Not all large galaxies formed together at the beginning of the universe
A team led by an astronomer from Indiana University has discovered a sample of massive galaxies with properties that suggest they formed relatively recently. This is contrary to the popular belief that the large luminous galaxies (like our Milky Way) began their formation process and evolved shortly after the Big Bang, about 13 billion years ago. Further research on the nature of these galaxies could open a window to study the origin and early evolution of galaxies.
John Seltzer, the principal investigator of a study published in the Astrophysical Journal Letters, says that the 15 galaxies in the sample show luminosity (a measurement of the total light emitted from them) indicating that they are massive systems like the Milky Way and other "giant" galaxies. However, these specific galaxies are unusual because the distribution of materials in them indicates that very few stars formed within them. They have a relatively low distribution of heavy elements (meaning heavier than helium, which astronomers call all metals, including oxygen, nitrogen and carbon). This indicates that these galaxies are relatively young on a cosmological scale, and may have been formed recently.
A simple explanation: every star that dies scatters into the space of the galaxy heavier substances that were formed in it - from oxygen and carbon to iron - if their cores also scatter, as well as heavier elements that are formed at the moment of the star's explosion - if it was massive enough to become a neutron star or a black hole. This material mixes in the clouds of dust and gas in the star-forming regions of the galaxies and the second generation of stars that are formed there is richer in heavy materials (it is possible that the thrust of the explosion even spurs the process of creating new stars and not just enriches them). The older the galaxy, the richer the stars that form in it are in heavier materials that were created as a result of the death of more generations of stars (and another note, a generation of stars is not constant. The bigger and more massive the star is, it 'lives' less time - a few million years or even less, compared to billions of years of solar life like ours).
The distribution of the chemical substances in the galaxies combined with some simple assumptions about the development of the stars and the enrichment process of galaxies in general, leads to the hypothesis that they are 3-4 billion years old and therefore formed 9-10 billion years after the big bang. Most theories of galaxy formation predict that such massive luminous galaxies should have formed much earlier.
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To Nisim, thank you very much for the explanation.
David Mir
There used to be a theory somewhat similar to yours - the "steady state" theory, which Fred Hoyle believed in.
Hubble showed us that the universe is expanding at a uniform rate - that is, at twice the distance, the rate of expansion is twice as great. The steady state theory claimed that the universe has existed forever and is constantly expanding. The galaxies are moving away from each other and every now and then a new galaxy is formed in the void created by the expansion. (I am greatly simplifying here). If this were true, we should see galaxies of all ages at all distances. But this is not the case - at great distances we only see young galaxies. To be precise - it seems to us that the galaxies are younger because of the long time that passed until their light reached us. That is - we actually know that the age of the galaxies everywhere is more or less the same. This contradicts your idea, and is the basis of the big bang theory.
Michael, you are really righteous, beware of Chaim Hecht
Friends:
(I am really proud to use this word in its deep meaning and not just as a form of address).
To me, honesty is much more important than information (not that I underestimate knowledge, but I value an honest person more than I value a knowledgeable person) and none of you fall short of me in this area.
I think it is not worth giving grades - even if they are good (and I have no doubt that the intention was good). This may damage the quality of discussions later because things may be weighed according to their words and not according to their content.
Therefore, in my opinion, it is correct to praise a certain response if you agree and think it contributed, but not to create a stigma according to which someone is better than others.
So the sole kingdom remains in the hands of Michael the Great 🙂
Thank you Chen T,
I enjoy explaining articles much more than defending science against creationism... It's a shame that not all responses and questions are like yours - with the goal of really learning and understanding.
But I must point out that my physical background, I believe, is "inferior" you could say to Michael's because of the difference in our academic fields of study. Since he has an affinity for mathematics he has more of a good understanding of some of my physical theories. Although I have a background in quantum and some background in physics, I believe his background is more grounded. I am also an astrophysics enthusiast even before I started my studies (in an unrelated field), so this gives me a certain "knowledge completion".
Just for a change I "got" it in my response 🙂
Basic approaches:
I don't think the effort was successful
Pine,
Now I understood the point and I thank you for the detailed explanation and the time you spent explaining it to me.
Michael,
I'm glad to see that there are other experts in Israel at your level and even with the same point of view :-))
There may be a place to deal with the cosmological issues, from a meta aspect, beyond the macro, such as a question asked in one of the articles by Ptolemy, if there are other universes, in addition to the universe created as a result of the big bang, or if simply our humanity, from a position of fixed comfort, tends to solve difficult issues at a skill level is tiny and limits itself to solutions with characteristics, either digital (discrete), or analog.
(N.B.), we will make a special effort this time, so that this basic approach will be understood a little better.
Chen T:
I just now came back to the site and again I am producing myself tomorrow holding after Oren.
Chen T,
On the contrary - I repeated in my own words what the article said. The research uses the direct dependence between the amount of heavy materials in the galaxy and the age of the galaxy and thus can estimate the age of the galaxy as we explained to you (and the article itself as well).
The article claims that the large luminous galaxies were previously believed to have formed at about the same time, a relatively "short" time after the formation of the universe. Another technique to rate the age of the galaxy, although less accurate, is according to the intensity of illumination relative to the size of the galaxy. It is assumed that all the massive galaxies (chosen according to their luminosity, which is a fairly reasonable thing) should have been about the same age by an order of magnitude, as I mentioned, shortly after the formation of the universe.
But the findings of this study showed that in some galaxies, despite a luminosity that indicates an age of a similar magnitude, the density of heavy materials is lower - which indicates that these galaxies are younger than they thought.
Again, this is an ambiguous conclusion and must be tested with different techniques. The simplest technique, the illuminance test (and I assume one of the least accurate) is estimated according to the research conclusions to be completely unreliable.
Hello Michael and Oren and thank you for your response,
But it seems to me that you justified the older theory in both explanations,
Then the article becomes less understandable..
Speaking of heavy stars (and no sarcasm - it's just an obvious play on words) I love Susan Boyle.
Chen T:
Oren's answer is correct.
I would like to address another aspect of your question that seems to me to reveal some misunderstanding.
you say:
"If anything, it makes more sense that if this average is constant, then the size of the galaxy would indicate that it is older. Because more stars have died over more years and therefore there is more material to make new stars, right?"
This is not true in the sense you were aiming for, since the stars that died were also composed of matter, so their death does not add matter.
Actually the opposite is true because during their life and also during their death they converted mass to energy and therefore actually the mass decreases.
What may happen (and happens many times) is that old galaxies meet other galaxies and merge with them, and therefore old galaxies also tend to be more massive and larger.
Chen T,
The more "older" the galaxy is, the more processes it has undergone: star growth, aging and the explosion of stars and the release of heavy elements (which happens during a supernova). Some of the materials that are released in the explosion of the stars are dispersed in the galaxy and form a "nucleation center" for new stars to be formed (and a new solar system), and the process repeats again. When the newly formed stars are already richer in heavy elements because of the previous generation.
Therefore, the older the galaxy, the more heavy elements were released during its life and the concentration of heavy elements is increasing in it.
It's in a simplistic way (I skipped some extra steps and features).
Michael, I have a question for you:
I don't understand much in the field of star formation, but there is an average amount of heavy matter in every million stars, for example, why would the above average change if the galaxy is young or old?
If anything, it makes more sense that if this average is constant, then the size of the galaxy will indicate that it is older. Because more stars have died over more years and therefore there is more material to make new stars, right?
ma lo nora
Sometimes the comments here are simply inspiring
How is it that they try to explain a phenomenon related to galaxies without bringing in the matter of dark matter and black energy?
Has anyone fallen asleep on duty?
"A new discovery challenges the theory of the formation of galaxies" - and perhaps "contradictory"? When it comes to a theory that is to a large extent still 'speculation', more or less, this is the required terminology.
"Most theories of galaxy formation predict that such massive luminous galaxies should have formed much earlier."
Which is saying something.