The Short Life of an Active Galaxy

The Short Life of an Active Galaxy - jet seen in wider...

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The Short Life of an Active Galaxy This model predicts that there should be many dead quasars lurking at the cores of galaxies. Astronomers are beginning to find the inactive supermassive black holes in some galaxies. In most galaxies the central black hole would have been smaller than the billions of solar mass black holes for quasars. This is why the less energetic active galaxies are more common than quasars. Our galaxy harbors a supermassive black hole in its core that has a mass of ``only'' 4.5 million solar masses. Astronomers are studying the cores of other normal galaxies to see if there are any signs of supermassive black holes that are now ``dead''. The beautiful grand-design spiral, the Whirlpool Galaxy Courtesy of NOAO/AURA/NSF X marks the spot in the core of the Whirlpool Galaxy! The darkest bar may be the dust ring seen edge-on. The
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Unformatted text preview: jet seen in wider fields of view is perpendicular to the darkest dust ring. The lighter bar may be another disk seen obliquely. A million solar mass black hole is thought to lurk at the center. Courtesy of Space Telescope Science Institute An important implication of the fact that there were more quasars billions of years ago than there are now, is that the universe changes over time. The conditions long ago were more conducive to quasar activity than they are today. In the next chapter you will explore the overall evolution of the universe. You will need to remember this point about a changing universe when you consider ideas for how the universe formed and grew. Also, the sharp drop in the quasar number for the earliest times is evidence for a beginning to the universe....
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