that numerical relativity should be applied increasingly in cosmology to probe some of the universe's biggest questions–including what happened before the Big Bang, whether we live in a multiverse, if our universe has collided with a neighboring cosmos, or whether our universe cycled through a series of bangs and crunches.

Einstein's equations of general relativity describe gravity and the motion of cosmic objects. But wind the clock back far enough and you'll typically encounter a singularity—a state of infinite density and temperature—where the laws of physics collapse.

Cosmologists simply cannot solve Einstein's equations in such extreme environments—their normal simplifying assumptions no longer hold. And the same impasse applies to objects involving singularities or extreme gravity, such as black holes.

One issue might be what cosmologists take for granted. They normally assume that the universe is "isotropic" and "homogeneous"—looking the same in every direction to every observer. This is a very good approximation for the universe we see around us, and one that makes it possible to easily solve Einstein's equations in most cosmic scenarios. But is this a good approximation for the universe during the Big Bang?

"You can search around the lamppost, but you can't go far beyond the lamppost, where it's dark—you just can't solve those equations," explains Lim. "Numerical relativity allows you to explore regions away from the lamppost."

[Continues . . .]

The paper is open access.   

"Cosmology using numerical relativity" | Living Reviews in Relativity

Abstract:

This review is an up-to-date account of the use of numerical relativity to study dynamical, strong-gravity environments in a cosmological context. First, we provide a gentle introduction into the use of numerical relativity in solving cosmological spacetimes, aimed at both cosmologists and numerical relativists.

Second, we survey the present body of work, focusing on general relativistic simulations, organised according to the cosmological history—from cosmogenesis, through the early hot Big Bang, to the late-time evolution of the universe. We discuss the present state-of-the-art, and suggest directions in which future work can be fruitfully pursued.

[Recusant]

Despite items like the previous, maybe partly because of them, I'm attracted to cosmology like a dog to a smelly spot on the ground.

Here we have scientists asking the question: Why didn't the Universe completely annihilate itself in its first few moments of existence? That is, as they understand it matter and antimatter should have been produced in equal amounts and then reacted in an immense burst of energy. There is evidence for the immense burst of energy (aka the Big Bang and cosmic inflation) yet the Universe is, as far as we can tell, composed of matter. There is no evidence of antimatter, which on encountering matter would produce an event we should be able to see.

As you likely already know (and mentioned in the article) current thinking has it that for some reason there was a very small discrepancy between the amount of matter and the amount of antimatter that came into existence--the matter in the Universe we inhabit is that relatively small amount of matter left over after the initial giant reaction. This experiment may show that there could be an alternative explanation. I think.

Also, I like the name of this particular baryon: the "beauty baryon."  Of course it follows that the experiment is called the "beauty experiment."

The title of the article may oversell things a bit but at least they stuck in the vital "may". 

"Major Antimatter Discovery May Help Solve Mystery of Existence" | Science Alert

We're now a step closer to understanding how the Universe avoided an antimatter apocalypse. CERN scientists have discovered tantalizing clues of a fundamental difference in the way physics handles matter and antimatter.

Experiments at the Large Hadron Collider (LHC) have verified an asymmetry between matter and antimatter forms of a particle called a baryon.

Known as a charge-parity (CP) violation, the effect has only previously been detected in another class of particles, called mesons. But experimental evidence in baryons, which make up the bulk of the Universe's matter, is something physicists have been long hunting for.

"It shows that the subtle differences between matter and antimatter exist in a wider range of particles, indicating that the fundamental laws of physics treat baryons and antibaryons differently," Xueting Yang, CERN physicist and first author of the study, told ScienceAlert.

[Continues . . .]

The paper is open access. 

"Observation of charge–parity symmetry breaking in baryon decays" | Nature

Abstract:

The Standard Model of particle physics—the theory of particles and interactions at the smallest scale—predicts that matter and antimatter interact differently due to violation of the combined symmetry of charge conjugation (C) and parity (P).

Charge conjugation transforms particles into their antimatter particles, whereas the parity transformation inverts spatial coordinates. This prediction applies to both mesons, which consist of a quark and an antiquark, and baryons, which are composed of three quarks.

However, despite having been discovered in various meson decays, CP violation has yet to be observed in baryons, the type of matter that makes up the observable Universe. Here we report a study of the decay of the beauty baryon Λ^b_O to the pK−π+π− final state, which proceeds through b → u or b → s quark-level transitions, and its CP-conjugated process, using data collected by the Large Hadron Collider beauty experiment at the European Organization for Nuclear Research (CERN).

The results reveal significant asymmetries between the decay rates of the Λ^b_O baryon and its CP-conjugated antibaryon, providing, to our knowledge, the first observation of CP violation in baryon decays and demonstrating the different behaviours of baryons and antibaryons.

In the Standard Model, CP violation arises from the Cabibbo–Kobayashi–Maskawa mechanism, and new forces or particles beyond the Standard Model could provide further contributions. This discovery opens a new path in the search for physics beyond the Standard Model.

[Recusant]

"We think it's probably caused by dark matter." Worthwhile if true. An intriguing observation in any case, and definitely worthy of further investigation. Maybe will provide some answers as to what dark matter actually is.

"Exceptional 'Einstein Cross' in Space Reveals Where Dark Matter Is Hiding" | Science Alert

A chance configuration of objects arrayed across deep space has just revealed the hiding place of a giant glob of dark matter.

Configurations like these, known as Einstein crosses, typically consist of four distinct points of light. This particular example, named HerS-3, has a feature never seen before. At the center of the cross appears a fifth blob of light.

"That's not supposed to happen," says theoretical astrophysicist Charles Keeton of Rutgers University-New Brunswick in the US. "You can't get a fifth image in the center unless something unusual is going on with the mass that's bending the light."

An Einstein cross in and of itself is a particularly rare cosmic phenomenon, created by light traveling through spacetime warped by the presence of an immense field of gravity. When light from a distant object, such as a galaxy, travels through this curved spacetime, it can split into four images of the galaxy that produced it, like the points of a cross.

Because the light is curved around the central mass, you don't see a fifth image of the background object in the center of the cross; if there is a light in the center, it's usually something in the foreground.

HerS-3 is a dusty, star-forming galaxy close to the edge of the visible Universe, emitting light that has traveled for 11.7 billion years to reach us.

Even at first glance, it seemed unusual. When a team led by astronomer Pierre Cox of the French National Center for Scientific Research (CNRS) took observations of it, they found their instincts correct: the light from the central dot was coming from the same distance as the four dots around it.

"We were like, 'What the heck?'" Cox says. "It looked like a cross, and there was this image in the center. I knew I had never seen that before."

To find out what was causing the strange image, the researchers ran through a gamut of possible explanations. Initially, they thought it was a glitch, but it turned out to be quite real. Computer modeling also ruled out any of the foreground galaxies as an explanation for the peculiar lensing.

Eventually, they could only conclude that the mechanism behind the warped region of spacetime had to be something we can't actually see: dark matter.

"We tried every reasonable configuration using just the visible galaxies, and none of them worked," says Keeton. "The only way to make the math and the physics line up was to add a dark matter halo. That's the power of modeling. It helps reveal what you can't see."

[. . .]

The researchers' modeling suggests that a closer group of galaxies whose light has traveled for about 8 billion years combines with a massive clump of dark matter, or dark matter halo, to produce the observed Einstein ring.

It's a remarkable find. That chance blob of dark matter sitting between us and HerS-3 magnifies the distant galaxy, giving us a much closer view of an active star-forming object in an early epoch of the Universe in which galaxies are usually too faint to resolve. It also offers a means of studying the nearer galaxy group, as well as the dark matter halo itself.

[Continues . . .]

The paper is open access:

"HerS-3: An Exceptional Einstein Cross Reveals a Massive Dark Matter Halo" | The Astrophysical Journal

Abstract:

We present a study of HerS-3, a dusty star-forming galaxy at z_spec = 3.0607, which is gravitationally amplified into an Einstein cross with a fifth image of the background galaxy seen at the center of the cross. Detailed 1 mm spectroscopy and imaging with NOEMA and the Atacama Large Millimeter/submillimeter Array resolve the individual images and show that each of the five images display a series of molecular lines that have similar central velocities, unambiguously confirming that they have identical redshifts.

The Hubble Space Telescope F110W image reveals a foreground lensing group of four galaxies with a photometric redshift z_phot ∼ 1.0. Lens models that only include the four visible galaxies are unable to reproduce the properties of HerS-3. By adding a fifth massive component, lying southeast of the brightest galaxy of the group, the source reconstruction is able to match the peak emission, shape, and orientation for each of the five images. The fact that no galaxy is detected near that position indicates the presence of a massive dark matter halo in the lensing galaxy group.

In the source plane, HerS-3 appears as an infrared luminous starburst galaxy seen nearly edge on. The serendipitous discovery of this exceptional Einstein cross offers a potential laboratory for exploring at small spatial scales a nuclear starburst at the peak of cosmic evolution and studying the properties of a massive dark matter halo associated with the lensing galaxy group.

[Icarus]

^ Mind bending stuff.

[Dark Lightning]

45 years on from my "Solar System Astrophysics" class at uni, that class is going to look a lot different. I'm just a groupie now, and don't have to do the math anymore. 

[Recusant]

Next, a paper on an apparently concentrated . . . region? aggregation? mass? . . . of dark matter that doesn't seem to have any stars associated with it. Another interesting if verified phenomenon. They went looking for the phenomenon specifically and found it, which is pretty cool.

"Astronomers detect lowest mass dark object ever measured using gravitational lensing" | Phys.org

Dark matter is an enigmatic form of matter not expected to emit light, yet it is essential to understanding how the rich tapestry of stars and galaxies we see in the night sky evolved. As a fundamental building block of the universe, a key question for astronomers is whether dark matter is smooth or clumpy, as this could reveal what it is made of. Since dark matter cannot be observed directly, its properties can only be determined by observing the gravitational lensing effect, whereby the light from a more distant object is distorted and deflected by the gravity of the dark object.

"Hunting for dark objects that do not seem to emit any light is clearly challenging," said Devon Powell at the Max Planck Institute for Astrophysics and lead author of the study. "Since we can't see them directly, we instead use very distant galaxies as a backlight to look for their gravitational imprints."

[. . .]

The team used a network of telescopes from around the world, including the Green Bank Telescope, the Very Long Baseline Array and the European Very Long Baseline Interferometric Network. The data from this international network were correlated at the Joint Institute for VLBI ERIC in the Netherlands, forming an Earth-sized super-telescope that could capture the subtle signals of gravitational lensing by the dark object.

They found that the object has a mass that is a million times greater than that of our sun and is located in a distant region of space, approximately 10 billion light years from Earth, when the universe was only 6.5 billion years old.

This is the lowest mass object to be found using this technique, by a factor of about 100. To achieve this level of sensitivity, the team had to create a high-fidelity image of the sky using radio telescopes located around the world.

John McKean from the University of Groningen, the University of Pretoria, and the South African Radio Astronomy Observatory, who led the data collection and is the lead author of a companion paper, stated, "From the first high-resolution image, we immediately observed a narrowing in the gravitational arc, which is the tell-tale sign that we were onto something. Only another small clump of mass between us and the distant radio galaxy could cause this."

The zoom in shows the pinch in the luminous radio arc, where the extra mass from the dark object is gravitationally 'imaged' using the sophisticated modeling algorithms of the team. The dark object is indicated by the white blob at the pinch point of the arc, but no light from it has so far been detected at optical, infrared or radio wavelengths.
Image credit: Keck/EVN/GBT/VLBA

[Continues . . .]

The paper is open access:

"A million-solar-mass object detected at a cosmological distance using gravitational imaging" | Nature Astonomy

Abstact:

Structure on subgalactic scales provides important tests of galaxy formation models and the nature of dark matter. However, such objects are typically too faint to provide robust mass constraints. Here we report the discovery of an extremely low-mass object detected by means of its gravitational perturbation to a thin lensed arc observed with milli-arcsecond-resolution very long baseline interferometry.

The object was identified using a non-parametric gravitational imaging technique and confirmed using independent parametric modelling. It contains a mass of m₈₀ = (1.13 ± 0.04) × 10⁶ M_⊙ within a projected radius of 80 pc at an assumed redshift of 0.881. This detection is extremely robust and precise, with a statistical significance of 26σ, a 3.3% fractional uncertainty on m₈₀ and an astrometric uncertainty of 194 μas.

This is the lowest-mass object known to us, by two orders of magnitude, to be detected at a cosmological distance by its gravitational effect. This work demonstrates the observational feasibility of using gravitational imaging to probe the million-solar-mass regime far beyond our local Universe.