NASA Observatory Confirms Black Hole Limits

February 16, 2005
Observation of material circling a supermassive black hole

The very largest black holes reach a certain point and then grow no more. That's according to the best survey to date of black holes made with NASA's Chandra X-ray Observatory. Scientists also discovered previously hidden black holes well below their weight limit.

These new results corroborate recent theoretical work about how black holes and galaxies grow. The biggest black holes, those with at least 100 million times the mass of the sun, ate voraciously during the early universe. Nearly all of them ran out of "food" billions of years ago and went onto a forced starvation diet.

On the other hand, black holes approximately 10 to 100 million solar masses followed a more controlled eating plan. Because they took smaller portions of their meals of gas and dust, they continue growing.

"Our data show some super massive black holes seem to binge, while others prefer to graze," said Amy Barger of the University of Wisconsin and University of Hawaii. Barger is lead author of the paper describing the results in the latest issue of The Astronomical Journal. "We understand better than ever how super massive black holes grow."

One revelation is there is a strong connection between the growth of black holes and the birth of stars. Previously, astronomers had done careful studies of the birthrate of stars in galaxies but didn't know as much about the black holes at their centers.

"These galaxies lose material into their central black holes at the same time they make their stars," Barger said. "So whatever mechanism governs star formation in galaxies also governs black hole growth."

Astronomers made an accurate census of both the biggest, active black holes in the distance, and the relatively smaller, calmer ones closer to Earth. Now, for the first time, the ones in between have been properly counted.

"We need to have an accurate head count over time of all growing black holes if we ever hope to understand their habits, so to speak," said co-author Richard Mushotzky of NASA's Goddard Space Flight Center, Greenbelt, Md.

This study relied on the deepest X-ray images ever obtained, the Chandra Deep Fields North and South, plus a key wider-area survey of an area called the "Lockman Hole." The distances to the X-ray sources were determined by optical spectroscopic follow-up at the Keck 10-meter telescope on Mauna Kea in Hawaii, and show the black holes range from less than a billion to 12 billion light-years away. X-rays can penetrate the gas and dust that block optical and ultraviolet emissions. The very long-exposure images are crucial to find black holes that otherwise would go unnoticed.

Chandra found many of the black holes smaller than about 100 million suns are buried under large amounts of dust and gas. This prevents detection of the optical light from the heated material near the black hole. The X-rays are more energetic and able to burrow through this dust and gas. However, the largest of the black holes show little sign of being obscured by dust or gas. In a form of weight self-control, powerful winds generated by the black hole's feeding frenzy may have cleared out the remaining dust and gas.

Source: NASA

Explore further: Why can't we see the center of the Milky Way?

Related Stories

Why can't we see the center of the Milky Way?

July 10, 2015

For millennia, human beings have stared up at the night sky and stood in awe of the Milky Way. Today, stargazers and amateur astronomers continue in this tradition, knowing that what they are witnessing is in fact a collection ...

Radio astronomers see black hole come to life

July 9, 2015

42 million light years away, 20 million times the mass of the Sun, and coming back to life. A team of radio astronomers, led by Dr Megan Argo of the Jodrell Bank Centre for Astrophysics, are watching a previously dormant ...

Swift satellite reveals a black hole bull's-eye

July 9, 2015

What looks like a shooting target is actually an image of nested rings of X-ray light centered on an erupting black hole. On June 15, NASA's Swift satellite detected the start of a new outburst from V404 Cygni, where a black ...

Star formation near supermassive black holes

June 22, 2015

Most if not all galaxies are thought to host a supermassive black hole in their nuclei, a finding that is both one the most important and amazing in modern astronomy. A supermassive black hole grows by accreting mass, and ...

Hubble views a bizarre cosmic quartet

June 18, 2015

This new NASA/ESA Hubble Space Telescope image shows a gathering of four cosmic companions. This quartet forms part of a group of galaxies known as the Hickson Compact Group 16, or HCG 16—a galaxy group bursting with dramatic ...

Recommended for you

'Expansion entropy': A new litmus test for chaos?

July 28, 2015

Can the flap of a butterfly's wings in Brazil set off a tornado in Texas? This intriguing hypothetical scenario, commonly called "the butterfly effect," has come to embody the popular conception of a chaotic system, in which ...

'Carbon sink' detected underneath world's deserts

July 28, 2015

The world's deserts may be storing some of the climate-changing carbon dioxide emitted by human activities, a new study suggests. Massive aquifers underneath deserts could hold more carbon than all the plants on land, according ...

Lobster-Eye imager detects soft X-ray emissions

July 28, 2015

Solar winds are known for powering dangerous space weather events near Earth, which, in turn, endangers space assets. So a large interdisciplinary group of researchers, led by the U.S. National Aeronautics and Space Administration ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.