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The most distant and therefore also the oldest galaxy so far has been discovered

Researchers, including an Israeli, reported that they discovered the most distant object so far - the galaxy named EGS8p7. It provides an excellent glimpse into the very early universe, only 600 million years after the big bang - at a time when the universe was full of hot and luminous galaxies but also of neutral hydrogen gas that engulfed our universe and made discoveries difficult

The galaxy EGS8p7 as seen from the Hubble Space Telescope (the large image and the image on the upper right, and by the Spitzer Space Telescope) lower right in infrared. I. Labbe, (Leiden University), NASA/ESA/JPL-Caltech
The galaxy EGS8p7 as seen from the Hubble Space Telescope (the large image and the image at the top right, and by the Spitzer Space Telescope) below right in infrared. I. Labbe, (Leiden University), NASA/ESA/JPL-Caltech

A team of Calcutta researchers searching for the earliest objects in the universe are now reporting the discovery of what may be the most distant galaxy yet discovered. In an article published in the Astrophysical Journal Letter, Adi Citrin, a postdoctoral fellow on a NASA scholarship (formerly at the School of Physics and Astronomy at Tel Aviv University) and Richard Ellis, who has since moved to University College London, describe the evidence that the galaxy known as EGS8p7 It is over 13.2 billion years old. The universe itself is about 13.8 billion years old.


A few months ago, EGS8p7 was identified as a candidate for follow-up research based on data from the Hubble and Spitzer space telescopes. They used the MOSFIRE infrared spectrometer at the Keck Observatory in Hawaii, and performed a spectrographic analysis of the galaxy to determine its redshift. The shift to red is caused by the Doppler effect - the same phenomenon that causes the sound of the ambulance horn to decrease in pitch when the ambulance passes. In celestial bodies, it is the light that is stretched and not the sound. Instead of a sonic drop in tone, there is a shift of the true color of the galaxy towards redder wavelengths.

Redshift is often used to measure distances to galaxies, but this is difficult when looking at the most distant - and therefore also the earliest - objects in the universe. Immediately after the big bang, the universe was a soup of ionized particles - electrons, protons and photons - the particles of light. Because the photons were scattered by colliding with the free electrons, the early universe could not radiate light. This period is called The dark ages of the universe.

About 380 years after the big bang, the universe cooled enough to allow the free electrons and protons to connect and create the hydrogen atoms that filled the universe and thus light was allowed to escape freely. Then, when the universe was about half a billion years old, the first galaxies formed and reionized the neutral gas. The universe remains ionized to this day.

Before ionization, however, the neutral hydrogen atoms could absorb some of the radiation produced by the newly formed galaxies—including the so-called Lyman-alpha line, the spectral signature of hot hydrogen gas that has been heated by the ultraviolet radiation from the new stars and is often used as a means of detecting stars in their early stages of formation. Due to this absorption, we should not have observed an alpha Lyman line in the light emitted from EGS8p7.

"When you look at galaxies in the early universe, you see that they contain a large amount of neutral hydrogen gas that is not transparent to these emissions," says Citrin. "We predicted that most of the radiation from these galaxies would be absorbed by the hydrogen in space in the way, but we still see Lyman-alpha lines from this galaxy."

The galaxy was discovered through the use of a MOSFIRE spectrometer that analyzes the chemical composition of every celestial body - from nearby stars to distant galaxies in the near infrared range 0.97-2.45 microns (microns - millionths of a meter).

"The surprising aspect of the current discovery is that we discovered Lyman alpha lines in a pale-looking galaxy at a redshift of 8.68, corresponding to a time when the universe was supposed to be full of hydrogen clouds that absorb the radiation." says Elias. Before this discovery, the most distant galaxy had a redshift of 7.73.

One possibility that the galaxy may be visible despite the hydrogen-absorbing clouds, the researchers say, is because the hydrogen ionization did not occur uniformly. "Evidence from several observations shows that the re-ionization process took place in the patches" said Citrin. "Some objects were so bright that they formed a bubble of ionized hydrogen around them, but the process was not consistent in all directions."

"The galaxy in which we observed EGS8p7 is unusually luminous, and it is possible that it was populated by extremely hot stars, with special properties that allowed it to form a bubble of ionized hydrogen much earlier than most typical galaxies during these periods," says Sirio Belli, a PhD student at Caltech who also worked on the project.

"We calculated in depth the exact chance of discovering this galaxy and observing the emission from it, in order to understand if we are required to change the time estimate regarding reionization, which is one of the key questions that must be answered in order to understand the evolution of the universe" says Citrin.

"In some ways, the period of reionization of the universe is the last missing piece in the puzzle of our understanding of the evolution of the universe" says Citrin. "In addition to pushing back the boundary to the time when the universe was only 600 million years old, what is exciting about the current discovery is that studying sources such as EGSY8p7 will provide us with insights into how this important process took place." Citrine summarizes.


For the announcement of the researchers on the website of the California Institute of Technology

for the scientific article


More of the topic in Hayadan:


  1. Ar Yair
    You wrote "Well, there are still the raisins left inside, right in the core, and there are raisins at different distances from the core, and there are the raisins in the shell, the ones that are a little charred from the heat of the oven, slightly caramelized..."

    And that's your mistake. The cake is endless. Therefore, each raisin feels really special, because it is, and only it is in the center! He does not feel that he is moving, but all the others are moving away from him, and those who are twice as far away, move away at twice the speed.

    The light from distant raisins travels for a long time, which means that the light received now, started a long time ago. That's why distant raisins look younger. At a certain stage, we will see raisins at the moment of their formation, even before there were even grapes on the vine. These raisins are close to 14 billion years old. But notice, from the moment the light started (the same light that reached us), these raisins moved even further, and are about 45 billion years away.

    Happy New Year 🙂

  2. Well, I guess I'll have to get to my own singular point first before I can get the mind-bending insights that good people here have tried to enrich me with.
    Thanks everyone and happy new year.

  3. Lar Yair
    I will try to deal with your question in a different way and in my understanding simpler.
    Well, an act that was like this was:
    Let's start at the 00000000000000:00000000000000 moment of the Big Bang and move right on
    For a moment……….. 00000000000000:00000000000001 of the bang. (let's say in second units)
    This period of time is called the inflationary age of the universe. In this short inflationary epoch, which lasted about a millionth of a second, the universe expanded from the size of a singular point to almost its current size.
    Starting from the end of the inflationary era, the universe continues to expand, and even at an accelerated rate, but at a much smaller acceleration (about 14 orders of magnitude) than the acceleration of its expansion in the initial, inflationary era.
    All the physical processes discussed in the article actually took place after the end of the inflationary era.
    That primordial galaxy reported in the article, if we could see it in its present state, might have looked similar to our galaxy.
    Conversely, it can be described that, if the people who are currently in that distant galaxy, now look at our galaxy, they see us as we were seen 13.2 billion light years ago.

  4. In other words (and correct me if I'm wrong, because I'm also a layman) instead of saying that the universe is expanding, you can say that all the objects (including the particles) in the universe are simply shrinking while the distance between them remains the same.

  5. Eitan, Nissim, thank you very much
    As for round 2, I understood, it works with the image of the balloon and the dots, the raisin cake, etc. and it is possible to accept that the cake will be inflated at a higher speed than light. OK. But there are still the raisins left inside right in the core and there are raisins at different distances from the core and there are the raisins in the shell, the ones that are a little charred from the heat of the oven, slightly caramelized…….
    Now let's say I'm a bacterium and let's say the cake is transparent except for the raisins. If I sit on a raisin in the center I see lots of raisins in every direction I look (and this is the mantra that is pumped in every explanation). But if I get a little bored and move to a more distant raisin then I will already feel that I am not in the center, if I look towards the center I will see a lot of raisins and in the opposite direction a horizon The raisins will be sparser (somewhat shriveled). The situation will of course become more extreme as I skip to raisins further away and finally when I reach an outer raisin the view will be total accordingly, looking in - full of raisins, looking out - zero raisins. Bottom line: according to my perception there is a center and there are sides, according to my feeling they will tell me that I am wrong....

  6. Ar Yair
    Think of it this way: imagine an infinite space of dots on a grid of cubes. Something like an infinite cube made of small cubes, with a dot in the center of each cube. Let's go back in time. In the beginning, there is a large distance between each point and its nearest neighbors, but over time this distance decreases, reaching a zero value. But note - the universe is still infinite :).

    In other words, "outside the universe" has no meaning.

  7. Ar Yair
    1. No.
    The bang was everywhere. It can be said that everywhere was a singularity of infinite density that spread (where did the singularity spread? It is unknown. But an infinite singularity has no problem spreading to infinite space).
    2. According to Einstein's theory of relativity, it is not possible to move at a speed exceeding the speed of light and not to reach the speed of light, but the prohibition applies to movement in space. There is no stopping space itself from expanding at a speed that exceeds the speed of light and along the way taking galaxies that are far enough away from us that we will never be able to see them (this is because the light coming out of them, even though it moves towards us at the speed of light, will only move away from us..)

  8. Ethan, at least two questions:
    1) The bang didn't happen starting at a certain singular point from which the matter (and the space with it) spreads to all the Hebrews?
    2) At a sufficiently large distance, the galaxies move away from each other at a speed that exceeds (!!!!) the speed of light?
    Like…….Einstein is not with us so can we riot?
    (Let there be no misunderstandings, I am grateful to all who answer me, but in the meantime I leave even more confused than when I entered).
    Thank you and good day. Yair

  9. Arnon R. Yair.
    The difference is that when space expands, a galaxy does not have to "move" and it will still "move away" from the other galaxies (except for neighboring galaxies that are affected by mutual attraction).
    Try to imagine the conveyor belt in the airport terminal. You stand on it without walking and still get away from duty free (or get closer if your vacation has just started). In this image, you are the galaxy and the conveyor belt is space (I don't know what duty free represents).
    Regarding the movement of the galaxies "inside" space, as far as I know, this movement has no specific directionality and is affected by the mutual attraction of neighboring galaxies in local clusters.
    In the past, there have been several observations of a region of space where there seemed to be a non-random pull of galaxies in a single direction. This attraction was called "dark flow" (link to the article in the science: However, more accurate observations made recently tend to eliminate the non-randomness of this attraction.

  10. Strong,
    I'm not disagreeing with you, just trying to understand.
    What is the difference between saying that they are moving away and saying that the space is expanding, if each one has a certain progress vector then it is possible to reverse direction and indicate a source no?
    The red shift effect only gives the relative speed between us, what about the vertical movement speed? Is it not missing to understand the overall movement or are there ways to measure it?

  11. Ar Yair
    If I understood your questions correctly, then there are several errors in your understanding of the Big Bang.
    1. The galaxies do not move away from a certain point where the bang happened. The explosion occurred at any point in space. Since then, space is expanding and therefore, the farther a point is from us, the faster it moves away from us. At a sufficiently large distance, the point moves away at a speed that exceeds the speed of light.
    2. In addition to this, light has speed, so the farther you see a point, it means that you are looking at an event further away in the past.
    Hope I helped.

  12. I think it's not just you, many others don't understand in these areas. including me. But I think I understood where you are wrong, so I will try to explain so that it is understandable not only to you:
    What you see is a static image.
    That is, in the lenses of the telescopes, the radiation is received from the same direction.
    This radiation took 13 billion years to pass through.
    In these 13 billion years, that galaxy has apparently already ceased to exist.
    When it was formed - our galaxy was not yet formed. So it is not possible that the galaxies were close (as you say).

  13. I just asked:
    If I see this galaxy as it looked 13 billion years ago, yes?
    Very shortly after the big bang,
    When she was then still very close to the starting point of the explosion...
    And the other galaxies were also close to this point,……
    And therefore very close to each other...
    So our galaxy was also close to all the others... wasn't it?
    If so, then one day we will "discover" the ancient Milky Way?
    And what will that tell us?
    That we cruised through space at a speed faster than the speed of light?
    (much faster than the speed of light,)
    that we opened such a "port" on the light
    So much so that we are here and he remains 13 billion years behind us?
    So how is this possible?
    How come I'm the only one asking this?
    How come no one ever explains this?
    Does anyone even understand this?
    Or is everyone just nodding and "doing" as if?
    Or is it actually just me?

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