Written on April 14, 2019
"When I saw the Hubble image of this galaxy for the first time, I immediately knew it was unusual," said Marc Postman of the Space Telescope Science Institute about the elliptical monster galaxy, with a central core larger than any previous one seen a mystery had seen before. "The core was very diffuse and very large. The challenge then was to understand all the data from the data we knew from previous Hubble observations and find a plausible explanation for the intriguing nature of this particular galaxy. "
Seven years before the event Horizon Telescope of the week, which released the gigantic black hole in the heart of the Galaxy M87, astronomers using the NASA / ESA Hubble Space Telescope in the fall of 2012 obtained a remarkable view of a monster's three-phase galaxy. In a few years, the galaxy is the most massive and brightest galaxy in the Abell 2261 Cluster, with a larger core than ever before. The galaxy has just over a million light-years and is about ten times the diameter of the Milky Way. The bloated galaxy belongs to an unusual group of galaxies filled with a starry sky, in which normally a concentrated point of light would be seen around a central black hole.
The core size of a galaxy is typically correlated with the dimensions of its host galaxy. In this case, however, the central area is much larger than astronomers would expect for the size of the galaxy. In fact, the inflated core is more than three times the size of other very bright galaxies.
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"Expecting to find a black hole in each galaxy is like finding a pit in a peach," says astronomer Tod Lauer of the National Optical Astronomy Observatory in Tucson. "With this Hubble observation, we cut off the biggest peach and can not find the pit. We do not know exactly that the black hole is not there, but Hubble shows that there is no concentration of stars in the core. "
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If you look at the core, you look like a city without a center, only houses that are scattered in a vast landscape. An international team of astronomers used Hubble's Advanced Camera for Surveys and Wide Field Camera 3 to measure the amount of starlight throughout the galaxy, cataloged as 2MASX J17222717 + 3207571, but more commonly than A2261-BCG (abbreviated to Abell 2261 Brightest Cluster Galaxy). ,
Hubble's observations revealed that the swollen nucleus of the galaxy, which measures about 10,000 light-years, is the largest one has ever seen. Astronomers using NASA's Hubble Space Telescope have been given a remarkable new view of this cluster of elliptical galaxies, possibly inflated by the action of one or more black holes in its core. The galaxy has just over a million light-years and is about ten times the diameter of our Milky Way galaxy.
If you look at the core, you look like a city without a city center, only houses that are scattered over a huge landscape.
Astronomers have suggested two options for the Puffy Core. One scenario is that a pair of black holes gravitationally swirled and scattered the stars. Another idea is that the converging black holes were ejected from the core. Without an anchor, the stars spread further and formed the swollen core.
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Earlier observations by Hubble have shown that supermassive black holes whose masses are million or more billion times higher than the Sun are located in the centers of almost all galaxies and may play a role in shaping these central regions.
The astronomers expected a slight point of light in the center of the galaxy, which marks the position of the black hole and its stars. Instead, the intensity of starlight throughout the galaxy remained fairly even. One possibility for the swollen nucleus may be that two central black holes orbit.
These black holes could have taken together billions of suns. One of the black holes would be native to the galaxy, while the second could be from a smaller galaxy devoured by the massive elliptical trainer.
In this scenario, the stars orbiting in the center of the vast galaxy came close to the two black holes. The stars then got a gravitational boot from the core. Each gravitational shooter robbed the black holes of the impulse and moved the pair closer and closer together until they finally merged to form a supermassive black hole that was still in the center of the galaxy.
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Another related possibility is that the fusion of black holes produced gravitational waves that are waves in space tissue. According to the general theory of relativity, a pair of black holes produces gravitational waves that radiate. If the black holes have an unequal mass, some of the energy in one direction can be more radiated, which corresponds to a rocket boost. The imbalance of forces would have ejected the unified black hole from the center at speeds of millions of kilometers per hour, leading to the rarity of a galaxy without a central black hole.
"The black hole is the anchor for the stars," explains Laurer, co-author of the Hubble study and member of the Nuker team: Hubble Space Telescope Surveys of Centers of Galaxies. "If you take it out, you suddenly have much less mass. The stars are not well held together and move outward, making the core even bigger. "
The team admits that the ejected black hole scenario sounds farfetched, "but that makes watching the universe so intriguing – sometimes you'll find the unexpected," says Postman.
"This is a system that is interesting enough to answer many questions," added Lauer.
"We've thought a lot about what black holes do. However, we could not test our theories. This is an interesting place where many of our ideas can come together and be tested. Exotic ideas about how black holes can dynamically interact with each other and how they would affect the surrounding stellar population. "
The Abell 2261 cluster is part of a Postman-led, multi-wavelength survey called the Cluster Lensing And Supernova Hubble Survey (CLASH). The survey examines the distribution of dark matter in 25 massive clusters of galaxies.
The huge galaxy cluster Abell 2744, also known as Pandora's Cluster, gets a ghostly look in this NASA / ESA Hubble Space Telescope view, which can be seen at the top of the page. In this picture, the entire starlight from the cluster was dyed artificially blue. This shows that not all starlight is contained in the star cities – the galaxies – that appear as light blue-white spots. Part of the starlight is also distributed throughout the cluster, as seen in the darker blue areas.
This light comes from dead galaxies. The galaxies were torn apart long ago by the gravitational forces of the cluster, and their stars were scattered into the so-called intracluster space, the space between the galaxies.
These orphan stars roam the cluster without being bound to a single galaxy. Since these extremely weak stars are the brightest at near-infrared wavelengths, this type of observation could only be achieved with the infrared sensitivity of Hubble for exceptionally low light. The non-blue colored galaxies are either in the foreground or background and are not part of the cluster
The Daily Galaxy via NASA / Hubble Space Telescope Science Institute