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Black Holes and Galaxies

Content About: Black Holes and Galaxies

Published: 11/22/2016 - 9:28am Type of Content: Article-Research Highlight

Galaxy mergers routinely occur in our Universe. And, when they take place, it takes years for the supermassive black holes at their centers to merge into a new, bigger supermassive black hole. However, a very interesting thing can happen when two black holes get close enough to orbit each other every 3–4 months, something that happens just before the two black holes begin their final desperate...

Published: 11/08/2016 - 9:56am Type of Content: Article-Research Highlight

Fellow Mitch Begelman’s new theory says it’s possible to form stars while a supermassive black hole consumes massive amounts of stellar debris and other interstellar matter. What’s more, there’s evidence that this is exactly what happened around the black hole at the center of the Milky Way some 4–6 million years ago, according to Associate Fellow Ann-Marie Madigan.

Relatively recently...

Published: 08/11/2016 - 10:06am Type of Content: Article-Research Highlight

Graduate student Greg Salvesen, JILA Collaborator Jake Simon (Southwest Research Institute), and Fellows Phil Armitage and Mitch Begelman decided they wanted to figure out why swirling disks of gas (accretion disks) around black holes often appear strongly magnetized. They also wanted to figure out the mechanism that allowed this magnetization to persist over time. In the process, they hoped...

Published: 08/14/2015 - 11:22am Type of Content: Article-Research Highlight

Ever wondered how magnetic pressure alone might be able to maintain the structure of an accretion disk around a black hole in an x-ray binary system? Fellow Mitch Begelman recently gave the idea a lot of thought. And, in the process of working on the idea with Fellow Phil Armitage and Chris Reynolds of the University of Maryland, Begelman came up with a new model for accretion disks around...

Published: 03/11/2015 - 8:05am Type of Content: Article-Research Highlight

Supermassive black holes at the center of active galaxies are known as blazars when they are extremely bright and produce powerful jets of matter and radiation visible along the line of sight to the Earth. Blazars can appear up to a thousand times more luminous than ordinary galaxies, and their associated jets are so powerful they can travel millions of light years across the Universe. Blazar...

Published: 01/29/2014 - 9:25am Type of Content: Article-Research Highlight

Black holes have a new item on their dinner menu: a three-dimensional glowing sphere of stellar debris that looks like a star. The sphere provides a sumptuous main course for a supermassive black hole, while emitting excess energy via jets erupting from its polar regions. The idea for this new type of gourmet feast for black holes comes compliments of graduate student Eric Coughlin and Fellow...

Published: 02/27/2013 - 9:57am Type of Content: Article-Research Highlight

Fellow Mitch Begelman and colleague Marek Sikora of the Polish Academy of Sciences have proposed a solution for the long-standing puzzle of what causes black holes to launch powerful jets. Jets are extremely energetic material (plasma) traveling at very close to the speed of light and spanning distances of thousands to hundreds of thousands of light years. The dominant factor in the creation...

Published: 04/10/2013 - 11:33am Type of Content: Article-Research Highlight

Research associate Bruno Giacomazzo recently studied the effects of magnetic fields and matter on the likelihood that the merger of two black holes will produce jets of light of different frequencies ranging from radio waves to X-rays. If such signals are generated, it may be possible to detect them with ground- or space-based observatories. Their detection would help astronomers identify...

Published: 03/06/2013 - 10:34am Type of Content: Article-Research Highlight

Fellow Mitch Begelman and his colleagues came up with the idea of quasistars to explain the origin of the supermassive black holes found at the center of most galaxies. According to Begelman, quasistars formed when massive amounts of gas were funneled into the center of protogalaxies. This prodigious amount of gas collapsed directly into black holes without forming stars. The resulting black...

Published: 02/09/2010 - 5:00pm Type of Content: Article-Research Highlight

Before there were galaxies with black holes in their centers, there were vast reservoirs of dark matter coupled to ordinary matter, mostly hydrogen gas. These reservoirs were sprinkled with the Universe’s early stars born in pregalactic dark matter halos. But according to Fellow Mitch Begelman, another population of atypical stars formed millions of years later during the creation of...

Published: 02/09/2010 - 5:00pm Type of Content: Article-Research Highlight

The merger of supermassive black holes is a hot topic in astrophysics. Such mergers may occur after the formation of black hole binaries during galaxy collisions. The mergers are predicted to emit gravitational waves, whose detection is the mission of the Laser Interferometer Space Antenna (LISA). In preparation for the LISA mission, which is scheduled for launch in 2018, Fellow Peter Bender...

Published: 07/08/2009 - 6:00pm Type of Content: Article-Research Highlight

Supermassive black holes inside blazar galaxies emit powerful jets of particles traveling in opposite directions near the speed of light. Some are aimed toward the Earth. These jets emit radio waves, which makes them visible to radio telescopes as they streak across the sky. By studying these radio waves, scientists have determined that the jets are traveling at about 99.5% the speed of...

Published: 02/09/2009 - 5:00pm Type of Content: Article-Research Highlight

The "dark ages" of the early Universe drew to a close with the appearance of enough stars to strip electrons off most of the hydrogen atoms in the gas clouds between galaxies. By a billion years after the Big Bang, these reionized atoms had rendered the Universe transparent to light. About 12.7 billion years later, visiting JILA member Gayler Harford, Fellow Andrew Hamilton, and...

Published: 09/29/2008 - 6:00pm Type of Content: Article-Research Highlight

Astrophysicists know that the centers of galaxies have supermassive black holes whose size correlates with the size of the galaxy surrounding them. They’ve also observed that galaxies collide and merge. In fact, galactic mergers were even more common billions of years ago in the Universe when today’s galaxies were still being assembled.

So what happens to the original...

Published: 09/26/2013 - 12:53pm Type of Content: Video Gallery

Take a ride on the Black Hole Flight Simulator, courtesy of Professor Andrew Hamilton. You can read about this work in this NY Times article... http://www.nytimes.com/2006/02/28/science/28prof.html?_r=0

Published: 07/08/2008 - 6:00pm Type of Content: Article-Research Highlight

Graduate student Robyn Levine, Fellow Andrew Hamilton, and colleagues from the University of Chicago’s Kavli Institute for Cosmological Physics are working on modeling how supermassive black holes grow inside galaxies. They recently published the first of what will be a series of papers on a unique cosmological simulation of the growth and evolution of a disk galaxy. What’s unusual about this...

Published: 02/09/2008 - 5:00pm Type of Content: Article-Research Highlight

Fellow Andrew Hamilton recently confirmed a prediction he made 10 years ago of the location of a reverse shock wave slowing the expansion of the debris from a supernova that occurred in 1006 AD. SN1006 was (and still is) the brightest supernova observed in recorded history; it was visible from Earth (without telescopes) for three years.

This particular stellar cataclysm resulted...

Published: 02/09/2008 - 5:00pm Type of Content: Article-Research Highlight

In Ray Bradbury’s book Something Wicked This Way Comes, people get older or younger depending on which direction they ride on a carnival carousel. Something similar may happen to black holes, except that they become gargantuan or just a smidgeon larger depending on how fast they spin while they’re sucking in matter. The slower they spin, the faster they expand, says Visiting...

Published: 04/08/2006 - 6:00pm Type of Content: Article-Research Highlight

Gamma-ray bursts signal the birth of a new black hole, whether it's created during the collapse of a massive star or via a merger between two compact objects such as neutron stars. Astrophysicists have determined that long gamma-ray bursts are associated with collapsing stars and short bursts are associated with binary mergers. In both cases, however, black-hole accretion powers the...

Published: 04/08/2005 - 6:00pm Type of Content: Article-Research Highlight

Rosalba Perna and colleagues Jonathan Granot of Stanford and Enrico Ramirez-Ruiz of Princeton's Institute for Advanced Study recently figured out the relationship between X-ray flashes, X-ray rich gamma-ray bursts, and gamma-ray bursts detected by different space-based observatories. X-ray flashes are transient astronomical X-ray sources that last from several seconds to a few minutes....

Published: 04/08/2005 - 6:00pm Type of Content: Article-Research Highlight

What really happens inside black holes?

Andrew Hamilton and Scott Pollack, a graduate student in the Physics Department, recently decided to investigate the answer to this question. In the process, they developed a model using realistic physics that they believe better describes the internal structure of black holes.

The starting point for most black hole models has been...

Published: 04/08/2005 - 6:00pm Type of Content: Article-Research Highlight

Andrew Hamilton and Jason Lisle, who received his Ph.D. in astrophysical and planetary sciences in 2004, have proposed a new model for the flow of matter into stationary and rotating black holes. In their "river model of black holes," space flows like a river through a flat background, while objects (like light rays) that move through the river abide by the rules of special...

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Black holes are some of the most mysterious and intriguing objects in the Universe. Gravitational forces near them are so strong that nothing—not even light—can escape their fatal attraction. Small- and intermediate-sized black holes are formed in the cataclysmic explosions that mark the death of large-to-massive stars. Supermassive black holes (millions to billions times more massive than our...

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