Milky Way’s Black Hole Munches On Supercooked Gas

It’s a simple menu, but smoking hot. The black hole at the center of the Milky Way galaxy is sucking in ultra-hot molecular gas, as seen through the eyes of the Herschel space telescope.

“The biggest surprise was quite how hot the molecular gas in the innermost central region of the galaxy gets. At least some of it is around 1000ºC [1832º F], much hotter than typical interstellar clouds, which are usually only a few tens of degrees above the –273ºC [-460ºF] of absolute zero,” stated the European Space Agency.

Herschel, which is out of coolant and winding down its scientific operations, will continue producing results in the next few years as scientists crunch the results. The telescope has found a bunch of basic molecules in the Milky Way that include water vapour and carbon monoxide, and has been engaged in looking to learn more about the gas that surrounds the massive black hole at our galaxy’s center.

In a region called Sagittarius* (Sgr A*), this huge black hole — four million times the mass of the sun — is thankfully a safe distance from Earth. It’s 26,000 light years away from the solar system.

Trouble is, there’s a heckuva lot of dust blocking our view to the center of the galaxy. Herschel got around that problem by taking pictures in the far-infrared, seeking heat signatures that can bely intense activity in and around the black hole.

“Herschel has resolved the far-infrared emission within just 1 light-year of the black hole, making it possible for the first time at these wavelengths to separate emission due to the central cavity from that of the surrounding dense molecular disc,” stated Javier Goicoechea of the Centro de Astrobiología, Spain, lead author of a paper reporting the results.

The science team supposes that there are strong shocks within the gas (which is magnetized) that help turn up the heat. The shocks could occur when gas clouds butt up against each other, or material shoots out Fast and Furious-style between stars and protostars (young stars.)

“The observations are also consistent with streamers of hot gas speeding towards Sgr A*, falling towards the very center of the galaxy,” stated Goicoechea. “Our galaxy’s black hole may be cooking its dinner right in front of Herschel’s eyes.”

image 1: Artist’s concept of a supermassive black hole at the center of a galaxy. credit: NASA/JPL-Caltech

image 2: At left, ionized gas in the galaxy as seen in radio wavelengths; at right, the spectrum at the center seen by Herschel. credit: Radio-wavelength image: National Radio Astronomy Observatory/Very Large Array (courtesy of C. Lang); spectrum: ESA/Herschel/PACS & SPIRE/J.R. Goicoechea et al. (2013).

New Kind of Cosmic Flash May Reveal Birth of a Black Hole

May 3, 2013 — A new kind of cosmic flash may reveal something never seen before: the birth of a black hole.

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(Source: thenewenlightenmentage, via bowtiesandapplepies)

atomstargazer:

Using black holes to measure the universe’s rate of expansion

Radiation emitted in the vicinity of black holes could be used to measure distances of billions of light years, says researcher.

A few years ago, researchers revealed that the universe is expanding at a much faster rate than originally believed — a discovery that earned a Nobel Prize in 2011. But measuring the rate of this acceleration over large distances is still challenging and problematic, says Prof. Hagai Netzer of Tel Aviv University’s School of Physics and Astronomy.

Now, Prof. Netzer, along with Jian-Min Wang, Pu Du and Chen Hu of the Institute of High Energy Physics of the Chinese Academy of Sciences and Dr. David Valls-Gabaud of the Observatoire de Paris, has developed a method with the potential to measure distances of billions of light years with a high degree of accuracy. The method uses certain types of active black holes that lie at the center of many galaxies. The ability to measure very long distances translates into seeing further into the past of the universe — and being able to estimate its rate of expansion at a very young age.

Published in the journal Physical Review Letters, this system of measurement takes into account the radiation emitted from the material that surrounds black holes before it is absorbed. As material is drawn into a black hole, it heats up and emits a huge amount of radiation, up to a thousand times the energy produced by a large galaxy containing 100 billion stars. For this reason, it can be seen from very far distances, explains Prof. Netzer.

Solving for unknown distances

Using radiation to measure distances is a general method in astronomy, but until now black holes have never been used to help measure these distances. By adding together measurements of the amount of energy being emitted from the vicinity of the black hole to the amount of radiation which reaches Earth, it’s possible to infer the distance to the black hole itself and the time in the history of the universe when the energy was emitted.

Getting an accurate estimate of the radiation being emitted depends on the properties of the black hole. For the specific type of black holes targeted in this work, the amount of radiation emitted as the object draws matter into itself is actually proportional to its mass, say the researchers. Therefore, long-established methods to measure this mass can be used to estimate the amount of radiation involved.

The viability of this theory was proved by using the known properties of black holes in our own astronomical vicinity, “only” several hundred million light years away. Prof. Netzer believes that his system will add to the astronomer’s tool kit for measuring distances much farther away, complimenting the existing method which uses the exploding stars called supernovae.

Illuminating “Dark Energy”

According to Prof. Netzer, the ability to measure far-off distances has the potential to unravel some of the greatest mysteries of the universe, which is approximately 14 billion years old. “When we are looking into a distance of billions of light years, we are looking that far into the past,” he explains. “The light that I see today was first produced when the universe was much younger.”

One such mystery is the nature of what astronomers call “dark energy,” the most significant source of energy in the present day universe. This energy, which is manifested as some kind of “anti-gravity,” is believed to contribute towards the accelerated expansion of the universe by pushing outwards. The ultimate goal is to understand dark energy on physical grounds, answering questions such as whether this energy has been consistent throughout time and if it is likely to change in the future.

Via Tel Aviv University

MY THOUGHTS ARE THAT HYPERVELOCITY STARS ARE REALLY RAD

LET ME TELL YOU ABOUT THEM

Also known as ‘rogue stars’, hypervelocity stars are basically stars that have been kicked out of their own galaxies and are now hurtling through intergalactic space. Six such stars have been discovered on the outskirts of the Milky Way, standing out due to their lonely location between the Milky Way and Andromeda galaxies, and by their red colouration.

The stars are thought to be red giants, with something called high metallicity. “Metallicity” is a proportional measure of the chemical elements (other than hydrogen and helium) that a star contains. The high metallicty of these hypervelocity stars indicates they were formed in the inner galactic regions—so they’re believed to have been ejected from the heart of our galaxy.

Evidence indicates that a supermassive black hole resides at the centre of the Milky Way, and it’s like a gravitational monster, jamming the mass of four million suns into a space smaller than Earth’s orbital region. But the stars didn’t come FROM the black hole—nothing can escape a black hole (except Hawking Radiation). To escape the gravitational grasp of our galaxy, hypervelocity stars need to be travelling incredibly fast—like over three million kilometres per hour fast—and one of the only things that could give stars such a kick is a close encounter with a supermassive black hole.

Since its gravitation field would be strong enough to accelerate stars to hypervelovity, astronomers basically think that the black hole at the centre of our galaxy acts as a slingshot. Typically, a binary star system would get caught in the black hole’s grip, and while one gets sucked in, the other one is flung away at enormous speeds. Another scenario could occur when a black hole is ingesting another, smaller black hole, and a star that ventures close to the circling pair could get a kick, like stellar pinball.

These hypervelocity stars would have been smaller, yellow stars like our own sun when they first got this kick, but even travelling at such huge speeds, it would’ve taken them around 10 million years to traverse 50,000 light years to the edge of the Milky Way. That’s why the stars detected are red giants, near the end of their stellar evolution.

Other than being really damn cool, hypervelocity stars are also useful because they could give us a glimpse at how stars are formed in the heart galaxy, which is cloaked in a halo of dust that obscures all but the brightest stars.

(Source: tmblr.co, via sciencesoup)

Black Hole’s Mystery ‘Wave’ Surprises Scientists

Astronomers studying an unusual black hole system have spotted a never-before-seen structure in the disk of matter encircling the system.

Swift J1357.2, an X-ray binary system that regularly emits outbursts of high energy, consists of a black hole slowly consuming its companion star. Matter from the doomed star falls into the accretion disk, which surrounds the black hole, feeding it dust and gas.

While observing the system, a team of scientists noticed an unusual vertical feature traveling through the material.

“It’s the first time we can resolve such [a] structure in an accretion disk, and it might be ubiquitous in X-ray binaries during the outburst state,” Jesus Corral-Santana, of the Astrophysical Institute of the Canary Islands in Spain, told SPACE.com by email.

A hidden structure
The black hole contained in Swift J1357.2 is one of the millions of stellar black holes that dot the Milky Way galaxy.

About three times as massive as the sun, the behemoth likely formed when a single star collapsed inward on itself. The resulting, city-sized body packed a great deal of mass into a tiny package, creating a strong gravitational pull on nearby dust and gas.

Located in the Virgo constellation, approximately 4,900 light-years from Earth, Swift J1357.2 also contains a small companion star, which has only a quarter the mass of the sun. This companion star orbits the pair’s center of mass every 2.8 hours, one of the shortest known orbital periods for such systems.

The black hole pulls material from the companion star into its accretion disk, occasionally emitting the X-ray bursts that enabled scientists to find this otherwise hard-to-spot system, researchers said.

Corral-Santana and his team took hundreds of optical images of the system using the Isaac Newton and the William Herschel Telescopes, both of which are in the Canary Islands. Studying the light produced by the accretion disk, the researchers noticed a periodic dimming in the system, sometimes occurring over the course of only a few seconds.

“Since the orbital period of the system is 2.8 hours, those dips cannot be produced by eclipses of the companion star. They are much faster,” Corral-Santana said. “Therefore, they must be produced by a hidden structure placed very close to the black hole, in the inner accretion disk.”

The new find can only been seen in the outer, optical portion of the accretion disk, not on the inside, where X-ray bursts originate. The X-ray emission, which shows no periodic variation, unlike its optical counterpart, indicated a vertical structure was hiding the black hole, Corral-Santana said.

Rather than appearing at a set, predictable time, the structure shows up over a steadily increasing period, indicating a wave-like movement through the accretion disk.

“It is a wave produced in the accretion disk, moving outward,” Corral-Santana said, “like the wave produced when a stone is dropped in calm water.”

The missing population
The wave-like feature also provides information about the orientation of the black hole.

Objects in space face Earth at a variety of angles, or inclinations. They can be seen edge-on, face-on or somewhere in between. Swift J1357.2 is the only one of 50 suspected similar black-hole systems found with an edge-on accretion disk — what scientists call a high inclination. However, astronomers think approximately 20 percent of these systems should provide such a perspective.

In order to see the wave-like structure in the accretion disk, scientists must have such an edge-on view of the disk, or one close to it. A view from a lower inclination, closer to face-on, would not reveal the sudden rises and falls in the total light coming from the system.

“Swift J1357.2 is the prototype of the hitherto missing population of high-inclination black holes in transient X-ray binaries,” Corral-Santana said.

Because Swift J1357.2 is the first such system to allow such an edge-on view, the presence of the vertical structure takes on an added significance. No signs of such structures appear in other similar systems, but that could result simply from their unfortunate angles. Such structures could in fact exist in other, previously discovered transient X-ray binary systems, hidden only by their observational angles.

The findings were published online today (Feb 28) in the journal Science.

image: This image is a simulation of the X-ray binary system Swift J1357.2-0933, a black hole and star system, in which the effect of a strange, vertical mystery structure are at their maximum.
credit: Gabriel Perez Diaz, Instituto de Astrofisica de Canarias (Servicio MultiMedia)

christinetheastrophysicist:

Simulations indicate Milky Way may have up to 2000 black holes in its halo

Valery Rashkov and Piero Madau, space scientists with the University of California have suggested that the Milky Way galaxy likely has between 70 and 2000 intermediate-mass black holes (IMBHs) existing in its outer edges. They came to this conclusion by building a computer model that mimics what they believe occurred when galaxies, and by extension, black holes merged during their formative years.

Read More.

ikenbot:

Black Hole Firewall: Trouble On The Edge

Ever wondered what happens to things as they are consumed by the black hole, the left over matter of dead stars? For a time, it used to be okay to assume matter was destroyed once it entered into a black hole, spaghettified and all.. but it turned out that this couldn’t be further away from the truth. NewScientists Anil Ananthaswamy has a wonderful 3 page piece getting into full details of this history and what questions scientists are asking now. If you love black holes, this is a definite recommend. Although registration (completely free!) is required to view the whole article. It’s pretty insightful and accurately presents the problems currently being faced with how black holes do what they do:

“Paradoxes are good in physics,” reflects John Preskill. “They help to point the way towards important discoveries.” Quantum mechanics and Einstein’s theories of relativity offer plenty to choose from. There’s the cat that can be dead and alive at the same time. Or the Back to the Future-style time traveller who kills his own grandfather, rendering his own birth impossible. Or the twins who disagree on their age after one returns from a near light-speed trip to a neighbouring star. Each perplexing scenario forces us to examine the fine print of the problem, thereby advancing our understanding of the theory behind it. A case in point is Einstein, whose own theories came from trying to resolve the paradoxes of his time.

Image: Ring of fireSam Chivers

Now Preskill, a theoretical physicist at the California Institute of Technology in Pasadena, is scratching his head over the latest one to surface. Nicknamed the black hole firewall paradox, it comes about when you consider what happens to someone falling into a black hole.

With the nearest black hole more than 1000 light years away, the question is very much a theoretical one. Yet just by studying such a possibility, physicists are hoping to make a breakthrough in their efforts to combine general relativity and quantum mechanics into a theory of quantum gravity – one of the most intractable problems in physics today.

Black holes have long been fertile breeding grounds for paradoxes. Back in 1974, Stephen Hawking, along with Jacob Bekenstein of the Hebrew University in Jerusalem, Israel, famously showed that black holes are not entirely black. Instead, they radiate energy known as Hawking radiation comprising photons and other quantum particles – an agonisingly slow process that eventually causes the black hole to evaporate completely.

Hawking spotted a problem with this picture. The radiation seemed so random that he surmised it couldn’t carry any information about the stuff that had fallen in. So as the black hole evaporates, the information it holds must eventually disappear. Yet this is in direct conflict with a central tenet of quantum physics, which says that information cannot be destroyed. The black hole information paradox was born.

Over the decades, physicists have struggled with this paradox. Hawking thought that black holes destroyed information and the answer was to question quantum mechanics. Others disagreed. After all, Hawking’s idea came from his efforts to meld general relativity and quantum mechanics – a mathematical feat so elusive that he was forced to make approximations. Preskill even made a bet with Hawking that black holes don’t destroy information.

Several arguments suggest that Hawking was wrong. One of the most compelling comes from thinking about what happens as the evaporating black hole gets smaller and smaller. If information can’t escape or be destroyed, then more and more has to be stored in an ever-shrinking volume. But if this is the case, quantum theory says the probability for making a tiny black hole increases from virtually nothing to almost infinity wherever matter collides against matter. “You should have seen it at the Large Hadron Collider, you should have seen it at Fermilab, you should have seen it in tiny room-sized particle accelerators from the 1930s,” says Don Marolf, a theorist at the University of California in Santa Barbara (UCSB). “You should see it when you go and jump up and down on the grass.”

Obviously that hasn’t happened. The other possibility – that matter and the information it carries can leak out from a black hole – is unlikely. Any material that falls in would need to travel faster than light to escape the black hole’s fearsome gravity.

Perhaps, instead, the answer lies with the Hawking radiation itself. Maybe it isn’t so featureless. “A common reaction was that Hawking had simply been careless,” says Joseph Polchinski, also at UCSB. “It wasn’t that information was lost, it was that he hadn’t kept track of it enough.”

Yet all early efforts to do away with the paradox proved unsuccessful. “Hawking had identified a really deep problem,” says Polchinski.

As it happened, Hawking changed his mind in 2004, partly due to work by an Argentinian physicist called Juan Maldacena (see “Hawking’s change of heart”). Black holes don’t destroy information after all, he conceded. He honoured the bet he made with Preskill and presented him with an encyclopaedia of baseball, which Preskill likened to a black hole, because it was heavy and it took effort to get information out of it.

Into The Abyss..

[Full Article]

distant-traveller:

Black hole wakes up and has a light snack

Astronomers have watched as a black hole woke up from a decades-long slumber to feed on a low-mass object – either a brown dwarf or a giant planet – that strayed too close. A similar feeding event, albeit on a gas cloud, will soon happen at the black hole at the centre of our own Milky Way Galaxy.

The discovery in galaxy NGC 4845, 47 million light-years away, was made by ESA’s Integral space observatory, with follow-up observations from ESA’s XMM-Newton, NASA’s Swift and Japan’s MAXI X-ray monitor on the International Space Station.

“The observation was completely unexpected, from a galaxy that has been quiet for at least 20–30 years,” says Marek Nikolajuk of the University of Bialystok, Poland, lead author of the paper inAstronomy & Astrophysics.

By analysing the characteristics of the flare, the astronomers could determine that the emission came from a halo of material around the galaxy’s central black hole as it tore apart and fed on an object of 14–30 Jupiter masses. This size range corresponds to brown dwarfs, substellar objects that are not massive enough to fuse hydrogen in their core and ignite as stars.

However, the authors note that it could have had an even lower mass, just a few times that of Jupiter, placing it in the range of gas-giant planets.

Recent studies have suggested that free-floating planetary-mass objects of this kind may occur in large numbers in galaxies, ejected from their parent solar systems by gravitational interactions.

The black hole in the centre of NGC 4845 is estimated to have a mass of around 300,000 times that of our own Sun. It also likes to play with its food: the way the emission brightened and decayed shows there was a delay of 2–3 months between the object being disrupted and the heating of the debris in the vicinity of the black hole.

Video credit: ESA

astrodidact:

Horizon: Black Holes (BBC)

 

All hail the Kaku!

Neil deGrasse Tyson, “Death by Black Hole” (via retromantique)

scienceisbeauty:

View of a Schwarzschild wormhole as would be seen by a free falling observer on a Schwarschild black hole. The region from which the observer originates is on the right. The black hole shadow is a black circle that becomes an annulus once the observer passed through.

Via Wikimedia Commons.

the-science-llama:

Particle Collisions Could Create Twin Black Holes at Large Hadron Collider

Back in 2008, physicists repeatedly assured us that a black hole produced by the Large Hadron Collider (LHC) was not going to swallow Earth. But that doesn’t mean they weren’t hoping to make one. Collisions between high energy particles, like the LHC’s protons, could theoretically squeeze enough mass and energy into a small enough space to create a tiny black hole—and making one might be a bit easier than physicists believed. It takes 2.4 times less energy than previously thought to create a black hole from a particle collision, according to a new paper in Physical Review Letters. That’s because when two particles smash into each other, their gravitational pull traps energy at two points on either side of the crash site. If enough energy gets concentrated at those points, it collapses into twin black holes that quickly gobble each other up and merge into one, as seen in the simulation above. Even with the new energy estimates, the chances of making a black hole in a particle accelerator are still vanishingly small. But because spotting one at the relatively low energy of the LHC would be solid experimental evidence for extra dimensions, physicists are keeping their fingers crossed.

Via sciencemag.org

thisweekinscience:

Event Horizons

Event Horizons are a boundary in spacetime beyond which events do not affect an outside observer. It is the point at which the gravitational pull becomes so great that nothing is able to escape it, not even light.  Light emitted from beyond the horizon can never reach the observer. Likewise, any object approaching the horizon from the observer’s side appears to slow down and never quite pass through the horizon, with its image becoming more and more redshifted as time elapses.

An observer crossing a black hole event horizon will be able to calculate the moment they have crossed it, but will not notice any change. Other objects that had entered the horizon along the same radial path but at an earlier time would appear below the observer but still above the visual position of the horizon, and if they had fallen in recently enough the observer could exchange messages with them before either one was destroyed by the gravitational singularity.

rhamphotheca:

CSI: Milky Way - Ancient Happenings at the Center of the Galaxy

by Dan Salisbury

These days the core of the Milky Way galaxy is a pretty tame place…cosmically speaking. The galactic black hole at the center is a sleeping giant. Existing stars are peacefully circling. Although conditions are favorable, there doesn’t even seem to be much new star formation going on.

But there is growing evidence that several million years ago the galactic center was the site of all manner of celestial fireworks. A pair of assistant professors – Kelly Holley-Bockelmannat Vanderbilt and Tamara Bogdanović at Georgia Institute of Technology – have come up with an explanation that fits these “forensic” clues.

Writing in the March 6 issue of the Monthly Notices of the Royal Astronomical Society, the astronomers describe how a single event – a violent collision and merger between the galactic black hole and an intermediate-sized black hole in one of the small “satellite galaxies” that circle the Milky Way – could have produced the features that point to a more violent past for the galactic core…

(read more: Vanderbilt University News)

(image: Julie Turner, Vanderbilt)

thisweekinscience:

Black Holes

Einstein’s theory of general relativity describes how gravity bends space-time and the light that passes through it. A black hole’s gravity is so strong that when it spins, it actually drags the space around it along. The surrounding material collects and forms an accretion disk, heats up due to friction and emits x-rays. Matter swirling in can be traced by these x-rays and the radiation seen is warped and distorted by particle motions and gravity