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Looking for a missing giant black hole



Black hole accretion disk diagram

Illustration of black hole.Image credit: Aurore Simonnet and NASA’s Goddard Space Flight Center

  • Astronomers are looking for signs of super mass Black hole In the galaxy cluster Abell 2261.
  • Almost all large galaxies contain a central black hole, and the central galaxy of Abel 2261 is expected to contain a particularly large galaxy.
  • Scientists believe that this galaxy has merged with another galaxy in the past, which may cause the ejection of newly formed larger black holes.
  • Despite careful searches using Chandra and other telescopes, astronomers still don’t know what happened to this huge black hole.

The mystery surrounding the whereabouts of the supermassive black hole has deepened.

Search though NASAChandra X-ray Observatory and Hubble Space TelescopeAstronomers have no evidence that a distant black hole can be found. It is estimated that its weight is 3 to 100 billion times the mass of the sun.

The missing black hole should be located in the huge galaxy at the center of the galaxy cluster Abell 2261, which is about 2.7 billion light-years away from Earth. The composite image of Abell 2261 contains optical data from the Hubble and Subaru telescopes, showing star clusters and galaxies in the background, and Chandra X-ray data showing hot gas (pink) throughout the cluster. The center of the image shows the large elliptical galaxy at the center of the cluster.

At the center of almost every large galaxy in the universe is a supermassive black hole whose mass is a million or billions of times that of the sun. Since the mass of the central black hole is usually the same as the mass of the galaxy itself, astronomers expect that the galaxy at the center of Abel 2261 will contain a supermassive black hole whose mass is comparable to the mass of some of the largest known black holes in the universe.

Abell 2261 optical infrared X-ray composite

This image of Abell 2261 contains X-ray data from Chandra (showing hot gas throughout the star cluster) and optical data from the Hubble and Subaru telescopes, which show star clusters and galaxies in the background. Astronomers use these telescopes to search galaxies in the center of the image, looking for evidence of a black hole, which is estimated to weigh between 3 and 100 billion times that of the sun. There is no sign of this black hole, which deepens the mystery about what is happening in the system. Image credit: X-ray: NASA/CXC/University of Michigan/K. Gutkin Optics: NASA / STScI and NAOJ / Subaru; Infrared: NSF / NOAO / KPNO

Using data obtained by Chandra in 1999 and 2004, astronomers have searched for signs of supermassive black holes in the center of the large central galaxy Abell 2261. They searched for material that had overheated when it fell towards the black hole and produced X-rays, but no such source was found.

Now, with the acquisition of longer new Chandra observations in 2018, a team led by Kayhan Gultekin of the University of Michigan in Ann Arbor has conducted a deeper search for the black hole at the center of the Milky Way. They also considered another explanation, in which the black hole is ejected from the center of the host galaxy. This violent event may be due to the merger of two galaxies to form an observed galaxy, and the central black hole in each galaxy merges to form a huge black hole.

When black holes merge, they will produce ripples in space and time, called Gravitational waves. If a large number of gravitational waves generated by such an event are stronger in one direction than the other, the theory predicts that new and even more massive black holes will be sent in the opposite direction away from the center of the Milky Way. This is called a recoil black hole.

Astronomers have not found definitive evidence of recoil black holes, nor do they know whether supermassive black holes are close enough to each other to generate gravitational waves and merge. So far, astronomers have only confirmed the merger of much smaller black holes. The detection of recoil supermassive black holes will make scientists who use and develop observing stations bold to find gravitational waves that merge with supermassive black holes.

The galaxy at the center of Abell 2261 is an excellent star cluster for finding recoil black holes, because there are two indirect signs that the two large black holes may have merged. First, optical observation data from Hubble and Subaru revealed a galactic core, that is, the central region where the number of stars in the Milky Way in a given galaxy patch is equal to or close to the maximum, which is much larger than expected. The galaxy of its size. The second sign is that the densest cluster of stars in the Milky Way is more than 2,000 light years away from the center of the Milky Way, which is very far away.

These features were first identified by Marc Postman of the Space Telescope Science Institute (STScI) and his collaborators in his earlier Hubble and Subaru images, and prompted them to propose a black hole merger in Abell 2261. idea. During the merger, the supermassive black hole in each galaxy sinks toward the center of the newly merged galaxy. If they are bound to each other under gravity and their orbits begin to shrink, the black hole will interact with surrounding stars and eject them from the center of the Milky Way. This can explain the core of Abell 2261. The eccentric concentration of stars may also be caused by violent events, such as the merger of two supermassive black holes and the subsequent merger of the recoil of a single larger black hole.

Even if there are signs of black hole mergers, Chandra and Hubble’s data show no evidence of black holes themselves. Gultekin, led by Sarah Burke-Spolaor of West Virginia University, and most of his co-authors have previously used Hubble to look for possible recoil black holes A cluster of stars. They studied three clumps near the center of the Milky Way and whether the motion of the stars in these clumps was high enough to imply that they contained a black hole with a mass of tens of billions of the sun. No obvious black hole evidence was found in either of the clusters, and the star in the other cluster was too weak to draw useful conclusions.

They also used NSF’s Karl G. Jansky very large array to study the observations of Abell 2261. Radio emissions detected near the center of the Milky Way show that super-large-scale black hole activity occurred here 50 million years ago, but it does not indicate that the center of the Milky Way currently contains such black holes.

Abell 2261 optical radio

Image source: NASA/CXC, NASA/STScI, NAOJ/Subaru, NSF/NRAO/VLA

Then they turned to Chandra to look for matter that had overheated and produced X-rays when X-rays fell into the black hole. Although Chandra’s data does show that the densest heat is not in the center of the Milky Way, they do not reveal any possible X-ray characteristics of the growing supermassive black hole-no X-rays have been found in the center of the cluster Source, or in any star cluster, or in the location of radio emission.

The authors concluded that there is no black hole in any of these locations, or it is pulling the material too slowly to produce a detectable X-ray signal.

Therefore, the mystery of the location of this huge black hole continues. Although the search was unsuccessful, there is still hope that astronomers will find this supermassive black hole in the future. Once started, James Webb Space Telescope It may reveal the existence of a supermassive black hole in the center of the Milky Way galaxy or one of the star clusters. If Weber cannot find the black hole, then the best explanation is that the black hole has completely retreated to the center of the Milky Way.

A paper describing these results has been published in the Journal of the American Astronomical Society. Gultekin’s co-author is Sarah Burke-Spolaor. Tod R. Lauer (National Optical Infrared Astronomy Research Laboratory in Tucson, Arizona); T. Joseph W. Lazio and Leonidas A. Moustakas (California Institute of Technology, Jet Propulsion Laboratory in Pasadena, California); Patrick Ogle and Marc Postman (Space Telescope Science Institute, Baltimore, Maryland).

Reference: “Kendra · Art 2261 Chandra observations of the brightest cluster syndicated, which is the recoil the black hole candidate host”, author: Kay Kim Han Gu Erte, Sarah Burke Crespo Lal , Todd R. Lauer, T. Joseph Lazio, Leonidas Mustacas, Patrick Ogle and Mark Postman, January 5, 2021 Astrophysical Journal.
DOI: 10.3847 / 1538-4357 / abc483

NASA’s Marshall Space Flight Center manages the Chandra program. The Chandra X-ray Center at the Smithsonian Astrophysical Observatory controls science in Cambridge, Massachusetts, and flight operations in Burlington, Massachusetts.




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