Tag Archives: gamma ray

Images showing steadily improve observations of gamma-rays emanated by the moon's surface. This image sequence shows how longer exposure, ranging from two to 128 months (10.7 years), improved the view. Credit: NASA/DOE/Fermi LAT Collaboration

The moon is actually brighter than the sun — in gamma rays

No one has ever gone blind from staring on the moon, while the same thing can’t be said about the sun’s glare. However, the moon is, in fact, brighter than the sun when it comes to gamma-ray radiation.

Images showing steadily improve observations of gamma-rays emanated by the moon's surface. This image sequence shows how longer exposure, ranging from two to 128 months (10.7 years), improved the view. Credit: NASA/DOE/Fermi LAT Collaboration

Images showing a steady improvement in the observations of gamma-rays emanated by the moon’s surface. This image sequence shows how longer exposure, ranging from two to 128 months (10.7 years), improved the view. Credit: NASA/DOE/Fermi LAT Collaboration

These grainy images were captured by NASA’s Fermi Gamma-Ray Space Telescope. They show the moon as a huge source of gamma-ray radiation — a form of electromagnetic radiation (EM) and the highest-energy photons of which we are aware of.

Gamma rays are created when electrically charged cosmic rays — protons accelerated by supernovae or jets produced by matter sucked into black holes — interact with matter, such as the surface of the moon.

They’re the most deadly type of EM radiation for living organisms. Luckily, they’re largely absorbed by Earth’s atmosphere.

However, on the moon, most of the gamma-ray radiation produced is absorbed by Earth’s natural satellite. Meanwhile, the sun only produces a fraction of its electromagnetic radiation in gamma rays — much less than the moon — because it has a very powerful magnetic field.

You can’t see gamma rays with the naked eye, but that’s where the Fermi Telescope comes in.

In a recent study, astronomers have calculated that the moon’s gamma rays can exceed 31 million electron volts, or 10 million times more powerful than visible light.

This brightness isn’t constant, though. Fermi LAT data show that the Moon’s brightness varies by about 20% over the Sun’s 11-year activity cycle.

“Seen at these energies, the Moon would never go through its monthly cycle of phases and would always look full,” said Francesco Loparco, co-author of the new study and a researcher at the National Institute of Nuclear Physics in Italy.

Although the moon is much brighter in gamma rays than the sun, occasionally cosmic rays will strike the dense part of the sun’s atmosphere, resulting in gamma rays above one billion electron volts. In this range, the sun is actually brighter.

The findings suggest that astronauts visiting the moon or living there over extended periods in a lunar outpost would be a great risk. Gamma rays and cosmic rays have a great penetrating power, which means shielding using elements such as lead is paramount.

NASA plans on sending humans back to the moon in 2024 as part of its Artemis program. Before that happens, we will have to be prepared for the threat of radiation exposure.

The most energetic light recorded thus far hits Tibetan plateau

Crab Nebula as seen by Hubble and Herschel. Credit: Wikimedia Commons.

An experiment involving over 600 particle detectors stretched over 36,900 square meters has measured the most energetic light ever witnessed on this planet. The photons were part of gamma rays emanating from the famous Crab Nebula, the remains of a supernova that was first observed in 1054 AD, which is located approximately 6,500 light years away. These photons measured tremendously high values exceeding 100 trillion electron volts (TeV), with one measurement clocking in 450TeV — the highest ever recorded. Previously, photons measuring no more than tens of trillions of electronvolts had been recorded.

Physicists started the Tibet Air Shower Gamma Collaboration, an observatory in the Tibetan Plateau some 4,300 meters above sea level because rarified air at this altitude allows more secondary particles to reach detectors. Secondary subatomic particles are created when cosmic rays and gamma rays interact with particles in the upper atmosphere.

By measuring and excluding muon particles — an elementary subatomic particle similar to the electron but 207 times heavier — physicists were able to backtrack the energy and origin of the incoming gamma rays that caused the showers. A total of 24 events caused by intense photons with energies higher than 100 trillion electronvolts were reported. To get a sense of the scale involved, regular photons that emanate from the sun — particles of visible light — have an energy of only a few electronvolts.

Now that scientists have experimental confirmation that high-energy photons reach Earth, they can elaborate a more precise model for how such particles are created and whether or not there’s a limit to how much energy they can carry.

In this particular case, researchers think that the gamma rays were accelerated by a process known as Inverse Compton scattering — a process during which super high-energy electrons bounce off lower energy photons. Inside the Crab Nebula, electrons may have scattered off low-energy photons from the cosmic microwave radiation (photons created soon after the Big Bang).

The findings appeared in the journal Physical Review Letters.

NASA names new constellations after Doctor Who, Hulk, and Godzilla

Thousands of years ago, when people looked at the night sky, they named the constellations based on their world and mythology. You have, for instance, Andromeda, Leo (the lion), and Hercules, all derived from Greek culture. But what would constellations be named in today’s culture? NASA did just that, and here’s what they came up with.

Image credits: NASA.

The new constellations include quite a few favorites of modern culture: from the Little Prince to Star Trek’s Enterprise, and from Godzilla with his heat ray to the time-warping TARDIS from Doctor Who. The Hulk, the product of a gamma-ray experiment gone awry, and Schrodinger’s cat are also featured.

The constellation collection was published to celebrate NASA’s Fermi Gamma-ray Space Telescope, which has been in operations for 10 years.

“Developing these unofficial constellations was a fun way to highlight a decade of Fermi’s accomplishments,” said Julie McEnery, the Fermi project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “One way or another, all of the gamma-ray constellations have a tie-in to Fermi science.

Since 2018, the Fermi Telescope has been surveying the night sky, probing dark matter, studying the high-energy behavior of gamma-ray bursts, and searching for micro-black holes, among many other objectives. Essentially, everything that features gamma-ray radiation can be studied to some extent by the telescope. Constellations are just a secondary bonus. The telescope’s official page reads:

“The Universe is home to numerous exotic and beautiful phenomena, some of which can generate almost inconceivable amounts of energy. Supermassive black holes, merging neutron stars, streams of hot gas moving close to the speed of light … these are but a few of the marvels that generate gamma-ray radiation, the most energetic form of radiation, billions of times more energetic than the type of light visible to our eyes.”

Fermi has been monumentally successful, says NASA’s Elizabeth Ferrara, who led the constellation project. The number of sources mapped by Fermi had expanded to 3,000 by 2015 — which is 10 times the number known before the mission.

If you want to explore the whole set of constellations, you’re in luck: Ferrara and Daniel Kocevski, an astrophysicist now at NASA’s Marshall Space Flight Center in Huntsville, Alabama, developed a web-based interactive to showcase the constellations.

The interactive website features lovely artwork from Aurore Simonnet, an illustrator at Sonoma State University, as well as a map of the whole gamma-ray sky from Fermi.

Although the original design featured a five-year lifetime (with a goal of ten years of operations), the telescope is still working as good as ever, and we can probably expect much more to come from it.

“Fermi is still going strong, and we are now preparing a new all-sky LAT catalog,” said Jean Ballet, a Fermi team member at the French Atomic Energy Commission in Saclay. “This will add about 2,000 sources, many varying greatly in brightness, further enriching these constellations and enlivening the high-energy sky!”

Researchers found a supermassive black hole choking on its meal

Scientists have found a supermassive black hole that seems to have bit more than it can chew. At the center of a galaxy some 300 million light years away from Earth, the black hole is straining to absorb the mass of a star it recently collapsed, “chocking” on its remains.

Artist’s impression of a supermassive black hole at a galaxy’s center. The blue color represents radiation pouring out from material very close to the black hole.
Image credits NASA/JPL-Caltech.

A team of researchers including members from MIT and NASA’s Goddard Space Flight Center have recently reported picking up on a peculiar “tidal disruption flare”, a massive burst of electromagnetic energy released when a black hole collapses a hapless star. The flare, named ASASSN-14li, first hit our sensors on Nov. 11, 2014, and researchers have since pointed all kinds of telescopes towards the source to learn as much as possible about how black holes evolve.

Led by MIT postdoc at the Kavli Institute for Astrophysics and Space Research Dheeraj Pasham, the team looked at data obtained with two different telescopes and found a strange pattern in the energy levels of the flare. As the supermassive black hole (I’ll just call it a SBH from not on) first began absorbing the former star’s matter, the team picked up on slight variations in the visible and ultraviolet intervals of the electromagnetic spectrum. Which in itself isn’t that weird — we’ll get to it in a moment. But the same pattern of fluctuations was picked up again 32 days later, this time in the X-ray band.

A flare of gluttony

So first off let’s get to know what these flares are and how they usually behave.

As I’ve said, tidal disruption flares are huge bursts of energy released when a black hole’s immense gravitational pull rips a star apart. The bursts propagate all over the electromagnetic spectrum, from radio, visible, and UV all the way to X-ray and gamma ray intervals. They’re pretty rare, so we didn’t witness that many of them despite the fact that they really stand out. But when we do, it’s a dead give away for hidden black holes — which would be almost impossible to spot otherwise.

“You’d have to stare at one galaxy for roughly 10,000 to 100,000 years to see a star getting disrupted by the black hole at the center,” Pasham, who’s also the paper’s first author, says.

“Almost every massive galaxy contains a supermassive black hole. But we won’t know about them if they’re sitting around doing nothing, unless there’s an event like a tidal disruption flare.”

So in a way we were lucky, but our sensors were also ready for it. The ASASSN-14li flare was picked up by the ASASSN (All Sky Automated Survey for SuperNovae) network of automated telescopes. Soon after, researchers pointed other telescopes towards the black hole, including the X-ray telescope aboard NASA’s Swift satellite — designed to monitor the sky for bursts of extremely high energy.

Artist’s rendering of the supermassive black hole that generated the flare and its accretion disk.
Image credits NASA / Swift / Aurore Simonnet, Sonoma State University.

“Only recently have telescopes started ‘talking’ to each other, and for this particular event we were lucky because a lot of people were ready for it,” Pasham says. “It just resulted in a lot of data.”

By looking at all the data they gathered on the event, Pasham and his team answered a long-standing mystery: where did these bursts of light originate in flares? By modeling a black hole’s dynamics, scientists have previously been able to explain that as a black hole rips its star apart, the resulting material can produce X-ray emissions very close to the event horizon. But the source for the visible and UV light proved elusive.

The team studied the 270 days after ASASSN-14li was first detected, with particular emphasis on the X-ray and optical/UV data taken by the Swift satellite and the Las Cumbres Observatory Global Telescope. Two broad peaks in the X-ray band were identified (one around day 50, and the other around day 110), and one short dip (around day 80). This was the exact same pattern they recorded for the visible/UV spectrum just 32 days earlier.

Their next step was to run simulations of the flare produced by a star collapsing next to a black hole and the resulting accretion disc (similar to how planets get them) — along with its presumed speed, size, and the rate which material falls onto the black hole.

Tug of war

 

The results suggest these energy fluctuations are a kind of electromagnetic echo. After the star was torn apart, its remains started swirling the supermassive black hole. As it drew nearer to the event horizon, the cloud of matter accelerated and became more tightly packed, releasing bursts of UV and visible light when its particles collided at high speeds. As the matter was pulled closer to the black hole it got even faster and denser, which also made it heat up. In this excited state of matter close to absorption into the event horizon, the collisions produced X- and gamma ray bursts instead of the lower-energy visible and UV bursts.

In the case of ASASSN-14li, this process happened much more slowly that usually because the great quantity of matter proved a bit too much for the black hole to chew in a single bite.

 

“In essence, this black hole has not had much to feed on for a while, and suddenly along comes an unlucky star full of matter.” Pasham explains. “What we’re seeing is, this stellar material is not just continuously being fed onto the black hole, but it’s interacting with itself — stopping and going, stopping and going. This is telling us that the black hole is ‘choking’ on this sudden supply of stellar debris.”

“For supermassive black holes steadily accreting, you wouldn’t expect this choking to happen. The material around the black hole would be slowly rotating and losing some energy with each circular orbit,” he adds.

“But that’s not what’s happening here. Because you have a lot of material falling onto the black hole, it’s interacting with itself, falling in again, and interacting again. If there are more events in the future, maybe we can see if this is what happens for other tidal disruption flares.”

The full paper “Optical/UV-to-X-Ray Echoes from the Tidal Disruption Flare ASASSN-14li” has been published in the journal Astrophysical Journal Letters.

 

 

Most convincing evidence for Dark Matter found – still not conclusive

Scientists have been analyzing high-energy gamma rays originating from the center of our galaxy and they’ve reported that there’s a good chance that at least some of them come from dark matter. This is the best indication of dark matter to ever be found.

What is dark matter?

Artistic representation of dark matter. There is no indication that dark matter is tangled like this.

Think about our universe for a moment – what is it made of? “Well I don’t know”, you might say, “stuff? Stars, planets, all that?”. Mmm, as it turns out, you’d be pretty off with that answer. Planets, stars, and everything that we call matter only makes up 5% of the Universe – that’s what the current understanding is. As for that 95%, dark energy is 68%, and dark matter is the rest, almost 27% – and we don’t know what those things are. We just know they’re there because we see their effects, but we don’t really know what they are. Dark energy is a hypothetical form of energy that permeates all of space and is believed to accelerate the expansion of the universe. But here, we’re more interested in dark matter.

To put it simply, dark matter is the thing which causes some gravitational effects and can’t be explained with anything else. It cannot be seen directly with telescopes; evidently it neither emits nor absorbs light or other electromagnetic radiation. Scientists can’t “see” or detect it directly in any way, but they observed some consistent gravitational effects where there shouldn’t be any gravity; the existence and properties of dark matter are inferred from its gravitational effects on visible matter, radiation, and the large-scale structure of the universe.

Detecting dark matter

Using data collected from NASA’s Fermi Gamma-ray Space Telescope, scientists from different institutions generated maps of the center of the galaxy. They found that some of the gamma-ray radiations can’t be explained through any known mechanism. It’s not just that they eliminated all the possible causes, they were still stuck with some radiation, and said “hey, look, this must be dark matter”. But then again… it’s not far off from that either.

The thing is, if dark matter particles with a particular mass are destroying each other, this would be a remarkable fit for the remaining emission. There is no real direct evidence to this, but there’s a lot of indirect indications. However, astronomers still warn that there might be other, currently unknown sources.

Elliott Bloom, a member of the Fermi collaboration, underlines that at this point, this can’t be confirmed or refuted as dark matter, but if they find a similar, stronger signal, that could confirm it.

“If we ultimately see a significant signal, it could be a very strong confirmation of the dark matter signal claimed in the galactic center.”

Source

An artist’s conception of the processes by which a star collapses and becomes a black hole, releasing high-energy gamma rays and X-rays, as well as visible light, in the process (credit: NASA)

Armada of instruments witness the brightest cosmic event of the century: the birth of a black hole

An artist’s conception of the processes by which a star collapses and becomes a black hole, releasing high-energy gamma rays and X-rays, as well as visible light, in the process (credit: NASA)

An artist’s conception of the processes by which a star collapses and becomes a black hole, releasing high-energy gamma rays and X-rays, as well as visible light, in the process (credit: NASA)

Astronomers all over the world rejoiced recently after they were treated to a most privileged event. Using the RAPTOR (RAPid Telescopes for Optical Response) system in New Mexico and Hawaii, in conjunction with the most sophisticated observatories in the world, researchers witnessed what may be the most brightest event this century: an extreme flash of light emanated as a massive star “drew its last breath”, giving birth to a black hole.

The event, dubbed GRB 130427A, took place somewhere in the  constellation Leo and generated a huge flash following the collapse of a massive star simultaneously releasing visible light, X-rays and gamma rays in one big gamma-ray burst. The whole burst lasted for around 80 seconds, which might not seem like much, but considering typically most gamma-ray bursts only last a couple fractions of a second to a few seconds, this should give you an idea of how massive the explosion was.

“This was a Rosetta-Stone event that illuminates so many things — literally,” said  astrophysicist Tom Vestrand. “We were very fortunate to have all of the NASA and ground-based instruments seeing it at the same time. We had all the assets in place to collect a very detailed data set. These are data that astrophysicists will be looking at for a long time to come because we have a detailed record of the event as it unfolded.”

[RELATED] Earth was hit by a massive gamma-ray burst in the 8th century

No doubt this was an extremely rare event and astronomers were very lucky to catch it in full sight. What’s even more fortunate, however, is that the flash was caught by an armada of instruments — including gamma-ray and X-ray detectors aboard NASA’s Fermi, NuSTAR and Swift satellites. This means that a slew of data on GRB 130427A is now available, painting maybe the most complete picture yet of such an event, and allowing scientists to learn more about what happens when a black hole is born. For instance, following the intense gamma-ray  a lingering “afterglow” that faded in lock-step with the highest energy gamma-rays was recorded.

“This afterglow is interesting to see,” said paper co-author Przemek Wozniak of Los Alamos’s Intelligence and Space Research Division. “We normally see a flash associated with the beginning of an event, analogous to the bright flash that you would see coinciding with the explosion of a firecracker. This afterglow may be somewhat analogous to the embers that you might be able to see lingering after your firecracker has exploded. It is the link between the optical phenomenon and the gamma-rays that we haven’t seen before, and that’s what makes this display extremely exciting.”

 

Astronomers identify the 514 most powerful objects in the Universe – they don’t know what 65 of them are

The Fermi Space Telescope has catalogued the 514 most powerful objects in the Universe, that we know of. Astrophysicists don’t know what over 10% of them are.

Why 514?

 

fermiThe idea was to catalog the objects which emit γ-ray sources at energies above 10 GeV. What’s a GeV? It stands for Giga electronvolt, which is 1 billion electronvolts. Aha, you may ask, but what’s an electonvolt? It’s a unit of energy, much like the Joule, except it’s much smaller (approximately 1.6×10−19 joules in 1 eV).

This energy range has not really been thoroughly studied – so the idea was to take all the objects in the known universe and separate those which are the most powerful energy sources.

“The idea is to have some sort of bridge catalogue between the typical catalogue done by Fermi… which contains thousands of sources, and the domain of the Cerenkov telescopes that have been operating over 20 years,” lead author of the new catalogue, David Paneque of the Max Planck Institute for Physics in Munich, Germany, explained.

But, as always with this kind of study, they also stumbled upon “unassociated sources”. So what are these unknown objects?

“What that means is that we know it’s a gamma-ray source, but we don’t know what kind of source,” he explained. “We can’t associate it with a radio object, with an optical object. It might be actually a new class of object – something that only emits in gamma rays.”

They could be things like dwarf galaxies composed of dark matter – things we don’t really know about, and astrophysicists would love to know more of. It could be unidentified quasars, but if this is the case, why haven’t astronomers identified them already?

Either way, something interesting will pop up – even if it’s only a small fraction, it’s more than enough to stir up an astronomic curiosity.

Original research

Fermi Space Telescope's map of gamma-ray emissions discovered so far. Nearly 600, a third of the total number of confirmed gamma-rays, have an untraceable origin.

One third of the discovered gamma rays so far have unknown sources

Fermi Space Telescope's map of gamma-ray emissions discovered so far. Nearly 600, a third of the total number of confirmed gamma-rays, have an untraceable origin.

Fermi Space Telescope's map of gamma-ray emissions discovered so far. Nearly 600, a third of the total number of confirmed gamma-rays, have an untraceable origin.

Set it went into operation, Fermi’s Large Area Telescope has detected 1873 gamma rays out in space, of which only two thirds have had their sources traced. Typically, gamma rays are huge bursts of energy generated by the collision between two stars or by black holes, however more than 600 discovered blasts still don’t have an explanation for their origin.

Several hypotheses have been launched around these untraceable super-energetic forms of light, the most popular possibility being that they’ve been triggered by some kind of dark matter event. Scientists know very little about dark matter, since it’s very hard to study due to the fact that it doesn’t emit any light, hence the “dark” adjective. What they do know is that it has a strong gravitational pull and that it makes up around 85% of the Universe, there rest being anything else we’re actually able to observe.

RELATED: Gamma ray bursts might cause extinction on Earth

This a very interesting hypothesis, which might lead to some staggering discoveries. Dark matter can’t be observed using conventional means like  a telescope or radio telescope, because it doesn’t shine, however inside a gamma ray blast, it might do. How would dark matter generate a gamma-ray blast?

“Some researchers believe that when two dark matter antiparticles bump into each other, they will annihilate, producing gamma rays. Concentrated clouds of dark matter could form a gamma ray source at specific wavelengths detectable by Fermi,” NASA explains.

“If we see a bump in the gamma-ray spectrum – a narrow spectral line at high energies corresponding to the energy of the annihilating particles – we could be the first to ‘apprehend’ dark matter,” Peter Michelson of Stanford University, the principal investigator for the Large Area Telescope said.

Watch NASA’s video “ScienceCasts: 600 Mysteries in the Night Sky” here:

NASA

Gamma-ray burst illustration. (c) NASA

Gamma-ray bursts might cause mass extinction on Earth

Gamma-ray burst illustration. (c) NASA

Gamma-ray burst illustration. (c) NASA

Most of us tend to believe the Earth is a safe heaven, with little regard to outerwordly consequences. The truth is our planet, although without a doubt a true gem within our galaxy, is susceptible to a slew of events triggered from within or well beyond our solar system. A lot of them are very dangerous to life on Earth, be it a menacing asteroid, a solar flare or even a terrifying gamma-ray burst.

Researchers of Washburn University, in Topeka, Kan. have studied gamma-ray bursts and its potential consequences, and now claim the Earth quite probably has been met by such events during its history, with dramatic consequences on the life harbored within it.

Gamma-ray bursts typically occur  when two stars collide, a process which leads to a giant energy burst into outer space. The gamma-ray bursts have the capability of depleting stratospheric ozone, allowing the most powerful and damaging forms of ultraviolet radiation to reach the Earth’s surface. Researchers are now beginning to connect the timing of these gamma-ray bursts to extinctions on Earth that can be dated through the fossil record.

“We find that a kind of gamma-ray burst — a short gamma-ray burst — is probably more significant than a longer gamma-ray burst,” study researcher Brian Thomas of Washburn University, in Topeka, Kan., said in a statement. “The duration is not as important as the amount of radiation.”

There are two types of gamma-ray bursts:  a longer, brighter burst caused by two collinding stars, as discussed earlier, and a short timed burst. The later caused by the collision of two black holes or neutron stars are even more harmful bursting an outrageous amount of radiation, even though the event only lasts a second.

Such an event, the researchers say, happens about once per 100 million years in any given galaxy. But if one did happen here, the results would be devastating. According to the scientists treating the study, if such an event should occur inside the Milky Way, dire consequences might afflict the Earth. The radiation, after reaching the atmosphere, would caused the depletion of the ozone by  knocking free oxygen and nitrogen atoms so they can recombine into ozone-destroying nitrous oxides. Earth would have been hit by several of these short-hard events over the course of its 4.5-billion-year history, according to the study authors.

The researchers are now looking of evidence of such an event. If a gamma-ray burst would have hit the Earth, the best sign of this would be the discovery of isotope iron-60. Isotopes like these   can reveal the strata of the events, it then becomes a matter of looking for extinction events that correlate and examining which species died and which survived.

“I work with some paleontologists and we try to look for correlations with extinctions, but they are skeptical,” said Thomas. “So if you go and give a talk to paleontologists, they are not quite into it. But to astrophysicists, it seems pretty plausible.”

 

Artist impression of a star getting ripped by a supermassive black hole. (c) Mark A. Garlick, University of Warwick

Intense Gamma Ray blast indeed traced back to supermassive black hole

Artist impression of a star getting ripped by a supermassive black hole. (c) Mark A. Garlick, University of Warwick

Artist impression of a star getting ripped by a supermassive black hole. (c) Mark A. Garlick, University of Warwick

We previously reported about an incredible gamma ray burst triggered by a black hole, so powerful that nothing like this was observed before, or even dimmed possible. A recently published paper in the journal Science sheds more light on the subject.

A typical gamma ray burst commonly occurs when massive stars explode due to collisions with other stars or simple from dying stars – these blasts of radiation usually last around 30 seconds, maybe a few minutes. This super Gamma Ray blast, first observed on 28th of March by the Swift telescope, went on it for days with high levels of radiation, and to this day it still hasn’t stop emitting. Actually, during its first couple of days of activity, the burst registered some wavelengths not visible to the naked eye as bright as a hundred billion suns, scientists report.

“This is probably the first time mankind has seen a phenomenon like this,” says astronomer Josh Bloom of the University of California- Berkeley, lead author of one of two studies on the outburst.

The study brings yet more evidence backing up the theory which say that the center of most big galaxies there’s a supermassive black hole, most of the time quite and dormant.

Swift and other satellites narrowed the origin of the March blast to the center of a galaxy about 22.4 billion trillion miles away or 3.8 billion light-years away, where a titanic black whole, weighing as much as 10 million times more than the sun, gobbled up a star and consumed its whole energy.

In addition, common gamma ray bursts are normally observed at the margin of a galaxy. Sw 1644+57, as the burst was dubbed, however was found in an unusual location – at the core of a galaxy.

“That’s the prime reason we started suspecting early on that a supermassive black hole was involved, because we know [galactic cores are] where these beasts reside.”

What’s remarkable is the game of chance which lead to the observation of this stunning phenomena. As the star was ripped apart by the black hole’s gravity, it was actually trained into a loop around the hole with the speed of light which caused a beam of radiation to spill out of latter’s center core. It took almost 4 billion years and precisely the perfect kind of geometry for the beam to hit Earth and astrophysicists to observe it.

“Seeing a star get ripped apart by a black hole from almost 4 billion light-years away, that’s a remarkable thing,” says astronomer Dave Goldberg, co-author of A User’s Guide to the Universe: Surviving the Perils of Black Holes, Time Paradoxes, and Quantum Uncertainty, who was not part of the studies. “We want to study black holes because they are tremendous natural laboratories for what happens to matter at very high energies.”

Dormant supermassive black holes are still a mystery for scientists, who still can’t unravel its spontaneous nature.

“What’s amazing,” Bloom said, “is that we have here an otherwise quiescent, starving black hole that has decided to go on a sudden feeding frenzy for a short period of time.”

Our galaxy, the Milky Way, seems to have a dormant supermassive black hole at its center as well, and if a Gamma Ray like the one presented earlier were to happen and point towards Earth, it would’ve wreak havoc. Chances something like this would ever happen, scientists assure, are astronomical.

Mysterious cosmic blast triggered by black hole

On the 28th of March the Swift telescope observed a peculiar gamma-ray blast in a distant corner of the visible universe, some 3.8 billion light years away, bewildered astronomers around the world. The powerful blast is theoretically caused, scientists say, by a black hole located in the center of the distant galaxy whose gravity tore apart a massive star which strayed too near. This happens all the time, however, the peculiar phenomena is linked to gamma-ray blast duration.

Typically, a gamma-ray burst last 30 seconds in average, but the one in question has been at it for 11 days now, still glaring. Also, as opposed to the the typical case, this fascinating cosmic blast seems to pulsate light, fading and then sparkling in repetitive intervals.

“It’s either a phenomenon we’ve never seen before or a familiar event that we’ve never viewed in this way before,” says Andrew Fruchter of the Space Telescope Science Institute in Baltimore.

“Tidal disruption of a star by a black hole seems very plausible,” says Andrew MacFadyen of New York University. The blast’s duration “is much longer than anything we’d naturally expect from [explosive] collapse of a single star,” which is the traditional model for producing a gamma-ray burst, he says.

Black hole in Dragon’s belly swallows star and everything goes nutty from here

Plot shows brightness changes recorded by telescopes. Credit: NASA/Swift/Penn State/J. Kennea

 

The Draco constellation (which is Latin for Dragon) is located at about 3.8 billion light years from Earth; just like every dragon that has at least some common sense, it breathes fire, especially after carelessly eating a nearby star.

Rewind. A mysterious cosmic blast in the Draco constellation is causing waves that continue to be observed long after researchers believe they should have stopped. Astronomers are scrambling, trying to find an answer to this puzzling question, but they haven’t been really successful, and nothing seems to explain this unusual situation; instead of the short lived gamma ray explosions that are typically associated with the death of a massive star that last only a few hours, the explosion continues to emit rays more than a week after the event.

This is a visible-light image of GRB 110328A's host galaxy (arrow) taken on April 4 by the Hubble Space Telescope's Wide Field Camera 3. The galaxy is 3.8 billion light-years away. (Credit: NASA/ESA/A. Fruchter - STScI)

 

“We know of objects in our own galaxy that can produce repeated bursts, but they are thousands to millions of times less powerful than the bursts we are seeing now,” said Andrew Fruchter, an astronomer at the Space Telescope Science Institute in Baltimore. “This is truly extraordinary.”

Images from Swift's Ultraviolet/Optical (white, purple) and X-ray telescopes (yellow and red) were combined in this view of GRB 110328A. The blast was detected only in X-rays, which were collected over a 3.4-hour period on March 28. (Credit: NASA/Swift/Stefan Immler)

 

Most galaxies, including our own, have supermassive black holes at their centers, with the mass more than a million times the Sun. But in a big galaxy, like the one we’re talking about, they can be even a thousand times bigger.

“Every spiral galaxy has a black hole at the center of it,” Paul Czysz, professor emeritus of aerospace engineering at St. Louis University, told TechNewsWorld. “At the center of our galaxy, there’s a lot of stars circulating around the black hole at the center of the Milky Way.”

Just like the Sun keeps the planets in our solar system spinning around it, a supermassive black hole does the same for a galaxy, but sometimes, it “chews” on one of the stars closest to it, thus generating the short lived gamma ray bursts I was telling you about earlier. However, this phenomenon could revolutionize researchers’ understanding of how supermassive black holes, which is quite important, considering we have one of them in the very center of the Milky Way.

The 8 coolest ways the Earth might be destroyed

We’ve all seen at least one movie in which our planet is destroyed, but most of them were quite repetitive and kind of uninteresting. Our planet deserves so much more!

Black holes

750px-bh_lmcWell, it seems the more we understand things about black holes, the more we find out things we don’t know, and the more we fear them. Let’s just make a short recap:
Black holes are regions of space with a gravitational field so powerful that absolutely nothing, not even light can escape them once it hits the event horizon, aka the point of no return (it’s believed that they do emit a radiation, but that’s not the topic here). Since light can not escape from them, we see them as black.

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There is no telling what the inside of a black hole looks like, but we can estimate certain things by analyzing the stars and planets surrounding it. The thing about the black holes is, they have a nasty habit of pulling things towards them. Now, when you’re dealing with something that can be as heavy as a thousand billions suns (1.000.000.000.000!!), you don’t wanna joke around with it. There is a supermassive black hole in the center of our galaxy, and researchers concluded that almost all, if not all galaxies have one, and these supermassive ones may have actually contributed to the creating of galaxies. Yeah, they may be the reason why we exist, and they may very well be the reason we cease to exist, according to some scientists.

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Supernova

cosmic_ray_supernovaDid you ever go out and see the sun shine right in your eye? Well, now think of the same thing, only a billion times brighter – a supernova can do just that. A supernova is basically a stellar explosion that’s extremely bright and expels much or all of the star’s material. In order for you to make an idea of just how bright it is, you should know that it often outshines the whole galaxy for several weeks or even months before finally fading away! In this short period of time, it emits about as much energy as the Sun emits in it entire lifespan.

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Supernovas occur every 50 years and if the Earth would be on the direction of one, it wouldn’t be destroyed, but the whole atmosphere will be wiped out and the supernova will bring clouds of dust and gas weighing several times as much as our whole solar system. However, we would be filthy rich, since researchers believe a supernovae created the heavy elements (gold and uranium, for example) found on our planet.
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Asteroid/Comet/other NEO impact

As Col. Gen. O’Neill so eloquently puts it – ‘I’ve seen this movie. It hits Paris‘.

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Well, when it comes to NEOs (near Earth objects), one thing’s for sure: our atmosphere saves us every week, literally. How often have you heard of a meteorite, for example, hitting Earth? I think not so often. Why not? Well, it’s either the government trying to hide everything, or they actually don’t hit our planet that often (protip: go for the 2nd option).

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In the vast majority of the cases, atmosphere causes a tremendous amount of friction that literally burns the meteorite (an asteroid becomes defined as a meteorite when it enters our atmosphere). However, what happens when the it’s so big that there’s not enough time for it to fully burn, and this massive fireball breaks through our atmosphere? There’s a belief that 65 million years ago, an asteroid destroying almost all (or all) of the large vertebrates, leaving our planet subject to a mass extinction. It’s practically impossible to accurately determine the chance of another one such as that to hit our planet again, but it’s estimated that one as big as 1/5 of it hits our planet every million of years or so. Well, I haven’t heard of such a big impact recently… maybe it’s overdue?

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Cannibal galaxies

It’s a dog eat dog out there, and this is natural selection at its best. Whether you believe it or not, sometimes galaxies grow by devouring their own; it gets even better – the Milky Way is no exception. Yep, that’s right. Just a few years ago, astronomer Steven Majewski showed that our galaxy feasted on the Sagittarius galaxy, which gets close to us every 750 million years or so. Even our own neighbor, Andromeda is planning to gobble up a galaxy named M33 in the constellation of Triangulum.

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As was the case with the black holes, galaxy formation and galaxy destruction go hand in hand. I can’t help but appreciate the irony.

Cosmic Cannibal

Gamma Ray Burst

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Gamma rays don’t only give Hulk his powers, they also have other extremely interesting properties. A gamma ray is basically an electromagnetic radiation of very high energy, practically most luminous electromagnetic waves that we have knowledge of. They have extremely high frequencies (10^19 Hz), and thus really high energies and small wavelengths.

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However, gamma ray bursts often have an afterglow effect as the longer wavelengths arrive slightly later. If our planet would be in the way of such a ray, the ozone would be depleted and our planet would be subject to all the UV rays, leading to a short and hopeless extinction. It’s believed that it was such a burst that caused the Ordovician-Silurian planetary extinction that took place about 444 million years ago.

Sun’s death

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Think of our sun as a huge power source, running on fuel that is not endless. Unless we someday find some way to reverse nuclear fusion, the sun will run out of fuel, will become a red giant, and then a white dwarf. Well, don’t worry, there’s still about 5 billion years until that happens, but the change is gradual. The sun gets hotter and hotter and probably by the time it (almost) becomes a red giant, life on Earth will already be extinct. Oh well, after 10 billion years of delivering heat and light towards our solar system, a permanent vacation is nothing short of what our sun deserves.

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The big rip

Well, the name pretty much speaks for itself here. The big rip is all about matter being ripped. Basically, it starts on the fact that the whole Universe is expanding, heavily relying on relies the type of dark energy in the universe. Dark energy is a hypothetical kind of energy that saturates all the universe and is ‘pulling’ its edges, making it expand. If this theory were to happen, a while before the big rip makes its final move, the Solar System will be gravitationally unbound. The stars and planets will just drift, and after that, they will be torn from their very core. The same thing will happen at atom scale.

The Heat death of our Universe

The heat death is explained the most easily in physical terms: it is a state in which the Universe has reached maximum entropy. It is a final stage in which the Universe can no longer provide thermodynamic free energy in order to sustain any form of life as we know it. The result would be that temperature would asymptotically be absolute 0. What we do know now is that entropy can be produced at least for 10^100 years (which is the time estimated for the black holes to ‘run out’), but after that, the Universe will enter it’s dark era, or to put it in layman’s terms, die.

The most distant object in the universe found so far

ESO’s Very Large Telescope has shown something that scientists concluded is the signature of the explosion of the object furthest away from Earth we have found so far, a redshift of 8.2; it’s estimated that the explosion took place more than 13 billion years ago (!!), just 600 million years after the Big Bang.

They found it using a technology that “spotted” a faint gamma ray burst just Thursday. Gamma ray bursts are very intense flashes of gamma rays that last from a split second to several minutes and release huge amounts of energy in very short times, making them the most powerful events we know so far; they’re mostly associated with the explosion of massive stars that collapse into black holes.

“We find that the light coming from the explosion has been stretched, or redshifted, considerably by the expansion of the Universe”, says Nial Tanvir, the leader of the team who made the VLT observations. “With a redshift of 8.2 this is the most remote gamma-ray burst ever detected, and also the most distant object ever discovered — by some way.”

“This discovery proves the importance of gamma-ray bursts in probing the most distant parts of the Universe”, says Tanvir. “We can now be confident that even more remote bursts will be found in the future, which will open a window to studying the very first stars and the ultimate end of the Dark Age of the Universe.”

Nasa discovers a dozen pulsars that change understanding about dying stars

Recently, NASA’s Fermi Gamma-ray Space Telescope discovered no more, no less than 12 pulsars, and it also detected gamma ray pulse from 18 others. These findings are forcing scientists to rethink what we know about dying stars, as they totally underestimated the power of these stellar cilinders.

“We know of 1,800 pulsars, but until Fermi we saw only little wisps of energy from all but a handful of them,” says Roger Romani of Stanford University, Calif. “Now, for dozens of pulsars, we’re seeing the actual power of these machines.”

Pulsars are rotating neutron stars, highly magnetized, that emit a beam of electromagnetic radiation with a period of the pulse variating from 8.5 seconds to just 1.5 miliseconds. They are what remains when a massive star explodes. They’re also incredible cosmic dynamos and despite the fact that scientists don’t fully understand this process, they can say for sure that very intense electric and magnetic fields spin and accelerate particles to speeds very close to that of light.

Most pulsars were found because they emitted pulses at radio wavelength which are emitted from the pulsar’s poles. If these poles and the star’s spin axis are not alligned exactly, then the beams would be swept across the sky, meaning that we can detect them only if such a beam meats a radio telescope. But data is often inaccurate or biased because these telescopes are situated on Earth

“That has colored our understanding of neutron stars for 40 years,” Romani says. The radio beams are easy to detect, but they represent only a few parts per million of a pulsar’s total power. Its gamma rays, on the other hand, account for 10 percent or more. “For the first time, Fermi is giving us an independent look at what heavy stars do. “

“We used to think the gamma rays emerged near the neutron star’s surface from the polar cap, where the radio beams form,” addsAlice Harding of NASA’s Goddard Space Flight Center in Greenbelt, Md. “The new gamma-ray-only pulsars put that idea to rest.”

Now, scientists have their hands full with this new class of gamma-ray pulsars, which they believe arise far above the neutron star. Due to the fact that rotation powers their emissions they tend to slow down a bit as they “age”; however, Fermi picked up emissions from gamma rays from seven millisecond pulsars (which are called this way because they spin somewhere between 100 and 1000 times a second!!!). They tend to sometimes “break the rules”, and “cohabitate” with a normal star, residing in binary systems.

Here are some animations to give you a better and more visual understanding of this.

Quick Time animation
Credit: NASA/Fermi/Cruz deWilde

These gamma-ray pulsars show that gamma rays must form in a broader region than believed previously. Here, you can see the radio beams (green) never intersect Earth, but the pulsed gamma rays (magenta) do.


Animation 2
Credit: NASA/Goddard Space Flight Center Conceptual Image Lab


But gamma ray pulsars are no longer lighthouses, as pointed out here.


Animation 3
Credit: NASA/Dana Berry

Isolated pulsars slowly slow down their spin, but if a pulsar “lives” in a binary system with a normal star, it actually goes faster and faster. As a result, you could have a pulsar that spins in just a few miliseconds. How fast can they go?? It’s still uncertain.