Early Galaxy Found from the Cosmic ‘Dark Ages’

Article written: 20 Sep , 2012
Updated: 23 Dec , 2015

In the big image at left, the many galaxies of a massive cluster called MACS J1149+2223 dominate the scene. Gravitational lensing by the giant cluster brightened the light from the newfound galaxy, known as MACS 1149-JD, some 15 times. At upper right, a partial zoom-in shows MACS 1149-JD in more detail, and a deeper zoom appears to the lower right. Image credit: NASA/ESA/STScI/JHU

Take a close look at the pixelated red spot on the lower right portion of the image above, as it might be the oldest thing humanity has ever seen. This is a galaxy from the very early days of the Universe, and the light from the primordial galaxy traveled approximately 13.2 billion light-years before reaching the Spitzer and Hubble space telescopes. The telescopes — and the astronomers using them — had a little help from a gravitational lens effect to be able to see such a faint and distant object, which was shining way back when our Universe was just 500 million years old.

“This galaxy is the most distant object we have ever observed with high confidence,” said Wei Zheng, a principal research scientist in the department of physics and astronomy at Johns Hopkins University in Baltimore who is lead author of a new paper appearing in Nature. “Future work involving this galaxy, as well as others like it that we hope to find, will allow us to study the universe’s earliest objects and how the dark ages ended.”

This ancient and distant galaxy comes from an important time in the Universe’s history — one which astronomers know little about – the early part of the epoch of reionization, when the Universe began to move from the so-called cosmic dark ages. During this period, the Universe went from a dark, starless expanse to a recognizable cosmos full of galaxies. The discovery of the faint, small galaxy opens a window onto the deepest, most remote epochs of cosmic history.

“In essence, during the epoch of reionization, the lights came on in the universe,” said paper co-author Leonidas Moustakas, from JPL.

Because both the Hubble and Spitzer telescopes were used in this observation, this newfound galaxy, named MACS 1149-JD, was imaged in five different wavebands. As part of the Cluster Lensing And Supernova Survey with Hubble Program, the Hubble Space Telescope registered the newly described, far-flung galaxy in four visible and infrared wavelength bands. Spitzer measured it in a fifth, longer-wavelength infrared band, placing the discovery on firmer ground.

Objects at these extreme distances are mostly beyond the detection sensitivity of today’s largest telescopes. To catch sight of these early, distant galaxies, astronomers rely on gravitational lensing, where the gravity of foreground objects warps and magnifies the light from background objects. A massive galaxy cluster situated between our galaxy and MACS 1149-JD magnified the newfound galaxy’s light, brightening the remote object some 15 times and bringing it into view.

Astronomers use redshift to describe cosmic distances, and the ancient but newly-found galaxy has a redshift, of 9.6. The term redshift refers to how much an object’s light has shifted into longer wavelengths as a result of the expansion of the universe.

Based on the Hubble and Spitzer observations, astronomers think the distant galaxy was less than 200 million years old when it was viewed. It also is small and compact, containing only about 1 percent of the Milky Way’s mass. According to leading cosmological theories, the first galaxies indeed should have started out tiny. They then progressively merged, eventually accumulating into the sizable galaxies of the more modern universe.

The epoch of reionization refers to the period in the history of the Universe during which the predominantly neutral intergalactic medium was ionized by the emergence of the first luminous sources, and these first galaxies likely played the dominant role in lighting up the Universe. By studying reionization, astronomers can learn about the process of structure formation in the Universe, and find the evolutionary links between the smooth matter distribution at early times revealed by cosmic microwave background studies, and the highly structured Universe of galaxies and clusters of galaxies at redshifts of 6 and below.

This epoch began about 400,000 years after the Big Bang when neutral hydrogen gas formed from cooling particles. The first luminous stars and their host galaxies emerged a few hundred million years later. The energy released by these earliest galaxies is thought to have caused the neutral hydrogen strewn throughout the Universe to ionize, or lose an electron, a state that the gas has remained in since that time.

The paper is available here (pdf document).

Source: JPL

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20 Responses

  1. That means the galaxy is 14.6-0.5 billion LYs away, right?

    • MikaViljakainen says

      No, you’re talking about travel time. Comoving distance from the present location to the small lensed galaxy is about 30.5 billion light years.

      Count it yourself: http://icosmos.co.uk/index.html

    • lcrowell says

      The scale factor of the universe obeys an equation

      (a’/a)^2 = 8??/3 – k/a^2, a’ = da/dt

      The Hubble parameter is H = a’/a.
      For k = 0 in a flat space this is easily seen to be

      a’ = sqrt{8??/3}a

      The solution is easily found as a(t) = a_0 exp(t sqrt{8??/3}). From the first equation this is also a(t) =
      a_0exp(Ht). For the time small or
      distance d = ct small Taylor theorem
      permits an expansion

      a(t) =~ a_0(1 + d/v sqrt{8??/3} + O(d^2))


      a(t) = a_0(1 + dH/c).

      This last term is then dH/c and in this regime of small v v/c <1
      we have v = Hd. This is the Hubble

      To state the distance is proportional to the time in light years only
      works in this approximation, The
      redshift factor z is such the velocity of a distant galaxy is v = zc, and for z
      much larger than one the linear Hubble relationship breaks down. With this calculator one can use H = 70km/sec/Mpc,
      and if I set v = c I get d = 14 billion
      ly or 4285Mpc. The calculator gives 3303.829 Mpc or 10.7756
      Gly, which is a bit less. The
      Hubble relationship gives a longer time, and for z large it would predict a
      much older universe The relationship
      between distance and time deviates from linearity.


  2. Member
    Aqua4U says

    It seems that once or twice a year, an ever further galaxy is discovered, which seems kind of like Moore’s Law? How long will this go on? I know… lets get a bigger and better telescope like the 4-meter Victor M. Blanco telescope with it’s 570 megapixel camera and take a lil ol look see!

    Seriously now.. What would that little tiny red galaxy look like today? Maybe it’s gravitationally lensing something just as far away? Mirror time?

    • The Latinist says

      Well, there would be a hard limit on our ability to see *anything* at decoupling. But, since the CMB is so uniform, galaxy formation must have occurred after that. I imagine we’re already fast approaching the limits.

      • Member
        Aqua4U says

        I guess I’m kind of thinking in terms of fractals? That is to say, in quantum mechanics, a photon that is observed looks like a particle, whereas a photon that is not observed evokes or appears to be a wave. A micro cosmic conundrum?

        Fractally spraking(?), given the expanding universe, what we see at ‘the limits’ of our instruments are small, reddish and still forming galaxies. Were we to change our POV, in present time, and be located close(r) to that red smudge of a galaxy as depicted above, that reddish smudge would be a more fully developed galaxy (Billions of years later). From there the universe’s expansion would appear to be even farther along our line of sight outwards. Looking back at our current position from there, in present time, _our_ galaxy would appear to be a small reddish and still forming galaxy? A macro cosmic conundrum? Or just an effect of time dilation? Fractal time anyone?

      • The Latinist says

        Well, I was responding to your musings about the possible limit to the discovery of new, more distant galaxies. The rest of your post, I confess, I found rather incomprehensible. I think the answer to your question is that if one were standing in the current location of the matter that once made up this early galaxy and looking in our direction he would see something quite similar at a redshift of 9.6 to what we see at that redshift. This is, in fact, the essence of the cosmological principle. It has nothing to do with fractals, nor is it a conundrum, nor does it have anything to do with time dilation.

  3. justafan says

    Dark energy is actually light itself. A weak force that is ubiquitous and acting in all directions at all times, on all mass. The unrelenting force of expansion of the universe and you heard it here first.

  4. It also is small and compact, containing only about 1 percent of the
    Milky Way’s mass. According to leading cosmological theories, the first
    galaxies indeed should have started out tiny.

    What is it with babies and cuteness!?

    I also like how they managed to cheat James Webb from one of its intended finds. (But JWST will no doubt have this find as a prime target.)

  5. let`s think at something: if we see a galaxy A at 14LY distance (or double if you consider now) , than we look in exactly the opposite direction and we see another galaxy B at 14 LY, how would one being from galaxy A calculate the distance to galaxy B (28LY or even double in distance ) and what will he believe about the BigBang theory we take as a religion today ? Please consider that galaxy A is the one we read about here , so i consider it is the “center” of the Universe.

    • The Latinist says

      A being in galaxy B would have no way of seeing or detecting Galaxy A or of calculating the distance to it) because the light from galaxy A will not reach his(its) current location for another 14 billion years. However, light that was emitted 14 billion years ago by similar primordial galaxies located where we are now (but which are now billions of light years from here) would just be reaching him(it), and, assuming his scientific knowledge and technology were similarly advanced, he(it) would be able to see the light from those galaxies.

      Presumably if he(it) has studied the skies and discovered that all nearly all galaxies appear to be moving away from him he(it) will conclude that space is expanding. He(it) will then probably make the effort to calculate backward and determine that approximately 14 billion years ago all of the visible matter and energy and space in the universe occupied a single point. He(it) will likely therefore conclude that the universe began with a high energy event that initiated the expansion of the universe: in short, a “big bang.”

      None of these conclusions would be religious in nature; they would be simple and logical conclusions based on measurable properties of the universe.

    • magnus.nyborg says

      “…how would one being from galaxy A calculate the distance to galaxy B”
      At galaxy A, galaxy B will be impossible to observe at all.
      “and what will he believe about the BigBang theory we take as a religion ”
      You may consider it a religion, but then you are wrong. At current, it is a testable model that seems to explain facts (testable details) better than competing models, i.e. a scientific theory.
      “Please consider that galaxy A is the one we read about here , so i consider it is the “center” of the Universe.”
      You consider wrongly.

  6. lcrowell says

    Thanks for this. I wrote a little program that does this on my TI calculator, but this makes things more convenient.


  7. tenstripe says

    The farther something is out in the universe that we see, the faster it is moving. The galaxy being pulled upon by this universe as it travels out. As it get farther out, the universe has less pull on that galaxy so it gets released from that gravitational grip causing an acceleration. So would that not deminish some of it’s age and just woo the speed at wich it has accomplished. The galaxy would not be older by being further out; Just lucky to have less nearby objects causing gravitational drag and hence faster. Since everything is the same age, can we date everything by the mere fastest anomally.

  8. Lord Haw-Haw. says

    A much appreciated beneficial link you provided many thanks friend!

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