Measuring the spin distribution of supermassive black holes is of critical importance for understanding how these black holes and their host galaxies form and evolve over time, yet this type of study is only in its infancy. This brief describes how astronomers measure spin in supermassive black holes using X-ray spectroscopy. It also reviews the constraints that have been placed on the spin distribution in local, bright active galaxies over the past six years, and the cosmological implications of these constraints. Finally, it summarizes the open questions that remain in this exciting new field of research and points toward future discoveries soon to be made by the next generation of space-based observatories.
"An introduction to quasars and black holes with information about their formation and characteristics. Includes diagrams, fun facts, a glossary, a resource list, and an index"--Provided by publisher.
“[A] skillfully told history of the quest to find black holes.” —Manjit Kumar, Financial Times Black holes are the best-known and least-understood objects in the universe. In Einstein’s Monsters, distinguished astronomer Chris Impey takes readers on a vivid tour of these enigmatic giants. He weaves a fascinating tale out of the fiendishly complex math of black holes and the colorful history of their discovery. Impey blends this history with a poignant account of the phenomena scientists have witnessed while observing black holes: stars swarming like bees around the center of our galaxy; black holes performing gravitational waltzes with visible stars; the cymbal clash of two black holes colliding, releasing ripples in space time. Clear, compelling, and profound, Einstein’s Monsters reveals how our comprehension of black holes is intrinsically linked to how we make sense of the universe and our place within it.
In the past, they were recognized as the most destructive force in nature. Now, following a cascade of astonishing discoveries, supermassive black holes have undergone a dramatic shift in paradigm. Astronomers are finding out that these objects may have been critical to the formation of structure in the early universe, spawning bursts of star formation, planets, and even life itself. They may have contributed as much as half of all the radiation produced after the Big Bang, and as many as 200 million of them may now be lurking through the vast expanses of the observable cosmos. In this elegant, non-technical account, Melia conveys for the general reader the excitement generated by the quest to expose what these giant distortions in the fabric of space and time have to say about our origin and ultimate destiny.
The authoritative story of the headline-making discovery of gravitational waves—by an eminent theoretical astrophysicist and award-winning writer. From the author of How the Universe Got Its Spots and A Madman Dreams of Turing Machines, the epic story of the scientific campaign to record the soundtrack of our universe. Black holes are dark. That is their essence. When black holes collide, they will do so unilluminated. Yet the black hole collision is an event more powerful than any since the origin of the universe. The profusion of energy will emanate as waves in the shape of spacetime: gravitational waves. No telescope will ever record the event; instead, the only evidence would be the sound of spacetime ringing. In 1916, Einstein predicted the existence of gravitational waves, his top priority after he proposed his theory of curved spacetime. One century later, we are recording the first sounds from space, the soundtrack to accompany astronomy’s silent movie. In Black Hole Blues and Other Songs from Outer Space, Janna Levin recounts the fascinating story of the obsessions, the aspirations, and the trials of the scientists who embarked on an arduous, fifty-year endeavor to capture these elusive waves. An experimental ambition that began as an amusing thought experiment, a mad idea, became the object of fixation for the original architects—Rai Weiss, Kip Thorne, and Ron Drever. Striving to make the ambition a reality, the original three gradually accumulated an international team of hundreds. As this book was written, two massive instruments of remarkably delicate sensitivity were brought to advanced capability. As the book draws to a close, five decades after the experimental ambition began, the team races to intercept a wisp of a sound with two colossal machines, hoping to succeed in time for the centenary of Einstein’s most radical idea. Janna Levin’s absorbing account of the surprises, disappointments, achievements, and risks in this unfolding story offers a portrait of modern science that is unlike anything we’ve seen before.
From the acclaimed author of Black Hole Blues and Other Songs from Outer Space—an authoritative and accessible guide to the most alluring and challenging phenomena of contemporary science. "[Levin will] take you on a safe black hole trip, an exciting travel story enjoyed from your chair’s event horizon.” —Boston Globe Through her writing, astrophysicist Janna Levin has focused on making the science she studies not just comprehensible but also, and perhaps more important, intriguing to the nonscientist. In this book, she helps us to understand and find delight in the black hole—perhaps the most opaque theoretical construct ever imagined by physicists—illustrated with original artwork by American painter and photographer Lia Halloran. Levin takes us on an evocative exploration of black holes, provoking us to imagine the visceral experience of a black hole encounter. She reveals the influence of black holes as they populate the universe, sculpt galaxies, and even infuse the whole expanse of reality that we inhabit. Lively, engaging, and utterly unique, Black Hole Survival Guide is not just informative—it is, as well, a wonderful read from first to last.
This book provides a general introduction to the rapidly developing astrophysical frontier of stellar tidal disruption, but also details original thesis research on the subject. This work has shown that recoiling black holes can disrupt stars far outside a galactic nucleus, errors in the traditional literature have strongly overestimated the maximum luminosity of “deeply plunging” tidal disruptions, the precession of transient accretion disks can encode the spins of supermassive black holes, and much more. This work is based on but differs from the original thesis that was formally defended at Harvard, which received both the Roger Doxsey Award and the Chambliss Astronomy Achievement Student Award from the American Astronomical Society.
A collection of essays on the cosmos, written by an American Museum of Natural History astrophysicist, includes "Holy Wars," "Ends of the World," and "Hollywood Nights."
Quasars, and the menagerie of other galaxies with "unusual nuclei", now collectively known as Active Galactic Nuclei or AGN, have, in one form or another, sparked the interest of astronomers for over 60 years. The only known mechanism that can explain the staggering amounts of energy emitted by the innermost regions of these systems is gravitational energy release by matter falling towards a supermassive black hole --- a black hole whose mass is millions to billions of times the mass of our Sun. AGN emit radiation at all wavelengths. X-rays originating at a distance of a few times the event horizon of the black hole are the emissions closest to the black hole that we can detect; thus, X-rays directly reveal the presence of active supermassive black holes. Oftentimes, however, the supermassive black holes that lie at the centers of AGN are cocooned in gas and dust that absorb the emitted low energy X-rays and the optical and ultraviolet light, hiding the black hole from view at these wavelengths. Until recently, this low-energy absorption presented a major obstacle in observational efforts to map the accretion history of the universe. In 1999 and 2000, the launches of the Chandra and XMM-Newton X-ray Observatories finally broke the impasse. The impact of these observatories on X-ray astronomy is similar to the impact that the Hubble Space Telescope had on optical astronomy. The astounding new data from these observatories have enabled astronomers to make enormous advances in their understanding of when accretion occurs.
