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Category: cosmology – Page 108

JWST’s recent observations of two quasars from the universe’s infancy reveal crucial insights into the early relationship between black holes and their galaxies, echoing mass ratios seen in the more recent universe.

New images from the James Webb Space Telescope (JWST) have revealed, for the first time, starlight from two massive galaxies hosting actively growing black holes – quasars – seen less than a billion years after the Big Bang. The black holes have masses close to a billion times that of the Sun, and the host galaxy masses are almost one hundred times larger, a ratio similar to what is found in the more recent universe. A powerful combination of the wide-field survey of the Subaru Telescope and the JWST has paved a new path to study the distant universe, reports a recent study in Nature.

Observations of giant black holes have attracted the attention of astronomers in recent years. The Event Horizon Telescope (EHT) has started to image the “shadow” of black holes at the galaxy centers. The 2020 Novel Prize in Physics was awarded to stellar motion observations at the heart of the Milky Way. While the existence of such giant black holes has become solid, no one knows their origin.

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It’s not every day astronomers say, “What is that?” After all, most observed astronomical phenomena are known: stars, planets, black holes, and galaxies. But in 2019 the newly completed ASKAP (Australian Square Kilometer Array Pathfinder) telescope picked up something no one had ever seen before: radio wave circles so large they contained entire galaxies in their centers.

As the astrophysics community tried to determine what these circles were, they also wanted to know why the circles were. Now a team led by University of California San Diego Professor of Astronomy and Astrophysics Alison Coil believes they may have found the answer: the circles are shells formed by outflowing galactic winds, possibly from massive exploding stars known as supernovae. Their work is published in Nature.

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So the idea is that intergalactic magnetic fields would tend to cluster electrons and ionized intergalactic hydrogen along their field lines, making those regions of the intergalactic voids just slightly denser than the rest of the void. This would cause dark matter to cluster a bit along the field lines as well. The gravitational effect would be extremely tiny, but over the entire history of the Universe, it would add up. So if primordial magnetic fields did form in the early Universe, tendrils of dark matter should be present along the same lines.

In a recent work in Physical Review Letters the authors argue that this effect would produce minihalos of dark matter. Just as galaxies are surrounded by a halo of dark matter due to gravitational clustering, faint halos of dark matter should exist around primordial magnetic field lines to do the gravitational tug of ionized matter along the field lines.

What’s interesting about this idea is that over time the charged ions and electrons would interact with the primordial magnetic fields and tend to cancel them out. The ions and electrons could even merge to create neutral hydrogen, so in the modern Universe, there would be no trace of these early magnetic fields in regular matter. But the microhalos of dark matter would still exist, and they could be seen through the gravitational lensing of distant light sources. These tendrils of dark matter could be the only evidence remaining of the earliest magnetic fields in the cosmos.

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The Dark Energy Survey took an entire decade to produce a value for the cosmological constant—and it’s smaller than you might think! There were other stories as well, including one about primeval black holes, and because I am inescapably drawn by the relentless gravity of black hole news, it’s included below, along with two other stories related in one way or another to heads.

Dogs’ primary sense is olfactory, and if their visual perception flags something interesting in the environment, the first thing they do is stick their cute little noses in it. But the opposite is true for humans; we are able to perceive millions of colors, but only a fraction of the olfactory stimuli dogs are usually way too engaged with.

If you smell in your house, you go looking for the source with your cute little retinas and their super-dense constellation of photoreceptive cells to determine that one of the gas knobs on the stove is open. Researchers at Johns Hopkins University grew retinal organoids in a lab to determine how human visual perception develops.

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Black holes are very important for galactic formation.

Astronomers have discovered that the supermassive black holes in the centers of early galaxies are much more massive than expected. These surprisingly hefty black holes offer new insights into the origins of all supermassive black holes, as well as the earliest stages of their host galaxy’s lives.

In nearby, mature like our Milky Way, the total mass of stars vastly outweighs the mass of the big black hole found at the galaxy’s center by about 1,000 to 1. In the newfound distant galaxies, however, that mass difference drops to 100 or 10 to 1, and even to 1 to 1, meaning the black hole can equal the combined mass of its host galaxy’s stars.

This picture of unexpectedly massive black holes in fledgling galaxies comes from the James Webb Space Telescope (JWST), NASA’s latest flagship observatory. Until JWST, which launched in late 2021, astronomers were generally limited in their studies of distant black holes to stupendously bright quasars, composed of monster, matter-devouring black holes that completely outshine the stars in their host galaxies.

Continue reading “Unexpectedly massive black holes dominate small galaxies in the distant universe” | >

Complexity of biological forms has fascinated humankind over the years. Different species of plants have different leaf shapes. Have you ever wondered why it is so? Why does this shape diversity exist? Plants can change their leaf shapes over time and space. But how?

Does the distinct of forms play a significant role in energy optimization? In fact, the shape of leaves has a lot to do with adapting to their surrounding environment. How is the unfolding of shape related to the evolutionary process of nature? These intriguing questions have led us to focus on quantitative approaches to the complexity of plant leaves.

Quantifying leaf shapes using Euclidean shapes, such as circles, triangles, etc., are appropriate to only a few . Therefore, various quantitative measures of leaf shapes have been developed with varying accuracy. But Is the shape of an object really its actual shape? Visual perception of definite shape or geometry of physical objects is only an abstraction.

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NASA scientists have identified unexpectedly massive clouds of cold gas within the spiral galaxy NGC 4,945, located 13 million light-years away.

As per the release, the revelation of this cold gas serves as the discovery of a “galactic fossil.”

The observations suggest that the gas likely rushed through this galaxy following the outburst from its supermassive black hole some five million years ago.

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