Chandra sees remarkable eclipse of black hole

Apr 12, 2007
Chandra sees remarkable eclipse of black hole
The large image shows an optical view of NGC 1365 from the ESO Very Large Telescope and the inset shows the Chandra X-ray Observatory view of the center of this galaxy. The bright source in the middle of the Chandra image shows the position of the supermassive black hole. During the eclipse the high energy X-rays from regions close to the black hole are blocked by dense gas clouds. Credit: X-ray: NASA/CXC/CfA/INAF/Risaliti Optical: ESO/VLT

A remarkable eclipse of a supermassive black hole and the hot gas disk around it has been observed with NASA's Chandra X-ray Observatory. This eclipse has allowed two key predictions about the effects of supermassive black holes to be tested.

Just as eclipses of the Sun and moon give astronomers rare opportunities to learn about those objects, an alignment in a nearby galaxy has provided a rare opportunity to investigate a supermassive black hole.

The supermassive black hole is located in NGC 1365, a galaxy 60 million light years from Earth. It contains a so called active galactic nucleus, or AGN. Scientists believe that the black hole at the center of the AGN is fed by a steady stream of material, presumably in the form of a disk. Material just about to fall into a black hole should be heated to millions of degrees before passing over the event horizon, or point of no return.

The disk of gas around the central black hole in NGC 1365 produces copious X-rays but is much too small to resolve directly with a telescope. However, the disk was eclipsed by an intervening cloud, so observation of the time taken for the disk to go in and out of eclipse allowed scientists to estimate the size of the disk.

"For years we've been struggling to confirm the size of this X-ray structure," said Guido Risaliti of the Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Mass, and the Italian Institute of Astronomy (INAF). "This serendipitous eclipse enabled us to make this breakthrough."

The Chandra team directly measured the size of the X-ray source as about seven times the distance between the Sun and the Earth. That means the source of X-rays is about 2 billion times smaller than the host galaxy and only about 10 times larger than the estimated size of the black hole's event horizon, consistent with theoretical predictions.

"Thanks to this eclipse, we were able to probe much closer to the edge of this black hole than anyone has been able to before," said co-author Martin Elvis from CfA. "Material this close in will likely cross the event horizon and disappear from the universe in about a hundred years, a blink of an eye in cosmic terms."

In addition to measuring the size of this disk of material, Risaliti and his colleagues were also able to estimate the location of the dense gas cloud that eclipsed the X-ray source and central black hole. The Chandra data show that this cloud is one hundredth of a light year from the black hole's event horizon, or 300 times closer than generally thought.

"AGN include the brightest objects in the Universe and are powerful probes of the early universe. So, it's vital to understand their basic structure," said Risaliti. "It turns out that we still have work to do to understand these monsters."

A series of six Chandra observations of NGC 1365 were made every two days over a period of two weeks in April 2006. During five of the observations, high energy X-rays from the central X-ray source were visible, but in the second one - corresponding to the eclipse - they were not.

Source: Chandra X-ray Center

Explore further: Black hole chokes on a swallowed star

add to favorites email to friend print save as pdf

Related Stories

Shadows cast by a warp in a planet forming system

Jan 08, 2015

Astronomers from MAD at Universidad de Chile present a viable scenario for the three dimensional geometry of a planet forming system. The finding is based on the discovery of shadows cast by a warped inner ...

Space exploration promises to be spectacular in 2015

Jan 06, 2015

There is no doubt that 2014 was a fantastic year for planetary sciences – the high points were the successful landing of Philae on comet 67P, the discovery of methane by the Curiosity rover on Mars and ...

Distorting the lens

Feb 09, 2012

( -- One of the most bizarre predictions of Einstein's Theory of General Relativity is the existence of back holes, objects that are so dense that not even light can escape from their gravitational ...

How to safely enjoy the October 23 partial solar eclipse

Oct 21, 2014

2014 – a year rich in eclipses. The Moon dutifully slid into Earth's shadow in April and October gifting us with two total lunars. Now it's the Sun's turn. This Thursday October 23 skywatchers across much ...

Partial solar eclipse over the U.S. on Thursday, Oct. 23

Oct 17, 2014

People in most of the continental United States will be in the shadow of the Moon on Thursday afternoon, Oct. 23, as a partial solar eclipse sweeps across the Earth. For people looking through sun-safe filters, from Los Angeles, ...

Recommended for you

Black hole chokes on a swallowed star

29 minutes 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

6 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

10 hours ago

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 : 0

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.