Black Holes | Universe Today

This artist's conception illustrates one of the most primitive supermassive black holes known (central black dot) at the core of a young, star-rich galaxy. Image credit: NASA/JPL-Caltech

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Recent observations of blazar jets require researchers to look deeper into whether current theories about jet formation and motion require refinement. This simulation, courtesy of Jonathan McKinney (KIPAC), shows a black hole pulling in nearby matter (yellow) and spraying energy back out into the universe in a jet (blue and red) that is held together by magnetic field lines (green).

"As the universe's biggest accelerators, blazar jets are important to understand," said Kavli Institute for Particle Astrophysics and Cosmology (KIPAC) Research Fellow Masaaki Hayashida, corresponding author on the recent paper presenting the new results with KIPAC Astrophysicist Greg Madejski. "But how they are produced and how they are structured is not well understood. We're still looking to understand the basics."

Blazars dominate the gamma-ray sky, discrete spots on the dark backdrop of the universe. As nearby matter falls into the supermassive black hole at the center of a blazar, "feeding" the black hole, it sprays some of this energy back out into the universe as a jet of particles.
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Centaurus A. Image credit: NASA

Dan Evans, a postdoctoral researcher at MIT Kavli Institute for Astrophysics and Space Research (MKI) thinks he knows why; it's because the jet-producing supermassive black holes are spinning backwards, relative to their accretion disks.
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This question was posed in an Astronomy Cast episode a while back. It offers an interesting thought experiment, although a reasonably definitive answer to the question can be arrived at. Read more…

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SDSS J1254+0846 in x-rays (blue), and optical (yellow)
(Credits: X-ray: NASA/CXC/SAO/Green et al Optical: Carnegie Obs/Magellan/Baade Telescope/Mulchaey et al)

"This is really the first case in which you see two separate galaxies, both with quasars, that are clearly interacting," says Carnegie astronomer John Mulchaey who made observations crucial to understanding the galaxy merger.

"The model verifies the merger origin for this binary quasar system," Thomas Cox, now a fellow at the Carnegie Observatories, says, referring to computer simulations of the merging galaxies he produced. When Cox's model galaxies merged, they showed features remarkably similar to what Mulchaey observed in the Magellan images. "It also hints that this kind of galaxy interaction is a key component of the growth of black holes and production of quasars throughout our universe," Cox added.
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SN 2009bb (Image Credit: NASA, Swift, Stefan Immler)

The answer to both questions is 'very likely, yes'! And what recent research points to those answers? Study of an Ic supernova (SN 2007gr), and an Ibc one (SN 2009bb), by two different teams, using archived Gamma-Ray Burst Coordination Network data, and trans-continental Very Long Baseline Interferometry (VLBI) radio observations.
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This image composite shows the spectacular spiral galaxy NGC 300 as seen in an image from the Digitized Sky Survey 2 (DSS2), as well as the position of the stellar-mass black hole in the galaxy in an image obtained with the FORS2 instrument on the VLT. Credit: ESO/ Digitized Sky Survey 2/P. Crowther

Not only is a newly found black huge, it also is the most far-away stellar-mass black hole ever detected. “This is the most distant stellar-mass black hole ever weighed, and it’s the first one we’ve seen outside our own galactic neighborhood, the Local Group,” said Paul Crowther, from the University of Sheffield. Using ESO's Very Large Telescope, astronomers peered six million light-years from Earth into a spiral galaxy called NGC 300 and found a black hole with a mass above fifteen times that of the Sun. This makes it the second most massive stellar-mass black hole ever found. But soon it could get bigger. The black hole appears to have a nearby partner, a massive Wolf–Rayet star which likely will become a black hole itself, and the two black holes could merge into an even more massive object.
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Caption: Latest Chandra image of Sgr A*. Credits: X-ray: NASA/CXC/MIT/F. Baganoff, R. Shcherbakov et al.

How long can you stare at an object? This Chandra image of the supermassive black hole at the center of the Milky Way Galaxy, known as Sagittarius A* (or Sgr A* for short)Sgr A* and the surrounding region is based on data from a series of observations lasting a total of about one million seconds, or almost two weeks. Such a deep observation has given scientists an unprecedented view of the nearby supernova remnant, known as Sgr A East, and the lobes of hot gas extending for a dozen light years on either side of the black hole. These lobes provide evidence for powerful eruptions occurring several times over the last ten thousand years. But this image also provides evidence that Sgr A* isn't a very good eater.
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Caption: An image of the galaxy COSMOS J100043.15+020637.2 taken with the Advanced Camera for Surveys on the Hubble Space Telescope. Image courtesy Dr. Julia Comerford.

Astronomers have discovered 33 pairs of merging black holes in cosmic dances around each other, a finding that was predicted or 'choreographed' by Isaac Newton. "These results are significant because we now know that these 'waltzing' black holes are much more common than previously known," said Dr. Julia Comerford of the University of California, Berkeley, at the American Astronomical Society meeting in Washington, DC. "Galaxy mergers are causing the waltzing, can use this finding to determine how often mergers occur. The black holes dancing towards us are shifted towards blue light, and those moving away from us are shifted toward the red. So it is like a cosmic disco ball showing us where the black holes are dancing."
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NGC 1399, an elliptical galaxy about 65 million light years from Earth. Credit: NASA, Chandra

A dense stellar remnant has been ripped apart by a black hole a thousand times as massive as the Sun. If confirmed, this discovery would be a cosmic double play: it would be strong evidence for an intermediate mass black hole — which has been a hotly debated topic — and would mark the first time such a black hole has been caught tearing a star apart. Scientists believe a mysterious intense X-ray emission, called an “ultraluminous X-ray source” or ULX is responsible for the destruction. “Astronomers have made cases for stars being torn apart by supermassive black holes in the centers of galaxies before, but this is the first good evidence for such an event in a globular cluster,” said Jimmy Irwin of the University of Alabama, who led the study.
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Cosmic rays – particles that have been accelerated to near the speed of light – stream out from our Sun all of the time, though they are positively sluggish compared to what are called Ultra-High-Energy Cosmic Rays (UHECRs). These types of cosmic rays originate from sources outside of the Solar System, and are much more energetic than those from our Sun, though also much rarer. The merger between a white dwarf and neutron star or black hole may be one source of these rays, and such mergers may occur often enough to be the most significant source of these energetic particles. Read more…

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A comparison of the Fermi images from November 3rd and December 2nd of this year, showing the brightening of 3C 454.3. Image Credit: NASA/DOE/Fermi LAT Collaboration

The blazar 3C 454.3, a bright source of gamma rays from a galaxy 7 billion light-years away just got a whole lot brighter. Observations from the Fermi gamma-ray telescope confirm that since September 15th the blazar has flared up considerably, increasing in gamma-ray brightness by about ten times in the from earlier this past summer, making it currently the brightest gamma-ray source in the sky.

3C 454.3 is a blazar, a jet of energetic particles that is caused by the supermassive black hole at the center of a galaxy. Most galaxies are thought to house a supermassive black hole at their center, and as it chomps down matter from the accretion disk that surrounds it, the supermassive black hole can form large jets that stream out light and energy in fantastic proportions. In the case of 3C 454.3, one of these jets is aimed at the Earth, which allows for us to see and study it. Read more…

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GX 339-4, illustrated here, is a binary system of a black hole and a star. Astronomers were able to measure how the disk around the black hole shrinks for the first time. Image Credit: Credit: ESO/L. Calcada

Homer Simpson would be sad: recent observations of the binary system of a black hole and its companion star have shown the retreat of the doughnut-shaped accretion disk around the black hole. This shrinking 'doughnut' was seen in observations of the binary system GX 339-4, a system composed of a star similar in mass to the Sun, and a black hole of ten solar masses.

As the black hole feeds on gas flowing out from the orbiting star, the change in flow of the gas produces a varying size in the disk of matter that piles up around the black hole in a torus shape. For the first time, the changes in the size of this disk have been measured, showing just how much smaller the doughnut becomes. Read more…

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The birth of galaxies is quite a complicated affair, and little is known about whether the supermassive black holes at the center of most galaxies formed first, or if the matter in the galaxy accreted first, and formed the black hole later. Observations of the quasar HE0450-2958, which is situated outside of a galaxy, show the quasar aiding a nearby galaxy in the formation of stars. This provides evidence for the idea that supermassive black holes can 'build' their own galaxies. Read more…

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Very likely, the last image that comes to mind when thinking of black holes is that they need to be nurtured, coddled and protected when young. But new research reveals the first large black holes in the universe likely formed and grew deep inside gigantic, starlike cocoons that smothered their powerful x-ray radiation and prevented surrounding gases from being blown away.
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