galaxies Archives

April 26, 2024April 26, 2024 by Mark Thompson

Black Holes Can Halt Star Formation in Massive Galaxies

This research published in Nature is the first direct confirmation that supermassive black holes are capable of shutting down galaxies

It’s difficult to actually visualise a universe that is changing. Things tend to happen at snails pace albeit with the odd exception. Take the formation of galaxies growing in the early universe. Their immense gravitational field would suck in dust and gas from the local vicinity creating vast collections of stars. In the very centre of these young galaxies, supermassive blackholes would reside turning the galaxy into powerful quasars. A recent survey by the James Webb Space Telescope (JWST) reveals that black holes can create a powerful solar wind that can remove gas from galaxies faster than they can form into stars, shutting off the creation of new stars.

March 29, 2024March 29, 2024 by Evan Gough

The Milky Way’s Smallest, Faintest Satellite Galaxy Found

Hidden in this deep sky image (left) is Uma3/U1, an ultra faint galaxy. It contains fewer than 100 hundred stars, a tiny amount for a galaxy. Credit: CFHT/S. Gwyn (right) / S. Smith (left)

The Milky Way has many satellite galaxies, most notably the Large and Small Magellanic Clouds. They’re both visible to the naked eye from the southern hemisphere. Now astronomers have discovered another satellite that’s the smallest and dimmest one ever detected. It may also be one of the most dark matter-dominated galaxies ever found.

March 24, 2024March 24, 2024 by Carolyn Collins Petersen

Webb Watches the Most Distant Galactic Merger Ever Seen

JWST shows details of massive galaxy merger 13 billion years ago. Credit: ASTRO 3D

Astronomers know that galaxies form through mergers. They’ve been happening since the earliest epochs of cosmic time. Using the Webb telescope (JWST) astronomers found a massive merger of young galaxies going on about a half million years after the Big Bang. It’s called Gz9p3, one of the earliest and most distant mergers ever witnessed.

March 19, 2024March 19, 2024 by Mark Thompson

Astronomers Find the Most Massive Supercluster to Date

The Earth’s place in space is a fairly familiar one with it orbiting an average star. The star – our Sun – orbits the centre of our Galaxy the Milky Way. From here onwards, the story is less well known. The Milky Way is part of a large structure called the Laniakea Supercluster which is 250 million light years across! That really is a whacking great area of space and it contains at least 100,000 galaxies. There are larger superclusters though like the newly discovered Einasto Supercluster which measures an incredible 360 million light years across and is home to 26 quadrillion stars!

March 13, 2024March 13, 2024 by Mark Thompson

Are Andromeda and the Milky Way Already Exchanging Stars?

Artist's illustration of Andromeda/Milky Way Merger. Credit: NASA; ESA; Z. Levay and R. van der Marel, STScI; T. Hallas; and A. Mellinger

I often drag out the amazing fact that the Andromeda Galaxy, that faint fuzzy blob just off the corner of the Square of Pegasus, is heading straight for us! Of course I continue to tell people it won’t happen for a few billion years yet but a recent study suggests that we are already seeing hypervelocity stars that have been ejected from Andromeda already. It is just possible that the two galaxies have already started to exchange stars long before they are expected to merge.

March 11, 2024March 11, 2024 by Brian Koberlein

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.

March 7, 2024March 8, 2024 by Carolyn Collins Petersen

This Galaxy Was Already Dead When the Universe Was Only 700 Million Years Old

False-color JWST image of a small fraction of the GOODS South field, with the galaxy JADES-GS-z7-01-QU highlighted Credit: JADES Collaboration

When a galaxy runs out of gas and dust, the process of star birth stops. That takes billions of years. But, there’s a galaxy out there that was already dead when the Universe was only 700 million years old. What happened to it?

February 28, 2024February 28, 2024 by Evan Gough

Dwarf Galaxies Banished the Darkness and Lit Up the Early Universe

The JWST used gravitational lensing to search for the sources of light that triggered the Epoch of Reionization and brought darkness to an end. The white hazy blobs are galaxies in Pandora's Cluster, which acts as the gravitational lens. The red objects are the distant and ancient objects magnified by the lens, some of them warped into arcs. Many of them are early dwarf galaxies, some of them responsible for the Epoch of Reionization. Image Credit: NASA/ESA/CSA JWST

During the Universe’s Dark Ages, dense primordial gas absorbed and scattered light, prohibiting it from travelling. Only when the first stars and galaxies began to shine in energetic UV light did the Epoch of Reionization begin. The powerful UV light shone through the Universe and punched holes in the gas, allowing light to travel freely.

New observations with the James Webb Space Telescope reveal how it happened. The telescope shows that faint dwarf galaxies brought an end to the darkness.

February 22, 2024February 22, 2024 by Nancy Atkinson

Powerful Jets From a Black Hole are Spawning Star Clusters

A composite image of cluster of galaxies called SDSS J1531+3414 in X-ray, optical, and radio light. The overall scene resembles a colorful display of lights as if viewed through a wet, glass window. Credit: X-ray: NASA/CXC/SAO/O. Omoruyi et al.; Optical: NASA/ESA/STScI/G. Tremblay et al.; Radio: ASTRON/LOFAR; Image Processing: NASA/CXC/SAO/N. Wolk.

Supermassive black holes are messy feeders, and when they’re gorging on too much material, they can hurl high-energy jets into the surrounding Universe. Astronomers have found one of the most powerful eruptions ever seen, emanating from a black hole 3.8 billion light-years away. The powerful jets are blowing out cavities in intergalactic space and triggering the formation of a huge chain of star clusters.

February 20, 2024February 20, 2024 by Evan Gough

JWST Sees a Milky Way-Like Galaxy Coming Together in the Early Universe

The ancient Firefly Sparkle galaxy is precursor to galaxies like the Milky Way. The JWST found ten separate clusters in the galaxy that show how the galaxy is growing through mergers. Image Credit: Mowla et al. 2024.

The gigantic galaxies we see in the Universe today, including our own Milky Way galaxy, started out far smaller. Mergers throughout the Universe’s 13.7 billion years gradually assembled today’s massive galaxies. But they may have begun as mere star clusters.

In an effort to understand the earliest galaxies, the JWST has examined their ancient light for clues as to how they became so massive.