Star Formation Might Depend on Galactic Magnetic Fields

The Hubble captured this image of Arp 220, the aftermath of a galactic merger about 250 million light-years away. It's the brightest of the three galactic mergers closest to Earth. Astronomers studied Arp 220 with the Submillimeter Array (SMA) to determine the role magnetic fields play in the formation of stars. Image Credit: NASA/ESA/STScI/HST

A galactic merger is a chaotic event. When two massive structures like galaxies merge, their powerful gravitational forces wrench stars out of their usual orbits in a process called violent relaxation. In essence, the merging galaxies are evolving rapidly, and small perturbations can be amplified as the system moves toward a more stationary state.

Intuition suggests that this chaos should disrupt the galaxy, including its star formation, but new observations of the Arp 220 galaxy merger show that something else happens: the merger creates a massive magnetic field that traps gas and encourages more stars to form.

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Hubble Takes a 2.5 Gigapixel Image of Andromeda

This the largest photomosaic ever assembled from NASA/ESA Hubble Space Telescope observations. It is a panoramic view of the neighboring Andromeda galaxy, located 2.5 million light-years away. Image Credit: NASA, ESA, B. Williams (University of Washington)

The Andromeda galaxy is our closest galactic neighbour, barring dwarf galaxies that are gravitationally bound to the Milky Way. When conditions are right, we can see it with the naked eye, though it appears as a grey smudge. It’s the furthest object in the Universe that we can see without telescopic help.

The Hubble Space Telescope has created a massive 2.5-gigapixel panorama of Andromeda. It took 10 years and more than 1,000 orbits to capture all of the images.

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We Might Finally Know How Galaxies Grow So Large

Spiral galaxies and elliptical galaxies both contain bulges, also called spheroids. How these spheroids form and evolve is a puzzling question, but new research brings us closer to an answer. Image Credit: ESA

Astronomers have spent decades trying to understand how galaxies grow so large. One piece of the puzzle is spheroids, also known as galactic bulges. Spiral galaxies and elliptical galaxies have different morphologies, but they both have spheroids. This is where most of their stars are and, in fact, where most stars in the Universe reside. Since most stars reside in spheroids, understanding them is critical to understanding how galaxies grow and evolve.

New research focused on spheroids has brought them closer than ever to understanding how galaxies become so massive.

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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.

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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.

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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.

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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.

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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.

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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.

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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. 

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