The director of the Institute for Theory and Computation at the Harvard-Smithsonian Center for Astrophysics, Prof. Avi Leib, says in an interview with the science website that locating these black holes in practice will make it possible to test Einstein's theory of gravity in the vicinity of strong gravitational fields * Prof. Leib comes every year to serve as a guest lecturer at the Weizmann Institute
It looks like a scene from a science fiction movie: rogue black holes moving through our galaxy threatening to damage anything that approaches them. In fact, according to new calculations by Abby Leib and Ryan O'Leary of the Harvard-Smithsonian Center for Astrophysics, hundreds of massive black holes, remnants of the early days of the universe, may be wandering the Milky Way.
The good news is that Earth is in a safe place. The nearest wandering black hole may be found hundreds of light years away. Astronomers are eager to locate them for the clues they will provide about the formation of the Milky Way.
"These black holes are remnants of the past of the Milky Way," said Leib, a graduate of the Hebrew University of Jerusalem and a visiting professor at the Weizmann Institute and currently the director of the Institute for Theory and Computation at the Harvard Smithsonian Center for Astrophysics at Harvard University, which has fifty researchers: "You can say that we are archaeologists studying these remains to study the The history of the galaxy and black holes in the early universe.
According to the theory, "rogue" black holes were originally formed in the centers of tiny, low-mass galaxies. Over billions of years, these tiny galaxies collided to form full-scale galaxies such as the Milky Way.
Whenever two proto-galaxies with black holes at their centers collided, their black holes merged to form one larger black hole. During the merger, directional emissions of gravitational radiation could have caused the black hole to recoil. A typical problem might send the black hole accelerating outward fast enough to escape from its host dwarf galaxy, to one not big enough to leave the galactic neighborhood entirely. As a result, such black holes will still be around today in the outer fringes of the Milky Way's halo.
Hundreds of "rogue" black holes may roam the edges of the Milky Way, each with a mass of one thousand to one hundred thousand suns. They would be difficult to detect by themselves because a black hole is only observable when it is ingesting or accelerating matter. One telltale sign might indicate a rogue black hole: a cluster of stars orbiting dwarf galaxies as the black hole escapes. Only the stars closest to the black hole will be attracted to it, so the cluster will be very compact.
Because of the cluster's tiny size in the sky, it will appear like a single star, and astronomers will be desperate for better clues to its existence and origin. For example, its spectrum will show the presence of several stars and together they will form extensive spectral lines. The stars in the cluster will move quickly, their orbit will be affected by the black hole's gravity.
"The star clusters close to the black hole will function like a lighthouse warning of a dangerous reef," explains O'Leary. "Without the stars shining and guiding us the way, the black hole would be difficult to locate."
The number of rogue black holes in our galaxy depends on how many proto-galactic building blocks contain black holes at their center and how they collided to form the Milky Way. Their discovery and investigation will provide new clues to the history of the Milky Way. Locating the clusters used as markers will advance us greatly.
In a conversation with the science site, Leib explains that this is indeed a theoretical work "but we are currently examining data from observational results that will give an indication that such blacks exist."
"Until now, astronomers have not looked for populations of highly compact star clusters in the Milky Way's halo," Leib said. "Now that we know what to expect, we can examine existing sky surveys for this type of object."
"For many years, people have known that if two black holes merge, they create a new black hole. And according to the theory, if the two black holes do not have the same mass, and therefore the smaller black hole falls into the larger one, an emission of gravitational radiation is created. The black hole gains speed in the opposite direction so that the total momentum remains.”
"However, until the last few years, they did not know how to calculate it accurately. In the last two years they succeeded Calculate this process well. The calculation is complicated because it requires a computer simulation that solves the equations of Einstein's general relativity. These are especially complex equations when it comes to two black holes. Today we are able to calculate how strong the kick will be, and what speed the resulting black hole will get."
"Immediately when I saw the results I thought what the consequences might be. We know that at the center of every galaxy in our environment, including the Milky Way, there is a black hole (in the case of the Milky Way, it is a black hole with a mass of 4 million solar masses). We also know that galaxies merge and that the Milky Way is made up of building blocks that were once smaller galaxies that merged into one galaxy. If each galaxy has a black hole in it, when two galaxies merge their black holes merge as well, and the resulting black hole gets pushed in a preferred direction. If the push is strong enough the black hole escapes from the remains of the small galaxy in which it was formed but still remains inside the large galaxy it merged into. If the black hole receives a boost, it will be shifted relative to the galaxy in which it is located, which means it will not be in its center but will hover at its edge," explains Leib.
"A year and a half ago I wrote an article in which I mentioned the fact that it would be possible to locate these black holes because they would take the form of quasars. Actually a quasar is a black hole that absorbs gas and therefore can be seen as a light source. The quasars were discovered already in the sixties, the creation process of the black hole is accompanied by the emission of light. When gas falls into the black hole it radiates. After that, people were looking for evidence that quasars are deflected from the centers of galaxies and that also led me to think of other implications. My partner in the current article is a student of mine. We came up with the idea that within the Milky Way galaxy itself there might be black holes that came from the building blocks that built the galaxy. Each of the building blocks had a black hole in it and when they connected the black hole flew away. It has left the small galaxies but still remains in the region that makes up the Milky Way. The result is the invention of hundreds of free black holes in the halo of the Milky Way." Prof. Leib emphasizes that the halo of the Milky Way, which is composed of dark matter, i.e. matter we do not know what it is, is 20 times larger than the volume of the star-studded region of the Milky Way. Therefore, this is a huge area, and it will be difficult to locate hundreds of black holes in it.
"Another important point is that when a black hole flies away from the center of a galaxy, it does not leave it completely naked, but also the stars that were close to it leave with it. The gravity that binds them to him is strong enough to take them with him. This means that those very black holes that are supposed to be in the halo will be surrounded by stars, and you should see hundreds of star clusters and this is the way to discover those black holes that have been blown away. The properties of these clusters will differ from the properties of other clusters that are generally less compact. The black hole's companion clusters will be small and the stars in them will move quickly because of the large mass of the black hole they surround."
Leib hopes that it will now be possible to locate these black holes according to the theoretical prediction developed by him and his partner both in new observations and in sky scanning data as bodies that have not been noticed until now. "Their discovery will teach us how the Milky Way galaxy was formed as a result of the merger of smaller galaxies and, in addition, it will give confirmation that a unified black star will receive a push in a preferred direction. This is a feature that has been calculated in computer programs and has no observational evidence yet. When we have evidence, it will be a confirmation of Einstein's theory of gravity. Einstein's theory of gravity was mostly tested in situations where the field is not strong. In contrast, near black holes the gravitational field is stronger. It will be a test of this theory in stronger fields than it has ever been tested in.
Leib, 47, served in the IDF in the Talfiot project, and was among the second cohort of this project and the first in which he received a doctorate in an academic subject - astrophysics. "At that time I worked in the IDF mainly in the development of practical fields" he explains. "Then, at the age of 26, I arrived at Princeton and was a postdoctoral researcher for almost five years, then I moved to Harvard, got tenure and I am the director of the Institute for Theory and Computing, which is the theoretical center in the field of astrophysics at Harvard, which has 50 researchers."
If he did not receive the tenure, Prof. Leib would have another option - to return to the seat of Beit Hanan where he was born and continue his father's farm.
to the notice of the researchers
More on the subject on the science website
37 תגובות
Tomer:
I hope you understand that I was joking.
To the point - if you want to be precise, then the repetition is not unnecessary, and if you don't need to be precise, then your addition is also unnecessary.
The expression "apart from this detail" is - from a logical point of view - a problematic expression because it is inclusive Self teaching
Michael
There is something in it, but this repetition is unnecessary (even though I understand why you put it there).
If you want to avoid getting into trouble, you can say: the only thing I know is that I know nothing except this detail.
Actually it's not "to the end" but "to infinity"
Tomer:
If so, then until the end 🙂
It should be added: "Besides that I know nothing but that I know nothing but that I know nothing but that I know nothing but that I know nothing……." infinite times.
A. Ben Ner
Did you mean Socrates' saying: "The only thing I know is that I know nothing"?
I should add to this sentence: except that I don't know anything.
By the way, a claim was also heard that somewhere during a cyclical circular motion that includes leaving the plane of our galaxy, our solar system passes through a cloud of rock fragments, and perhaps this explains the bombardment of meteors at more or less regular intervals, just as the Earth passes through the Leonids every August.
I don't remember the time spans but about a few hundred thousand years.
Fascinating article!
Peace be upon Yehuda
You probably know that the black hole itself cannot be seen, but only indirectly inferred.
I interpret the lack of decisiveness in the lecturer's words as a necessary caveat to the matter found in the research and for which the evidence is indirect.
In the same way, one can ask whether science is "sure" of the existence of the electron?...and in general, what is "sure"?
In my opinion "safe" is a concept more related to the world of religion, commerce, lying and cheating and not to the world of science.
Surely you know what the only safe thing in the world is?
No. Ben-Ner
The lecture was interesting. I was surprised that precisely the medium-sized holes of several thousand or tens of thousands of solar masses were not discovered.
But above all, I noticed that the lecturer was careful to say the things with full confidence and when he was asked by me if he was sure of the existence of the holes whose existence he deduced from the X-rays coming out of their area (but not only from them), then he answered something along the lines of: "What chirps like a bird And it looks like a bird, so it must be a bird."
In my humble opinion, our confidence in the matter in question is from us onwards, and the uncertainty is high.
Good Day
Sabdarmish Yehuda
I was present (and listened) last night, to Dr. Shai Caspi's lecture, as part of the Astronomical Club at UNTA, on the subject of "Black Holes". And the idea of "medium" black holes in the sg mass of hundreds and thousands of solar masses, was presented as a fairly old theoretical idea, although no evidence has yet been found for the existence of such black holes. This is in contrast to massive and supermassive black holes, in the centers of galaxies, with a mass of millions to billions of solar masses, and in contrast to "small" black holes with a mass of 1.4 tens of solar masses, which are created in supernova explosions.
The innovation here, then, is in the idea of the method of discovering the "medium" black holes and not in their actual existence
the theoretical
We read about a month ago, in Yael Petar's article, that our solar system moves in a cyclical motion, "above" and "below" the plane of the galaxy.
Is it possible that our sun, (and maybe other stars),
moving around such an errant black hole, with a radius large enough not to be sucked into it, and thus the circular path of the sun can be explained. It was also mentioned in the same article that our solar system moves to the interior of the galaxy and to the exterior of the galaxy in a cyclical manner. It is possible that this movement can also be explained by relying on the movement of "our" wrong black hole in the expanses of the galaxy, in an elliptical orbit.
Pine:
Flattering or not - this is a fact.
By the way, this is the best achievement that an Israeli team has ever achieved in this competition.
It is worth emphasizing that this is a competition for high school students.
Australia*
It's a silly statement, especially if you don't mind having Esotralia on the list...
Japan is not exactly Asia, it is an island next to Asia
And in your opinion is it flattering that we bypassed those 17 specific countries?
I'm not sure... and why isn't Japan on the list?
22 countries:
The following teams have sent confirmations of their participation of the APhO X:
Australia
Brunei
Cambodia
China
Hong Kong
India
Indonesia
Israel
Laos.
Kazakhstan
Kyrgyzstan
Macau
Malaysia
Mongolia
Philippines
Singapore
Sri Lanka
Taiwan (Chinese Taipei)
Tajikistan
Thailand
Turkmenistan
Vietnam
Michael,
Out of how many participants?
The Israeli delegation to the Asian Physics Olympiad won fifth place - after China, Indonesia, Thailand (the host) and Taiwan.
Nice story the milky way turned into swiss cheese
point,
You also forgot to say - something deadly, but prophetic! 🙂 And somehow related to our chakras, I'm pretty sure of that... or at least that's how quite a few people on the site try to convince me.
Michael,
Yes - that's what I meant. This was one of the translations I suggested. Probably temporary dyslexia made me write the word "wrong" instead of "stray".
Avi and Oren:
In my opinion, the correct Hebrew translation is "stray" (like a stray ball)
aqwa I think you are right
OREN I don't know what it will be that will kill us, but it must be something deadly.
This natural phenomenon consumed a more appropriate name than the name "black hole" I suggest the name
"The broom stars" because that is the appropriate description for their work
Of course it is not a 'black star' but a 'black hole'.
A fascinating article.
By the way: it is worth paying attention to the review under the title 'Upper limit to the mass of a black star', the reference to which is attached to the announcement by the researchers Leib and O'Leary. have a fun read.
point,
What do you think will kill us first? Gamma radiation from an exploding star or a massive black hole/elephant entering our solar system? 🙂 Maybe it will just be a "rogue" star (=wandering according to my translation)
Avi,
The unidentified user with the linguistic "advice" comes from me.
And in the link I provided they brought several possible translations. I meant a few specific ones:
– A wandering beggar; a vagrant
– Large, destructive, and anomalous or unpredictable: a rogue wave; a rogue tornado.
- Operating outside normal or desirable controls
What to do. There is no truly equivalent word in Hebrew, and the word must be translated according to the situation and not according to the translation that is always accepted (that's how I think). In any case, the article was interesting regardless of how you translate the word 🙂
I have a feeling that such a black hole is going to enter our solar system within 3 years. Will be interesting.
rogue:
2. an elephant or other large wild animal with destructive tendencies driven away or living apart from the herd
And also in the link you sent me to.
The concept of crooks came from Babylon.
Avi,
The use of the word rogue is sometimes intended to mean "wrong" (=lost), or "deviate from the norm" and also "unexpected". In fact, I think that's where the more contemporary phrase "crooks" comes from - because they erred from the usual and unexpected path...
I think you should change the translation, because in Hebrew it doesn't fit. Maybe "wandering" or "unpredictable". Or something else, you're the writer, I'm sure you'll find a more suitable word.
(I looked in Google's dictionary and they translated it to "playful", it doesn't seem very catchy to me either...)
I even found a suitable link:
http://www.thefreedictionary.com/rogue
Go to the article that started the process that caused me to call Avi Live. She is linked, and look what they called her.
It is not fair to call such veteran black holes "crooks", they in SA do what they know how to do.
good week
Sabdarmish Yehuda