Tag Archives: Black Holes

Possibly the Largest Black Hole Discovered

Astronomers led by Remco van den Bosch, from the Max-Planck Institute in Heidelberg, Germany have discovered a massive black hole at the center of a galaxy 250 million light-years away. The black hole has a mass equivalent to 17 billion of our sun. It is quite possibly the largest black hole ever discovered and is turning galaxy evolution models on their side.

ngc 1277
Image credit: NASA / ESA / Andrew C. Fabian / Remco C. E. van den Bosch (MPIA)

Picture above, you can see the disk shape galaxy NGC 1277 that was captured by the Hubble Space Telescope. At the center of this galaxy is the black hole that scientists are saying accounts for 14% of the galaxy’s weight. To put the size of this black hole in perspective, our own milky way galaxy has a black hole equivalent to the mass of 4 million suns. NGC 1277 has the mass of 17 billion suns!

It has typically been thought that the mass of a galaxies black hole correlates to the mass of the stars in a galaxy. After this discovery however, it seems that theory may not be true. The ratio of this black hole to the mass of the stars in its galaxy are way off the typical charts. Small disk shaped galaxies typically have much smaller black holes that usually account for less than 1% of their mass. Finding one that accounts for 14% of its mass is truly rare. Black holes of this size are usually found elliptical galaxies.

It appears after further examination that this phenomenon isn’t as rare as once thought. Other black holes with similar characteristics have been found since NGC 1277 was discovered to contain a super massive black hole. According to a Space.com article, Remco van den Bosch is quoted as saying, “You always expect to find one sort [of a phenomenon], but now we have six of them,” van den Bosch said. “We didn’t expect them, because we do expect the black holes and the galaxies to influence each other.” It appears now scientists will have to determine if this phenomenon only exists in the early universe and how this information affects our theories of galaxy evolution.

For more information, visit the journal Nature.

Indian Led Team Discovers Giant Black Holes

A team of researchers from the University of Cambridge, led by Dr Manda Banerji, has discovered previously undetected supermassive black holes in the deepest regions of the early universe. The study is published in the Monthly Notices of the Royal Astronomical Society.

Infrared colour image of ULASJ1234+0907 located 11 billion light years from Earth and one of the reddest objects in the sky. (UKIDSS / Wide-Field Infrared Survey Explorer Observatory)

A Royal Astronomical Society press release said the team used “cutting-edge infrared surveys of the sky to discover a new population of enormous, rapidly growing supermassive black holes in the early Universe”. Apparently, these black holes have been hidden from our site due to a thick layer of dust that surrounds them. One of the super massive black holes, labeled ULASJ1234+0907, is 10,000 times the size of our own Milky Way galaxy. It, and other black holes like it, is emitting enormous radiation through violent interactions with its  host galaxy.

Dr Manda Banerji said, “Most black holes of this kind are seen through the matter they drag in. As the neighboring material spirals in towards the black holes, it heats up. Astronomers are able to see this radiation and observe these systems.” He went on to say, “Although these black holes have been studied for some time, the new results indicate that some of the most massive ones may have so far been hidden from our view.”

Most of the massive black holes are located at the center of galaxies. Due to collisions with other galaxies, they are often surrounded by massive clouds of dust. The team from Cambridge used infrared surveys being carried out on the UK Infrared Telescope (UKIRT) to look past the dust and locate the giant black holes for the first time. This research could have significant impact on the way black holes are studied in the future. For more information, visit http://www.ras.org.uk.

Discovered: Monster Black Holes, The Most Massive Ones Ever!

There are monsters out there that are larger than anything we can imagine or know! This feeling was once again reaffirmed yesterday, when scientists published results that told them of two new supermassive blackholes that turn out to be bigger than any known so far. These two weigh in at an estimated 9.7 Billion Solar masses!

An artist's impression of the transit of a blackhole across a cosmic structure.

Supermassive blackholes are known to reside in the centers of galaxies. They are presumed to grow in size by gobbling up all matter and gases that come their way. The one at the center of our own Milky Way Galaxy is estimated at a million solar masses! If you think that is big, then be prepared to be blown away.

The Giants

The largest known black hole was the Messier 87 black hole. This weighed in at a gigantic 6.3 billion solar masses. A new blackhole found in NGC 3842 in the Leo cluster is a gigantic 9.7 billion solar mass monster. This is located 320 million light years away from us. Another one has been found in NGC 4889, in the Coma cluster. This one is 335 million light years away and is similar in mass. The event horizon or the boundary beyond which nothing, not even light, can escape the gravitational force of the blackhole is bigger than the radius of the orbit of Pluto! Compare this to the Milky way blackhole, whose event horizon, by comparison, is a small one at just about one-fifth the size of the orbit of Mercury.

The Centaurus-A quasar. The photo is a merged false-color photo. It contains data from the Chandra X-ray Telescope and ground based radio telescope. The short blue emissions are X-ray emissions (caught by Chandra) and the longer orange-yellowish plumes are radio-emissions. The central galaxy is captured in optical by Hubble Space Telescope. (Courtesy: NASA/GSFC/Chandra/Hubble)

These blackholes are found by looking at the emission of the accretion disks. Matter falling in becomes so hot that it emits light in many wavelengths, including X-Ray and radio. Scientists know objects which are just about the size of a typical spiral galaxy, or even smaller, but emit radiation, which is unusually high. Such structures are called quasars’, shortened from Quasi-Stellar Objects. They are believed to be powered’ by a central blackhole engine!

The research is going to be published in Nature on 8th December.

Discovered: Two Nearby Supermassive Black Holes Gobbling Up Each Other

This is cannibalism on the cosmic scale. Two black holes have been found by the Chandra X-Ray Telescope gobbling matter from one another. The black holes are in the process of merging with one another. The real excitement is that this is close to home on the scale of the cosmos about 160 million light years away.

The Giants!

The galaxy in the limelight is NGC3393. The two black holes are separated by only 490 light years. One of them has a mass of 30 million suns and other is much smaller at one million solar mass. The bigger one is gobbling up matter surrounding the smaller one.

Chandra's Picture of the twin black holes. (Photo Courtesy: NASA/CXC/SAO/G.Fabbiano et al; Optical: NASA/STScI)

The close proximity of the black holes has also got scientists excited. It is because these supermassive black holes are so close that Chandra could resolve them into two distinct objects. When a black hole accretes matter, i.e. just gathers by sucking the matter around it, the matter gets hot enough to radiate profusely in the X-Ray region. These radiations occur close to the event horizon and this is where Chandra X-Ray Telescope can work its magic. But even Chandra couldn’t have spotted such a double black hole system if it were farther away.

Many that got away?

What we are seeing is really a merger. Black holes merge to become even bigger black holes. It is surprising that NGC3393 still retains the elliptic shape that it originally had. The perturbations occur near the central part and do not propagate throughout the galaxy. NASA scientists think that this is one reason why black hole mergers or double black hole systems have rarely been observed till date. The expected tell-tale signs like galactic perturbations are not really there. Astronomers now want to train Chandra’s eagle-eye on more boring candidates.

The findings were published yesterday in the science journal Nature.

The Universe is not only queerer than we imagine. It is, by all means, queerer than we can possibly imagine!

Discovered: A Super Massive Black Hole Weighing As Much As Two Billion Suns

This is a big astrophysical find, literally big! The Chandra X-Ray telescope has detected the signature of a supermassive black hole by observing the hot gases falling into it. The estimated mass of the black hole is a huge 2 Billion times the mass of the Sun!

The compact object lies at the heart of the galaxy known as NGC 3115, located at a distance of 32 million light-years away from Earth, making this the closest billion-solar-mass object to Earth. Astronomers have long been interested in the activity in this region, especially the gas falling into the central object. There have been various observations in the various frequencies, but this is only the first time when the X-Ray signatures have been clearly observed. The Chandra data suggests a huge mass for the black hole, given the temperature of the glowing gas falling into it. Only if the gas glows extremely intensely, does it give off X-Rays. NGC 3115 is about a million times brighter in X-Rays than in visible light.

How They Found Out the Mass

There is a term, called Bondi radius, named after the astrophysicist Hermann Bondi, which describes how the gas is affected by the black hole gravity. It is defined as the distance at which the gravity first starts dominating the random kinetic motion of the gas and the gas starts spiraling into the black hole.

The NGC 3115 galaxy

The data from the Chandra telescope suggests that the Bondi Radius is 700 light years away from the black hole!! In comparison, the closest star to Earth, after the Sun, is about 4 light years away. This gives an estimate of the mass of the black hole and the calculation suggests 2 billion solar masses!!

Any Use?

This finding is not only one for public consumption, but also scientific fodder. It may help to explain how matter flows into a black hole, as a tremendous amount of data is available due to the luminosity of the black hole.

It also brings up questions. Scientists still don’t know how such extremely massive black holes stay dim. As Dr. Jimmy Irwin, assistant professor of University of Alabama’s Physics Department says:

A leading mystery in astrophysics is how the area around massive black holes can stay so dim, when there’s so much fuel available to light up.

It is often said that astronomy is a humbling science. This just confirms that saying.

Cygnus X-1 Is Indeed a Black Hole; Stephen Hawking Was Wrong

Stephen Hawking has been proved wrong, but he knew this was coming. The irony is that a team from Harvard Smithsonian for Astrophysics from Cambridge proved him wrong; Stephen Hawking is the Lucasian Professor of Mathematics at the University of Cambridge.

The famous wager

The story harks back four decades. In 1971, cosmologists from across the world said that Cygnus X-1, a strong X-rays source, was in fact a black hole. (You know what a black hole is, right?) The intensity of the X-ray emissions was off the charts, given its estimated distance of 6050 light years. Cygnus was soon realized to be a double star system a dark star and a blue star orbiting one another. Cygnus X-1, since then, has been an object of intensive studies for astrophysicists all around the globe. Everyone believed that it was a black hole and all evidence pointed to that. Stephen Hawking disagreed.

Both smiling: Stephen Hawking (left) And Kip Thorne (right)

In 1974, Hawking and Caltech astrophysicist Kip Thorne made a friendly wager. Hawking claimed that the compact object emitting the X-rays was a neutron star, in spite of evidence that the intensity was too high to account for that. What was the bet? Hawking described it in his record shattering best seller, A Brief History of Time':

This was a form of insurance policy for me. I have done a lot of work on black holes, and it would all be wasted if it turned out that black holes do not exist. But in that case, I would have the consolation of winning my bet, which would win me four years of the magazine Private Eye. If black holes do exist, Kip will get one year of Penthouse. When we made the bet in 1975, we were 80% certain that Cygnus was a black hole. By now [1988], I would say that we are about 95% certain, but the bet has yet to be settled.

Hawking enjoying weightlessness

Hawking conceded defeat in 1998.

Getting a bit more serious: The modern perspective

Astrophysicists from Harvard-Smithsonian Institute measured the distance and the mass of the stars using direct methods. The reason is simple. If we know the radiation intensity we receive from a star in a certain small band of the electromagnetic spectrum, then, by measuring its distance and mass, we can figure out how powerful a source the star is. However, X-rays are much harder to study than radio waves and, fortunately, Cygnus X-1 is also a strong radio wave emitter. This is a common feature in many compact objects. They are generally bright in both the X-ray and radio frequencies.

Cygnus X-1

The Smithsonian team, led by Mark Reid, took to the Very Large Array (VLA) Very Large Baseline Array (VLBA)  radio telescope, which is scattered from Hawaii to New England, and focused it on Cygnus X-1. The resolution was a hundred times better than Hubble and was crucial in measuring the distance using the parallax method.

The distance was pegged at 6050 light years, give or take 400 light years. (If you’re not into astronomy, you’ll probably not be able to appreciate the fact that this is really a small margin of error.)

The mass of Cygnus X-1’s dark star is 14.8 solar masses and the orbiting blue star, slowly getting its mass torn apart by the compact dark star, weighs in at a heavier 19 solar masses. This is way above the mass required for a compact object to become a black hole it is much too heavy to remain a neutron star. It must be a black hole.

The team further measured the orbital speed (the spin) of the gas falling into the star. Measuring the temperature of the gas, using radiation emission data, the team found that it is so hot the innermost gas must be spinning really fast. They even put a number on it – 670 revolutions per second, or at 50 % the speed of light!!

The final words

The findings of the team are not reported in any paper as yet, but the Astrophysical Journal has acknowledged receiving three papers on this work. I’d imagine that both Kip Thorne and Stephen Hawking are happy – Thorne for being proved right and Hawking for being proved wrong.