Hanny's Voorwerp. Credit: ASTRON

Black Holes Supply Lifeblood for Galaxies

Chandra X-ray image of M84. Credit: X-ray (NASA/CXC/MPE/A.Finoguenov et al.); Radio (NSF/NRAO/VLA/ESO/R.A.Laing et al); Optical (SDSS)

Obviously, today is the day for news on black holes. While one group of astronomers studied the violent flares of energy sent out by black holes in the near infrared and submillimeter wavelengths, another group used the Chandra X-Ray Observatory to see how black holes can pump energy in a gentler and rhythmic fashion, rather than violently. These scientists say the powerful black holes at the center of massive galaxies act as hearts to the systems, pumping energy out at regular intervals to regulate the growth of the black holes themselves, as well as star formation. “Just like our hearts periodically pump our circulatory systems to keep us alive, black holes give galaxies a vital warm component. They are a careful creation of nature, allowing a galaxy to maintain a fragile equilibrium,” said Alexis Finoguenov, of the Max-Planck Institute for Extraterrestrial Physics in Germany.
Read more…

Milky Way's Black Hole Sending Out Flares

Left: Submillimetre and infrared view of the Galactic Centre Right: Flares from the disk of material surrounding the black hole Sagittarius A*. Credit: ESO/APEX/2MASS/A. Eckart et al. , ESO/L. Calçada

Two different telescopes simultaneously observed violent flares from the supermassive black hole in the center of the Milky Way. The outbursts from this region, known as Sagittarius A*, reveal material being stretched like bread dough out as it orbits in the intense gravity close to the central black hole. Using ESO's Very Large Telescope(VLT) and the Atacama Pathfinder Experiment (APEX) telescope, both in Chile, to study light from Sagittarius A* at near-infrared wavelengths and the longer submillimeter wavelengths, astronomers have for the first time concurrently caught a flare with these telescopes. "Observations like this, over a range of wavelengths, are really the only way to understand what's going on close to the black hole," says Andreas Eckart of the University of Cologne, who led the team.
Read more…

Even Early Galaxies Had Supermassive Black Holes

Artist’s conception of the 4C60.07 system of colliding galaxies. Credit: David A. Hardy/UK ATC

We're learning more about black holes and the early universe all the time, with the help of all the amazing ground-based telescopes astronomers now have at their disposal. Astronomers think that many - perhaps all - galaxies in the universe contain massive black holes at their centers. New observations with the Submillimeter Array now suggest that such colossal black holes were common even 12 billion years ago, when the universe was only 1.7 billion years old and galaxies were just beginning to form. The new conclusion comes from the discovery of two distant galaxies, both with black holes at their centers, which are involved in a spectacular collision.
Read more…

The Violent Variations of Black Holes

Artist impression of a black hole. Credit: ESO/L. Calçada

What is the environment around a black hole really like? Astronomers are getting a better idea by observing the light coming from the accretion disk surrounding black holes. The light is not constant — it flares, sputters and sparkles – and this flickering provides new and surprising insights into the colossal amount of energy emanating from around black holes. By mapping out how well the variations in visible light match those in X-rays on very short timescales, astronomers have shown that magnetic fields must play a crucial role in the way black holes swallow matter.
Read more…

Black Hole Surfaces, Magnetic Field Strengths, and the Speed of Gravitons

Click here to download the episode.

Or subscribe to: astronomycast.com/podcast.xml with your podcatching software.

Black Hole Surfaces, Magnetic Field Strengths, and the Speed of Gravitons show notes.

Super-massive and Small Black Holes Both Suck

Sorry, couldn't resist that title. Astronomers studying black holes are able to "see" them due to the fact that the gas getting sucked in gets extremely hot and emits X-rays. These X-ray pulses are commonly seen among smaller black holes, but until now, had not been detected from super-massive black holes. But astronomers using the XMM Newton X-ray satellite have discovered a strong X-ray pulse emitting from a giant black hole in a galaxy 500 million light years from Earth, created by gas being sucked in by gravity. "Scientists have been looking for such behaviour for the past 20 years and our discovery helps us begin to understand more about the activity around such black holes as they grow," said Dr. Marek Gierlinski from Durham University. Gierlinski and his colleagues say this finding is the "missing link" between small and super-massive black holes.
Read more…

Black Holes Can Only Get So Big

Black holes are thought to exist throughout the universe, with the largest and most massive found at the centers of the largest galaxies. These supermassive black holes have been shown to have masses upwards of one billion times that of our own Sun. But an astronomer studying black holes says there's an upper limit to how big a black hole can get. Priyamvada Natarajan, an associate professor of astronomy and physics at Yale University has shown that even the biggest of these gravitational monsters can’t keep growing forever. Instead, they appear to curb their own growth – once they accumulate about 10 billion times the mass of the Sun.
Read more…

Astronomers Link Telescopes to Zoom In On Milky Way's Black Hole

An international team of astronomers has obtained the closest views ever of what is believed to be a super-massive black hole at the center of the Milky Way galaxy. The astronomers linked together radio dishes in Hawaii, Arizona and California to create a virtual telescope more than 2,800 miles across that is capable of seeing details more than 1,000 times finer than the Hubble Space Telescope. The target of the observations was the source known as Sagittarius A* ("A-star"), long thought to mark the position of a black hole whose mass is 4 million times that of the sun.
Read more…

New "Sunglasses" Help Astronomers See Light Near Black Holes

Although we can't actually see a black hole, we can see the black hole's effect on nearby matter. But even that is difficult because infrared light from clouds of dust and gas usually pollutes the view. But astronomers have found a way to get a clean view of the disks surrounding black holes by using a polarizing filter in the infrared. This technique works in particular when the region immediately surrounding the black hole emits a small amount of scattered light. Since scattered light is polarized, astronomers can use a filter that works like polarized sunglasses on large telescopes to detect this small amount of scattered light and measure it with unprecedented accuracy. Scientists have theorized these luminous disks existed around black holes, but until now have not been able to observe them.
Read more…

How do you Weigh a Supermassive Black Hole? Take its Temperature

Working out the mass of huge black holes, like the ones hiding in the centre of galactic nuclei, is no easy task and attempts are being made to find novel ways to weigh them. Using data from the Chandra X-ray Observatory, two scientists have confirmed a theory they conceived ten years ago, that the supermassive black holes in the centre of galaxies strongly influence the nature of the gases surrounding them. So, acting like a remote thermometer, Chandra is being used to probe deep into the neighbourhood of these exotic objects, gauging their masses very accurately…
Read more…

Can Light be "Squeezed" to Improve Sensitivity of Gravitational Wave Detectors?

The search is on to detect the first evidence of gravitational waves travelling around the cosmos. How can we do this? The Laser Interferometer Gravitational-Wave Observatory (LIGO) uses a system of laser beams fired over a distance of 4 km (2.5 miles) and reflected back and forth by a system of mirrors. Should a gravitational wave pass through the volume of space-time surrounding the Earth, in theory the laser beam will detect a small change as the passing wave slightly alters the distance between mirrors. It is worth noting that this slight change will be small; so small in fact that LIGO has been designed to detect a distance fluctuation of less than one-thousandth of the width of a proton. This is impressive, but it could be better. Now scientists think they have found a way of increasing the sensitivity of LIGO; use the strange quantum properties of the photon to "squeeze" the laser beam so an increase in sensitivity can be achieved…
Read more…

How to Escape From a Black Hole

According to Einstein's theory of general relativity, black holes are regions of space where gravity is so strong that not even light can escape. And in the 1970's physicist Stephen Hawking asserted that any information sucked inside a black hole would be permanently lost. But now, researchers at Penn State have shown that information can be recovered from black holes.
Read more…

Stars Orbiting Close to Black Holes Flattened like Hot Pancakes

Playing with black holes is a risky business, especially for a star that is unlucky enough to be orbiting one. Assuming an unfortunate star hasn't already had all of its hydrogen fuel and other component elements stripped from its surface, the powerful tidal forces will have some fun with the doomed stellar body. First the star will be stretched out of shape and then it will be flattened like a pancake. This action will compress the star generating violent internal nuclear explosions, and shockwaves will ripple throughout the tormented stellar plasma. This gives rise to a new type of X-ray burst, revealing the sheer power a black hole's tidal radius has on the smaller binary sibling. Sounds painful…
Read more…

Magnetic Fields Shape the Jets Pouring Out of Supermassive Black Holes (with video)

The cores of galaxies contain supermassive black holes, containing hundreds of millions of times the mass of Sun. As matter falls in, it chokes up, forming a super hot accretion disk around the black hole. From this extreme environment, the black hole-powered region spews out powerful jets of particles moving at the speed of light. Astronomers have recently gotten one of the best views at the innermost portion of the jet.
Read more…

X-Ray Flare Echo Reveals Supermassive Black Hole Torus

The light echo of an X-ray flare from the nucleus of a galaxy has been observed. The flare almost certainly originates from a single star being gravitationally ripped apart by a supermassive black hole in the galactic core. As the star was being pulled into the black hole, its material was injected into the black hole accretion disk, causing a sudden burst of radiation. The resulting X-ray flare emission was observed as it hit local stellar gases, producing the light echo. This event gives us a better insight to how stars are eaten by supermassive black holes and provides a method to map the structure of galactic nuclei. Scientists now believe they have observational evidence for the elusivemolecular torus that is thought to surround active supermassive black holes.
Read more…

Why are there Black Holes in the Middle of Galaxies?

What Happens When Three Black Holes Collide?

The consequences of two black holes colliding may be huge, the energy produced by such a collision could even be detected by observatories here on Earth. Ripples in space-time will wash over the Universe as gravitational waves and are predicted to be detected as they pass through the Solar System. Taking this idea one step further, what would happen if three black holes collide? Sound like science fiction? Well it's not, and there is observational evidence that three black holes can cluster together, possibly colliding after some highly complex orbits that can only be calculated by the most powerful computers available to researchers…
Read more…

Astronomers Find the Smallest Black Hole

Black holes seem to have no upper limit; some weigh in at hundreds of millions of times the mass of the Sun. But how small can they be? Astronomers have discovered what they think is the least massive black hole ever seen, with a mere 3.8 times the mass of the Sun, and a diameter of only 25 km (15 miles) across.
Read more…

When Black Holes Explode: Measuring the Emission from the Fifth Dimension

Primordial black holes are remnants of the Big Bang and they are predicted to be knocking around in our universe right now. If they were 10¹²kg or bigger at the time of creation, they have enough mass to have survived constant evaporation from Hawking radiation over the 14 billion years since the beginning of the cosmos. But what happens when the tiny black hole evaporates so small that it becomes so tightly wrapped around the structure of a fifth dimension (other than the "normal" three spatial dimensions and one time dimension)? Well, the black hole will explosively show itself, much like an elastic band snapping, emitting energy. These final moments will signify that the primordial black hole has died. What makes this exciting is that researchers believe they can detect these events as spikes of radio wave emissions and the hunt has already begun…
Read more…

Greedy Supermassive Black Holes Dislike Dark Matter

It is widely accepted that supermassive black holes (SMBHs) sit in the centre of elliptical galaxies or bulges of spiral galaxies. They suck in as much matter as possible, generating blasts of radiation. Stars, gas and everything else nearby forms a compact "halo" and then falls to a gravitationally enforced death spiral. The greedy nature and the sheer size of these black holes have led to the idea that dark matter may supply (or may have supplied) the SMBH with some mass during its evolution. But could it be that dark matter may not be significantly involved after all? This might be one cosmic phenomenon dark matter can't be blamed for…
Read more…

What Happens When Supermassive Black Holes Collide?

As galaxies merge together, you might be wondering what happens with the supermassive black holes that lurk at their centres. Just imagine the forces unleashed as two black holes with hundreds of millions of times the mass of the Sun come together. The answer will surprise you. Fortunately, it's an event that we should be able to detect from here on Earth, if we know what we're looking for.
Read more…

Synthetic Black Hole Event Horizon Created in UK Laboratory

Researchers at St. Andrews University, Scotland, claim to have found a way to simulate an event horizon of a black hole - not through a new cosmic observation technique, and not by a high powered supercomputer… but in the laboratory. Using lasers, a length of optical fiber and depending on some bizarre quantum mechanics, a "singularity" may be created to alter a laser's wavelength, synthesizing the effects of an event horizon. If this experiment can produce an event horizon, the theoretical phenomenon of Hawking Radiation may be tested, perhaps giving Stephen Hawking the best chance yet of winning the Nobel Prize.
Read more…

"Listening" for Gravitational Waves to Track Down Black Holes

Gravitational waves are predicted by Einstein's 1916 general theory of relativity, but they are notoriously hard to detect and it's taken many decades to come close to observing them. Now, with the help of a supercomputer named SUGAR (Syracuse University Gravitational and Relativity Cluster), two years of data collected by the Laser Interferometer Gravitational-Wave Observatory (LIGO) will be analyzed to find gravitational waves. Once detected, it is hoped that the location of some of the Universes most powerful collisions and explosions will be found, perhaps even hearing the distant ringing of celestial black holes…
Read more…

Black Holes Seen Spinning at the Limits Predicted by Einstein

The supermassive black holes that lurk at the hearts of the most massive galaxies might be spinning faster than astronomers ever thought. In fact, they might be spinning at the very limits predicted by Einstein's theory of relativity. Perhaps it's this extreme rotational speed that generates the energetic jets that blast out of the most massive and active galaxies.
Read more…

Supercomputer Will Simulate Colliding Black Holes