Astronomers unravel the history of galaxies for the first time

August 27, 2015, Cardiff University
Credit: NASA, ESA, and the Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration

A team of international scientists, led by astronomers from Cardiff University's School of Physics and Astronomy, has shown for the first time that galaxies can change their structure over the course of their lifetime.

By observing the sky as it is today, and peering back in time using the Hubble and Herschel telescopes, the team have shown that a large proportion of have undergone a major 'metamorphosis' since they were initially formed after the Big Bang.

By providing the first direct evidence of the extent of this transformation, the team hope to shed light on the processes that caused these dramatic changes, and therefore gain a greater understanding of the appearance and properties of the Universe as we know it today.

In their study, which has been published in the Monthly Notices of the Royal Astronomical Society¸ the researchers observed around 10,000 galaxies currently present in the Universe using a survey of the sky created by the Herschel ATLAS and GAMA projects.

The researchers then classified the galaxies into the two main types: flat, rotating, disc-shaped galaxies (much like our own galaxy, the Milky Way); and large, oval-shaped galaxies with a swarm of disordered stars.

Using the Hubble and Herschel telescopes, the researchers then looked further out into the Universe, and thus further back in time, to observe the galaxies that formed shortly after the Big Bang.

The researchers showed that 83 per cent of all the stars formed since the Big Bang were initially located in a disc-shaped galaxy.

However, only 49 per cent of stars that exist in the Universe today are located in these disc-shaped galaxies—the remainder are located in oval-shaped galaxies.

The results suggest a massive transformation in which disc-shaped galaxies became oval-shaped galaxies.

A popular theory is that this transformation was caused by many cosmic catastrophes, in which two disk-dominated galaxies, straying too close to each other, were forced by gravity to merge into a single galaxy, with the merger destroying the disks and producing a huge pileup of stars. An opposing theory is that the transformation was a more gentle process, with stars formed in a disk gradually moving to the centre of a disk and producing a central pile-up of stars.

Lead author of the study Professor Steve Eales, from Cardiff University's School of Physics and Astronomy, said: "Many people have claimed before that this metamorphosis has occurred, but by combining Herschel and Hubble, we have for the first time been able to accurately measure the extent of this transformation.

"Galaxies are the basic building blocks of the Universe, so this really does represent one of the most significant changes in its appearance and properties in the last 8 billion years."

Professor Asantha Cooray, a co-author of the study from the University of California, said: "This study is important as it establishes statistics showing that almost all stars formed in spiral galaxies in the past, but a large fraction of these now appear as large, dead, today. This study will require us to refine the models and computer simulations that attempt to explain how galaxies formed and behaved over the last 13 billion years."

Dr David Clements, a co-author of the study from Imperial College London, said: "Up to now we've seen individual cases in the local where galaxy collisions convert spirals into ellipticals. This study shows that this kind of transformation is not exceptional, but is part of the normal history of galaxy evolution."

Matthew Allen, a Ph.D. student at Cardiff University and a member of the team, said: "This is a huge step in understanding how the galactic population has evolved over billions of years. Using some of the most cutting edge data and techniques, we are finally beginning to understand the processes that have shaped our Universe."

Explore further: 'Galaxy fingerprinting' yields new clues about galaxy evolution

More information: "H-ATLAS/GAMA: quantifying the morphological evolution of the galaxy population using cosmic calorimetry." Monthly Notices of the Royal Astronomical Society. (October 01, 2015) 452 (4): 3489-3507. DOI: 10.1093/mnras/stv1300

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Tuxford
1 / 5 (9) Aug 27, 2015
"This study is important as it establishes statistics showing that almost all stars formed in spiral galaxies in the past, but a large fraction of these now appear as large, dead, elliptical galaxies today. This study will require us to refine the models and computer simulations that attempt to explain how galaxies formed and behaved over the last 13 billion years."


Without a fundamental rethink, merger maniacs have no chance. The natural evolution is from spiral to large 'dead' elliptical. Only the elliptical are not dead! Since their cores are producing more new matter at an even increasing rate, growing the galaxy into the final elliptical stage. Just more confirmation of LaViolette's Continuous Creation model. How embarrassing!
docile
Aug 27, 2015
This comment has been removed by a moderator.
docile
Aug 27, 2015
This comment has been removed by a moderator.
NIPSZX
not rated yet Aug 28, 2015
This is much scarier than pole shifts, it is nice to think the Universe is still and quiet, from a human's perspective.
wduckss
not rated yet Aug 28, 2015
"The researchers showed that 83 per cent of all the stars formed since the Big Bang were initially located in a disc-shaped galaxy.
However, only 49 per cent of stars that exist in the Universe today are located in these disc-shaped galaxies-the remainder are located in an oval-shaped galaxies. "

When (how far) telescopes no longer measure the distance, when beginning a age of the universe (after 1 million ... 1 billion ... light years)?
The most distant galaxies moving at speeds of 270,000 km / sec, us closer to the galaxy at speeds to 1 or 2,000 km / sec. Different speeds (conditions) different statistics.
docile
Aug 28, 2015
This comment has been removed by a moderator.
my2cts
5 / 5 (5) Aug 29, 2015
Dark matter and energy, you fucking moron! So typical. Reject the answers and then stand there in awe at the "mystery". Christians fucking love to be ignorant. Islam places science and astronomy on a pedastal. Just the act of viewing celestial objects is considered an act of worship. For Christians, that means saying nothing and chanting like a bunch of druids. For Muslims that means using your brain and doing your best to understand it; that's appreciation. That's what I will never get about Christians is how they think ignorance can be pious. I have to conclude they have no choice. Having a low IQ must be a terrible prison.

What are you ranting about? Ignorance is rampant in the muslim world.
my2cts
5 / 5 (4) Aug 29, 2015
merger maniacs have no chance.

Tuxford, the inevitable antimerger maniac.
Steelwolf
not rated yet Aug 30, 2015
Well docile, this takes off from Hawkings BH thread also, and I agree, globular clusters, the small sphericals, are first, merging into larger groups and eventually becoming the larger types of galaxy, up to what I noted was the fully realized magnetic field type of Elliptical galaxy, growing at the edges of a large cluster.

Also realizing that each of the stars along those magnetic lines I propose, would have it's own magnetic fields, like our own sun, and others, as well as later stage stars such as neutron stars and/or Magnetars, and since this is a red-dead type population, in general, being fed on cool gas and only creating new stars slowly, having scavenged much of the cool gas in it's orbit already, it only gets a fraction of what it had before, still maintaining an AGN and thus keeping it's magnetic field strength and shape.

Sorry for keeping on with this particular subject, but is one I have put a lot of thought into, and continuously learn more and update ideas.
Steelwolf
not rated yet Aug 30, 2015
Continuing on my previous:
@ docile and @Enthusiastic F.
I just found this picture of an elliptical galaxy from end on, it says 'showing dust lanes from a possible recent merger, but, they look a lot more like magnetic filaments, and the area around the central galaxy was apparently a sphere of stars, denser towards the center near the ends, and then dimmer at the edge. Article here, picture at the top:

http://phys.org/n...tml#nRlv

A Fully Realized Elliptical galaxy, presumably with an AGN, from the brightness with the magnetic field viewed from an fop down perspective rather than the side perspective I showed in that Awesome NASA Pic I posted in the other thread (http://www.nasa.g..._hi.jpg) the galaxy the dim elliptical at the 2 O' Clock Position, Not the central object (although those filaments Are leaving star formations behind them, according to the article with the pic).

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