Galaxy Mergers Archives

September 6, 2024September 6, 2024 by Evan Gough

JWST Reveals Star Formation at Cosmic Noon

A massive galaxy cluster named MACS-J0417.5-1154 is warping and distorting the appearance of galaxies behind it, an effect known as gravitational lensing. This natural phenomenon magnifies distant galaxies and can also make them appear in an image multiple times, as NASA’s James Webb Space Telescope saw here. Two distant, interacting galaxies — a face-on spiral and a dusty red galaxy seen from the side — appear multiple times, tracing a familiar shape across the sky. NASA, ESA, CSA, STScI, V. Estrada-Carpenter (Saint Mary's University).

Understanding the star formation rate (SFR) in a galaxy is critical to understanding the galaxy itself. Some galaxies are starburst galaxies with extremely high SFRs, some are quenched or quiescent galaxies with very low SFRs, and some are in the middle. Researchers used the JWST to observe a pair of galaxies at Cosmic Noon that are just beginning to merge to see how SFRs vary in different regions of both galaxies.

September 3, 2024September 3, 2024 by Evan Gough

This Ancient Galaxy Merger Will Produce a very Luminous Quasar

This illustration depicts two quasars in the process of merging. There are many unanswered questions around galaxy mergers and the quasars that can result. Image Credit: NOIRLab/NSF/AURA/M. Garlick)

In the contemporary Universe, massive galaxies are plentiful. But the Universe wasn’t always like this. Astronomers think that galaxies grew large through mergers, so what we see in space is the result of billions of years of galaxies merging. When galaxies merge, the merger can feed large quantities of gas into their centers, sometimes creating a quasar.

Much of this is theoretical and shrouded in mystery, but astronomers might have found evidence of a galaxy merger creating a quasar.

July 30, 2024July 30, 2024 by Evan Gough

No Merger Needed: A Rotating Ring of Gas Creates A Hyperluminous Galaxy

This is a distant Hyper Luminous Infrared Galaxy named PJ0116-24. These galaxies experience rapid star formation that astronomers think is triggered by mergers. But this one suggests otherwise. Warm gas is shown in red and cold gas is shown in blue. Image Credit: PJ0116-24

Some galaxies experience rapid star formation hundreds or even thousands of times greater than the Milky Way. Astronomers think that mergers are behind these special galaxies, which were more abundant in the earlier Universe. But new results suggest no mergers are needed.

June 10, 2024June 10, 2024 by Evan Gough

The Milky Way’s Last Merger Event Was More Recent Than Thought

Our home galaxy as seen by the European Space Agency’s Gaia satellite. Image Credit: ESA/Gaia/DPAC

The Milky Way is only as massive as it is because of collisions and mergers with other galaxies. This is a messy process, and we see the same thing happening with other galaxies throughout the Universe. Currently, we see the Milky Way nibbling at its two satellite galaxies, the Large and Small Magellanic Clouds. Their fate is likely sealed, and they’ll be absorbed into our galaxy.

Researchers thought the last major merger occurred in the Milky Way’s distant past, between 8 and 11 billion years ago. But new research amplifies the idea that it was much more recent: less than 3 billion years ago.

May 17, 2024May 17, 2024 by Evan Gough

The Venerable Hubble Space Telescope Keeps Delivering

The Hubble Space Telescope is amazing! It's still going strong more than 34 years after it was launched. This Hubble image showcases a nearly edge-on view of the lenticular galaxy NGC 4753. ESA/Hubble & NASA, L. Kelsey

The world was much different in 1990 when NASA astronauts removed the Hubble Space Telescope from Space Shuttle Discovery’s cargo bay and placed it into orbit. The Cold War was ending, there were only 5.3 billion humans, and the World Wide Web had just come online.

May 12, 2024May 12, 2024 by Scott Alan Johnston

Do Clashing Galaxies Create Odd Radio Circles?

This multiwavelength image of the Cloverleaf ORC (odd radio circle) combines visible light observations from the DESI (Dark Energy Spectroscopic Instrument) Legacy Survey in white and yellow, X-rays from XMM-Newton in blue, and radio from ASKAP (the Australian Square Kilometer Array Pathfinder) in red. X. Zhang and M. Kluge (MPE), B. Koribalski (CSIRO)

Within the last five years, astronomers have discovered a new type of astronomical phenomenon that exists on vast scales – larger than whole galaxies. They’re called ORCs (odd radio circles), and they look like giant rings of radio waves expanding outwards like a shockwave. Until now, ORCs had never been observed in any wavelength other than radio, but according to a new paper released on April 30 2024, astronomers have captured X-rays associated with an ORC for the first time.

March 6, 2024March 7, 2024 by Mark Thompson

Astronomers Find the Most Massive Pair of Supermassive Black Holes Ever Seen

Artist's illustration of binary black holes

Supermassive black holes have been found at the heart of most galaxies but understanding how they have formed has eluded astronomers for some time. One of the most popular theories suggests they merge over and over again to form larger black holes. A recent discovery may support this however the pair of supermassive black holes are orbiting 24 light years apart and measure an incredible 28 billion solar masses making it the heaviest ever seen.

February 8, 2024February 8, 2024 by Evan Gough

Hubble Sees a Bridge of Stars Connecting Two Galaxies

The galaxy NGC 5427 shines in this new NASA Hubble Space Telescope image. Image Credits: NASA, ESA, and R. Foley (University of California – Santa Cruz); Processing: Gladys Kober (NASA/Catholic University of America)

The poetic-minded among us like to point out how Nature is a dance. If they’re right, then galaxies sometimes form unwieldy pairs. With the Hubble Space Telescope, we can spot some of these galactic pairs as they approach one another.

January 18, 2024January 18, 2024 by Evan Gough

The JWST Solves the Mystery of Ancient Light

This image shows the galaxy EGSY8p7, a bright galaxy in the early Universe where light emission is seen from, among other things, excited hydrogen atoms — Lyman-alpha emission. The galaxy was identified in a field of young galaxies studied by Webb in the CEERS survey. In the bottom two panels, Webb’s high sensitivity picks out this distant galaxy along with its two companion galaxies, where previous observations saw only one larger galaxy in its place. This discovery of a cluster of interacting galaxies sheds light on the mystery of why the hydrogen emission from EGSY8p7, shrouded in neutral gas formed after the Big Bang, should be visible at all. Image Credit: ESA/Webb, NASA & CSA, S. Finkelstein (UT Austin), M. Bagley (UT Austin), R. Larson (UT Austin), A. Pagan (STScI), C. Witten, M. Zamani (ESA/Webb)

The very early Universe was a dark place. It was packed with light-blocking hydrogen and not much else. Only when the first stars switched on and began illuminating their surroundings with UV radiation did light begin its reign. That occurred during the Epoch of Reionization.

But before the Universe became well-lit, a specific and mysterious type of light pierced the darkness: Lyman-alpha emissions.

April 25, 2023April 25, 2023 by Evan Gough

JWST Sees Merging Galaxies Releasing the Light of a Trillion Suns

ARP 220 is a pair of merging galaxies about 250 million light years away. Image Credit: NASA, ESA, CSA, STScI, Alyssa Pagan (STScI)

If we want to know what it’ll look like in about 4.5 billion years when our galaxy merges with Andromeda, we might take a look at ARP 220. ARP 220 is a pair of galaxies that are in the process of merging. The merging galaxies emit brilliant infrared light, and the James Webb Space Telescope captured that light in a vivid portrait.