galaxies Archives

September 19, 2023September 19, 2023 by Evan Gough

Galaxies Breathe Gas, and When They Stop, No More Stars Form

Artist concept of how a galaxy might accrete mass from rapid, narrow streams of cold gas. These filaments provide the galaxy with continuous flows of raw material to feed its star-forming at a rather leisurely pace. Credit: ESA–AOES Medialab

For most of the history of astronomy, all we could see were stars. We could see them individually, in clusters, in nebulae, and in fuzzy blobs that we thought were clumps of stars but were actually galaxies. The thing is, most of what’s out there is much harder to see than stars and galaxies. It’s gas.

Now that astronomers can see gas better than ever, we can see how galaxies breathe it in and out. When they stop breathing it, stars stop forming.

September 19, 2023September 19, 2023 by Brian Koberlein

Polar Ring Galaxies Are Bizarre and Rare. Astronomers Just Found Two More

A galaxy with a polar ring of hydrogen gas, known as a polar ring galaxy. Credit: Jayanne English, Nathan Deg & WALLABY Survey, CSIRO/ASKAP, NAOJ/Subaru Telescope

Galaxies come in a range of shapes, from elegant spirals to egg-shaped ellipticals. We often categorize galaxies by their shape, which was traditionally done based on what we could observe in the visual spectrum. But as we expanded astronomy into radio, infrared, ultraviolet, and x-ray light, learned that often galaxies have structures invisible to our eyes. Take, for example, an odd type of galaxy known as polar ring galaxies (PRGs).

September 18, 2023September 18, 2023 by Carolyn Collins Petersen

A Collision Between Gigantic Galaxy Clusters. Too Big, Too Early

Hubble Space Telescope image of the El Gordo galaxy cluster. This and other gigantic galaxy clusters are challenging the most common theory of the evolution of structure in the Universe. Credit: NASA, ESA, and J. Jee (University of California, Davis)

Just when cosmologists have a workable theory for when and how galaxy collisions happened in the early Universe, something challenges it. In this case, the challenger is a collision of two massive galaxy clusters that combined to form a gigantic galaxy cluster.

September 15, 2023September 15, 2023 by Evan Gough

Strong Evidence that Supermassive Black Holes Affect Their Host Galaxy’s Chemistry

This is a composite image of the spiral galaxy Messier 77 (NGC 1068), as observed by ALMA and the Hubble Space Telescope. Red and blue are different chemicals. Red are cyanide radicals concentrated mostly in the center and a large-scale ring-shaped gas structure, but also along the bipolar jets extending from the center towards the northeast (upper left) and southwest (lower right). Blue is carbon monoxide isotopes which avoid the central region. Image Credit: ALMA (ESO/NAOJ/NRAO), NASA/ESA Hubble Space Telescope, T. Nakajima et al.

Supermassive Black Holes (SMBHs) are impossible to ignore. They can be billions of times more massive than the Sun, and when they’re actively consuming stars and gas, they become luminous active galactic nuclei (AGN.) A galaxy’s center is a busy place, with the activity centred on the SMBH.

New research provides strong evidence that while going about their business, SMBHs alter their host galaxy’s chemistry.

September 7, 2023September 7, 2023 by Brian Koberlein

The Most Distant Galactic Field Lines Ever Seen

Mapping of the magnetic field in the distant 9io9 galaxy. Credit: ALMA (ESO/NAOJ/NRAO)/J. Geach et al.

The galaxies in our local Universe all have magnetic fields. Galactic magnetic fields can be generated by ionized gas within a galaxy, and these same magnetic fields affect the evolution of galaxies. But while modern galaxies have magnetic fields, did early ones? Astronomers are still trying to understand how galactic magnetic fields arise in young galaxies, but this can be a challenge without observational data. Now a team using data from the Atacama Large Millimeter/submillimeter Array (ALMA) has observed the magnetic field of a galaxy when the Universe was just 2.5 billion years old. The galaxy is known as 9io9. It takes 11 billion years for its light to reach us, making it the most distant galaxy for which we have observed a magnetic field.

August 29, 2023August 29, 2023 by Nancy Atkinson

The Whirlpool Galaxy, Seen by JWST

The graceful winding arms of the grand-design spiral galaxy M51 stretch across this image from the NASA/ESA/CSA James Webb Space Telescope. New JWST observations of the early Universe are upending our understanding of galaxy evolution. Credit: ESA/Webb, NASA & CSA, A. Adamo (Stockholm University) and the FEAST JWST team

The Whirlpool Galaxy, aka M51, is one of the most well-known objects in the night sky. It’s close enough and prominent in the northern sky that amateur astronomers have shared stunning pictures of it for decades. But you’ve never seen anything like this: M51 as seen by the James Webb Space Telescope (JWST). This image contains data from the telescope’s NIRCam and MIRI instruments, which shows incredible detail and reveals hidden features among the spiral arms.

August 27, 2023August 27, 2023 by Brian Koberlein

The Early Universe Should Be Awash in Active Galaxies, but JWST Isn't Finding Them

Artist view of an active black hole in the early universe. Credit: Boston University/Cosmovision

For decades the most distant objects we could see were quasars. We now know they are powerful active black holes. Active galactic nuclei so distant that they resemble star-like points of light. It tells us that supermassive black holes in the early Universe can be powerful monsters that drive the evolution of their galaxies. We had thought most early supermassive black holes went through such an active phase, but a new study suggests most supermassive black holes don’t.

August 18, 2023August 18, 2023 by Evan Gough

This Distant Galaxy Cluster is Totally Relaxed, Unharassed for a Billion Years

Astronomers have discovered a galaxy cluster with an important characteristic; it's “relaxed, meaning that it shows no signs of having been disrupted by violent collisions with other clusters of galaxies. This composite image contains X-rays from Chandra (blue), which helped identify SPT2215 along with other telescopes, and data from Hubble (cyan and orange). Image Credit: X-ray: NASA/CXC/MIT/M. Calzadilla; UV/Optical/Near-IR/IR: NASA/STScI/HST; Image processing: N. Wolk

In the span of a human lifetime, much of the Universe seems unchanging. But that’s an illusion; things are always changing, and that fact can make galaxies and the clusters they reside in very unruly places due to mergers and collisions.

However, some galaxy clusters seem much calmer than others.

June 28, 2023June 28, 2023 by Brian Koberlein

What Would the Milky Way Look Like From Afar?

A view of the Milky Way from Paranal, Chile. Credit: ESO/Y. Beletsky

Our understanding of galaxies is rooted in the fact that we can see so many of them. Some, such as the Andromeda and Pinwheel galaxies are fairly close, and others are more distant, but all of them give a unique view. Because of this, we can see how the various types of galaxies appear from different points of view, from face-on to edge-on and all angles in between. But there is one galaxy that’s a bit harder to map out, and that’s our own. Because we are in the galactic plane of the Milky Way, it can be difficult to create an accurate bird’s-eye view of our home galaxy. That’s where a recent study in Nature Astronomy comes in.

June 20, 2023June 20, 2023 by Matt Williams

JWST Glimpses the Cosmic Dawn of the Universe

This still image shows the timeline running from the Big Bang on the right, towards the present on the left. In the middle is the Reionization Period where the initial bubbles caused the cosmic dawn. Credit: NASA SVS

The James Webb Space Telescope (JWST) continues to push the boundaries of astronomy and cosmology, the very job it was created for. First conceived during the 1990s, and with development commencing about a decade later, the purpose of this next-generation telescope is to pick up where Spitzer and the venerable Hubble Space Telescope (HST) left off – examining the infrared Universe and looking farther back in time than ever before. One of the chief objectives of Webb is to observe high-redshift (high-Z) galaxies that formed during Cosmic Dawn.

This period refers to the Epoch of Reionization, where the first galaxies emitted large amounts of ultraviolet (UV) photons that ionized the neutral hydrogen that made up the intergalactic medium (IGM), causing the Universe to become transparent. The best way to measure the level of star formation is the H-alpha emission line, which is visible in the mid-infrared spectrum for galaxies with high redshifts. Using data from the Mid-Infrared Instrument (MIRI), an international team of researchers was able to resolve the H-alpha line and observe galaxies with redshift values higher than seven (z>7) for the first time.