Supermassive Black Holes Got Started From Massive Cosmic Seeds

The J0148 quasar circled in red. Two insets show, on top, the central black hole, and on bottom, the stellar emission from the host galaxy. Credit: NASA

Supermassive black holes are central to the dynamics and evolution of galaxies. They play a role in galactic formation, stellar production, and possibly even the clustering of dark matter. Almost every galaxy has a supermassive black hole, which can make up a small fraction of a galaxy’s mass in nearby galaxies. While we know a great deal about these gravitational monsters, one question that has lingered is just how supermassive black holes gained mass so quickly.

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The Universe Could Be Filled With Ultralight Black Holes That Can't Die

This simulated image shows how black holes bend a starry background and capture light. Credit: NASA’s Goddard Space Flight Center

It’s that time again! Time for another model that will finally solve the mystery of dark matter. Or not, but it’s worth a shot. Until we directly detect dark matter particles, or until some model conclusively removes dark matter from our astrophysical toolkit the best we can do is continue looking for solutions. This new work takes a look at that old theoretical chestnut, primordial black holes, but it has a few interesting twists.

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A Cold Brown Dwarf is Belching Methane Into Space

This artist concept portrays the brown dwarf W1935. Credit: NASA, ESA, CSA, Leah Hustak (STScI)

Brown dwarfs span the line between planets and stars. By definition, a star must be massive enough for hydrogen fusion to occur within its core. This puts the minimum mass of a star around 80 Jupiters. Planets, even large gas giants like Jupiter, only produce heat through gravitational collapse or radioactive decay, which is true for worlds up to about 13 Jovian masses. Above that, deuterium can undergo fusion. Brown dwarfs lay between these two extremes. The smallest brown dwarfs resemble gas planets with surface temperatures similar to Jupiter. The largest brown dwarfs have surface temperatures around 3,000 K and look essentially like stars.

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Neutron Stars Could be Heating Up From Dark Matter Annihilation

Artist’s impression of the magnetar in the star cluster Westerlund 1. Credit: ESO/L. Calçada

One of the big mysteries about dark matter particles is whether they interact with each other. We still don’t know the exact nature of what dark matter is. Some models argue that dark matter only interacts gravitationally, but many more posit that dark matter particles can collide with each other, clump together, and even decay into particles we can see. If that’s the case, then objects with particularly strong gravitational fields such as black holes, neutron stars, and white dwarfs might capture and concentrate dark matter. This could in turn affect how these objects appear. As a case in point, a recent study looks at the interplay between dark matter and neutron stars.

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The First Atmospheric Rainbow on an Exoplanet?

Artist impression of glory on exoplanet WASP-76b. Credit: ESA

When light strikes the atmosphere all sorts of interesting things can happen. Water vapor can split sunlight into a rainbow arc of colors, corpuscular rays can stream through gaps in clouds like the light from heaven, and halos and sundogs can appear due to sunlight reflecting off ice crystals. And then there is the glory effect, which can create a colorful almost saint-like halo around objects.

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Hubble Sees a Star About to Ignite

The FS Tau multi-star system. Credit: NASA, ESA, K. Stapelfeldt (NASA JPL), G. Kober (NASA/Catholic University of America)

We know how stars form. Clouds of interstellar gas and dust gravitationally collapse to form a burst of star formation we call a stellar nursery. Eventually, the cores of these protostars become dense enough to ignite their nuclear furnace and shine as true stars. But catching stars in that birth-moment act is difficult. Young stars are often hidden deep within their dense progenitor cloud, so we don’t see their light until they’ve already started shining. But new observations from the Hubble Space Telescope have given us our earliest glimpse of a shiny new star.

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Merging Stars Can Lead to Blue Supergiants

Artistic image of a binary system of a red giant star and a younger companion that can merge to produce a blue supergiant. Credit: Casey Reed, NASA

In the constellation of Orion, there is a brilliant bluish-white star. It marks the right foot of the starry hunter. It’s known as Rigel, and it is the most famous example of a blue supergiant star. Blue supergiants are more than 10,000 times brighter than the Sun, with masses 16 – 40 times greater. They are unstable and short-lived, so they should be rare in the galaxy. While they are rare, blue supergiants aren’t as rare as we would expect. A new study may have figured out why.

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Dwarf Galaxies Could be the Key to Explaining Dark Matter

Dark matter map in Galaxy Cluster Abell 1689. Credit: NASA, ESA, and D. Coe (NASA JPL/Caltech and STScI)

If you have a view of the southern celestial sky, on a clear night you might see two clear smudges of light set off a bit from the great arch of the Milky Way. They are the Large and Small Magellanic Clouds, and they are the most visible of the dwarf galaxies. Dwarf galaxies are small galaxies that typically cluster around larger ones. The Milky Way, for example, has nearly two dozen dwarf galaxies. Because of their small size, they can be more significantly affected by dark matter. Their formation may even have been triggered by the distribution of dark matter. So they can be an excellent way to study this mysterious unseen material.

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A 790,000 Year-Old Asteroid Impact Could Explain Seafloor Spherules

A 0.4-millimeter diameter iron-rich spherule. Credit: Avi Loeb/The Galileo Project

Our solar system does not exist in isolation. It formed within a stellar nursery along with hundreds of sibling stars, and even today has the occasional interaction with interstellar objects such as Oumuamua and Borisov. So it’s reasonable to presume that some interstellar material has reached Earth. Recently Avi Loeb and his team earned quite a bit of attention with a study arguing that it had found some of this interstellar stuff on the ocean seabed. But a new study finds that the material has a much more local origin.

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Black Holes Need Refreshing Cold Gas to Keep Growing

A pair of disc galaxies in the late stages of a merger. Credit: NASA

The Universe is filled with supermassive black holes. Almost every galaxy in the cosmos has one, and they are the most well-studied black holes by astronomers. But one thing we still don’t understand is just how they grew so massive so quickly. To answer that, astronomers have to identify lots of black holes in the early Universe, and since they are typically found in merging galaxies, that means astronomers have to identify early galaxies accurately. By hand. But thanks to the power of machine learning, that’s changing.

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