NASA's Swift space telescope finds decisive evidence for the question of why certain black holes - as a percentage of all black holes in the centers of galaxies - are more active than others and some of them - quasars - are considered the brightest objects in the universe
The intense emission from the centers of the galaxies, or as they are called, the nuclei, appears near supermassive black holes that are between a million and a billion times the mass of the Sun. If they emit billions of times the energy of the Sun, some of these active galactic nuclei (AGN) – galaxies with a massive black hole at their center – are the most luminous objects in the universe. They include quasars and lasers (BL-Lac objects that are considered a link between radio galaxies and quasars and are called lasers in slang).
"Theorists have shown that the violence in galaxies that are in the process of merging (a move that occurs when two galaxies collide) can feed a black hole at the center of the galaxy," says Michael Koss, lead author of the study and a graduate student at the University of Maryland in College Park. He adds that "the research elegantly explains how black holes ignite".
Until Swift's powerful X-ray scan, astronomers were never sure they had counted most of the galaxies with a supermassive black hole at their center. Heavy clouds of dust and gas surround the black hole in an active galaxy, and these can block ultraviolet, optical, and low-energy light and soft x-rays. Infrared radiation from hot dust can pass through matter, but it can be confused with emissions from regions of the galaxy where stars are forming. Whereas strong x-rays can help scientists directly discover the energetic black hole.
Since 2004, the telescope on the Swift satellite called BAT - the Burst Alert Telescope - has been mapping the sky using powerful x-rays. "The BAT telescope is the largest and most sensitive X-ray scanner that scans the sky most completely at these energies," says Neil Gehrles, SWIFT principal investigator at NASA's Goddard Space Center in Greenbelt. The scan, which is sensitive to active galactic nuclei even 650 million light-years away, covered dozens of previously undetected systems.
"Swift's BAT provides a very different picture of active galactic nuclei," Koss adds. The team found that about a quarter of the BAT galaxies are in the process of merging or are close pairs. "Maybe 60 percent of these galaxies will completely merge in the next billion years. We think we have the overwhelming evidence for the active galactic nuclei that were created as a result of the merging of galaxies as the theorists predicted."
The Swift satellite was launched in November 2004 and is managed by the Goddard Center. NASA built and operated it jointly with Penn State University in Pennsylvania, Los Alamos National Laboratory in New Mexico and General Dynamics in Place Church, Virginia. The University of Leicester and the Mullard Space Science Laboratory in Great Britain as well as Mitzpe Barrera and the Space Agency in Italy were partners - including other partners from Germany and Japan.
The research in question also involved Richard Mushotsky and Sylvain Willocks from the University of Maryland and Lisa Winter from the Center for Astrophysics and Space Astronomy at the University of Colorado at Boulder.
22 תגובות
A 'hard' spectrum is a spectrum in which the average photon has a higher energy (ie shorter frequencies)
Accordingly, a 'soft' spectrum is a spectrum in which the average photon has a longer frequency.
A radio source is therefore softer than an X-ray source for example.
The specified BL Lac have a hard spectrum - most of the energy is emitted in the frequencies of gamma radiation.
Tzvi a question:
What is a "hard" \ "soft" spectrum?
Active galactic nuclei are called in English AGNs and in the singular AGN.
As Michael pointed out, they really originate from matter attached to the black hole and in the process emits enormous amounts of light. In fact, the first proposal concerning the existence of massive black holes in the centers of galaxies was issued following the discovery of such enormous light sources in the centers of galaxies and the inability to explain them by any other means (nuclear variations such as those occurring in the sun are 100 times less efficient than absorption into a black hole).
The question answered by the article is why some galaxies have an active galactic nucleus and most do not, the answer given is that it depends on the last collision of the galaxy with another galaxy.
A few notes about AGNs:
AGN has a very complex spectrum and it varies from one AGN to another, apparently depending on the nature of the black hole (rotating or not), the host galaxy, and above all the angle at which we look at the AGN. In any case, the classification of the AGN into the different types is complicated and complex and many concepts are used in confusion.
A fundamental separation (not due to the angle of view but from the physics of the AGN - most likely the nature of the black hole) is the separation between the radio active AGNs (approximately 15% of the AGNs) and those that do not emit radio radiation (85%).
The three types of AGN mentioned here: the radio galaxies, quasars and blazars are all three examples of radio active AGN (they are the more interesting in many respects) and apparently, they are very similar and just seen from different angles.
A question for Gali:
The comment that the BL Lacs themselves are connecting objects between the radio galaxies and quasars is not clear to me - as far as I know, the question is actually at what angle do you look at the AGN, we will define the angle with respect to the vector perpendicular to the accretion disk like this:
The radio galaxies (FR1, FR2) are characterized by large angles (close to 90 degrees)
The quasars (FSRQ and SSRQ) are characterized by medium angles.
Whereas the blazars (FSRQ with a 'hard' spectrum, BL Lac) are characterized by small angles (scale of a few degrees).
If so,
Why do you say that the BL Lac is a connecting link between the radio galaxies and the quasars?
Based on the general data that appears in the animation on the NASA website, I calculated
Soon the data of the relative speed between the galaxies and I received that, in the first stage,
From the beginning of the video (estimating the initial distance between the centers of the galaxies - 150,000 light years)
and until their centers pass by each other at the closest point, the average relative speed
of the galaxies here is soon 5,000 km per second (or about 20 million km per hour).
Another note regarding the computer animation on the NASA website.
Note that in the upper left corner of the picture there is a "clock"
The "measures" the duration of the collision of the galaxies.
The general time is about 2,000,000,000 (2 billion) years.
That is, every second in the video represents a realistic period of time of about 15,000,000 (15 million)
years.
To all my knowledgeable friends
Recommended = worth entering through the link at the end of the article,
to the article on the NASA website and enter the computer animation
About 1:38 seconds long, demonstrating the collision of two galaxies
and the merging of black holes.
Ghost:
its up to you.
And the bottom is a ghost...
And the rest of the photos are a secret prototype of glasses from Opticana.
Yes, of course the monster came to say hello.
Thanks for the explanation. What fun it is to correspond with you when you are not cursing. 🙂
Did you notice that the third picture from the bottom is nothing but the Flying Spaghetti Monster?
Thanks for the explanations. They really helped to understand the article.
Yes.
This is what the research shows, and it was, as written in the article - expected.
An older galaxy that is not in the process of colliding is already quite stable and all the interstellar gas that was around the nucleus has already fallen into the black hole. The black hole environment is therefore relatively quiet.
When colliding galaxies reach the vicinity of the nucleus of each of them interstellar gas and even entire stars that before the collision were far from the nucleus in their parent galaxy and now, following the collision, they find themselves being sucked into a black hole.
During the swirling into the black hole the gas particles and the stars rub against each other and emit the radiation in question.
Happy and happy that my first response woke up the science commenters from slumber and literally everything lit up like an energetic black hole.
So cheeky!
good week
Sabdarmish Yehuda
That is, an extremely active nucleus (one that emits a lot of -relative to other active nuclei- energy) was created as a result of a merger of galaxies?
That is to say, certain nuclei emit a small amount of energy and when the galaxies in which they are found merge,
Will the nucleus become more 'active'?
Yes.
There are some and there are some.
An active nucleus is a nucleus that emits a lot of energy.
That is, there are galaxies whose core is inactive and they do not collide, and there are galaxies whose core is active and they are the ones that collide?
And what does 'active core' mean? (I didn't quite understand the article)
And it's time for people to understand that blacks are not "vacuum cleaners" that vacuum everything without limit.
For anyone outside of the black hole's event horizon, the black hole functions just like a normal star of the same mass.
There is no such chance.
Actually the question is meaningless because the black holes are part of the galaxy and the whole of one galaxy is drawn to the whole of the other (including the black holes which are only a tiny part of the mass of the galaxy).
Anyway, the article is not about "why galaxies collide" but about "why some galaxies have active nuclei" or - alternatively "what are the results (not the causes) of colliding galaxies".
What is the chance that instead of the galaxies colliding with each other and feeding the black holes, it will be the black holes that are attracted to each other and create a collision between the galaxies and 'suck' the galaxies?
I want to respond but I just didn't understand a single word of the article
Responds on Saturday.
I don't understand how an article that is so sympathetic to the small, large and colliding black holes receives such blatant disdain from the science commenters who find no reason to say a good word about them.
This shows contempt for the conventional general approach!
I hope, dear respondents, that you did not do this due to the sanctity of the Sabbath or repentance, God forbid!
So don't be shy and respond.
Looking forward to your reading
Shabbat Shalom
Sabdarmish Yehuda