A new way to weigh giant black holes

Jul 16, 2008
A composite image from NASA's Chandra X-ray Observatory (shown in purple) and Hubble Space Telescope (blue) shows the giant elliptical galaxy NGC 4649. By applying a new technique, scientists used Chandra data to measure the black hole at its center to be about 3.4 billion times more massive than the Sun. The value from this X-ray technique is consistent with a more traditional method using the motions of stars near the black hole. NGC 4649 is now one of only a handful of galaxies for which the mass of a supermassive black hole has been measured with two different methods. Credit: X-ray: NASA/CXC/Univ. of California Irvine/P.Humphrey et al.; Optical: NASA/STScI

How do you weigh the biggest black holes in the universe? One answer now comes from a completely new and independent technique that astronomers have developed using data from NASA's Chandra X-ray Observatory.

By measuring a peak in the temperature of hot gas in the center of the giant elliptical galaxy NGC 4649, scientists have determined the mass of the galaxy's supermassive black hole. The method, applied for the first time, gives results that are consistent with a traditional technique.

Astronomers have been seeking out different, independent ways of precisely weighing the largest supermassive black holes, that is, those that are billions of times more massive than the Sun. Until now, methods based on observations of the motions of stars or of gas in a disk near such large black holes had been used.

"This is tremendously important work since black holes can be elusive, and there are only a couple of ways to weigh them accurately," said Philip Humphrey of the University of California at Irvine, who led the study. "It's reassuring that two very different ways to measure the mass of a big black hole give such similar answers."

NGC 4649 is now one of only a handful of galaxies for which the mass of a supermassive black hole has been measured with two different methods. In addition, this new X-ray technique confirms that the supermassive black hole in NGC 4649 is one of the largest in the local universe with a mass about 3.4 billion times that of the Sun, about a thousand times bigger than the black hole at the center of our galaxy.

The new technique takes advantage of the gravitational influence the black hole has on the hot gas near the center of the galaxy. As gas slowly settles towards the black hole, it gets compressed and heated. This causes a peak in the temperature of the gas right near the center of the galaxy. The more massive the black hole, the bigger the temperature peak detected by Chandra.

This effect was predicted by two of the co-authors -- Fabrizio Brighenti from the University of Bologna, Italy, and William Mathews from the University of California at Santa Cruz -- almost 10 years ago, but this is the first time it has been seen and used.

"It was wonderful to finally see convincing evidence of the effects of the huge black hole that we expected," said Brighenti. "We were thrilled that our new technique worked just as well as the more traditional approach for weighing the black hole."

The black hole in NGC 4649 is in a state where it does not appear to be rapidly pulling in material towards its event horizon, nor generating copious amounts of light as it grows. So, the presence and mass of the central black hole has to be studied more indirectly by tracking its effects on stars and gas surrounding it. This technique is well suited to black holes in this condition.

"Monster black holes like this one power spectacular light shows in the distant, early universe, but not in the local universe," said Humphrey. "So, we can't wait to apply our new method to other nearby galaxies harboring such inconspicuous black holes."

These results will appear in an upcoming issue of The Astrophysical Journal.

Source: Chandra X-ray Center

Explore further: Astronomers find evidence of water clouds in brown dwarf atmosphere

add to favorites email to friend print save as pdf

Related Stories

What lit up the universe?

8 hours ago

New research from UCL shows we will soon uncover the origin of the ultraviolet light that bathes the cosmos, helping scientists understand how galaxies were built.

Coal gas boom in China holds climate change risks

Aug 22, 2014

Deep in the hilly grasslands of remote Inner Mongolia, twin smoke stacks rise more than 200 feet into the sky, their steam and sulfur billowing over herds of sheep and cattle. Both day and night, the rumble ...

Toothpaste fluorine formed in stars

Aug 21, 2014

The fluorine that is found in products such as toothpaste was likely formed billions of years ago in now dead stars of the same type as our sun. This has been shown by astronomers at Lund University in Sweden, ...

New survey begins mapping nearby galaxies

Aug 18, 2014

A new survey called MaNGA (Mapping Nearby Galaxies at Apache Point Observatory) has been launched that will greatly expand our understanding of galaxies, including the Milky Way, by charting the internal ...

Recommended for you

Evidence for supernovas near Earth

1 hour ago

Once every 50 years, more or less, a massive star explodes somewhere in the Milky Way. The resulting blast is terrifyingly powerful, pumping out more energy in a split second than the sun emits in a million ...

Eta Carinae: Our Neighboring Superstars

17 hours ago

(Phys.org) —The Eta Carinae star system does not lack for superlatives. Not only does it contain one of the biggest and brightest stars in our galaxy, weighing at least 90 times the mass of the Sun, it ...

Best view yet of merging galaxies in distant universe

21 hours ago

Using the Atacama Large Millimeter/submillimeter Array, and other telescopes, an international team of astronomers has obtained the best view yet of a collision that took place between two galaxies when the ...

Image: Hubble stirs up galactic soup

Aug 25, 2014

(Phys.org) —This new NASA/ESA Hubble Space Telescope image shows a whole host of colorful and differently shaped galaxies; some bright and nearby, some fuzzy, and some so far from us they appear as small ...

Spectacular supernova's mysteries revealed

Aug 22, 2014

(Phys.org) —New research by a team of UK and European-based astronomers is helping to solve the mystery of what caused a spectacular supernova in a galaxy 11 million light years away, seen earlier this ...

User comments : 5

Adjust slider to filter visible comments by rank

Display comments: newest first

thales
1 / 5 (1) Jul 16, 2008
This method, which apparently only requires one observation, sounds like it's WAY faster than measuring star motions, which requires multiple observations. I'd bet we'll suddenly start hearing about the masses of all kinds of black holes, and the records of the biggest and smallest will soon be broken.
jamesrm
3 / 5 (2) Jul 16, 2008
This might change their views?
http://www.theoni...evidence

Regards
James
brant
1 / 5 (1) Jul 16, 2008
Baloney. The HSK is good science!!!
out7x
1 / 5 (1) Jul 17, 2008
weight and temperatures do not distinguish between a blackhole and many stars orbiting each other.
scottpittman
not rated yet Jul 28, 2009
how could the research done by Evan Scannapieco and Marcus Brüggen (http://www.physor...07.html) on the turbulence created by black holes as cooler gas is drawn toward its center then pushed out by its jets, affect this method of determining the mass of a black hole??