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A candidate for the farthest galaxy

By combining the power of the Hubble and Spitzer space telescopes and the help of the phenomenon of "gravitational lensing" in space, astronomers managed to achieve a new record of discovering the most distant galaxy in the universe.

MACS0647-JD - Galaxy considered the oldest observed so far (November 2012). Photo: Hubble Space Telescope
MACS0647-JD – galaxy considered the oldest observed so far (November 2012). Photo: Hubble Space Telescope

By combining the power of the Hubble and Spitzer space telescopes and the help of the "gravitational lensing" phenomenon in space, astronomers managed to achieve a new record of discovering the most distant galaxy in the universe.

The most distant galaxy looks like a tiny bulb and is only a fraction of the size of our Milky Way. However, it allows us a glimpse in time to a time when the universe was only 3% of its current age.
The light of the new galaxy, known as MACS0647-JD, came towards us when the universe was 420 million years old after the Big Bang. Ora traveled to us for 13.3 billion years.

The find is the latest discovery in a program that uses natural lenses to reveal galaxies in the early universe. The Hubble Space Telescope's Cluster Lensing And Supernova Survey (CLASH) - an international group led by Mark Postman from the Space Telescope Science Center in Baltimore, uses massive galaxy clusters as cosmic telescopes that magnify the light of galaxies behind them. This effect is known as "gravitational flushing".

Along the way, about 8 billion years after the light from MACS0647-JD began its journey it had to take a detour on several paths around the massive galaxy cluster MACS J0647+7015. Without the cluster's amplification capabilities, astronomers could not see this distant galaxy. Thanks to gravitational cooling, CLASH researchers were able to view three magnified images of MACS0647-JD with the Hubble Space Telescope. The cluster's gravity accelerated the light from the distant galaxy and made the images appear 8, 7 and XNUMX times brighter respectively than they would have appeared without the dimming and this allowed astronomers to discover the galaxy more efficiently and with greater certainty.

"The cluster does what no man-made telescope can do." Says Postman "Without the magnification, it would take a huge effort to observe this galaxy."

MACS0647-JD is so small that it may just be the first step in the formation of a larger galaxy. A preliminary analysis shows that the diameter of the galaxy is barely 600 light years. Based on observations of closer galaxies, astronomers estimate that a typical galaxy of a similar age should be 2,000 light-years in diameter. For comparison, the diameter of the Large Magellanic Cloud - a dwarf galaxy that accompanies the Milky Way is about 14 thousand light years and the diameter of the Milky Way is about 150 thousand light years.

"This object may be one of the many building blocks of a galaxy," says the project's lead researcher, Dan Ko from the Space Telescope Science Center. "During the last 13 billion years, tens or even hundreds of mergers with other galaxies and galaxy fragments may have occurred."

The galaxy was observed using 17 filters, from the near-ultraviolet to the near-infrared, using Hubble's Wide Field Camera 3 (WDC3) to the infrared with the Advanced Survey Camera (ACS). Koh, a member of the CLASH team, discovered the galaxy in February when he examined a catalog of thousands of gravitational lenses discovered in Hubble's observations of 17 clusters in the CLASH survey, but the galaxy is only visible in two infrared filters.

Therefore, either MACS0647-JD is a very red object, shining only in the near-red light ranges, or it is very far away and its light has been redshifted to these frequencies, or a combination of the two." Ko said. "We are looking at the whole range of possibilities."

The CLASH team identified multiple images of eight galaxies co-hosted by the same galaxy cluster. Their location allowed the team to map the mass of the cluster, which consists mainly of dark matter.
Dark matter is an invisible configuration of matter that makes up a significant portion of the mass of the universe. "It's like a big puzzle," says Ko. "We are required to organize the mass of the cluster so that we can isolate the light from each galaxy to the observed location."

The team's analysis revealed that the mass distribution of the cluster produces three compressed images of MACS0647-JD at the positions and relative brightness observed in the Hubble images.

Ko and his collaborators spent months systematically ruling out other alternative explanations for the object's detection, including red stars, brown dwarfs, and red galaxies (due to age or dust) in the medium between the galaxy and Earth. They came to the conclusion that the assumption that it is a very distant (distant) galaxy is the correct explanation.

The article will appear in the December 20 issue of the Astrophysical Journal.

to the notice of the researchers

19 תגובות

  1. It is not clear to me how the following two things can be said: (I think there is an internal contradiction here between the two claims):
    a) The universe was created in a "big bang" meaning that a certain point was the point from which everything began.
    b) The universe is homogeneous.

    The reason is simple:
    If the universe is homogeneous then there is no region in the universe that is different from other regions.
    That is :
    If we close a ball with a finite diameter around the point of the "big bang" it will not be different from any other ball that will be closed around any other point in the universe. But this contradicts that the matter in the universe moves away from a certain starting point.
    If, for example, the direction of progress of the galaxies were measured, then all the galaxies would have to move away from one common center.
    This center point is a special point in the universe. This means that the universe is not homogeneous. It also contradicts the theory of relativity.
    I would be very happy if someone could resolve this contradiction.

  2. Thanks for treatment. I'm probably still a prisoner of primitive mechanics where when both time and distance are unknown, at least one of the two must be known with certainty in order to calculate the other.

  3. Your logical fallacy is not understanding the concept of a light year. It is a concept of distance on the one hand, and also indicates the time that has passed since the light left that point.
    As the term km/h indicates both with speed and from what distance the vehicle left until it reached the current point.

  4. The question is over:
    The redshift phenomenon is used both to estimate the distance of galaxies in time from the beginning of the universe and to estimate their distance from us in space, isn't it?
    It gives me a gut feeling of discomfort, as if we are using the same figure to discover two disappearances, each of which is needed to decipher the other. Want to say - necessarily in order to use the redshift to draw conclusions about the age of the universe, or alternatively - its size, we have to assume the requested about one of the two figures, right? Or is there another figure that allows us to test the validity of this assumption (say - the luminosity of galaxies of the same type to confirm the distance figure)?
    Doesn't this require us to presuppose, as an axiom, that galaxies farther from the "center of the universe" are necessarily older? And what if it is not so?
    In short, where is my logical fallacy that prevents me from understanding this?

  5. I'm not particularly well versed in calculations or know all the data, but - in my understanding the universe at that time was very young and much smaller. Our galaxy did not yet exist (and therefore its distance at that time from that ancient galaxy is also irrelevant) but was created later with the expansion of the universe. This can explain how light took so long to "catch us". Buy me, or not.

  6. After about 420 million years the light will cross the initial distance between the galaxies.

    A galaxy whose speed is 4% of the speed of light will travel a distance of about 29.4 million light years in the same period of time.

    The signal will reach the receding galaxy after a total time of about 437.5 million light years.

    This result is significantly smaller than 13 billion years.

  7. The question asked here is basically correct. The basic answer is that galaxies move away from each other at a speed that is mainly influenced (when it comes to galaxies that are far from each other) by the growth of space itself.

    And so, first of all, 420 million years after the big bang, the size of the universe could be much larger than 840 million light years, because the expansion of the universe may be much faster than the speed of light (you can calculate the amount of expansion relative to the edges for that time).

    Second thing, the light that set out then, also got further away during its way to us, again due to the expansion of space.

    What all this means is that scientists who see the galaxy today, and estimate its distance from us, then for convenience translate the distance into light changes and it comes out to them about 13 billion years, this does not at all indicate the time that the light actually left its source, because the distance increases along the way, so The actual time of departure was much shorter in relation to the distance, which again changes the calculation regarding the age of the universe at the time of departure, which again can affect the distance it was at the time of departure. So the issue seems unclear.

    You have to take into account that in any case, at the moment the physical galaxy is probably already at a much greater distance.

  8. I answered you so I won't do it again
    Just note that your simple calculation will cost 4% of the speed of light and not 40% (which works out well since that is just a far-fetched calculation).

  9. A simple calculation will show that a signal arriving after about 13 billion years from a receding galaxy, when the initial distance was about 420 million light years,
    Requires an average relative speed between the galaxies of about forty percent of the speed of light during the entire period.

    Does it fit the accepted theories today?

  10. Asks,

    As I said - when the light came out the galaxy may have been more than 420 million light years away.
    Furthermore - during the movement of the light, the distance between its location and the Milky Way increases, so even if the distance was initially X light years, the light will reach the Milky Way after more than X years.

  11. I don't understand how signals that were transmitted from a galaxy while it was about 420 million light years away from Earth,

    absorbed only after about 13 billion years have passed.

  12. I don't remember much from astrophysics and cosmology so I can get confused and make mistakes in what I write here.
    But as Zvi wrote - there is no such thing as the most distant galaxy
    There is a horizon in the universe beyond which we cannot see due to the ratio between the speed of the expansion of the universe and the speed of light regions that move away from us faster than the speed of light - we will never see them.
    If the universe is expanding at an accelerating rate (which they thought the last time I learned about it) then this horizon should shrink over time.
    Within the part of the universe that is in front of this horizon - we can talk about the more distant galaxy - although from the homogeneity of the universe I think that is also quite meaningless.

  13. Asks,

    The definition of distance in cosmology is not simple and different things, which usually seem to us to be reasonable definitions of distance, get different results in cosmology (for details, see
    In any case, since it is assumed that the universe is homogeneous (that is, not a single point is different from its surroundings) the universe necessarily has no end. Furthermore, since the universe is, as far as we know, flat (that is, it does not have the structure of a "four-dimensional sphere") - then there is no question of a maximum distance between two galaxies - every galaxy that is further away from us, there is always a more distant galaxy.
    In light of all this, there is nothing to talk about except the edge of the observable universe, that is, the most distant point that can be seen - this point may move away and thus more galaxies can enter our field of vision and indeed, today you can see galaxies that could not be observed from the Milky Way 10 billion years ago.

    Max Power,
    Acceleration is indeed a strange concept in relation to light - however, since acceleration is a change in speed (both in the sense of changing the magnitude of the speed and in the sense of changing its direction) then gravity can certainly change the direction of the movement of a light beam and this indeed happens in gravitational lenses like the one discussed in the article.

  14. "The gravity of the cluster accelerated the light from the distant galaxy" Is it possible to accelerate the light?

  15. 420 million years after the bang, the "new" galaxy was at a maximum distance of 840 million light years from Earth. (with the maximum assumption that the galaxies moved at the speed of light and in opposite directions)
    How is it possible that signals that were transmitted when the maximum distance between the galaxies was about 800 million light years, reached the earth after about 13 billion years?

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