Deep space objects > Quasars
The most interesting thing in science is finding something unusual. At first, scientists do not understand at all what they are faced with and spend decades, and sometimes centuries, to understand the phenomenon that has arisen. So it was with the quasar.
In the 1960s, terrestrial telescopes faced a mystery. Radio waves came from the Sun, the galaxy and some stars. But unusual sources were also found that had not previously been observed. They were tiny, but incredibly bright.
They were called quasi-stellar objects (“quasars”). But the name did not explain the nature and reason for the appearance. At the initial stages, it was only possible to find out that they move from us at 1/3 the speed of light.
Quasars are incredibly interesting objects, because with their brilliant radiance they can outshine entire galaxies. These are distant formations powered by black holes and billions of times more massive than the Sun.
The first data obtained on the amount of incoming energy plunged scientists into a real shock. Many could not believe in the existence of such objects. Skepticism made them look for another explanation for what was happening. Some thought that redshift did not indicate distance and was related to something else. But subsequent research discarded alternative ideas, which is why we had to agree that we are really one of the brightest and most amazing universe objects.
The study began in the 1930s when Karl Jansky realized that statistical interference on transatlantic telephone lines came from the Milky Way. In the 1950s. scientists used radio telescopes to study the sky and combine signals with visible observation.
It is also surprising that the quasar has not so many sources for such an energy reserve. The best option is a supermassive black hole. This is a certain area in space with such a strong gravity that even light rays cannot escape from it. Small black holes are created after the death of massive stars. The central ones reach billions of solar masses. One more moment is surprising. Although they are incredibly massive objects, they can reach the solar system in radius. No one can understand how such supermassive black holes are formed.
A huge gas cloud revolves around the black hole. Once the gas is in the black hole, its temperature rises to millions of degrees. This causes it to create thermal radiation, making the quasar as bright in the visible spectrum as it is in the X-ray spectrum.
But there is a border called the Eddington limit. This indicator depends on the massiveness of the black hole. If a large amount of gas enters, then a strong pressure is created. It slows down the gas flow, keeping the brightness of the quasar below the Eddington line.
You need to understand that all quasars are remote from us at significant distances. The closest is located 800 million light years away. So, we can say that there are no more of them in the modern Universe.
What happened to them? Nobody knows for sure. But, based on the power source, then, most likely, the whole point is that the fuel supply has come to zero. The gas and dust in the disk ran out, and the quasars could no longer shine.
Quasars – Remote Lights
If we are talking about a quasar, then we should explain what a pulsar is. It is a rapidly rotating neutron star. It is created in the process of supernova destruction, when a highly compacted core remains. It is surrounded by a powerful magnetic field (1 trillion times larger than Earth’s), which causes the object to generate noticeable radio waves and radioactive particles from the poles. They accommodate various types of radiation.
Gamma Pulsars reproduce influential gamma rays. When the neutron type turns towards us, we notice radio waves whenever one of the poles points at us. This sight resembles a lighthouse. This light will flicker at different speeds (size and mass affect). Sometimes it happens that a binary companion appears in the pulsar. Then it can invade the companion’s matter and speed up its rotation. At a fast pace, it is capable of pulsating 100 times per second.
What is a quasar?
There is no exact definition for a quasar yet. But recent evidence suggests that quasars can be created by supermassive black holes that swallow matter in an accretion disk. As the rotation accelerates, it heats up. Collisions of particles create a large amount of light and transmit it to other forms of radiation (X-rays). A black hole in this position will feed on matter equal to the solar volume per year. In this case, a significant amount of energy will be ejected from the server and south pole of the hole. This is called cosmic jets.
Although there is an option that we have young galaxies. Since little is known about them, the quasar may represent only an early stage of the ejected energy. Some believe that these are distant spatial points where new matter enters the Universe.
Search for quasars
The first quasar found was named 3C 273 (in the constellation Virgo). It was found by T. Matthews and A. Sangem in 1960. Then it seemed that he belongs to the 16th star, similar to the object. But after three years, they noticed that he had a serious redshift. Scientists figured out what was going on when they realized that intense energy is produced in a small area.
Quasars are now found due to redshift. If they see that the object is high, then it is entered into the list of applicants. Today there are more than 2000 of them. The main search tool is the Hubble Space Telescope. With the development of technology, we will be able to reveal all the secrets of these mysterious universal lights.
Light jets in quasars
Scientists think the dots are signals from galactic nuclei that eclipse galaxies. Quasars can only be found in galaxies with supermassive black holes (one billion solar masses). Although light is unable to escape from this location, some particles do break through near the edges. While dust and gas is sucked into the hole, other particles move away at almost the speed of light.
Most of the quasars in the universe have been discovered billions of light years away. Let’s not forget that it takes time for the light to reach us. Therefore, studying such objects, we seem to be returning to the past. Many of the 2,000 quasars found existed at the beginning of galactic life. Quasars are capable of generating energy up to a trillion electric volts. This is more than the amount of light from all the stars in the galaxy (10-100000 times brighter than the glow of the Milky Way).
Types of quasars
Quasars belong to the class of “active galactic nuclei”. Among others, you can also notice the Seyfert galaxies and blazars. Each of them needs a supermassive black hole to fuel it.
The Seyfert ones are inferior in energy, creating only 100 keV. Blazars consume a lot more. Many people believe that these three types are one and the same object, but from different perspectives. Jets of quasars flow at an angle in the direction of the Earth, which is also capable of blazars. The Seyfert jets are not visible, but there is an assumption that their emission is not directed at us, therefore, they are not noticed.
Quasars show early structure of galaxies
By scanning the oldest universe objects, scientists are able to understand what the Milky Way looked like in its youth.
The Atacama large millimeter-wave grating is capable of capturing the “infantile” state of galaxies like ours, showing the moment when the stars were just born. This is surprising, because they are returning to a period when the universe was only 2 billion years old. That is, we are literally looking into the past.
By observing the two ancient galaxies at infrared wavelengths, scientists noticed that in their early development there were what looked like elongated discs of hydrogen gas, surpassing the much smaller inner regions of star formation. In addition, they already possessed rotating disks of gas and dust, and stars were appearing at a fairly rapid rate: 100 solar masses per year.
Objects under study: ALMA J081740.86 + 135138.2 and ALMA J120110.26 + 211756.2. The observations were assisted by quasars, whose light came from the background. We are talking about supermassive black holes around which bright accretion disks are concentrated. They are believed to play the role of centers of active galaxies.
Quasars shine much brighter than galaxies, so if they are located in the background, then the galaxy is lost from sight. But the ALMA observation allows us to detect infrared light emanating from ionized carbon, as well as hydrogen in the glow of quasars. Analysis shows that carbon creates a glow at a wavelength of 158 micrometers and characterizes the galactic structure. The birthplaces of stars can be found thanks to the infrared light from the dust.
Scientists have noticed another moment in luminous carbon – its location has been shifted in relation to hydrogen gas. This is a hint that galactic gases are moving very far from the carbon site, which means that every galaxy can find a large hydrogen halo.
When looking at foreground objects, the researchers expected to capture a faint ejection above the quasar. But instead, they noticed two bright galaxies at a great distance from the quasar.
The analysis also confirmed that young galaxies have already started the rotation process. And this is one of the signs of belonging to the spiral type. This project started in 2003, when the idea of using quasar spectra to identify foreground galaxies was just being developed. This mechanism is called the damped Lyman-alpha system, due to the fact that the hydrogen gas does not allow determining the wavelength of light from the quasar.
ALMA has finally helped to understand the process of galaxy formation. It is now clear that some of the early ones had halos that turned out to be much wider than expected. They can provide material for galactic growth.