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.
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.
The International Bestseller On April 10, 2019, award-winning astrophysicist Heino Falcke presented the first image ever captured of a black hole at an international press conference—a turning point in astronomy that Science magazine called the scientific breakthrough of the year. That photo was captured with the unthinkable commitment of an intercontinental team of astronomers who transformed the world into a global telescope. While this image achieved Falcke’s goal in making a black hole “visible” for the first time, he recognizes that the photo itself asks more questions for humanity than it answers. Light in the Darkness takes us on Falcke’s extraordinary journey to the darkest corners of the universe. From the first humans looking up at the night sky to modern astrophysics, from the study of black holes to the still-unsolved mysteries of the universe, Falcke asks, in even the greatest triumphs of science, is there room for doubts, faith, and a God? A plea for curiosity and humility, Light in the Darkness sees one of the great minds shaping the world today as he ponders the big, pressing questions that present themselves when we look up at the stars.
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.
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] 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.
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."
The formation of the first supermassive black holes is one of the main open questions in our understanding of high-redshift structure formation. In this book, we aim to provide a summary of state-of-the-art modern research on this topic, exploring the formation of massive black holes from a fluid-dynamical, stellar-dynamical and chemical perspective. The book thus presents a solid theoretical foundation, a comparison with current observations and future observational perspectives with upcoming missions such as the Square Kilometre Array, the European Extremely Large Telescope, the Euclid satellite as well as possible detections via gravitational waves.
Deep within galaxies like the Milky Way, astronomers have found a fascinating legacy of Einstein's general theory of relativity: supermassive black holes. Connected to the evolution of the galaxies that contain these black holes, galactic nuclei are the sites of uniquely energetic events, including quasars, stellar tidal disruptions, and the generation of gravitational waves. This textbook is the first comprehensive introduction to dynamical processes occurring in the vicinity of supermassive black holes in their galactic environment. Filling a critical gap, it is an authoritative resource for astrophysics and physics graduate students, and researchers focusing on galactic nuclei, the astrophysics of massive black holes, galactic dynamics, and gravitational wave detection. It is an ideal text for an advanced graduate-level course on galactic nuclei and as supplementary reading in graduate-level courses on high-energy astrophysics and galactic dynamics. David Merritt summarizes the theoretical work of the last three decades on the evolution of galactic nuclei, the formation of massive black holes, and the interaction between black holes and stars. He explores in depth such important topics as observations of galactic nuclei, dynamical models, weighing black holes, motion near supermassive black holes, evolution of nuclei due to gravitational encounters, loss cone theory, and binary supermassive black holes. Self-contained and up-to-date, the textbook includes a summary of the current literature and previously unpublished work by the author. For researchers working on active galactic nuclei, galaxy evolution, and the generation of gravitational waves, this book will be an essential resource.
