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Mitch Begelman

Content About: Mitch Begelman

Published: 05/31/2017 - 1:09pm Type of Content: News

Eric Coughln has been named winner of the 2016 Ph.D. Thesis Prize from the High Energy Phenomena and Fundamental Physics Division of the International Astronomical Union. He will receive the prize at the next IAU General Assemply, which will be held in Vienna in August 2018. Coughlin is also winner of the 2017 Dissertation Prize from the High Energy Astrophysics Division of the American...

Published: 03/03/2017 - 8:39am Type of Content: Article-Research Highlight

The lovely Crab Nebula was created by a supernova and its spinning-neutron-star remnant known as a pulsar. Pulsar wind nebulae, such as the Crab, shine because they contain plasmas of charged particles, such as electrons and positrons, traveling at near the speed of light. A key question in astrophysics has long been: What process accelerates some of the charged particles in plasmas to...

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: 08/04/2016 - 8:45am Type of Content: News

Eric Coughlin has won the 2016 R. N. Thomas Award. The $1000 award comes from a fund established by Dr. Nora Andreasian, the widow of JILA co-founder Dick Thomas. Coughlin will also receive a book about Thomas’ storied career in astrophysics.

A talented and productive theorist, Coughlin published eight papers as a graduate student, with two more in the works. His thesis work spanned two...

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: 08/06/2015 - 9:04am Type of Content: Article-Research Highlight

When an ordinary star like our Sun wanders very close to a supermassive black hole, it’s very bad news for the star. The immense gravitational pull of the black hole (i.e., tidal forces) overcomes the forces of gravity holding the star together and literally pulls the star apart. Over time, the black hole swallows half of the star stuff, while the other half escapes into the interstellar...

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: 05/27/2014 - 11:48am Type of Content: News

Graduate student Greg Salvesen is the winner of the 2014 R. N. Thomas Award. The award of about $500 comes from a fund established by Nora Thomas, the widow of JILA co-founder Dick Thomas. In addition to the monetary award, Salvesen received a book about Thomas’ exemplary career in astrophysics.

Salvesen is a fifth-year graduate student in Astrophysical and Planetary Sciences. He works...

Published: 02/03/2014 - 8:21am Type of Content: Article-Research Highlight

Fellows Mitch Begelman and Phil Armitage have just solved the 40-year old mystery of what causes the gas of stellar debris surrounding black holes in binaries to flip back and forth cyclically between a spherical cloud and a luminous disk.

When stellar-sized black holes orbit around another star, the black holes feed themselves by pulling material off their companion stars, funneling it...

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: 05/28/2013 - 2:16pm Type of Content: News

Susanna Kohler has won this year's Richard N. Thomas award, given in honor of the late Dick Thomas, co-founder of JILA. The award  honors an outstanding JILA graduate student in astrophysical and planetary sciences. It was presented to Kohler on May 17, 2013, by Nora Thomas, widow of Dick Thomas. Congratulations, Susanna!

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: 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: 03/19/2012 - 6:00pm Type of Content: Article-Research Highlight

On Earth, people use enormous linear accelerators and synchrotrons for such purposes as high-energy physics experiments, chemical composition analysis, and drug research. Linear accelerators ramp up the speeds of electrons and other charged subatomic particles close to the speed of light. Synchrotrons also accelerate charged particles (in a circular track) that, when deflected through...

Published: 12/28/2010 - 5:00pm Type of Content: Article-Research Highlight

There are two competing ideas about the origin of the monster black holes at the center of galaxies. Both include exceptional stars that have never actually been observed: (1) massive population III (Pop III) stars (as big as a thousand Suns) made of pure hydrogen and helium that would have formed less than 100 million years after the Big Bang, and (2) gigantic quasistars whose shining...

Published: 06/17/2013 - 1:18pm Type of Content: News

The delightful and engaging second edition of Gravity’s Fatal Attraction: Black Holes in the Universe by Mitchell Begelman and Martin Rees recently appeared on bookshelves on both sides of the Atlantic.  In this popular science book, the authors systematically present a fascinating history of how astrophysicists came to understand the nature of black holes and how they are formed. They...

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: 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: 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: 04/08/2007 - 6:00pm Type of Content: Article-Research Highlight

Two egg-shaped necklaces of magnificent stars orbit the enormous black hole known as Sagittarius A* (Sgr A*) at the center of the Milky Way Galaxy. Sgr A* (shown right) has long been thought to be well past promoting new star formation; until the necklaces were discovered, the black hole was considered to be just an aging, depleted relic of its glory days of organizing the Galaxy.

...

Published: 09/29/2006 - 6:00pm Type of Content: Article-Research Highlight

There is an enormous black hole at the center of every galaxy, gobbling up matter over eons of time - some for as long as 13 billion years. One of the great questions of modern astronomy is: Where did the seeds for all these black holes come from? Not, as you might think, from the fiery collapse of massive hot stars formed in the early Universe, says Fellow Mitch Begelman. That may well be...

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

Galaxy clusters contain enormous clouds of gas whose cooling should result in the formation of a multitude of new stars. But that's not what NASA's Chandra X-ray Observatory is detecting. Instead there's a whole lot less gas cooling and new star formation than scientists had predicted. Perhaps the most mysterious discovery of all is that the clusters are humming – a low B-...

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

Black holes are pretty strange, sucking in not only nearby matter but also the space around it. These cosmic vacuum cleaners are powered by thin, gaseous accretion disks in orbit around them. Something drives the orbiting gas to spiral in toward the black hole, where all trace of it disappears forever into the singularity. One of the exciting challenges in astrophysics is to figure out the...

Published: 09/29/2005 - 6:00pm Type of Content: Article-Research Highlight

Gamma-ray jets produced deep within massive stars can blow apart the star when they emerge, creating a supernova. The jets are very light and travel near the speed of light toward the star's surface. They are created by a complex interaction of a black hole, an accretion disk, and very strong magnetic fields that come into being when a massive star depletes its supply of hydrogen fuel...

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