Quasars and Active Galaxies

In 1963, an astronomer in California stared at a spectrum of what appeared to be a faint star and realized he was looking at something billions of light-years away, producing more energy than an entire galaxy of hundreds of billions of stars from a region smaller than the solar system. He had discovered quasars. Nobody had predicted they could exist. Nobody had any idea what powered them. This book explains how we found out.Quasars and Active Galaxies is a complete account of the most energetic phenomena in the universe, written for adult readers who want the real science. You will understand how a supermassive black hole converts infalling matter into radiation at efficiencies up to 40 percent, an advantage of 60 times over the nuclear fusion in stars, and why this makes a region smaller than the solar system outshine an entire galaxy. You will follow the complete history from Karl Jansky's 1932 accidental discovery of cosmic radio emission, through Maarten Schmidt's 1963 identification of quasar redshifts, to the Event Horizon Telescope's 2022 direct image of the shadow of the Milky Way's own supermassive black hole. You will learn how blazars point their relativistic jets directly at Earth and produce apparent motions faster than light, how radio galaxy jets stretch for millions of light-years and heat the gas in entire galaxy clusters, and how quasar feedback has shaped the evolution of every large galaxy in the universe including our own.Twelve chapters cover the full landscape: the discovery history, the physics of accretion disks and relativistic jets, Seyfert galaxies, radio galaxies, blazars, the unified model, AGN feedback and galaxy co-evolution, quasars as probes of the cosmic web, and the Event Horizon Telescope results for both M87 and Sagittarius A*. Every major type of active galaxy is explained, every key physical mechanism is derived from first principles, and the current state of every major open question is honestly assessed.Part of the Stars and Galaxies Adult Series.

In 1963, an astronomer in California stared at a spectrum of what appeared to be a faint star and realized he was looking at something billions of light-years away, producing more energy than an entire galaxy of hundreds of billions of stars from a region smaller than the solar system. He had discovered quasars. Nobody had predicted they could exist. Nobody had any idea what powered them. This book explains how we found out.Quasars and Active Galaxies is a complete account of the most energetic phenomena in the universe, written for adult readers who want the real science. You will understand how a supermassive black hole converts infalling matter into radiation at efficiencies up to 40 percent, an advantage of 60 times over the nuclear fusion in stars, and why this makes a region smaller than the solar system outshine an entire galaxy. You will follow the complete history from Karl Jansky's 1932 accidental discovery of cosmic radio emission, through Maarten Schmidt's 1963 identification of quasar redshifts, to the Event Horizon Telescope's 2022 direct image of the shadow of the Milky Way's own supermassive black hole. You will learn how blazars point their relativistic jets directly at Earth and produce apparent motions faster than light, how radio galaxy jets stretch for millions of light-years and heat the gas in entire galaxy clusters, and how quasar feedback has shaped the evolution of every large galaxy in the universe including our own.Twelve chapters cover the full landscape: the discovery history, the physics of accretion disks and relativistic jets, Seyfert galaxies, radio galaxies, blazars, the unified model, AGN feedback and galaxy co-evolution, quasars as probes of the cosmic web, and the Event Horizon Telescope results for both M87 and Sagittarius A*. Every major type of active galaxy is explained, every key physical mechanism is derived from first principles, and the current state of every major open question is honestly assessed.Part of the Stars and Galaxies Adult Series.