The Sky Holds A Billion Supermassive Black Holes

Made with over 7 million seconds of Chandra observing time, this image is part of the Chandra Deep Field-South (CDF-S) and the deepest X-ray image ever obtained. CDF-S gives astronomers the best look yet at the growth of black holes over billions of years starting soon after the Big Bang. Low, medium, and high-energy X-rays that Chandra detects are shown as red, green, and blue respectively. Credit: X-ray: NASA/CXC/Penn State/B.Luo et al.

All those red, white and blue dots? Nearly every one is a supermassive black hole in a galaxy billions of light years away. There are 1,008 visible in the image made using NASA’s orbiting Chandra X-Ray Observatory. To capture so many, Chandra spent 7 million seconds (almost 12 weeks) of observing time focused on a spot in the sky just 20 arc seconds across.

Do you know how tiny that is? The full moon is ½° or 3o arc minutes in diameter. Since a minute of arc is equal to 60 arc seconds, the field of view is 1/90th the size of the full moon or about as wide as a moderate-sized lunar crater. The central part of the image contains the greatest concentration of black holes. If we extrapolate their number across the entire sky, the total number of galaxies with supermassive black holes approaches one billion!

This time-lapse animation is made from 4 million seconds of Chandra data. Every sparkling dot is a supermassive black hole gobbling up stars, planets and cosmic dust. X-ray: NASA/CXC/Penn State/B.Luo et al.

The photo is part of the Chandra Deep Field-South (CDF-S) in the constellation Fornax the Furnace (visible in fall and early winter). Using the new data, researchers have found evidence that black holes in the early universe may have started out big from the get-go, seeded by the collapse of chunky clouds of interstellar dust and gas with masses 10,000 to 100,000 times that of the sun. It appears that if they instead began as lightweights with only 100 times the sun’s mass, they’d never have enough time to grow into the behemoths we see today.

Hard to believe that’s considered a “seed,” but when it comes to supermassive black hole formation, it appears you don’t start small. Nature’s scale of creation is vast: a piece of dust seeds the growth of a snowflake or raindrop.

This artist’s impression depicts a rapidly spinning supermassive black hole surrounded by an accretion disc. This thin disc of rotating material consists of the leftovers of a Sun-like star or cloud of gas and dust which was ripped apart by the tidal forces of the black hole. Shocks in the colliding debris as well as heat generated in accretion cause the disk to glow. The black hole appears truly black because even light can’t escape it. Credit: ESA/Hubble, ESO, M. Kornmesser

The new data hint that black holes instead grew mostly in spurts — call it binging — rather than by the slow accumulation of matter from stray stars, dust, gas and wayward planets.

Do you find it as amazing as I do that so much mass in the universe has been swallowed by such massive entities? Makes a guy want to watch his step the next clear night.

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