Mysteries of "The Redshift Desert" --Why Do Galaxies in the Early Universe Appear Old?
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March 30, 2012

Mysteries of "The Redshift Desert" --Why Do Galaxies in the Early Universe Appear Old?

 

           Galaxies_no_txt_med


These highly developed galaxies, whose star-forming youth is in fact long gone, just shouldn't be there, but are." 

Dr. Karl Glazebrook (Johns Hopkins University).

Some of the faintest spectra in the universe raise a glaring question: Why do Galaxies in the early universe appear old? Until recently, astronomers have been nearly blind when looking back in time to survey an era when most stars in the Universe were expected to have formed. This critical cosmological blind-spot was removed in 2011 by a team using the Frederick C. Gillett Gemini North Telescope located on Mauna Kea, Hawaii, showing that many galaxies in the young Universe are not behaving as they would have expected some 8-11 billion years ago.

The surprise: these galaxies appear to be more fully formed and mature than expected at this early stage in the evolution of the Universe.

"Theory tells us that this epoch should be dominated by little galaxies crashing together," said Dr. Roberto Abraham (University of Toronto) who was a Co-Principal Investigator of the team that conducted the observations at Gemini. "We are seeing that a large fraction of the stars in the Universe are already in place when the Universe was quite young, which should not be the case. This glimpse back in time shows pretty clearly that we need to re-think what happened during this early epoch in galactic evolution. The theoreticians will definitely have something to gnaw on!"

These observations are from a multinational investigation, called the Gemini Deep Deep Survey (GDDS), which used a special technique to capture the faintest galactic light ever dissected into the rainbow of colors called a spectrum. In all, spectra from over 300 galaxies were collected, most of which are within what is called the "Redshift Desert," a relatively unexplored period of the Universe seen by telescopes looking back to an era when the universe was only 3-6 billion years old.

 

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These spectra represent the most complete sample ever obtained of galaxies in the Redshift Desert. By obtaining large amounts of data from four widely separated fields, this survey provides the statistical basis for drawing conclusions that have been suspected by past observations done by the Hubble Space Telescope, Keck Observatory, Subaru Telescope and the Very Large Telescope over the past decade.

Studying the faint galaxies at this epoch when the Universe was only 20-40% of its current age presents a daunting challenge to astronomers, even when using the light-gathering capacity of a very large telescope like Gemini North with its 8-meter mirror. All previous galaxy surveys in this realm have focused on galaxies where intense star formation is occurring, which makes it easier to obtain spectra but produces a biased sample.

The GDDS was able to select a more representative sample including those galaxies which hold the most stars–normal, dimmer, and more massive galaxies–that demand special techniques to coax a spectrum from their dim light.

"The Gemini data is the most comprehensive survey ever done covering the bulk of the galaxies that represent conditions in the early Universe. These are the massive galaxies that are actually more difficult to study because of their lack of energetic light from star formation. These highly developed galaxies, whose star-forming youth is in fact long gone, just shouldn't be there, but are," said Co-Principal Investigator Dr. Karl Glazebrook of Johns Hopkins University.

"It is unclear if we need to tweak the existing models or develop a new one in order to understand this finding," said the survey's third Co-Principal Investigator, Dr. Patrick McCarthy with the Observatories of the Carnegie Institution. "It is quite obvious from the Gemini spectra that these are indeed very mature galaxies, and we are not seeing the effects of obscuring dust. Obviously there are some major aspects about the early lives of galaxies that we just don't understand. It is even possible that black holes might have been much more ubiquitous than we thought in the early Universe and played a larger role in seeding early galaxy formation."

What is arguably the dominant galactic evolution theory postulates that the population of galaxies at this early stage should have been dominated by evolutionary building blocks. Aptly called the Hierarchical Model, it predicts that normal to large galaxies, like those studied in this work, would not yet exist and would instead be forming from local beehives of activity where big galaxies grew. The GDDS reveals that this might not be the case.

Caltech astronomer, Dr. Richard Ellis commented, "The Gemini Deep Deep Survey represents a very significant achievement, both technically and scientifically. The survey has provided a new and valuable census of galaxies during a key period in cosmic history, one that has been difficult to study until now, particularly for the quiescent component of the galaxy population."

Making observations in the Redshift Desert has frustrated modern astronomers for the last decade. While astronomers have known that plenty of galaxies must exist in the Redshift Desert, it is only a "desert" because we couldn't get good spectra from many of them. The problem lies in the fact that key spectroscopic features used to study these galaxies have been redshifted–due to the expansion of the Universe–into a part of the optical spectrum that corresponds to a faint, natural, obscuring glow in the Earth's nighttime atmosphere.

To overcome this problem, a sophisticated technique called "Nod and Shuffle" was used on the Gemini telescope.

"The Nod and Shuffle technique enables us to skim off the faint natural glow of the night sky to reveal the tenuous spectra of galaxies beneath it. These galaxies are over 300 times fainter than this sky glow," explains Dr. Kathy Roth, an astronomer at Gemini who was also part of the team and obtained much of the data. "It has proven to be an extremely effective way to radically reduce the "noise" or contamination levels that are found in the signal from an electronic light detector."

Previous studies in the Redshift Desert have concentrated on galaxies that were not necessarily representative of mainstream systems. For this study, galaxies were carefully selected based upon data from the Las Campanas Infrared Survey in order to assure that strong ultraviolet emitting starburst galaxies were not oversampled.

"This study is unique in that we were able to study the red end of the spectrum, and this tells us about the ages of old stars," says Dr. Abraham. "We undertook incredibly long observations with Gemini–about ten times as long as typical exposures. This let us look at much fainter galaxies than is usually the case, and let us focus on the bulk of the stars, instead of just the flashy young ones. This makes it a lot easier for us to work out how the galaxies are evolving. We are no longer guessing at it by studying young objects and assuming the old objects were not contributing much to the story of galaxy evolution. It turns out that there are lots of old galaxies out there, but they're really hard to find."

The Gemini Multi-Object Spectrograph used on the Frederick C. Gillett Gemini Telescope on Mauna Kea to make the GDDS observations is one of two identical instruments, which are used on both Gemini telescopes. GMOS is primarily designed for spectroscopic studies where several hundred simultaneous spectra are required, such as when observing star and galaxy clusters. GMOS also has the ability to focus astronomical images on its array of over 28 million pixels.

The Gemini Observatory is an international collaboration that has built two identical 8-meter telescopes. The Gemini South telescope is located on Cerro Pachón in central Chile (Gemini South), and hence provide full coverage of both hemispheres of the sky. Both telescopes incorporate new technologies that allow large, relatively thin mirrors under active control to collect and focus both optical and infrared radiation from space.

The Daily Galaxy via gemini.edu

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Comments

these are "dark galaxies"....


Or maybe is that everything we think we know is not right at all... could it be so?

Our current understanding of the age of the universe is wrong. It is much, MUCH, older than we can imagine.

One possibility is the light has a lifetime and 13.7 billion years is it. that is why we can't see any farther. just a thought

Well i think we are hindered by our current level of telescope technology. Yes we can see very far, even close to the beginning but is what we are seeing things that are real? We are in fact not seeing things as they are in this time, but as they were billions of years ago when the light first began it's journey towards us. So i think until we can side step that time oriented view point. We will not truly see the universe as it is, but as it was.

There is a great leap in our ability to observe the Universe. Unfortunately we 'pollute' the conclusions with our ignorance and 'scientific' prejudices.

This is such an instance :-)

Well, shucks. The grown-ups are baffled. The fact is that no one wants to look at these galaxies because it will suggest that the universe is older than 13 billion years--assuming it takes galaxies anywhere from 7-10 billion years to form. (Our galaxy's age keeps getting updated. Last I read it was about 11 billion years old. Its globular clusters are at least 12-14 billion years old.) So much for the Big Bang or Inflation.

Bill Nye has posted something similar to a posting I made last year about the age of the universe,I postulated that maybe light fades to almost nothing after traveling 13 plus billion light years, dust clouds gravity fields bending it or reflecting it leave it virtually non existant to earth based observers. I have always thought that 13.7 billion years is not really that long a time on a universal scale. I think eventually we may find that our universe is rotating since most things in space rotate as do things on earth, storms whirlpools. Nature likes rotation.

Why? Because redshift galaxies are on the borderline of disappearing from the visible universe (that is our view) they are SO far away, that NONE of their light reaches us, which could mean that a) the universe is older than we originally suspected b) All galaxies are being racing away towards (possibly) another huge super-cluster of galaxies that form another 'universe.'

Essentially what constitutes our universe is really nothing more than a large grouping of galaxies - billions in numbers.

But I wouldn't be surprised if other such grouping exists far beyond our view.

As we know light is energy. And a theory of light being bent,and refracted would be the most reasonable hypothesis. 13 billion years indeed is a long period. I just don't think its even close to the time scales we are looking for. A more reasonable number I would assume would be in hundreds of billions of years old.

In addition energy can not be made or destoryed "but light traveling through the vacume of space and time will grow dimmer of what we can see.

Anybody notice that this "news" is from 2004 - over 8 years old? Astrophysicists today find that galaxy evolution expected from theory is generally compatible with the most recent observations.

on every article that i get there's a note on the right side column saying that the video that i'm trying to watch cannot be viewed from my country or location (romania, btw). am i missing anything?

Observing the universe from earth is like standing in a dark room with a flashlight. All we know is what we see. We can assume that all we see is everything - until we get a brighter flashlight and then see more. Then we can assume that all we see is everything - until we get a an even brighter flashlight and then see more. It is pretty presumptuous to assume that we are the center of everything, that we are alone in the room, and that we know the size and age of the room based on what we can see without regard to everything we cannot see.

Now start spinning while running around in circles while the room itself is spinning.

If red shift is the affect of motion on spectrographic readings then what does all the combine motions of our planet do to effect this red shift? What would the red shift look like if we factored out all these composite motions? - earth spinning, earth revolving around sun, sun revolving around our galaxy, our galaxy moving through space, ect.

Obviously the universe is much older than we know. Perhaps the universe is infinitely old and is just continually being created and destroyed recreated and redestroyed. No wait energy cannot be created or destroyed only converted from one form to another. So maybe this vast universe is a gigantic recycling machine that constantly recycles energy from cosmic energy down to matter and then back to cosmic energy in an endless cycle. Never beginning and never really ending.

we don`t want to see those galaxies exactly like we don`t want to spread the word about the tens of billions planets in Milky Way, because it`s no word about them in the bible. All this bigbang theory sucks bigtime, but noone has enough courage to contardict an old man on a wheelchair. Any direction you look our universe is identical, with identical age galaxies. But we continue with this stupid theory that we`re exactly on the middle way from the "center" of the universe to the "border"... Conveniently we can`t see the "center" nor the "border" of the universe... We are born from a small dot that came from nowhere and we`re going to nowhere...BS. And while infinite space is denied, infinite time isn`t.

@Rick47933 That is probably one the most intelligent things i have ever read. Thank you.

Gaugain: that is possibly the stupidest thing I have ever read. Thank you.

Another plus for Fred Hoyle......!!!!

We are not at the center of the universe. We are only at the center of the OBSERVABLE universe... and that is because we can see an equal distance in all directions.

If you were 1000 miles out in a boat on the ocean and observed all around you it would appear that you were in the center of a giant body of water, when infact you are not.

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Red shift is an illusion. It is created by the movement of expanding ether which eminates from black holes at the centre of each galaxy, where ether is created by destroying matter. The ether is then used by suns to generate matter and light. Etheric presure creates gravity, electricity and magnetism. Magnetism is the result of etheric movement being diverted by magnetic materials. This creates high and low presure zones at opposite poles which we call attraction and repulsion. The light from the sun travels via waves and doesn't travel as a photon. Photons don't exist. Galaxies are in a constant cycle of birth and death which exists individually in a circular motion from the outer rim spiraling into the centre.

@Steve - If redshift is an illusion caused by the ether then why is it observed on earth in a variety of situations which have nothing to do with black holes? Stars produce light by nuclear fusion and their emitted spectra attest to this. Maxwell demonstrated that magnetism is the same as electricity and light, and Einstein showed that this is mediated by photons. If photons don't exist then explain the photoelectric effect using the ether instead.

@Rick47933 - The amount of redshift produced by the motion of the earth and sun are negligible in comparison. They are also easily accounted for. You seem to be labouring under the assumption that the relatively docile motion of either body is far more problematic than it really is.

Everyone seems to be in need of some research, as the majority of the posters here are making untenable assumptions on the basis of what appears to be a near-nonexistent knowledge of physics or cosmology. Try reading through some open-access journals, like Arxiv, before spamming up the comments with your preferred hypothesis. For example, Coward et al (2012) show how some of these galaxies can be explained and also go into detail regarding the presumptions of which many of you are guilty.

@Chris May 19- You are spot on! I am tempted to ask your immediate impressions of this data that seems to "red-shift" back to William Tifft at the University of Arizona in The 70's. But after Bill Nye ( if that really was his post) prematurely postulates that light has a half life, I shudder to risk my inquiry on this forum. With the static nature displayed at mostly groups of 72m/s( and derivatives there of) and with such old looking groups of galaxies do you see a mad dash to plug the giant hole in the unsinkable S.S.Big Bang or will we see a wide open Wild West battle for the new theory on the block?


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