Polarizing filter allows astronomers to see disks surrounding black holes

July 24, 2008

(Santa Barbara, Calif.) - For the first time, a team of international researchers has found a way to view the accretion disks surrounding black holes and verify that their true electromagnetic spectra match what astronomers have long predicted they would be. Their work will be published in the July 24 issue of the science journal Nature.

A black hole and its bright accretion disk have been thought to form a quasar, the powerful light source at the center of some distant galaxies. Using a polarizing filter, the research team, which included Robert Antonucci and Omer Blaes, professors of physics at the University of California, Santa Barbara, isolated the light emitted by the accretion disk from that produced by other matter in the vicinity of the black hole.

"This work has greatly strengthened the evidence for the accepted explanation of quasars," said Antonucci.

According to Antonucci, the physical process that astronomers find most appealing to explain a quasar's energy source and light production involves matter falling toward a supermassive black hole and swirling around in a disk as it makes its way to the event horizon - the spherical surface that marks the boundary of the black hole. In the process, friction causes the matter to heat up such that it produces light in all wavelengths of the spectrum, including infrared, visible, and ultraviolet. Finally, the matter falls into the black hole and thereby increases the black hole's mass.

"If that's true, we can predict from the laws of physics what the electromagnetic spectrum of the quasar should be," said Antonucci. But testing the prediction has been impossible until now because astronomers have not been able to distinguish between the light emanating from the accretion disk and that of dust particle and ionized gas clouds in the area of the black hole.

By attaching a polarizing filter to the United Kingdom Infrared Telescope (UKIRT) on Mauna Kea in Hawaii, the research team, led by Makoto Kishimoto, an astronomer with the Max-Plank Institute for Radio Astronomy in Bonn, and a former postdoctoral fellow at UCSB, eliminated the extraneous light and was able to measure the spectrum of the accretion disk. Doing so, they demonstrated that the spectrum matches what previously had been predicted. The researchers also used extensive data gathered from the polarization analyzer of the Very Large Telescope, an observatory in Chile that is operated by the European Space Observatory.

What makes the polarizing filter able to perform its magic is the fact that direct light is not polarized - that is, it has no preference in terms of the directional alignment of its electrical field. The accretion disk emanates direct light, as do the dust particles and ionized gas. However, a small amount of light from the accretion disk, which is the exact light the researchers want to study, reflects off gas located very close to the black hole. This light is polarized.

"So if we plot only polarized light, it's as if the additional light isn't there and we can see the true spectrum of the accretion disk," Antonucci said. "With this knowledge we have a better understanding of how black holes consume matter and expand."

Studying the spectrum of a glowing object such as a quasar provides astronomers with an incredible amount of valuable information about its properties and processes, Antonucci noted. "Our understanding of the physical processes in the disk is still rather poor, but now at least we are confident of the overall picture," he said.

University of California - Santa Barbara

---

---

	Black Hole by Charles Burns (Author) Winner of the Eisner, Harvey, and Ignatz Awards The setting: suburban Seattle, the mid-1970s. We learn from the outset that a strange plague has descended upon the area’s teenagers, transmitted by sexual contact. The disease is manifested in any number of ways — from the hideously grotesque to the subtle (and concealable) — but once you’ve got it, that’s it. There’s no turning back. As we inhabit the heads of several key characters — some kids who have it, some who don’t, some who are about to get it — what unfolds isn’t the expected battle to fight the plague, or bring heightened awareness to it , or even to treat it. What we become witness to instead is a fascinating and eerie portrait of the nature of high school alienation itself — the savagery,...
	Death by Black Hole: And Other Cosmic Quandaries by Neil deGrasse Tyson (Author) A vibrant collection of essays on the cosmos from the nation's best-known astrophysicist. “One of today’s best popularizers of science.”—Kirkus Reviews.Loyal readers of the monthly "Universe" essays in Natural History magazine have long recognized Neil deGrasse Tyson's talent for guiding them through the mysteries of the cosmos with stunning clarity and almost childlike enthusiasm. Here, Tyson compiles his favorite essays across a myriad of cosmic topics. The title essay introduces readers to the physics of black holes by explaining the gory details of what would happen to your body if you fell into one. "Holy Wars" examines the needless friction between science and religion in the context of historical conflicts. "The Search for Life in the Universe" explores astral life from...
	Black Holes (True Books: Space) by Ker Than (Author)
	An Introduction To Black Holes, Information And The String Theory Revolution: The Holographic Universe by Leonard Susskind (Author), James Lindesay (Author) Over the last decade the physics of black holes has been revolutionized by developments that grew out of Jacob Bekenstein s realization that black holes have entropy. Stephen Hawking raised profound issues concerning the loss of information in black hole evaporation and the consistency of quantum mechanics in a world with gravity. For two decades these questions puzzled theoretical physicists and eventually led to a revolution in the way we think about space, time, matter and information. This revolution has culminated in a remarkable principle called The Holographic Principle , which is now a major focus of attention in gravitational research, quantum field theory and elementary particle physics. Leonard Susskind, one of the co-inventors of the Holographic Principle as well as one of...
	The Black Hole War: My Battle with Stephen Hawking to Make the World Safe for Quantum Mechanics by Leonard Susskind (Author) At the beginning of the 21st century, physics is being driven to very unfamiliar territory--the domain of the incredibly small and the incredibly heavy. The new world is a world in which both quantum mechanics and gravity are equally important. But mysteries remain. One of the biggest involved black holes. Famed physicist Stephen Hawking claimed that anything sucked in a black hole was lost forever. For three decades, Leonard Susskind and Hawking clashed over the answer to this problem. Finally, in 2004, Hawking conceded. THE BLACK HOLE WAR will explain the mind-blowing science that finally won out, and the emergence of a new paradigm that argues the world--this catalog, your home, your breakfast, you--is actually a hologram projected from the edges of...
	Black Holes and Time Warps: Einstein's Outrageous Legacy (Commonwealth Fund Book Program) by Kip S. Thorne (Author), Stephen Hawking (Foreword) Ever since Albert Einstein's general theory of relativity burst upon the world in 1915 some of the most brilliant minds of our century have sought to decipher the mysteries bequeathed by that theory, a legacy so unthinkable in some respects that even Einstein himself rejected them.Which of these bizarre phenomena, if any, can really exist in our universe? Black holes, down which anything can fall but from which nothing can return; wormholes, short spacewarps connecting regions of the cosmos; singularities, where space and time are so violently warped that time ceases to exist and space becomes a kind of foam; gravitational waves, which carry symphonic accounts of collisions of black holes billions of years ago; and time machines, for traveling backward and forward in time. ...
	Black Holes: And Other Bizarre Space Objects (Science Frontiers) by David Jefferis (Author)
	Cracking the Einstein Code: Relativity and the Birth of Black Hole Physics by Fulvio Melia (Author), Roy Kerr (Afterword) Albert Einstein’s theory of general relativity describes the effect of gravitation on the shape of space and the flow of time. But for more than four decades after its publication, the theory remained largely a curiosity for scientists; however accurate it seemed, Einstein’s mathematical code—represented by six interlocking equations—was one of the most difficult to crack in all of science. That is, until a twenty-nine-year-old Cambridge graduate solved the great riddle in 1963. Roy Kerr’s solution emerged coincidentally with the discovery of black holes that same year and provided fertile testing ground—at long last—for general relativity. Today, scientists routinely cite the Kerr solution, but even among specialists, few know the story of how Kerr cracked Einstein’s...
	Introduction to Black Hole Physics by Valeri P. Frolov (Author), Andrei Zelnikov (Author) This book is about black holes, one of the most intriguing objects of modern Theoretical Physics and Astrophysics. For many years, black holes have been considered as interesting solutions of the theory of General Relativity with a number of amusing mathematical properties. Now after the discovery of astrophysical black holes, the Einstein gravity has become an important tool for their study. This self-contained textbook combines physical, mathematical, and astrophysical aspects of black hole theory. Pedagogically presented, it contains 'standard' material on black holes as well as relatively new subjects such as the role of hidden symmetries in black hole physics, and black holes in spacetimes with large extra dimensions. The book will appeal to students and young scientists interested...
	Black Hole by Sunil Doiphode (Author), Ewen Glass (Translator) interconnecting portals which turn out to be black holes that transcend time and reality