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Unified model of active galactic nucleus confirmed by VLTI – Vaughan Today

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L ‘Avalanche Black hole theory confirmations with a statement fromwho – which Who accompanies printed in the famous newspaper temper nature Which can be freely referenced in arXiv. In 2015, we celebrated Centenary of Einstein’s final discovery of his theory of general relativity In the same year, gravitational waves were discovered on Earth for the first time from another amazing prediction of his theory of relativity gravity, black holes. In 2019, the first image of a black hole taken was revealed toevent horizon telescopeThe black hole at the heart of galaxy M87.

For decades it was believed that these stars Relativity in its supermassive form, that is, it contains at least one million people masses Solar energy, sometimes several billion, is the origin of active galactic nuclei (AGN where active galactic nucleus, in English) has been particularly highlighted by radio astronomers, but also by Astronomy scientists Without AGN necessarily being sources radio. These active galactic nuclei are characterized by particularly active phenomena of one form or another, for example Jets of relativistic matter over thousands of light yearsa discovery that interests them and which is now at the fore thanks to the observations made withInterferometer the very large telescope European Southern Observatory (ESO’s VLTI).

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Active galactic nuclei (AGNs) are highly energetic sources fueled by supermassive black holes. This short video provides insight into these particular objects through the recent discovery of an active galactic nucleus in the center of the Messier 77 galaxy. European Southern Observatory (which – which)

A zoo of active galactic cores

The most exciting active galactic nuclei are quasars Which at first glance seems stars seen at telescope While they are powerful radio sources, their precise determination of the distances observed in the early 1960s led to the recognition that they were objects whose size wasthe size the solar systemable, however, to launch as many as possibleenergy of great stars galaxy It’s all like the Milky Way.

In the end, astronomers understood that AGNs can be described in three main categories, radio galaxies, de sievert galaxies and the quasars with partitions. Some are very bright both in the visible and in the radio, and others are in only one of these spectral ranges. Some have jets of Themeothers do not.

Thus, radio galaxies are rather ordinary looking galaxies elliptical galaxies giants or lenticular galaxies, but emit strongly in the radio field. The emitted radio radiation can be hundreds of times stronger than that of so-called ordinary galaxies – we know for example the state of the so-called source chicken, which is a million times brighter than our Milky Way. An important feature of radio galaxies is their presence, and sometimes thousands of themlight years From their center, from the two lobes where mostepisode radio. This is the end of very high ejection material jets Speed The ones we mentioned earlier and in which we can see an artist’s illustration in the video above.

sievert galaxies are spiral galaxies It was first observed in 1943 by Karl Seifert. We can mention galaxies NGC 1410 in constellation From Eridano and Messier 77 in the Baleine region. It is much brighter than an ordinary galaxy, not only in the radio, but also in the visible with its nucleus in particular emitting as much light as the rest of the stars of these galaxies.

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Jean-Pierre Lumenet, director of research at CNRS and Françoise Coombes, professor at Collège de France, spoke to us about black holes and especially supermassive black holes in galaxies that lie behind AGNs. © Fondation Hugot of the College of France

We ended up developing the idea, described by the so-called Unified Model of AGN, that behind all these AGNs were hiding the same type of object, but seen from different angles and at different time intervals.beingit has been said, supermassive black holes that emit a huge amount of energy after complex, and not always well understood, processesaccumulation of matter (Mainly in the form of cold bristles) and relative hydrodynamics.

Thus, in a region almost no larger than the solar system at most, there must be a hoop of dust and Gas ambient neutrals a Accumulation disk of dust, gas, and finally matter ionized by the heat emitted by the viscous friction in this disk and falling on a black hole care alternately.

Hot plasma enters the atmosphere of a black hole, that is, a regionspacetime Any falling object rotates radially, then participates in a complex mechanism, explained in part by Blandford and Znajik, in which the gravitational energy of falling matter and especially the rotational energy of a black hole is converted into intense radiation and jets of matter along the axis of rotation of the compressed star.

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Astronomers have observed different types of AGNs. Some, called blazars, are very bright and can show differences in brightness over time scales of only hours or days, while another type, called quasars, are also very bright but tend to show lower fluctuations than blazars. Severt galaxies, which come in two forms (1 and 2), are another type of active galactic nucleus, surrounded by easily detectable host galaxies. The galaxies Seyfert 1 and Sefert 2 have a bright core. However, those of the Seyfert 2 type tend to be more conservative. The unified AGN model states that despite their differences, all AGNs have the same basic structure: a supermassive black hole surrounded by a thick ring, or hoop, of dust. According to this model, any difference in appearance between AGNs results from the angle from which we observe the black hole and its massive ring from Earth. Thus, the type of active galactic nuclei we observe depends on how dark the black hole is along its line of sight, sometimes completely obscured by the ring. © European Southern Observatory (ESO), L. Calçada and M. Kornmesser

Unified model of active galactic nuclei

Today, it is therefore a teamastrophysicists, led by doctoral student Violetta Jamez-Rosas from Leiden University in the Netherlands, who has just provided new evidence of the importance of a unified AGN model by making the most accurate observations yet of the galactic center. 47 million light-years from the Milky Way in the constellation Pisces, revealing a thick disk of cosmic dust and gas hiding giant black hole.

ESO press release revealing this discovery, made possible by the Matisse tool (Medium Infrared Multiple Spectrophotometer) Installed on the VLTI, he presents it as a very serious confirmation of the viability of the unified model developed thirty years ago. located in desert From Atacama in Chile, this machine collects light Infrared They were collected by the four 8.2-meter telescopes that make up very large telescope (VLT) from ESO using a technology called Interferometry The optics are long base, which actually makes it possible to have a much larger telescope, powerful Precision Superior detail control like never before.

« Matisse is able to detect a wide range of wavelengths Infrared, allowing us to see dust and measure temperatures accurately. Since the VLTI consists of a very large interferometer, it provides sufficient resolution to study phenomena that occur within distant galaxies such as Messier 77. The obtained images show differences in temperature andabsorb From clouds Gas around a black hole ‘,” outlines Walter Jaffe, co-author of the study and professor at Leiden University.

« The true nature of dust clouds, their role in feeding the black hole, as well as the appearance they take on as seen from Earth, have long been fundamental questions for any researcher working on active galactic nuclei. Although no single result can answer all the questions that arise, a major step has just been taken in our understanding of how AGNs work.explains Violetta Gamez Rosas who adds, Our results should provide a better understanding of the inner workings of the AGN. It could also help us better understand the history of the Milky Way, which has a supermassive black hole at its center that may have been active in the past. »

The researchers now want to extend their observations, using ESO’s VLTI, to a larger sample of galaxies, in order to confirm the validity of the unified AGN model.

Bruno Lopez, l’un des membres de l’équipe et responsable principal de l’instrument Matisse à l’Observatoire de la Côte d’Azur, situé à Nice en France, ajoute quant à lui et toujours dans le communiqué de l’ESO that : “ Messier 77 is a true AGN prototype. His study prompts us to expand our observations program and improve Mattis in order to study a larger sample of AGNs. ».

This research program should take on a new dimension when itvery large telescope (ELT) of ESO will enter service before the end of this contract.

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« Very greedy supermassive black holes. All galaxies have a supermassive black hole at their center, the masses of which range from one million to a few billion solar masses. There is a proportional relationship between the mass of these black holes and the mass of galactic bulges, indicating that star formation and black hole feeding occur simultaneously. Somehow, galaxies and their black holes grow in a symbiosis. When gas falls toward the center of the galaxy, the black hole swallows as much of it as possible, but the mass it can absorb is limited. The fall of matter into the black hole releases a great deal of energy, in the form of radiation, and also in the form of kinetic energy. A galactic nucleus becomes active, either a sievert nucleus or a quasar. Winds and jets of plasma from the black hole attract the surrounding interstellar gas. Molecular gas flows around active cores have recently been revealed, carrying so much mass that they can have a major impact on host galaxy evolution, regulating or even halting the gas supply to star formation. Voracious black holes, by spitting out their own food, regulate star formation. We will explain in detail these phenomena, perhaps at the origin of the proportionality between the masses of black holes and LEDs. Françoise Combs is an astronomer at the Paris Observatory in the Laboratory for the Study of Radiation and Matter in Astrophysics (Lerma). His current field of research concerns the formation and evolution of galaxies. © Ecole Normale Supérieure – PSL

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Astronauts may need to jump in space to fight bone loss – Space.com

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When astronauts spend extended periods of time in space, many surprising and sometimes harmful changes can occur in their bodies. Unfortunately, there aren’t always ways to avoid or mitigate these effects. 

One such health concern is a loss in bone density and bone strength due to the effects of microgravity and, to a lesser extent, radiation exposure. A NASA-funded study in 2009 found that astronauts’ bone strength decreased by at least 14% on average during a six-month stay in space. Other studies have found much higher rates of bone loss.

But a new study suggests that astronauts and mission planners could employ an effective weapon in the fight against bone-density loss: jumping and other forms of high-impact exercise.

Related: Landmark NASA twins study reveals space travel’s effects on the human body

Out of the 17 astronauts who participated in the new study (opens in new tab), which was published online Thursday (June 30) in the journal Scientific Reports, only eight regained full bone mass density one year after returning from flight. Bone density loss was found to be much higher in astronauts who flew on missions longer than six months.

But the researchers also found that astronauts who engaged in resistance-based training while in space were able to recover bone mineral density after they returned. The authors thus propose adding  “jumping resistance-based exercise that provides high-impact dynamic loads on the legs” to astronauts’ existing exercise routines to prevent bone loss and promote bone growth while on spaceflight missions.

NASA astronaut Reid Wiseman, Expedition 40 flight engineer, gets a workout on the advanced Resistive Exercise Device (aRED) in the Tranquility node of the International Space Station. (Image credit: NASA)

“Jumping provides short bouts of high-impact, dynamic loads that promote osteogenesis [bone growth],” the researchers wrote, while adding that “neither running, cycling, squats, nor heel raise volume were associated with bone recovery.” Adding jumping exercise routines to astronauts’ existing exercise regimens may prevent bone loss and actually reduce the amount of exercise time needed each day, the authors suggest.

Of course, any new jumping regimen would require specialized equipment, and space is always limited aboard any spaceflight. “Successful implementation of high-load jump-training on-orbit will require an exercise device that mitigates forces transferred to the vehicle, along with an exercise regimen that accounts for astronaut deconditioning,” the researchers wrote in the new study. The authors acknowledge that since living quarters are typically cramped aboard spaceflights, “exercise equipment will need to be optimized for a smaller footprint.”

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Obviously, a study size of 17 astronauts isn’t exactly conclusive, and the authors note that much more data is needed before any firm conclusions can be drawn regarding the effects of resistance training on astronaut bone loss.  

Astronauts already engage in regular exercise while in space to combat the effects of microgravity, and scientists have already tried feeding astronauts genetically modified vegetables to help stimulate bone growth and fish oil rich in omega-3 fatty acids to help mitigate bone breakdown. With bone loss still plaguing astronauts on long flights, there is still a need for more methods to mitigate it. 

Email Brett at BTingley@Space.com or follow Brett on Twitter at @bretttingley. Follow us on Twitter @Spacedotcom or on Facebook.  

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'Permanent bone loss': Calgary study finds astronauts suffer on return to Earth – Cochrane Today

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CALGARY — The experience may be out-of-this-world but research indicates those who travel to outer space suffer from increased bone loss. 

A study released Thursday from the Cumming School of Medicine at the University of Calgary followed 17 astronauts before and after their spaceflights. 

The TBone study, conducted over a seven-year period starting in 2015, found that prolonged weightlessness accelerated bone loss in the astronauts. 

“You see on average they lose about two decades of bone. We found that weight-bearing bones only partially recovered in most astronauts one year after spaceflight,” said Dr. Leigh Gabel, an assistant professor in the faculty of kinesiology and lead author of the study. 

“After a year of recovery, they tend to regain about half of that. This suggests the permanent bone loss due to spaceflight is about the same as a decade worth of age-related bone loss on Earth.” 

The researchers travelled to Johnson Space Center in Houston to scan the wrists and ankles of the astronauts before they left for space, on their return to Earth, after six months and then one year. 

The findings, published in Scientific Reports, said the loss happens because bones that would normally be weight-bearing on Earth, such as the legs, don’t have to carry weight in a zero-gravity setting. 

“We’ve seen astronauts who had trouble walking due to weakness and lack of balance after returning from spaceflight to others who cheerfully rode their bike on Johnson Space Center campus to meet us for a study visit,” said Dr. Steven Boyd, director of the McCaig Institute for Bone and Joint Health and professor in the Cumming School of Medicine. 

“There is quite a variety of response among astronauts when they return to Earth.” 

Boyd said new scanning technology has made a world of difference.

“We’re using new technology that can measure the fine details of the bone that are even finer than a human hair in terms of resolution. We can see detail there that wasn’t possible to see before in these astronauts.”

The study found some astronauts who flew on shorter missions — under six months — recovered more bone strength and density in the lower body compared to those who flew for longer durations. 

The study’s next iteration plans to look at the effects of even longer trips to support astronauts who may one day travel beyond the International Space Station. 

“NASA’s really interested in understanding if longer-term spaceflight could lead to even further bone loss, which would not be very good for the astronaut,” said Boyd.

“The next phase is to do a study that would incorporate crew members who spend a year on the International Space Station, which will give us some more insight on whether you lose even more bone after that one year period.”

The University of Calgary’s former chancellor and astronaut, Robert Thirsk, said he knows how difficult it can be to be back on solid ground. 

“Just as the body must adapt to spaceflight at the start of a mission, it must also readapt back to Earth’s gravity field at the end,” he said. 

“Fatigue, light-headedness and imbalance were immediate challenges for me on my return. Bones and muscles take the longest to recover following spaceflight. But within a day of landing, I felt comfortable again as an Earthling.” 

The study was funded by the Canadian Space Agency in partnership with the European Space Agency, NASA and astronauts from North America, Europe, and Asia. 

This report by The Canadian Press was first published June 30, 2022. 

Bill Graveland, The Canadian Press

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James Webb Space Telescope's powers will be revealed in just weeks and scientists can't wait – Space.com

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BALTIMORE — The James Webb Space Telescope’s first images are coming soon and scientists can’t wait for us to see them.

On Wednesday (June 29), NASA held a media day at the Space Telescope Science Institute (STScI) in Baltimore in advance of the release of the first science-quality images from the James Webb Space Telescope, which will occur during a live event on July 12. NASA scientists and administrators gave updates on the telescope, discussed Webb’s planned science during its first year in operation and hinted at the contents of some of Webb’s first official images.

“In a real sense, we’re sort of the first users of the observatory and using it for what it’s built for,” Klaus Pontoppidan, Webb project scientist at STScI, said during the news conference. “We recognize that we’re standing on the shoulders of all the scientists and engineers who’ve worked hard for the past six months to make this possible.” 

Live updates: NASA’s James Webb Space Telescope mission
RelatedHow the James Webb Space Telescope works in pictures

Although NASA has already released a few images taken while aligning Webb, the images released on July 12 will be from a fully operational observatory, in full color, and they will show what each of the instruments on the telescope can contribute to science. 

These first images will include a deep-field image peering farther into the past than ever before, scientists said during the briefing. NASA will also release Webb’s first spectroscopic data — precise data on the type of light that Webb detects that will allow scientists to learn more about the ingredients of distant cosmic objects. This data will include Webb’s first spectrum of an exoplanet, scientists said. While the images will be visually spectacular, the new information they reveal using Webb’s infrared-observing powers will distinguish them from images taken by other telescopes. 

“The real difference is the new scientific information and then really opening up the longer wavelengths, infrared wavelengths in a way that we’ve really never seen before,” Jonathon Gardner, deputy senior project scientist for Webb, said during the news conference.

Each of the four instruments on Webb, including its main camera, two near-infrared spectrographs and a mid-infrared camera and spectrograph, will contribute to notable research in its first year of operation. They will collect data at nearly every scale and timescale, from our solar system today to the birth of our universe. Though scientists can detect radiation from near the beginning of our universe, no telescope has ever been able to detect light from some of the universe’s first stars and galaxies. Webb will be the first such observatory. 

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“The initial goal for this mission was to see the first stars and galaxies,” Eric Smith, Webb program scientist at NASA, said during the news conference. “Not the first light of the universe, but to watch the universe turn the lights on for the first time.”

Although Webb is already a remarkable feat, its first images represent the start of hopefully decades of science. Webb scientists said they have confirmed that the telescope has enough fuel to carry out science for the next 20 years. Data collected during these years could redefine how we understand our universe.

“This is really only the beginning,” Pontoppidan said. “We’re only scratching the surface.”

Follow us on Twitter @Spacedotcom and on Facebook.  

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