New from Space: Simulations and X-Rays Point to Dark Matter

center_universe2The cosmic hunt for dark matter has been turning up some interesting clues of late. And during the month of June, two key hints came along that might provide answers; specifically simulations that look at the “local Universe” from the Big Bang to the present day and recent studies involving galaxy clusters. In both cases, the observations made point towards the existence of Dark Matter – the mysterious substance believed to make up 85 per cent of the mass of the Universe.

In the former case, the clues are the result of new supercomputer simulations that show the evolution of our “local Universe” from the Big Bang to the present day. Physicists at Durham University, who are leading the research, say their simulations could improve understanding of dark matter due to the fact that they believe that clumps of the mysterious substance – or halos – emerged from the early Universe, trapping intergalactic gas and thereby becoming the birthplaces of galaxies.

universe_expansionCosmological theory predicts that our own cosmic neighborhood should be teeming with millions of small halos, but only a few dozen small galaxies have been observed around the Milky Way. Professor Carlos Frenk, Director of Durham University’s Institute for Computational Cosmology, said:

I’ve been losing sleep over this for the last 30 years… Dark matter is the key to everything we know about galaxies, but we still don’t know its exact nature. Understanding how galaxies formed holds the key to the dark matter mystery… We know there can’t be a galaxy in every halo. The question is: ‘Why not?’.

The Durham researchers believe their simulations answer this question, showing how and why millions of halos around our galaxy and neighboring Andromeda failed to produce galaxies. They say the gas that would have made the galaxy was sterilized by the heat from the first stars that formed in the Universe and was prevented from cooling and turning into stars. However, a few halos managed to bypass this cosmic furnace by growing early and fast enough to hold on to their gas and eventually form galaxies.

dark_matterThe findings were presented at the Royal Astronomical Society’s National Astronomy Meeting in Portsmouth on Thursday, June 26. The work was funded by the UK’s Science and Technology Facilities Council (STFC) and the European Research Council. Professor Frenk, who received the Royal Astronomical Society’s top award, the Gold Medal for Astronomy, added:

We have learned that most dark matter halos are quite different from the ‘chosen few’ that are lit up by starlight. Thanks to our simulations we know that if our theories of dark matter are correct then the Universe around us should be full of halos that failed to make a galaxy. Perhaps astronomers will one day figure out a way to find them.

Lead researcher Dr Till Sawala, in the Institute for Computational Cosmology, at Durham University, said the research was the first to simulate the evolution of our “Local Group” of galaxies, including the Milky Way, Andromeda, their satellites and several isolated small galaxies, in its entirety. Dr Sawala said:

What we’ve seen in our simulations is a cosmic own goal. We already knew that the first generation of stars emitted intense radiation, heating intergalactic gas to temperatures hotter than the surface of the sun. After that, the gas is so hot that further star formation gets a lot more difficult, leaving halos with little chance to form galaxies. We were able to show that the cosmic heating was not simply a lottery with a few lucky winners. Instead, it was a rigorous selection process and only halos that grew fast enough were fit for galaxy formation.

darkmatter1The close-up look at the Local Group is part of the larger EAGLE project currently being undertaken by cosmologists at Durham University and the University of Leiden in the Netherlands. EAGLE is one of the first attempts to simulate from the beginning the formation of galaxies in a representative volume of the Universe. By peering into the virtual Universe, the researchers find galaxies that look remarkably like our own, surrounded by countless dark matter halos, only a small fraction of which contain galaxies.

The research is part of a program being conducted by the Virgo Consortium for supercomputer simulations, an international collaboration led by Durham University with partners in the UK, Germany, Holland, China and Canada. The new results on the Local Group involve, in addition to Durham University researchers, collaborators in the Universities of Victoria (Canada), Leiden (Holland), Antwerp (Belgium) and the Max Planck Institute for Astrophysics (Germany).

ESO2In the latter case, astronomers using ESA and NASA high-energy observatories have discovered another possible hint by studying galaxy clusters, the largest cosmic assemblies of matter bound together by gravity. Galaxy clusters not only contain hundreds of galaxies, but also a huge amount of hot gas filling the space between them. The gas is mainly hydrogen and, at over 10 million degrees celsius, is hot enough to emit X-rays. Traces of other elements contribute additional X-ray ‘lines’ at specific wavelengths.

Examining observations by ESA’s XMM-Newton and NASA’s Chandra spaceborne telescopes of these characteristic lines in 73 galaxy clusters, astronomers stumbled on an intriguing faint line at a wavelength where none had been seen before. The astronomers suggest that the emission may be created by the decay of an exotic type of subatomic particle known as a ‘sterile neutrino’, which is predicted but not yet detected.

dark_matter_blackholeOrdinary neutrinos are very low-mass particles that interact only rarely with matter via the so-called weak nuclear force as well as via gravity. Sterile neutrinos are thought to interact with ordinary matter through gravity alone, making them a possible candidate as dark matter. As Dr Esra Bulbul – from the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, USA, and lead author of the paper discussing the results – put it:

If this strange signal had been caused by a known element present in the gas, it should have left other signals in the X-ray light at other well-known wavelengths, but none of these were recorded. So we had to look for an explanation beyond the realm of known, ordinary matter… If the interpretation of our new observations is correct, at least part of the dark matter in galaxy clusters could consist of sterile neutrinos.

The surveyed galaxy clusters lie at a wide range of distances, from more than a hundred million light-years to a few billion light-years away. The mysterious, faint signal was found by combining multiple observations of the clusters, as well as in an individual image of the Perseus cluster, a massive structure in our cosmic neighborhood.

The supermassive black hole at the center of the Milky Way galaxy.The implications of this discovery may be far-reaching, but the researchers are being cautious. Further observations with XMM-Newton, Chandra and other high-energy telescopes of more clusters are needed before the connection to dark matter can be confirmed. Norbert Schartel, ESA’s XMM-Newton Project Scientist, commented:

The discovery of these curious X-rays was possible thanks to the large XMM-Newton archive, and to the observatory’s ability to collect lots of X-rays at different wavelengths, leading to this previously undiscovered line. It would be extremely exciting to confirm that XMM-Newton helped us find the first direct sign of dark matter. We aren’t quite there yet, but we’re certainly going to learn a lot about the content of our bizarre Universe while getting there.

Much like the Higgs Boson, the existence of Dark Matter was first theorized as a way of explaining how the universe appears to have mass that we cannot see. But by looking at indirect evidence, such as the gravitational influence it has on the movements and appearance of other objects in the Universe, scientists hope to one day confirm its existence. Beyond that, there is the mystery of “Dark Energy”, the hypothetical form of energy that permeates all of space and is believed to be behind accelerations in the expansion of the universe.

As with the discovery of the Higgs Boson and the Standard Model of particle physics, detecting these two invisible forces will at last confirm that the Big Bang and Cosmological theory are scientific fact – and not just working theories. When that happens, the dream of humanity finally being able to understand the universe (at both the atomic and macro level) may finally become a reality!

Source: sciencedaily.com, (2)

Remembering the Shuttle Challenger Disaster

Challenger_explosionToday marks the 28th anniversary of the Shuttle Challenger Disaster, an incident which has lived on in the memories of people around the world and to many, signaled the end of an era. The shuttle’s explosion, which took place at 11:39:13 am EST on January 28th, 1986, occurred just 73 seconds into flight after it took off from Cape Canaveral on the Florida coast.

According to investigators, the accident occurred when the O-ring seal in the shuttle’s solid rocket booster failed during liftoff, which allowed pressurized hot gas from within the solid rocket motor to reach the outside. This malfunction led to the separation of the right-hand solid rocket booster’s aft attachment and the structural failure of the external tank.

Challenger_flight_51-l_crewThe fallen crew members included NASA astronauts Greg Jarvis, Ronald McNair, Ellison Onizuka, Judith Resnik, Michael J. Smith and Dick Scobee, as well as school teacher Christa McAuliffe. It was because of McAuliffe’s presence on the shuttle –  as the first member of the Teacher in Space Project – that roughly 17 percent of Americans were tuned to their TVs during the time of the accident and witnessed the tragedy.

The disaster resulted in a 32-month hiatus in the shuttle program and the formation of the Rogers Commission, a presidential commission charged with investigating the accident. It revealed, amongst other things, that NASA’s organizational culture was in part responsible for the disaster. In short, NASA managers had known that the O-Rings in the Solid Rocket Booster (SRB) design contained a fatal flaw, one which was overlooked.

???????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????The investigation also revealed that engineers at Morton Thiokol, the manufacturer of the rocket boosters, had warned them prior to the launch of the flaw. One such engineer was Roger Boisjoly, who realized that a shuttle launch in the cold weather that Florida was experiencing would pose a grave danger. As he had indicated, the rockets weren’t designed to launch safely in weather below 40 degrees Fahrenheit.

NASA officials at the time rejected Boisjoly’s warning, saying that he was acting on a gut feeling rather than science. Boisjoly told The Times in an interview in 2003 that NASA tried to blacklist him from the industry, and  went so far as to argue that some NASA officials should be indicted for manslaughter charges, and the agency should be abolished.

Challenger_learning_centerThere are many memorials to the fallen crew, but one of the most cited in education is the 40 Challenger Learning Centers that are located in the United States, Canada, United Kingdom and South Korea. The network was founded by June Scobee Rogers (the widow of commander Scobee) and includes participation from other Challenger family members.

According to their website, their goal is to:

[G]ive students the chance to become astronauts and engineers and solve real-world problems as they share the thrill of discovery on missions through the Solar System.

As a result of the disaster, the Air Force decided to cancel its plans to use the Shuttle for classified military satellite launches from Vandenberg Air Force Base in California, deciding to use the Titan IV instead. Media coverage of the accident was also extensive, with one study indicating that 85 percent of Americans had heard the news within an hour of the accident.

astronaut_memorial_foundationChallenger’s anniversary comes in a week that includes other tragic anniversaries, including the Apollo 1 pad fire that occurred on Jan. 27th, 1967 and claimed the lives of three astronauts’ lives; the Columbia shuttle breakup that happened on Feb. 1st, 2003 and killed seven. Many other astronauts have died in training accidents, and their names are listed at the Astronaut Memorial Foundation.

The disaster has also been used as a case study in many discussions of engineering safety and workplace ethics. And it serves as a constant reminder of the bravery of those who choose to go into space for the sake of advancing science and our understanding of the cosmos. It’s also a reminder that the only safeguard against tragic accidents is eternal vigilance!

Let us all hope and pray no such incidents happen as we embark on a renewed age of space exploration and discovery!

Looking for Dark Matter: The DarkSide-50 Project

darkmatter1If 2013 will go down in history as the year the Higgs Boson was discovered, then 2014 may very well be known as the year dark matter was first detected. Much like the Higgs Boson, our understanding of the universe rests upon the definitive existence of this mysterious entity, which alongside “dark energy” is believed to make up the vast majority of the cosmos.

Before 2014 rolled around, the Large Underground Xenon experiment (LUX) – located near the town of Lead in South Dakota – was seen as the best candidate for finding it. However, since that time, attention has also been directed towards the DarkSide-50 Experiment located deep underground in the Gran Sasso mountain, the highest peak in the Appennines chain in central Italy.

darkside-50This project is an international collaboration between Italian, French, Polish, Ukrainian, Russian, and Chinese institutions, as well as 17 American universities, which aims to pin down dark matter particles. The project team spent last summer assembling their detector, a grocery bag-sized device that contains liquid argon, cooled to a temperature of -186° C (-302.8° F), where it is in a liquid state.

According to the researchers, the active, Teflon-coated part of the detector holds 50 kg (110 lb) of argon, which provides the 50 in the experiment’s name. Rows of photodetectors line the top and bottom of the device, while copper coils collect the stripped electrons to help determine the location of collisions between dark matter and visible matter.

darkside-50-0The research team, as well as many other scientists, believe that a particle known as a WIMP (weakly interacting massive particle) is the prime candidate for dark matter. WIMP particles have little interaction with their surroundings, so the researchers are hoping to catch one of these particles in the act of drifting aloof. They also believe that these particles can be detected when one of them collides with the nucleus of an atom, such as argon.

By cramming the chamber of their detector with argon atoms, the team increases their chance of seeing a collision. The recoil from these collisions can be seen in a short-lived trail of light, which can then be detected using the chamber’s photodetectors. To ensure that background events are not interfering, the facility is located deep underground to minimize background radiation.

darkmatterTo aid in filtering out background events even further, the detector sits within a steel sphere that is suspended on stilts and filled with 26,500 liters (7000 gallons) of a fluid called scintillator. This sphere in turn sits inside a three-story-high cylindrical tank filled with 946,350 liters (250,000) of ultrapure water. These different chambers help the researchers differentiate WIMP particles from neutrons and cosmic-ray muons.

Since autumn of 2013, the DarkSide-50 project has been active and busy collecting data. And it is one of about three dozen detectors in the world that is currently on the hunt for dark matter, which leads many physicists to believe that elusive dark matter particles will be discovered in the next decade. When that happens, scientists will finally be able to account for 31.7% of the universe’s mass, as opposed to the paltry 4.9% that is visible to us now.

planck-attnotated-580x372Now if we could only account for all the “dark energy” out there – which is believed to make up the other 68.3% of the universe’s mass – then we’d really be in business! And while we’re waiting, feel free to check out this documentary video about the DarkSide-50 Experiment and the hunt for dark matter, courtesy of Princeton University:

Sources: gizmag.com, princeton.edu

News From Space: Gaia Lifts Off!

gaia_liftoffThis morning, the European Space Agency’s Gaia mission blasted off from Europe’s Spaceport in Kourou, French Guiana, on the head of a Soyuz rocket. This space observatory aims to study approximately 1 billion stars, roughly 1% of the Milky Way Galaxy, and create the most accurate map yet of the Milky Way. In so doing, it will also answer questions about the origin and evolution of our home Galaxy.

As the successor to the Hipparcos mission – an ESA astrometry satellite that was launched in 1989 and operated until 1993 – it is part of ESA’s Horizon 2000 Plus long-term scientific program. Repeatedly scanning the sky, Gaia will observe each of the billion stars an average of 70 times each over the five years and measure the position and key physical properties of each star, including its brightness, temperature and chemical composition.

The Milky Way Shines on ParanalThe Soyuz VS06 launcher, operated by Arianespace, lifted off at 09:12 GMT (10:12 CET). About ten minutes later, after separation of the first three stages, the Fregat upper stage ignited, delivering Gaia into a temporary parking orbit at an altitude of 175 km. A second firing of the Fregat 11 minutes later took Gaia into its transfer orbit, followed by separation from the upper stage 42 minutes after liftoff.

Gaia is now en route towards an orbit around a gravitationally-stable virtual point in space called L2 Lagrange Point, some 1.5 million kilometres beyond Earth.  Tomorrow, engineers will command Gaia to perform the first of two critical thruster firings to ensure it is on the right trajectory towards its L2 home orbit. About 20 days after launch, the second critical burn will take place, inserting it into its operational orbit around L2.

Gaia_spacecraftJean-Jacques Dordain, ESA’s Director General, had this to say about the launch:

Gaia promises to build on the legacy of ESA’s first star-mapping mission, Hipparcos, launched in 1989, to reveal the history of the galaxy in which we live.

ESA’s Gaia project scientist Timo Prusti expressed similar sentiments, highlighting how the Gaia mission’s ultimate purpose is to advance our understanding of the cosmos:

Along with tens of thousands of other celestial and planetary objects, this vast treasure trove will give us a new view of our cosmic neighbourhood and its history, allowing us to explore the fundamental properties of our Solar System and the Milky Way, and our place in the wider Universe.

By taking advantage of the slight change in perspective that occurs as Gaia orbits the Sun during a year, it will measure the stars’ distances and their motions across the sky. This motions will later be put into “rewind” to learn more about where they came from and how the Milky Way was assembled over billions of years from the merging of smaller galaxies, and into “fast forward” to learn more about its ultimate fate.

Gaia_galaxyThis is an especially ambitious mission when you consider that of the one billion stars Gaia will observe, 99% have never had their distances measured accurately. The mission will also study 500,000 distant quasars and will conduct tests of Einstein’s General Theory of Relativity. So as the mission continues and more data comes in, scientists and astronomers will be able to construct more detailed models of how the universe was created, and perhaps how it will end…

The current consensus is that the universe began with a creation event known as The Big Bang. However, the question of how it will end, either through a “Big Crunch” event – where the expansion of the universe will eventually cease and all matter will collapse back in on itself – or simply continue to expand until all stars and galaxies consume their fuel and burn out, remains something of a mystery.

Gaia_spacecraft2Personally, I call Big Crunch, mainly because I like to the think that our universe is one of many. Not just in the parallel dimension sense, but in the temporal sense as well. Like the city of Ilium (aka. Troy), existence as we know it is built upon the foundations of countless others, stretching backwards and forwards into infinity…

Deep stuff, man! In the meantime, enjoy this video of the Gaia’s mission’s liftoff, courtesy of the ESA:


Sources: universetoday.com, esa.int

Evidence for the Big Bang

planck-attnotated-580x372The Big Bang Theory has been the dominant cosmological model for over half a century. According to the theory, the universe was created approximately 14 billion years ago from an extremely hot, dense state and then began expanding rapidly. After the initial expansion, the Universe cooled and began to form various subatomic particles and basic elements. Giant clouds of these primordial elements later coalesced through gravity to form stars, galaxies, and eventually planets.

And while it has its detractors, most of whom subscribe to the alternate Steady State Theory – which claims that new matter is continuously created as the universe expands – it has come to represent the scientific consensus as to how the universe came to be. And as usual, my ol’ pal and mentor in all things digital, Fraser Cain, recently released a video with the help of Universe Today discussing the particulars of it.

big_bangAddressing the particulars of the Big Bang Theory, Cain lists the many contributions made over the past century that has led this so-called theory to become the scientific consensus has come to exist. They are, in a nutshell:

  1. Cosmic Expanion: In 1912, astronomer Vesto Slipher calculated the speed and distance of “spiral nebulae” (galaxies) by measuring the light coming from them. He determined most were moving away. In 1924, Edwin Hubble determined that these galaxies were outside the Milky Way. He postulates that the motion of galaxies away from our own indicates a common point of origin.
  2. Abundance of Elements: Immediately after the big bang, only hydrogen existed and compressed into a tiny area of space under incredible heat and pressure. Like a star, this turned hydrogen into helium and other basic elements. Looking out into the universe (and hence back in time) scientists have found that great distances, the ratios of hydrogen to basic elements is consistent with what is found in star’s interiors.
  3. Cosmic Microwave Background (CMB) Radiation: In the 1960’s, using a radiotelescope, Arno Penzias and Robert Wilson discovered a background radio emission coming from every direction in the sky, day or night. This was consistent with the Big Bang Theory, which predicted that after the Big Bang, there would have been a release of radiation which then expanded billions of light years in all directions and cooled to the point that it shifted to invisible, microwave radiation.
  4. Large Scale Structure: The formation of galaxies and the large-scale structure of the cosmos are very similar. This is consistent with belief that after the initial Big Bang, the matter created would have cooled and began to coalesce into large collections, which is what galaxies, local galactic groups, and super-clusters are.

These are the four pillars of the Big Bang Theory, but they are no means the only points in its favor. In addition, there are numerous observational clues, such as how we have yet to observe a stars in the universe older than 13 billion years old, and fluctuations in the CMB that indicate a lack of uniformity. On top of that, there is the ongoing research into the existence of Dark Matter and Dark Energy, which are sure to bear fruit in the near future if all goes well.

big_bang1In short, scientists have a pretty good idea of how the universe came to be and the evidence all seems to confirm it. And some mysteries remain, we can be relatively confident that ongoing experimentation and research will come up with new and creative ways to shed light on the final unknowns. Little reason then why the Big Bang Theory enjoys such widespread support, much like Evolution, Gravity, and General Relativity.

Be sure to check out the full video, and subscribe to Universe Today for additional informative videos, podcasts, and articles. As someone who used to write for them, I can tell you that it’s a pretty good time, and very enlightening!

Zodiac

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Zodiacal light, the kind that takes millions of years to come

What revelations will it share, which are already so old?

The edge of the universe, the boundary of creation

Pulsing with the same power that once beget it all.

How can it be, when a billion are swirled into one,

And a billion more circle each other ad infinitum,

That I can think myself the paragon of creation?

But a billion billion voices still seem to cry out with one voice,

To letting me know how small and insignificant I truly am

And at the same time, so very rare and precious.

But more than this, how very much I am not alone.