The model has been widely adopted by the scientific community
The model accepted by cosmology researchers (the study of the universe) suggests that galaxies were formed by the fall of gas, mainly hydrogen and helium, under the influence of gravity into the centers of the galactic halos. Until recently, it was assumed that when the gas penetrates into the halo, it passes through a "shock wave" that causes it to heat up to temperatures of millions of degrees (about a million degrees in the Milky Way galaxy). After that, a cooling process begins through radiation emission, which causes the cooled gas to fall in under the influence of gravity to the center of the halo and drain into the disk. In the disc, luminous stars are formed from the gas, and a galaxy is formed.
From astronomical observations made by a ground telescope called SDSS (Sloan Digital Sky Survey) scans the sky every night and compiled for several years tremendous statistics about the properties of the galaxies such as their color, size, etc., it turns out that the largest disc galaxies have a mass of about one hundred billion (910*100 or 10 to the 11th power) suns. Smaller galaxies accumulate gas and grow very efficiently but their growth stops abruptly when the halo within which they are growing passes the mass of a trillion (1210) Suns. The researchers struggled to explain why the transition from cooling gas to non-cooling gas happens so suddenly when the mass of the halo crosses the threshold of a trillion solar masses.
The cosmologist Dr. Yuval Birnbaum found a solution to this problem as part of the doctorate he wrote under the guidance of Prof. Avishai Dekel from the Institute of Physics at the Hebrew University of Jerusalem. According to the new model, the key to the efficient formation of a galaxy is the absence of a stable "shock wave" at the edge of the galactic halo when the mass of the halo is less than a trillion suns. In such haloes the gas penetrates into the halo without interruption and flows rapidly while still cold to the center. On the other hand, in massive haloes that exceed the masses of a trillion suns, a stable "shock wave" is created that prevents the free fall of the gas inward.
Dr. Birnbaum and Prof. Deckel formulated their conclusions through theoretical calculations and using advanced computer simulations of the formation of galaxies in the universe. The new model has become the accepted explanation for the formation of disc-shaped galaxies with a maximum mass of a trillion suns and as a cornerstone in the understanding of the formation of different types of galaxies in the universe.
In response to the science site's question about how the dark mass is discovered in the first place, Birnbaum said:dark mass is measured using its effect on the trajectories of the visible mass in the galaxy ("rotation curves"). The gas and the stars move by a gravitational force created by a mass much greater than the apparent mass. To measure dark mass in galaxy clusters (halos a hundred times larger containing dozens of galaxies) you can also use gravitational lenses.
Does the dark mass have anything to do with the shape of the galaxies (elliptical or spiral)?
Dr. Birnbaum: "There is a relationship between the size of a galaxy and its shape. Large galaxies tend to be "elliptical" and small "spiral". Spiral galaxies contain cold gas. Since it does not have enough pressure (the fact that it is cold) it would have collapsed to a single point if it had not been stopped by its angular momentum. As it rotates, it feels a centrifugal force that prevents it from falling perpendicular to the axis of rotation. In the direction parallel to the axis of rotation, nothing prevents it from falling, so the disk is very thin, hence the appearance of the spiral galaxies looking like a flat omelette. In contrast, elliptical galaxies are formed from collisions between smaller galaxies that occurred after the stars were formed. Because of this, elliptical galaxies have a more spherical shape and are not flat (stars do not flow according to pressure and can be treated as a point mass, so they cannot cool and fall to the center of the galaxy like gas). The dynamics of the galaxies is related to dark mass both through the rotation speed of the disk ("rotation curve") and from stability considerations: the disk would break up into blocks (fragmentation) if it were not surrounded by dark mass that stabilizes it.
Is there a difference between these types of galaxies in other properties besides the thickness?
Birnbaum: "There is a correlation between young galaxies in which there is extensive activity of new star formation and a spiral shape. On the other hand, there is also a correlation between galaxies that contain only old stars and in which no new stars are born and an elliptical shape. There is a very sharp transition between one population and the other, and there are almost no intermediate forms, as one could assume would exist if the transition were gradual. The observation of the digital sky scanner Sloan showed a correlation between the size of the galaxies and their color, and also illustrated that there are many small blue galaxies, many Big red galaxies and almost none in the middle.
And your mechanism tries to explain why there are no galactic intermediates?
Birnbaum: In order to have two populations that are so sharply separated from one another, the existence of a critical phenomenon is required. We have proposed a theoretical explanation for the issue of such a sharp transition. According to our explanation, which as mentioned has been accepted at this stage as the standard explanation, when the galaxies are inside halos that are less than 10 to the power of 12 solar masses, the gas that falls from the halo into the galaxy falls without interruption and causes both the formation of the stars and the spiral shape of the galaxy. All halos containing visible gas and dark matter are constantly growing because all the large objects in the universe are constantly absorbing dark matter and gas, both from the thin bingalactic gas scattered in the universe and through the ingestion of other galaxies, and thus growing. From the moment the mass of the halo crosses the threshold at once, a shock wave is created in the center of the galaxy which moves outward very quickly and turns the entire halo of the galaxy into a shock wave. From now on, the gas inside the galaxy no longer cools, and we do not produce stars, therefore the galaxy changes its color to red sharply and quickly.
14 תגובות
Chest:
They may not be able to say it's an error but despite their "inability" they said it in all their letters to you.
It turns out that there are people who do what they are unable to do.
In relation to the fact that you explain what the readers do not understand, I repeat and direct all my questions to you.
I did not receive an explanation for even one of them.
Let's start with one of them for illustration:
How do you conclude that black holes rotate and how do you explain why? I remind you that this is a taunt you raised in the previous discussion towards the scientists, but when I answered you and showed you that your taunt has no basis, I also went back and turned the question towards you.
You and all the readers are invited to go back and review the discussion that I linked to in a previous response.
This is something I don't understand and you are welcome to explain it.
By the way - your response regarding the speed of rotation does not make sense and the reality described in it would have caused all matter to escape from the galaxy, therefore even in your previous response you did not explain to me what I do not understand, if we summarize it - based on your words in the last response it can be formulated as follows:
What balances the centrifugal force (which increases in direct proportion to the radius as the angular velocity increases)?
It cannot be the force of gravity which is precisely small as a (quadratic) function of the radius!
To Michael,
On this matter I had a "discussion" with the Hebrew Academy.
They can't say it's a mistake.
And in my opinion, writing in full spelling without the e at the end is the error...
http://www.kaspit.com/hebrew/hebrew.htm
I do not enter into the discussion, just explaining what is not understood by the readers.
First, the whole story of "dark matter" is a "grandmother's story".
The rotation speed of the "disk" is given because of the rotational torque of the material ejected from the center of the galaxy.
Therefore, it goes without saying that the entire disk of the galaxy (emphasis on the disk that contains the arms) will rotate as one block.
incidentally,
Any other theory cannot explain why the angular velocity is uniform...
The world is funny, so laugh 🙂
If there was a discussion here, I would add the following question to my questions:
It is assumed today that the uniform rotation speed (which does not correspond to the amount of visible matter) is caused by the dark matter.
Various measurements showed that this substance is generally dispersed in a spherical form and therefore, obviously, is not dispersed using the noble mechanism.
What causes the uniform rotational speed in this theory?
By the way: write "understood" and not "understood"
even though,
A small response "to the little brother"
She just didn't understand what was written there.
The entire disk of the galaxy rotates at the same angular speed, and this is self-evident as described in the theory.
It says there that the rotation speed of the stars that are on the arms of the galaxy is higher than the rotation speed of stars that are not on the arms of the galaxy.
There are two systems here that move at different rotational speeds,
But in both systems, the angular speed of rotation remains constant (_approximately).
Hezi
My mistake, my huge mistake!
(I did a short search on the Internet, heard the voices and read some of the judgments...)
I got you bro!!! you are great cutie
(I know Michael, I also know the two leading theories to explain the issue.)
Hezi,
Nevertheless, have you thought about how it is that the structure of the arms does not break down over time? Do you have a new idea on the subject? You surely know that they have already thought about my questions...
And... if it is a cone as you say, then spiral galaxies were thin in the center and thick at the edges, right?. In practice they look the other way around, there are very detailed pictures of Andromeda for example.
So I don't underestimate Hazy, and it will be interesting to hear new thinking. I just saw the discussion Michael pointed to. But if you are interested in presenting your idea... you really don't have to confront!.
Friends:
See this discussion:
https://www.hayadan.org.il/two-of-the-milky-ways-spiral-arms-go-missing-210808/
Hezi Atzil wants to say his words without being argued with.
He says he doesn't want to convince, but if it were true he wouldn't respond at all.
What to do? People also have such a section.
Assuming that the word mass would have the same sound in Spanish as well, I would translate it in the words:-
masa oskura
which is like dark mass
But they may have another word for dark mass
Just my wild guess
Good night
Sabdarmish Yehuda
Hezi,
I read your interesting explanation.
The claims, based on measurements, show that the rotation speed of stars in spiral galaxies is the same. That is, the angular velocity of a star close to the center of the galaxy is the same as the angular velocity of a star at the edge of the galaxy. Contrary to what you wrote on your website.
But... why do we really see the shape of the spiral arms in the observations?, if the rotation is plastic?, apparently the distribution of the stars should have been quite uniform?
Hey, your links lead to a site that downloads an EXE file. With all due respect, I do not endanger the surfers.
My father, a number of questions arise:
A]. Where does the shock wave start, inside the galaxy, and in which direction does it spread?
B]. What is the speed of the transfer of the gravitational information from the edge of the galaxy's halo (once it absorbs the "threshold mass") to the place in the center of the galaxy where the shock wave was created?
third]. What is the essence of the generated shock wave? Is it due to a change in the structure of the material in the galaxy?
D]. What is the approximate speed of that shock wave?
God]. Is it possible to add a reference to the article?
Thanks.
Correcting the link to the site
http://www.kaspit.com/assil2.htm
nonsense squared…
How do they explain the symmetrical shapes of the galaxy's arms?
The real and correct theory is explained on the website:
http://www.kaspit.com/assil2
What place do the massive black holes in the centers of galaxies occupy in this whole story?