Nearby black hole is feeble and unpredictable

May 25, 2010
The large image here shows an optical view, with the Digitized Sky Survey, of the Andromeda Galaxy, otherwise known as M31. The inset shows Chandra images of a small region in the center of Andromeda. The image on the left shows a sum of Chandra images taken before January 2006 and the image on the right shows a sum of images taken after January 2006. Before 2006, three X-ray sources are clearly visible, including one faint source close to the center of the image. After 2006, a fourth source, called M31*, appears just below and to the right of the central source, produced by material falling onto the supermassive black hole in M31. Credit: X-ray (NASA/CXC/SAO/Li et al.), Optical (DSS)

For over 10 years, NASA's Chandra X-ray Observatory has repeatedly observed the Andromeda Galaxy for a combined total of nearly one million seconds. This unique data set has given astronomers an unprecedented view of the nearest supermassive black hole outside our own Galaxy.

Astronomers think that most galaxies - including the Milky Way - contain giant black holes at their cores that are millions of times more massive than the Sun. At a distance of just under 3 million light years from Earth, Andromeda (also known as M31) is relatively close and provides an opportunity to study its black hole in great detail.

Just like the one in the center of the Milky Way, the black hole in Andromeda is surprisingly quiet. In fact, Andromeda's black hole, known as M31*, is ten to one hundred thousand times fainter in X-ray light that astronomers might expect given the reservoir of gas around it.

"The black holes in both Andromeda and the Milky Way are incredibly feeble," said Zhiyuan Li of the Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Mass. "These two 'anti-quasars' provide special laboratories for us to study some of the dimmest type of accretion even seen onto a ."

The decade-long study by Chandra reveals that M31* was in a very dim, or quiet, state before 2006. However, on January 6, 2006, the black hole became more than a hundred times brighter, suggesting an outburst of X-rays. This was the first time such an event had been seen from a supermassive black hole in the nearby, local universe.

After the outburst, M31* entered another relatively dim state, but was almost ten times brighter on average than before 2006. The outburst suggests a relatively high rate of matter falling onto M31* followed by a smaller, but still significant rate.

"We have some ideas about what's happening right around the black hole in Andromeda, but the truth is we still don't really know the details," said Christine Jones, also of the CfA.

The overall brightening since 2006 could be caused by M31* capturing winds from an orbiting star, or by a gas cloud that spiraled into the black hole. The increase in the rate of material falling towards the black hole is thought to drive an X-ray brightening of a relativistic jet.

The cause of the outburst in 2006 is even less clear, but it could be due to a sudden release of energy, such as magnetic fields in a disk around the black hole that suddenly connect and become more powerful.

"It's important to figure out what's going on here because the accretion of matter onto these black holes is one of the most fundamental processes governing the evolution of galaxies," said Li, who presented these results at the 216th meeting of the American Astronomical Society meeting in Miami, FL.

These results imply that the feeble, but erratic behavior of the black hole in the Milky Way may be typical for present-day supermassive .

Explore further: Black hole chokes on a swallowed star

Related Stories

How do supermassive black holes get so big?

Apr 26, 2010

( -- At the center of most galaxies lie supermassive black holes that can grow to become more than a billion times larger than our Sun. However, astrophysicists don’t fully understand the formation ...

Chandra data reveal rapidly whirling black holes

Jan 10, 2008

A new study using results from NASA's Chandra X-ray Observatory provides one of the best pieces of evidence yet that many supermassive black holes are spinning extremely rapidly. The whirling of these giant ...

Supermassive black hole is thrown out of galaxy

May 11, 2010

( -- Undergraduate student Marianne Heida of the University of Utrecht has found what appears to be a supermassive black hole leaving its home galaxy at high speed. As part of an international ...

Galaxy cluster takes it to the extreme

May 30, 2007

Evidence for an awesome upheaval in a massive galaxy cluster was discovered in an image made by NASA’s Chandra X-ray Observatory. The origin of a bright arc of ferociously hot gas extending over two million light years ...

M82: 'Survivor' Black Holes May Be Mid-Sized

Apr 29, 2010

( -- New evidence from NASA's Chandra X-ray Observatory and ESA's XMM-Newton strengthens the case that two mid-sized black holes exist close to the center of a nearby starburst galaxy. These "survivor" ...

Recommended for you

Black hole chokes on a swallowed star

14 hours ago

A five-year analysis of an event captured by a tiny telescope at McDonald Observatory and followed up by telescopes on the ground and in space has led astronomers to believe they witnessed a giant black hole ...

Swarm of microprobes to head for Jupiter

20 hours ago

A swarm of tiny probes each with a different sensor could be fired into the clouds of Jupiter and grab data as they fall before burning up in the gas giant planet's atmosphere. The probes would last an estimated ...

A recoiling, supermassive black hole

Jan 26, 2015

When galaxies collide, the central supermassive black holes that reside at their cores will end up orbiting one another in a binary pair, at least according to current simulations. Einstein's general theory ...

Chandra celebrates the International Year of Light

Jan 23, 2015

The year of 2015 has been declared the International Year of Light (IYL) by the United Nations. Organizations, institutions, and individuals involved in the science and applications of light will be joining ...

Why is Andromeda coming toward us?

Jan 23, 2015

I don't want to alarm you, but there's a massive galaxy heading our way and will collide with us in a few billion years. But aren't most galaxies speeding away? Why is Andromeda on a collision course with ...

User comments : 5

Adjust slider to filter visible comments by rank

Display comments: newest first

1 / 5 (4) May 25, 2010
I doubt the existence of massive black holes.

Neutron repulsion (NR) prevents the collapse of neutron stars into black holes.

NR causes massive neutron stars to fragment explosively to produce galaxies of ordinary stars.

NR causes neutron-emission from the neutron star at the core of ordinary stars. Then neutron-decay produces the Hydrogen that pours from the surfaces of ordinary stars to fill interstellar space.

With kind regards,
Oliver K. Manuel
1 / 5 (2) May 26, 2010
Neutrons are just one step in the particle hiearchy... IMO black holes are rather neutrino or axion stars.

BTW The repulsion of neutrons isn't the only mechanism preventing the collapse of massive stars...


5 / 5 (3) May 26, 2010
The 4 million solar mass BH in our galaxy, Sag A*, has a date to meet the 4 million solar mass BH M 31* some 5 billion years in the future when the Milky Way is expected to merge with the Andromeda Galaxy. By that time, though, our sun will likely be a cooling white dwarf and the Earth will have been fried.
1 / 5 (4) May 29, 2010
My Firm Belief: There are NO "Black Holes." Center of galaxies contain immense luminosity from SUNS who are "generating" new Suns via birth/create/shedding a portion of themselves. The above stated "reservoir of gas around it (erroneous black hole)" is the AFTERBIRTH of Suns creating Suns. When a birth occurs, the outburst of LIGHT is immense; in Time will diminish. My "Sun Creation Theory" of 2008 and 2009 presentation says it all in very simplistic language. Yes, it is the replacement (finally) for the Big Bang Theory. Time for new thinking.
5 / 5 (3) May 29, 2010
My Firm Belief: There are NO "Black Holes."
We are observing massive stars at the center of galaxy, which are revolving some massive, yet invisible object.

This looks pretty much as an evidence of black hole.

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.