The Ins and Outs of Black Hole Accretion

在大多数星系的中心存在着一个比太阳大数百万甚至数十亿倍的超大质量黑洞。其中一些怪物非常活跃，它们可以使周围的物质比宿主星系中的所有恒星都要亮。距离黑洞最近的物质，就在它即将跃出视界的时候，温度非常高，它会辐射出x射线，并受到宇宙中最剧烈的条件的影响。黑洞的极端引力可以撕裂恒星，并在物质最终被吸收之前以接近光速的速度四处抛掷。有时，这种物质会被猛烈地抛出，以至于完全从黑洞区域抛出，并被抛回邻近的星系，在那里它可能对宿主星系的状况产生巨大的影响。

A supermassive black hole that is millions or even billions of times more massive than the Sun resides at the centres of most galaxies. Some of these monsters are so active that they can make the surrounding material shine brighter than all the stars in its host galaxy. The material closest to the black hole, just as it is about to plunge beyond the event horizon, is so hot it radiates X-rays and it is subjected to the most violent conditions in the Universe. The extreme gravity of the black hole can tear stars apart and fling matter around at velocities close to the speed of light before it is finally ingested. Sometimes this material can be thrown out so violently that it is completely ejected from the black hole region and hurled back into the galactic neighbourhood where it may have a resounding effect on the conditions in the host galaxy. Observing these active galaxies with space-based X-ray observatories may be the only way to study the exotic physics at work in the black hole environment. What does the environment look like? How is material falling into the black hole and what is it made of? How does material near a black hole get ejected from the system? How does this ejecta influence the host galaxy that the black hole resides in? These are only a few questions that my team will be tackling over the course of this work to try understanding how black holes grow and galaxies evolve. In 2021, the XRISM X-ray observatory will be launched and it will have the highest energy resolution instruments every available in X-ray astronomy. This means we can accurately determine the composition and temperature of the material around black holes, and the direction and speed at which it is moving. We will be able to accurately distinguish material that is falling into or escaping from the black hole. We will be able to determine the geometry and kinematics of the material around black holes. Our Canadian students will be the ones answering the fundamental questions posed by this research program. By confronting Nature's most exotic creatures, we are building capacity and knowledge in space-based research in Canada.