NASA Observatory Confirms Black Hole Limits

Feb 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: Mysteries of space dust revealed

add to favorites email to friend print save as pdf

Related Stories

NuSTAR celebrates two years of science in space

Aug 01, 2014

(Phys.org) —NASA's Nuclear Spectroscopic Telescope Array, or NuSTAR, a premier black-hole hunter among other talents, has finished up its two-year prime mission, and will be moving onto its next phase, ...

Black hole fireworks in nearby galaxy

Jul 03, 2014

(Phys.org) —Celebrants this Fourth of July will enjoy the dazzling lights and booming shock waves from the explosions of fireworks. A similarly styled event is taking place in the galaxy Messier 106, as ...

Are ultra-luminous galaxies colliding?

Jun 27, 2014

(Phys.org) —ltra-luminous infrared galaxies ((ULIRGs) are galaxies whose luminosity exceeds that of a trillion suns, By way of comparison, our Milky Way galaxy has a typical modest luminosity of only about ...

Celebrating a decade of the Submillimeter Array

Jun 25, 2014

(Phys.org) —Ten years ago, eight antennas on the summit of Mauna Kea, Hawai'i, united to form a telescope unlike any other. Since then the Submillimeter Array (SMA) has examined the universe in unprecedented ...

Herschel sees budding stars and a giant, strange ring

Jun 13, 2014

The Herschel Space Observatory has uncovered a weird ring of dusty material while obtaining one of the sharpest scans to date of a huge cloud of gas and dust, called NGC 7538. The observations have revealed ...

Recommended for you

Mysteries of space dust revealed

Aug 29, 2014

The first analysis of space dust collected by a special collector onboard NASA's Stardust mission and sent back to Earth for study in 2006 suggests the tiny specks open a door to studying the origins of the ...

A guide to the 2014 Neptune opposition season

Aug 29, 2014

Never seen Neptune? Now is a good time to try, as the outermost ice giant world reaches opposition this weekend at 14:00 Universal Time (UT) or 10:00 AM EDT on Friday, August 29th. This means that the distant ...

How can we find tiny particles in exoplanet atmospheres?

Aug 29, 2014

It may seem like magic, but astronomers have worked out a scheme that will allow them to detect and measure particles ten times smaller than the width of a human hair, even at many light-years distance.  ...

Spitzer telescope witnesses asteroid smashup

Aug 28, 2014

(Phys.org) —NASA's Spitzer Space Telescope has spotted an eruption of dust around a young star, possibly the result of a smashup between large asteroids. This type of collision can eventually lead to the ...

User comments : 0