Universe Today

Are the relativistic jets of long gamma ray bursts (GRBs) produced by brand new black holes? Do some core-collapse supernovae result in black holes and relativistic jets?

The answer to both questions is 'very likely, yes'! And what recent research points to those answers? Study of an Ic supernova (SN 2007gr), and an Ibc one (SN 2009bb), by two different teams, using archived Gamma-Ray Burst Coordination Network data, and trans-continental Very Long Baseline Interferometry (VLBI) radio observations.
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Want a black hole wallpaper for your computer desktop background? Here's a nice collection. Just click on an image to see the larger version. Then right-click on the image and choose "Set as Desktop Background".

Here's an artist's illustration of a black hole drawing material away from a stellar companion. Since black holes are invisible, we can only see them when they're actively feeding, in this case, pulling material away from a star several times the mass of our Sun.

This is a top-down artist's illustration of a black hole. You can see the black event horizon, where light can't escape. Surrounding this is a swirling disk of hot gas and dust with powerful magnetic fields.

This is a photograph of two galaxies colliding together. And at their centers, astronomers think their supermassive black holes are merging together into an even larger black hole.

This is an image of a hot jet blasting out of a supermassive black hole. It's reaching across hundreds of light years into space. The region around a supermassive black hole becomes like the center of a star, creating intense radiation.

Here's an image of an enormous black hole at the heart of a galaxy cluster. A black hole like this could weigh a billion times the mass of our Sun, built up over mergers with other galaxies.

We've written many stories about black holes for Universe Today. Here's an article about a shrinking doughnut around a black hole, and here's an article about how the first black holes might have formed.

If you'd like more info on black holes, check out NASA's World Book on Black Holes, and here's more information from NASA from their educational pages.

We've also recorded an episode of Astronomy Cast all about black holes. Listen here, Episode 18: Black Holes Big and Small.

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Here are some cool black hole images.

This is an artist's illustration of the smallest known black hole, recently discovered by astronomers. Of course, astronomers don't actually know how small a black hole really is, so this is all about the size of the black hole's event horizon.

Here's a picture of a black hole pulling material away from a nearby stellar companion. Sometimes this is the only way you can detect a black hole, since it's invisible unless it's feeding on material.

This is an artist's illustration of a low-mass black hole spewing out jets from its poles. These microquasars form when a black hole sucks material off a stellar companion.

This is an artist's image of a huge optical jets blasting out of a galaxy that contains a supermassive black hole at its center. We don't see the black hole itself, but the superheated torus of gas and dust surrounding the black hole. This material heats up to mimic the cores of stars, releasing a tremendous amount of energy.

Here's an image of what a supermassive black hole might look like. You can see the dark sphere – the event horizon – in the middle, surrounded by a swirling disk of gas and dust. The rapid rotation of the black hole creates powerful magnetic fields which whip up the the material and form powerful jets that can travel for hundreds of light-years.

We've written many stories about black holes for Universe Today. Here's an article about a black hole breaking the distance record, and here's an article about how an intermediate mass black hole could be destroying stars.

If you'd like more info on black holes, check out NASA's World Book on Black Holes, and here's more information from NASA from their educational pages.

We've also recorded an episode of Astronomy Cast all about black holes. Listen here, Episode 18: Black Holes Big and Small.

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Not only is a newly found black huge, it also is the most far-away stellar-mass black hole ever detected. “This is the most distant stellar-mass black hole ever weighed, and it’s the first one we’ve seen outside our own galactic neighborhood, the Local Group,” said Paul Crowther, from the University of Sheffield. Using ESO's Very Large Telescope, astronomers peered six million light-years from Earth into a spiral galaxy called NGC 300 and found a black hole with a mass above fifteen times that of the Sun. This makes it the second most massive stellar-mass black hole ever found. But soon it could get bigger. The black hole appears to have a nearby partner, a massive Wolf–Rayet star which likely will become a black hole itself, and the two black holes could merge into an even more massive object.
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Caption: An image of the galaxy COSMOS J100043.15+020637.2 taken with the Advanced Camera for Surveys on the Hubble Space Telescope. Image courtesy Dr. Julia Comerford.

Astronomers have discovered 33 pairs of merging black holes in cosmic dances around each other, a finding that was predicted or 'choreographed' by Isaac Newton. "These results are significant because we now know that these 'waltzing' black holes are much more common than previously known," said Dr. Julia Comerford of the University of California, Berkeley, at the American Astronomical Society meeting in Washington, DC. "Galaxy mergers are causing the waltzing, can use this finding to determine how often mergers occur. The black holes dancing towards us are shifted towards blue light, and those moving away from us are shifted toward the red. So it is like a cosmic disco ball showing us where the black holes are dancing."
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NGC 1399, an elliptical galaxy about 65 million light years from Earth. Credit: NASA, Chandra

A dense stellar remnant has been ripped apart by a black hole a thousand times as massive as the Sun. If confirmed, this discovery would be a cosmic double play: it would be strong evidence for an intermediate mass black hole — which has been a hotly debated topic — and would mark the first time such a black hole has been caught tearing a star apart. Scientists believe a mysterious intense X-ray emission, called an “ultraluminous X-ray source” or ULX is responsible for the destruction. “Astronomers have made cases for stars being torn apart by supermassive black holes in the centers of galaxies before, but this is the first good evidence for such an event in a globular cluster,” said Jimmy Irwin of the University of Alabama, who led the study.
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When astronomers try to gauge the mass of another object, they use the mass of the Sun for comparison. This is a solar mass. So the mass of objects, like black holes will be measured in solar masses. A massive star might have 5-10 solar masses. A supermassive black hole could have hundreds of millions of solar masses.

The mass of the Sun is 1.98892 x 10³⁰ kilograms. So this is 1 solar mass. Astronomers will refer to this with an M beside a symbol that looks like a circle with a dot in the middle – M_⊙. To show a star that has 5 times the mass of the Sun, or 5 solar masses, it would be 5 M_⊙.

The Sun's mass is actually slowly decreasing over time. There are two processes at work here. The first is the fusion reactions in the core of the Sun, converting atoms of hydrogen into helium. Some of the Sun's mass is lost through the fusion process, as atoms of hydrogen are converted into energy. The warmth we feel from the Sun, is the Sun's lost mass. The second way is the solar wind, which is constantly blowing protons and electrons into outer space.

A solar mass is about 332,950 times the mass of the Earth or 1,048 times the mass of Jupiter.

We've written many articles about how astronomers use solar mass to compare massive objects like black holes. Here's an article about the biggest star in the Universe, and here's an article about the lowest mass black hole ever found.

If you'd like more info on the Sun, here's NASA's World Book on the Sun, and here's a link to NASA's World book on black holes.

We've also recorded several episodes about stars for Astronomy Cast. Here's a good one, Episode 75: Stellar Populations.

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Homer Simpson would be sad: recent observations of the binary system of a black hole and its companion star have shown the retreat of the doughnut-shaped accretion disk around the black hole. This shrinking 'doughnut' was seen in observations of the binary system GX 339-4, a system composed of a star similar in mass to the Sun, and a black hole of ten solar masses.

As the black hole feeds on gas flowing out from the orbiting star, the change in flow of the gas produces a varying size in the disk of matter that piles up around the black hole in a torus shape. For the first time, the changes in the size of this disk have been measured, showing just how much smaller the doughnut becomes. Read more…

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A super massive black hole – also known as a supermassive black hole, and abbreviated as SMBH – is a black hole with a mass of a million (or so) sols (one sol = the mass of our Sun) up to billions of sols (and beyond).

Where to find a SMBH? In the nucleus of a galaxy! In fact, it seems that all spiral galaxies with bulges, and all elliptical galaxies (except, perhaps, dwarf ellipticals) have a super massive black hole at the center of their nuclei (and some may have two).

How to 'weigh' a SMBH? There are two techniques – for our own galaxy, observe stars in orbit around the SMBH (which is SgrA*), apply the equations of orbital mechanics (Kepler's laws will do), turn the handle (that means 'do the calculations'), and out comes an estimate of the SMBH's mass. For other galaxies, take a spectrum of the nucleus, estimate the line of sight velocity of the stars (or gas), work out how it changes across the very center, apply equations derived from Newtonian mechanics and gravitation (you could use general relativity, but Newton is good enough), turn the handle, and … (as above).

When a super massive black hole eats (i.e. when matter falls into it), an accretion disc forms around it (conservation of angular momentum) – which emits enormous quantities of electromagnetic radiation – and a pair of jets emerge in the directions of the poles (of course nothing comes from the SMBH itself; matter is funneled into the jets by mechanisms that are not yet well understood). Now you have an active galactic nucleus (AGN), and, if it's particularly active, a quasar (or, if you are looking right down the barrel of the jet, a blazar).

Super massive black holes are part of every astronomy course, it seems; Supermassive Black Holes, for example, is part of a University of Tennessee course. NASA's World Book has an entry on super massive black holes, as does Cornell University's Ask an Astronomer.

Universe Today has many articles on super massive black holes; here are a few: Astronomers Find Most Distant Supermassive Black Hole Yet, Greedy Supermassive Black Holes Dislike Dark Matter, Super-Supermassive Black Hole, and Supermassive Black Hole Mashes Up and Consumes Star.

There are two Astronomy Cast episodes of particular interest to this topic: Black Holes Big and Small, and Quasars.

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According to Einstein's general theory of relativity, a black hole in space is a place where the gravity well is so great that a gravitational time dilation has occurred. This causes time to stop. This causes an event horizon into which objects can fall or be pulled, but those objects will never reappear. They are referred to as black because they do not reflect anything that hits them. They absorb all light. Analysis has shown that a black hole does posses a temperature and Hawking radiation.

Although it is invisible, a black hole in space can be observed through its interaction with other matter. One can be inferred by tracking the movement of a group of stars that orbit a region in space which looks empty. Also, one can see gas falling into a relatively small black hole, from a companion star. This gas spirals inward, heating up to very high temperatures and emitting large amounts of radiation that can be detected from Earth bound and Earth-orbiting telescopes. Such observations have resulted in the scientific consensus that black holes exist in our universe.

The existence of a black hole in space was first postulated in 1783. 1915 saw the release of Einstein's theory of general relativity, but it was not until a few years later that Karl Schwarzchild found a solution that the existence of a black hole was possible. His solution is called the Schwarzchild radius. It is used to define the radius of the event horizon of a non rotating black hole.

Some scientists, and many sci-fi fanatics, believe that if you could find a way to connect black holes you could travel across space quickly and efficiently. Others believe that creating a black hole in an enclosed area would allow you to create a spacecraft engine that would never fail and launch our race into interstellar travel.

There are good articles about black holes here and here. WE have a great article here on Universe Today about the proposed "black hole drive". Astronomy Cast offers a good episode about stars forming in and around a black hole.

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One of the most awe inspiring phenomenon in space is the black hole. Black hole facts are searched for every day. Amateur astronomers as well as the professionals often ponder questions related to black holes. So, for the fun of it and because we want to help educate you, we here on Universe Today decided to put together a few black hole facts to intrigue your mind and satisfy a little of your curiosity.

Fact 1

As black hole facts go, this is basic one. A black hole is a place where the gravity well is so great that a gravitational time dilation has occurred. This causes time to stop. This causes an event horizon into which objects can fall or be pulled, but those objects will never reappear. That is the basic definition according to Einstein's theory of general relativity.

Fact 2

There is no limit to how small or how large a black hole can be. The size and mass of a black hole are directly related. The more massive a black hole is, the more space it takes up. In fact, the Schwarzschild radius ( the radius of the event horizon of a black hole) and the mass are directly proportional to one another. Therefore, if one black hole weighs ten times as much as another, its radius is ten times as large. For example, a black hole with a mass equal to that of our Sun would have a radius of 3 kilometers, a typical 10-solar-mass black hole would have a radius of 30 kilometers, and so on.

Fact 3

The nearest black hole is 1,600 light years away. That is about 16 quadrillion kilometers for Earth.

Fact 4

One the interesting black hole facts is that they can not suck up all of the matter in the Universe. Each black hole has its own event horizon, much like the gravitational field of a planet. If matter is not in that horizon it will never get sucked into the black hole.

Fact 5

This one tips the scales on the heavy end as black hole facts go: there is a super massive black hole at the center of the Milky Way galaxy. It weighs in at about 4 million solar masses. Luckily, there is no reason to worry. This giant sucker is over 30,000 light years away.

Fact 6

The last of the black hole facts I have to offer today is that many theorists believe that a black hole can eventually evaporate. How is that? Steven Hawking proposed that black holes were not entirely black. They emit radiation. The energy that produces the radiation comes from the mass of the black hole. As the radiation is emitted, the black hole loses mass. The black hole emits more radiation the smaller it gets. In effect, a black hole evaporates more quickly as it shrinks.

These black hole facts are just a few of the little tidbits and teasers that you can find by doing some research. Here is a list of a few more. Here on Universe Today we have a great article about a practical use for black holes: as spacecraft engines. No one can get to a black hole without space travel. Astronomy Cast offers a good episode about interstellar travel.

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What is a black hole? A black hole is an object which has been compressed down by gravity so tightly that nothing, not even light can escape its pull.

Here on Earth, the gravity you feel on your feet comes from the mass of the planet. If the Earth had more mass, you would feel less gravity. But if the Earth was shrunk down smaller, say to the size of the Moon, you would experience more gravity on its surface because the mass is more concentrated. It would take more energy to jump up. And if the Earth was shrunk down to the size of a marble, it would be impossible to jump up. In fact, the pull of gravity would be so intense that not even light could escape. In essence, that is a black hole.

Black holes are created in nature when a star with about 10 times the mass of our Sun runs out of energy. Without the light energy pushing it apart, gravity is able to crush it together. The pull of gravity is so strong that electrons are crushed together with protons to make neutrons, and then these neutrons are crushed even further. At some point, the star is crushed down to that point when light can no longer escape its pull. Astronomers aren't sure how small they become, but it's possible that a star once many times the mass of our own Sun is crushed down smaller than an atom. That's when it becomes a black hole.

There is another kind of black hole as well: supermassive black holes. These lurk at the heart of galaxies and can contain millions, and even billions of times the mass of the Sun. These monster black holes formed with their galaxies billions of years ago and continue to pile on material. The discovery of these supermassive black holes helped explain mysterious objects called quasars. Astronomers now know that quasars are the cores of galaxies where the supermassive black hole is actively feeding on material. This material piles up around the black hole, like water waiting to go down the drain, and becomes like the core of a star shining with more energy than the rest of the galaxy.

We've written many articles about black holes for Universe Today. Here's an article about how black hole drives could power future spaceships, and here's an article about the search for medium-sized black holes.

If you'd like more info on black holes, check out the Hubble animation about black holes, and here's NASA's World Book on black holes.

We have also done many episodes of Astronomy Cast about black holes. Start here, Episode 18: Black Holes Big and Small.

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The birth of galaxies is quite a complicated affair, and little is known about whether the supermassive black holes at the center of most galaxies formed first, or if the matter in the galaxy accreted first, and formed the black hole later. Observations of the quasar HE0450-2958, which is situated outside of a galaxy, show the quasar aiding a nearby galaxy in the formation of stars. This provides evidence for the idea that supermassive black holes can 'build' their own galaxies. Read more…

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Very likely, the last image that comes to mind when thinking of black holes is that they need to be nurtured, coddled and protected when young. But new research reveals the first large black holes in the universe likely formed and grew deep inside gigantic, starlike cocoons that smothered their powerful x-ray radiation and prevented surrounding gases from being blown away.
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The Black hole is an object that is considered the most dense form of matter in the universe. It is so dense that it has a gravitational force that can prevent light from escaping and literally create a hole in space time. You may know something about black holes from science fiction and space movies. In fiction they are often seen as ways to travel long distances in space, or a limitless supply of energy. However there are some interesting facts that you may not know about them.

A black hole is something that is predicted by Einstein's theory of relativity. It is not something that has been directly observed by scientists. However there is evidence that we have found from its effects on surround objects and matter in space. A black hole is essentially supposed to be the end result of a star's life cycle. As you may know as a star runs out of the hydrogen it needs to fuel its fusion reaction it first expands then star starts to collapse on itself. The core in the process becomes more and more dense. In becoming a black hole, the core becomes so dense that not even light can escape its gravity and it warps space and time creating what we know as a black hole. The black hole has two key parts. One is the singularity. This is the super condensed star core that is the main party of the black hole. The other part is the event horizon. This where the hole in the fabric of space-time is. It is said that the gravity created by the singularity makes time literally stop in proximity of the event horizon. So if you were to pass the event horizon it would be the point of no return.

Scientists first theorized about black holes in the late 1800s but it was not mathematically described until Einstein's General Theory of Relativity in 1913. This was further supported by the interesting observations of astronomers. For one while it is impossible to directly look at a black hole it can be visible under certain circumstances. For example a black hole can be visible when near a star. The gas drawn by the black hole is compressed and creates great explosions of radiation that are detectable. That is how many of the ones we know about have been found.

If you enjoyed this article there are several others that you would enjoy. There is a great article on black holes being used to power star ships and another great one on super massive black holes.

There are some great articles about black holes online. There is a great article that goes into more detail on howstuffworks.com. There is also a great article on the UC Berkeley website.

You can also check out Astronomy Cast. Episode 135 about Gamma Ray Astronomy will show you how astronomers spot black holes.

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