A group of astronomers led by the University of Arizona observed a luminous quasar at a distance of 1
In addition to being the most distant and earliest quasar, this celestial body is also the first of its kind. It shows one-fifth of the wind escaping from the black hole around the black hole. The speed of light. In addition to revealing strong quasar-driven winds, the new observations also show strong star-forming activity in the host galaxy where the quasar (formally known as J0313-1806) is located.
Researchers will present their findings, which have been accepted and published in Astrophysical Journal LetterAt the press conference and scientific lectures at the 237th meeting of the American Astronomical Society held from January 11 to 15,
The previous record holder of quasars in the baby universe was discovered three years ago. The UArizona team also contributed to this discovery. Quasars are thought to be caused by supermassive black holes engulfing surrounding matter (such as gas or even entire stars), causing vortices of overheated matter (called accretion disks) to spin around the black hole. Due to the huge amount of energy involved, quasars are one of the brightest light sources in the universe and are usually more dazzling than their host galaxies.
Although J0313-1806 is only 20 million light-years away from the previous record holder, the new quasar contains a supermassive black hole whose weight is twice that. This marked a major advancement in cosmology because it provided the strongest constraint on the formation of black holes in the early universe.
Hubble researcher Feige Wang of UArizona Steward Observatory said: “This is the earliest evidence of how supermassive black holes affect galaxies around them.” “By observing galaxies far away, we know that this must happen, but we never I have seen it happen so early in the universe.”
When the universe was small, quasars had accumulated millions or even billions of solar masses in their black holes, which posed a challenge for scientists to try to explain how they existed without time. A generally accepted explanation for the formation of black holes is that a star explodes in the form of a supernova at the end of life and collapses into a black hole. When such black holes merge over time, in theory, they can grow into supermassive black holes. But, just as it takes many people to spend a dollar a year to build a retirement fund, so quasars in the early universe are a bit like toddler millionaires. They must have gained their quality in other ways.
The newly discovered quasars provide a new benchmark by excluding two current models that form supermassive black holes on such a short time scale. In the first model, massive stars are mainly composed of hydrogen and lack most of the other elements that make up later stars, including metals, which formed the first generation of stars in young galaxies and provided food for new black holes. . The second model involves dense star clusters that collapse into a huge black hole from the beginning.
However, according to the team that discovered it, quasar J0313-1806 has a black hole that is too large to be explained by the above situation. The research team calculated that if the center of the black hole formed 100 million years after the Big Bang and grew as fast as possible, then it must still have at least 10,000 solar masses.
“This tells you that no matter what you do, the seeds of this black hole must be formed by different mechanisms,” said co-author Fan Xiaohui, deputy director of the Department of Astronomy at the University of Arizona. “In this case, the gas involving a large amount of primitive cold hydrogen directly collapses into the seed black hole.”
Because this mechanism does not require mature stars as raw materials, it is the only mechanism that allowed the supermassive black hole of quasar J0313-1806 to grow to 1.6 billion solar masses at such an early stage. Fan explained that this is what makes the newly recorded quasars so valuable.
He said: “Once you reduce the redshift, all models can explain the existence of quasars that are farther away and have lower mass.” “In order to make the black hole grow to the size we see in J0313-1806, it It must start with a seed black hole of at least 10,000 solar masses, and this is only possible if it collapses directly.”
The newly discovered quasar seems to provide a rare glimpse of the life in the Milky Way at the dawn of the universe, when many of the Milky Way formation processes that have slowed down or stopped for a long time are still in full swing.
According to the current galaxy evolution model, the growth of supermassive black holes in its center may be the main reason why galaxies eventually stop producing new stars. The role of a quasar is like a blowtorch with cosmic proportions. It will violently bombard the surrounding environment and effectively remove a large amount of cold gas in its host galaxy, which is the raw material for star formation.
Fan said: “We think these supermassive black holes are the reason why many large galaxies stop forming stars at some point.” “We have observed this kind of’quenching’ at lower redshifts, but until now, we still I don’t know how this process started in the history of the universe. This quasar is the earliest evidence that the quenching may have occurred very early.”
By measuring the luminosity of quasars, Wang’s team calculated that the supermassive black hole at its center absorbs an average of 25 solar equivalents per year, which is believed to be the main reason why its high-speed hot plasma wind blows into the star. The Milky Way around it at a relativistic speed. For comparison, most of the black hole in the center of the Milky Way is dormant.
Although the Milky Way galaxy forms stars at a leisurely rate of about one solar mass per year, J0313-1806 produced 200 solar masses during the same period.
Wang said: “This is a relatively high star formation rate, similar to that observed in other quasars of similar age, and it tells us that the host galaxy is growing very fast.”
Fan added: “These quasars may still be in the process of establishing their supermassive black holes.” “Over time, the effluent of the quasars heats up and expels all the gas out of the Milky Way, and then the black hole no longer has food for food. , And will stop growing. This is evidence of how these earliest large galaxies and their quasars grew.”
The second author of the report, researcher Peter A. Strittmatter of the Steward Observatory, stated that the researchers expect to find more quasars in the same period, including potential new record breakers. Yang and Fan were observing on the 6.5-meter Magellan Baade telescope at Las Campanas Observatory in Chile and found J0313-1806 at night.
Yang said: “Our quasar survey has a very wide range and can scan almost half of the sky.” “We have selected more candidates and we will observe them in more detail.”
Researchers hope to discover more about the secrets of quasars through future observations, especially the NASA James Webb Space Telescope currently scheduled to launch in 2021.
Wang said: “Using ground-based telescopes, we can only see a point light source.” “Future observations may make it possible to resolve quasars in more detail, showing the structure of quasars and the extent of wind towards their galaxies, which will enable We have a better understanding of its evolutionary stage.”
The Milky Way survived the black hole
“The most distant quasar in the universe”, Faige Wong, January 12, 4:10-4:20 pm Eastern Standard Time. aas.org/meetings/aas237
Luminous quasar on Redshift 7.642, arXiv: 2101.03179 [astro-ph.GA] arxiv.org/abs/2101.03179
Provided by the University of Arizona
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