#galaxy evolution

Using the James Webb Space Telescope (JWST) and the Atacama Large Millimeter/submillimeter Array (ALMA), astronomers may have uncovered new clues about a longstanding mystery in galaxy evolution: why so many massive galaxies in the early universe appear to have died far sooner than expected.

Galaxies are often considered "alive" when they are actively forming stars and "dead" when star formation has largely ceased. In today's universe, dead galaxies are common. But astronomers have been surprised to find large numbers of them in the early universe, when galaxies were expected to be rapidly growing and churning out stars. Using ALMA and JWST observations of a distant galaxy, researchers have detected a "galaxy-killing" wind — an enormous, high-speed outflow of gas — that is powerful enough to strip a galaxy of the raw material needed to make new stars. The discovery could help explain the puzzling population of massive "dead" galaxies found throughout the young cosmos, according to a statement from the Royal Astronomical Society.

"Dense regions of the universe are like very active cities," Rebecca Davies, lead author of the study from Swinburne University of Technology in Melbourne, said in the statement. "Galaxies collide and undergo frenzied bursts of star formation. But when the biggest stars burn out, they explode as supernovas, launching powerful winds that blast away the very gas galaxies need to keep forming stars."

Davies and colleagues observed a galaxy called CRISTAL-02 as it appeared just one billion years after the Big Bang, catching it in the midst of a rapid growth spurt.

Like ripples that span out from a object dropped into water, the oldest spiral galaxy found so far, also appears to exhibit the same rippling, and has opened up a few interesting ideas to how it formed.

The galaxy BRI 1335-0417 may not be an astronomical household name, but for those looking to understand how early galaxies evolved, it's on their list !

Recent observations from ALMA has thrown up some interesting features, two primary arms, and a ripple effect across the galaxy.

Above NGC 1300 (a whole lot closer to us !!) shows how these two armed spirals look, but there's another feature in the centre, a bar.

Our Milky Way has a bar, a central section that the arms appear to attach to. What actually happens in these galaxies is that the arms pull in dust and gas from around the galaxy, and funnel it towards the centre, both feeding the supermassive black hole, but creating a lot of new stars too in the process.

The discovery of a bar on BRI 1335-0417 is the first detected on such an early galaxy, and answers a few questions about how they form. For many years astronomers believed that the bar is a final part of a galaxies evolution, created by stars being pulled towards the centre, a stellar build up, but finding a bar in such a young galaxy, suggests another possibility.

NGC1365, two spiral arms and a long bar connecting to the central supermassive black hole.

The ripples are thought to have occurred due to a huge intake of intergalactic gas and dust, and the existence of the arms suggest it's not stars that have found themselves pushed to the centre, but instead, the dust and gas, maybe suggesting that bars are not a elderly prize, but a youthful aspect of a galaxy.

Two Hubble images of interacting galaxy pair IC1623. The first one is a composition of optical and infrared images. The second one combines observations from eight different filters with wavelengths ranging from infrared to ultraviolet.

At this stage of their collision, the two galaxies are still relatively separate, but eventually they'll merge into a single object. The merging process will also trigger intense star formation, causing the resulting galaxy to be classified as a starburst.

Can This Newfound Dark, Massive Galaxy Be Astronomy's 'Missing Link' In The Universe?

“Up until now, scientists have been waiting for the James Webb Space Telescope — humanity's next-generation, space-based infrared observatory — to peer through the light-blocking dust and solve the mystery of how our Universe grew up. While Webb will certainly teach us more about these early, growing galaxies and reveal details that remain unseen, we've learned that these obscured monsters really are out there, and might be the missing link in galaxy growth and evolution.

Either we've gotten incredibly lucky in finding a very rare type of galaxy in such a small region of space, or this new find is an indicator that these behemoths really are everywhere. For now, this new discovery should leave us all hopeful that ALMA will continue to find more of these galaxies, and that when James Webb comes online, one more piece of the cosmic puzzle might slide perfectly into place.”

When you think about the story of how galaxies formed, it should involve small regions where stars have formed first merging together to grow up into proto-galaxies and eventually into the full-fledged mature, evolved galaxies we see today. The problem is that we see both the young, unevolved ones and the old, mature ones but not the intermediate ones. This is a problem because we’re not seeing the star-formation rates needed to make all the stars in a sufficient time.

From SpaceTelescope.Org Picture of the Week; December 20, 2010:

Barred Spiral Bares All

The galaxy captured in this image, called UGC 12158, certainly isn’t camera-shy: this spiral stunner is posing face-on to the NASA/ESA Hubble Space Telescope’s Advanced Camera for Surveys, revealing its structure in fine detail.

UGC 12158 is an excellent example of a barred spiral galaxy in the Hubble sequence — a scheme used to categorise galaxies based on their shapes. Barred spirals, as the name suggest, feature spectacular swirling arms of stars that emanate from a bar-shaped centre. Such bar structures are common, being found in about two thirds of spiral galaxies, and are thought to act as funnels, guiding gas to their galactic centres where it accumulates to form newborn stars. These aren’t permanent structures: astronomers think that they slowly disperse over time, so that the galaxies eventually evolve into regular spirals.

The appearance of a galaxy changes little over millions of years, but this image also contains a short-lived and brilliant interloper — the bright blue star just to the lower left of the centre of the galaxy is very different from the several foreground stars seen in the image. It is in fact a supernova inside UGC 12158 and much further away than the Milky Way stars in the field — at a distance of about 400 million light-years! This stellar explosion, called SN 2004ef, was first spotted by two British amateur astronomers in September 2004 and the Hubble data shown here form part of the follow-up observations.

This picture was created from images taken with the Wide Field Channel of Hubble’s Advanced Camera for Surveys. Images through blue (F475W, coloured blue), yellow (F606W, coloured green) and red (F814W, coloured red) as well as a filter that isolates the light from glowing hydrogen (F658W, also coloured red) have been included. The exposure times were 1160 s, 700 s, 700 s and 1200 s respectively. The field of view is about 2.3 arcminutes across.

This composite image combines data from both the James Webb Space Telescope and Chandra X-ray Observatory. (Image credit: X-ray: NASA/CXC/SAO; Infrared: NASA/ESA/CSA/STScI/Webb; Image Processing: NASA/CXC/SAO/L. Frattare)

Recently, two NASA space telescopes, the James Webb Space Telescope and Chandra X-Ray Observatory, captured images of two galaxies beginning to collide. NASA released a composite image showing both the visible and X-ray spectra of the collision. The smaller galaxy, IC 2163, is at the upper left, while NGC 2207 dominates the center and lower right. Their long, silvery-blue spiral arms are peppered with bright knots and specks, the telltale signposts of active, messy astrophysics in progress.

Arp 87 - The Dancing Galaxies

In what may look like a very slow motion dance, NGC 3808A holds hands with his partner NGC 3808B 330 Million light years from us in the constellation of Leo.

But this dance has a deadly outcome, as currently the stretched out arm covers 70,000 light years, it's grip will now pull the already irregular and messed up B towards it and ultimately to a merger.