Category: Black Holes

There’s a book by Larry Niven called “Hole Man”, where a group of explorers on Mars come across an alien communications device. One of the scientists thinks there’s a microscopic black hole inside, which powers the device, and to prove it, he turns off the containment field. The black hole falls into Mars, consuming the planet from within, and threatening the entire solar system.

Just science fiction? Maybe not. According to B.E. Zhilyaev, a researcher at the Main Astronomical Observatory in Ukraine, in the research paper Singular Sources of Energy in Stars and Planets, the Universe could be buzzing with these microscopic blackholes. They might even be inside stars and planets.

This isn’t a new concept. Physicists have been theorizing about the possibility of microscopic, primordial black holes for years, and used them to explain everything from dark matter to gamma ray bursts.

It takes a star several times the mass of our Sun to form a black hole naturally when it dies, so there probably isn’t a process that can make them any more. But during the first few moments after the Big Bang, the entire Universe was compressed into a microscopic singularity. These primordial black holes could have been generated right at the beginning, and have been with us ever since.

It’s also theorized that the new Large Hadron Collider might be capable of creating microscopic black holes through the collision of particles at relativistic velocities.

Before you can wrap your head around this research, consider how big a black hole has to be. For a stellar mass black hole, the event horizon – the point at which nothing can escape – is only a few kilometres from its centre. A black hole with the mass of the Earth? It would be less than 2 cm across. A black hole with the mass of a mountain? Smaller than a hydrogen atom.

Even though a microscopic black hole might contain the mass of a mountain, it would experience almost no friction as it passed through regular matter. It would fall through regular material as if it wasn’t there.

In most encounters with stars, these black holes would pass right through. But in a three-body interaction, between a star and a planet for example, the black hole could be trapped inside the star. The black hole would then orbit inside the star for billions of years until it comes to rest at the centre. They could form with the stars and planets from a protostellar cloud of gas and dust, or be captured and incorporated later.

So how do you know if you’ve got a black hole in your star? As the black hole grows over time, it starts to change the amount of heat generated by the star. A large enough black hole could cause the star to expand in size, and even undergo a supernova prematurely. According to Zhilyaev the interactions between stars and microscopic black holes could be detectable through bursts of gamma rays.

And if a black hole gets inside your planet? You get additional heat. This might account for unusual temperatures seen on Saturn and Jupiter, which are hotter than they should be from solar heating alone. A black hole inside the Earth might actually raise temperatures on the surface enough to sustain animal life long after the Sun dies out.

A power source that would last for eons, providing the most efficient possible conversion of matter to energy. Just don’t think about the monster consuming the ground beneath your feet as it keeps you warm.

Galaxies get bigger and bigger through galactic mergers. Two small galaxies come together, merge their stars, and you get a bigger galaxy. But astronomers have always wondered, what happens with the two supermassive black holes that seem to always lurk at the heart of galaxies. What happens when two compact objects with millions of times the mass of our sun collide? Good question.

An international team of physicists have developed a computer simulation designed to answer this very question. And in a recent article in Science Express, they published the results of the simulation.

It turns out the interaction depends a lot on the amount of hot gas surrounding each black hole. As they start to interact, this gas exerts a frictional force on the black holes, slowing down their spin rate. Once they get within the width of our solar system, they should start emitting gravitational waves, which continues to extract energy from the system. This causes them to continue coming together, and eventually merge.

This simulation is good news for experiments designed to search for gravitational waves. The mergers should be so energetic, they’ll generate gravitational waves detectable across space.

Original Source: Stanford News Release

An international team of astronomers have discovered a supermassive black hole at the very edge of the observable Universe, located 13 billion light-years away. Since the Universe is 13.7 billion years old, we’re seeing this object when the Universe was only 700 million years old. Wow.

Active galactic nuclei, or quasars, occur when a supermassive black hole is feasting on infalling material. Material piles up faster than the black hole can feed, and it starts to glow so brightly that astronomers can see it clear across the Universe. This object, CFHQS J2329-0301, was discovered as part of a new distant quasar survey performed with the MegaCam imager on the Canada-France-Hawaii Telescope (CFHT).

The black hole powering the quasar is thought to have 500 million times the mass of the Sun – that makes it hungry and bright. And because the quasar is so bright, astronomers can use it as a background object to examine the gas in front. And with follow up observations, they can get more details about what kind of galaxy it formed inside.

Original Source: Canada-France-Hawaii Telescope News Release

You know the saying: nothing, not even light can escape a black hole. That makes them invisible. Amazingly, researchers from the University of Maryland have determined how fast a supermassive black hole is spinning. You won’t be surprised to know it’s spinning insanely fast, at the limits predicted by relativity.

The researchers used ESA’s XMM-Newton X-Ray telescope to examine the quantity of iron in an accretion disk around a supermassive black hole at the centre of galaxy MCG-06-30-15. Because the disk is spinning so rapidly, the light from the disk is warped relativistically. According to their calculation, the black hole must be spinning at least 98.7% of the maximum spin rate allowable by Einstein’s Theory of General Relativity.

This result helps astronomers understand how black holes grow over time. If supermassive black holes formed by slowly pulling in surrounding matter, they would be expected to spin faster and faster, until they reach this relativistic limit. If the supermassive black holes were instead formed by colliding smaller black holes, they’d be spinning much more slowly.

Original Source: UM News Release

Supermassive black holes lurk at the heart of galaxies, containing the mass of millions of stars. Stellar mass black holes can contain the mass of a few suns. But astronomers have been perplexed why they haven’t been able to turn up intermediate mass black holes, containing merely hundreds or thousands of times the mass of our Sun.

Well, now they have. Astronomers using the NSF’s Very Large Array (VLA) radio telescope have turned up a globular cluster in the Andromdeda Galaxy (M31) that seems to contain a black hole with the mass of 20,000 times the mass of the Sun; one of these long-sought intermediate black holes.

Researchers originally detected X-rays emitted from this globular cluster, and then did follow up observations in the radio spectrum to confirm that a high mass, compact object is inside the cluster. Although the best explanation is a black hole, it could also be a cluster of compact objects, like neutron stars and black holes. The quantity of radio emissions coming from the object fits the curve perfectly between stellar and supermassive black holes.

Original source: NRAO News Release

The huge majestic spiral galaxy we live in today was built up over billions of years through mergers with other galaxies. And in 5-10 billion years from now, we’ll merge together with the Andromeda Galaxy. Since both galaxies are thought to have a supermassive black hole at their centre, what will happen when they merge together? One possibility is that one black hole will get ejected from the combining galactic core at a tremendous velocity.

Astronomers have suspected this kind of interaction might happen. The velocities and gravitational forces are so great during a black hole merger, that one of the objects could be flung out like a slingshot. It was believed that the black hole would be stripped of its accretion disk as it’s flung out into the galaxy, so it would be impossible to detect.

But new calculations by Avi Loeb, a researcher with the Harvard-Smithsonian Center for Astrophysics, indicate that an ejected black hole might be able to bring its accretion disk along for the ride. And the radiation pouring out of this disk might be detectable here on Earth.

If the calculations are correct, the two merging black holes will be releasing torrents of gravitational radiation in the direction they’re orbiting. The momentum from this radiation will give one black hole a kick in the opposite direction, ejecting it at 16 million km/hour (10 million mph). At this speed, a black hole would traverse its galaxy in just 10 million years.

According to Loeb, as long as the gas within the disk was orbiting at a speed far great than the black hole ejection speed, it would follow the black hole on its journey. It could last a few million years, consuming this disk of material, and blazing brightly enough that powerful telescopes could detect it. The host galaxy would seem to have a double quasar.

Original Source: CfA News Release

Astronomers have located an ongoing galactic merger, pinpointing the exact location of each galaxy’s supermassive black hole. These twin monsters are swirling around each other, and in several million years, they’ll merge together, releasing a powerful blast of gravitational radiation.

The twin galaxies are collectively known as NGC 6240, located about 300 million light years away, and they were recently imaged by the powerful adaptive optics system of the W.M. Keck Observatory in Hawaii. Under Keck’s vision, NGC 6240 was revealed to have two rotating disks of stars, each of which had its own supermassive black hole.

Millions of years ago, these would have been two separate galaxies that got to close to one another, and began merging. This process of galactic evolution is similar to the process that built up our own Milky Way, over billions of years. Astronomers are starting to understand the connection between the black holes and the total mass of the galaxy that surrounds them. As galaxies grow, the mass of their supermassive black holes grows too.

The twin supermassive black holes are slowly falling in to a common centre of gravity. In the next 10 to 100 million years, they’ll spiral into each other and merge into a single black hole. This collision will release waves of gravitational radiation.

Original Source: UCSC News Release

It might sound surprising, but one of the most difficult tasks astronomers have is determining the mass of objects. It takes a binary system, where two stars or orbiting one another, to be able to make an accurate mass calculation. And determining the mass of black holes is even more difficult because they’re invisible.

But the clever astronomers have figured out a way, by measuring the location of the swirling accretion disk of material waiting to be consumed around a black hole. Since material can pile up faster than the black hole can consume it, it compresses together, heats up, and emits radiation that astronomers can detect. Researchers have discovered that there is a direct relationship between a black hole and the size of its surrounding accretion disk. Astronomers have calculated that this hot gas piles up in a location that scales up with the mass of the black hole. The more massive the black hole, the farther out the congestion occurs.

This technique has helped astronomers identify likely intermediate black holes, which contain thousand of times the mass of the Sun. Much more than a stellar mass black hole, but much less than the hundreds of millions of suns worth of mass in supermassive black holes.

Original Source: ESA News Release