Of all the major astronomy discoveries in recent years, one of the top findings is that the center of every large galaxy scrutinized with the Hubble Space Telescope, the Chandra X-ray Observatory, and other instruments shows evidence for a supermassive black hole. Our own Milky Way, for example, contains a black hole with about 4 million solar masses. The giant elliptical galaxy M87 in the Virgo Cluster contains a black hole with a whopping 3 billion solar masses!

Even more astonishing, astronomers began to realize in the late 1990s that there is a deep relationship between supermassive black holes and their host galaxies. The more massive the galaxy, the more massive its central black hole. This relationship is so tight and linear that it could not have arisen by chance. Astronomers realized immediately that the evolution of a galaxy and its central black hole must be intimately connected. Black holes must be able to influence their environments, and not just their immediate surroundings, but at distances of tens of thousands or even hundreds of thousands of light-years. How?

This Chandra image of the Centaurus galaxy cluster shows a long plume-like feature resembling a twisted sheet. [More]...

Over the past few years, observations by Chandra and other telescopes have shown large outflows of gas coming from the centers of many large galaxies, driven by powerful winds emanating from the central black holes. These flows can clear gas from a galaxy, preventing it from growing and forming new stars, and choking off the material that could feed the central black hole. In other words, supermassive black holes can drive powerful outflows that can choke off their own growth, and the growth of their host galaxy. Complex feedback loops are at work, which regulate the growth of galaxies and their black holes, leading to the tight mass relationship observed between black holes and their host galaxies.

The Constellation-X mission, part of the Beyond Einstein program, will probe this “cosmic feedback” loop in more detail by observing these outflows at much greater distances, when our Universe was younger and black-hole activity was more intense. It will also be able to provide more specifics about how black-hole activity affects the surrounding gas. By seeing this activity rise and fall over billions of years of cosmic history, Constellation-X will provide profound insights on how black holes and their host galaxies coevolved and produced the Universe we see around us today.