Universe is expanding faster than expected


Photo Source: Thinkstock
Washington: The universe is expanding 5 to 9 per cent faster than thought, astronomers using NASA's Hubble Space Telescope have discovered. "This surprising finding may be an important clue to understanding those mysterious parts of the universe that make up 95 per cent of everything and don't emit light, such as dark energy, dark matter, and dark radiation," said study leader and Nobel Laureate Adam Riess of the Space Telescope Science Institute and The Johns Hopkins University in the US. Researchers made the discovery by refining the universe's current expansion rate to unprecedented accuracy, reducing the uncertainty to only 2.4 per cent. The team made the refinements by developing innovative techniques that improved the precision of distance measurements to faraway galaxies. They looked for galaxies containing both Cepheid stars and Type Ia supernovae. Cepheid stars pulsate at rates that correspond to their true brightness, which can be compared with their apparent brightness as seen from Earth to accurately determine their distance. Type Ia supernovae, another commonly used cosmic yardstick, are exploding stars that flare with the same brightness and are brilliant enough to be seen from relatively longer distances. By measuring about 2,400 Cepheid stars in 19 galaxies and comparing the observed brightness of both types of stars, researchers accurately calculated distances to roughly 300 Type Ia supernovae in far-flung galaxies. They compared those distances with the expansion of space as measured by the stretching of light from receding galaxies. The team used these two values to calculate how fast the universe expands with time, or the Hubble constant. The improved Hubble constant value is 73.2 km per second per megaparsec. A megaparsec equals 3.26 million light-years. The new value means the distance between cosmic objects will double in another 9.8 billion years. This refined calibration presents a puzzle, however, because it does not quite match the expansion rate predicted for the universe from its trajectory seen shortly after the Big Bang. Measurements of the afterglow from the Big Bang by NASA's Wilkinson Microwave Anisotropy Probe and the European Space Agency's Planck satellite mission yield predictions for the Hubble constant that are 5 per cent and 9 per cent smaller. "If we know the initial amounts of stuff in the universe, such as dark energy and dark matter, and we have the physics correct, then you can go from a measurement at the time shortly after the big bang and use that understanding to predict how fast the universe should be expanding today," said Riess. "However, if this discrepancy holds up, it appears we may not have the right understanding, and it changes how big the Hubble constant should be today," he said. The research appears in The Astrophysical Journal. — PTI. Source: http://www.tribuneindia.com/
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So you want to know the secrets of the universe...?

The fragments were passed to scientists by teachers from Novosibirsk, who were in the village Emanzhelinka, Chelyabinsk region when the meteorite struck on 15 February. Picture: The Siberian Times 
By Kate Baklitskaya: Fragments of the meteorite which exploded over the Urals have revealed their geological identity to Siberian scientists. The main minerals of these samples are silicates: olivine (Mg, Fe) 2SiO4 and orthopyroxene (Mg, Fe) 2Si2O6, it was disclosed. Iron and nickel sulfides (troilite, FeS, heazlewoodite Ni3S2), and native metals Fe and Ni (kamacite, taenite) were found in smaller amounts. In addition scientists found chromite (Fe, Mg) Cr2O4, clinopyroxene (diopside CaMgSi2O6), plagioclase (Ca, Na) Al2Si2O8, as well as glass feldspar composition in the fragments of a meteorite. The analysis was carried out using scanning microscopy and a gas chromatography-mass spectrometer at the V S Sobolev Institute of Geology and Mineralogy, part of the Siberian Branch of the Russian Academy of Sciences.  Experts from the Central Siberian Geological Museum Institute were also involved. 
Such preliminary data is important for the reconstruction of the early stages of the solar system: it is believed that meteorites are similar to the very stuff which, in fact, formed the planets. Pictures: SORAN media centre 
The geologists explained it is likely that a small amount of iron and nickel phosphide is present among the elements. According to the scientists, they obtained information about the composition of volatile components in the meteorite fragments, Siberian Branch of Russian Academy of Science media centre reported. Such preliminary data is important for the reconstruction of the early stages of the solar system: it is believed that meteorites are similar to the very stuff which, in fact, formed the planets. The fragments were passed to scientists by teachers from Novosibirsk, who were in the village Emanzhelinka, Chelyabinsk region when the meteorite struck on 15 February. Siberian geologists also have samples collected by geographer and mineralogist Sergei Kolesnichenko and Novosibirsk State University graduate Igor Karlov, near the village Zauralskiy Chelyabinsk region. Now these pieces of the meteorite are being studied. Source: http://siberiantimes.com
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A New Way To See The High-Energy Sky

Credit: HAWC Collaboration
University of Maryland (UMD) physicists pioneered development of observatory that has located new high-energy sources in the universe and provided more detail on known sources in first year of full operation. HAWC observations show that a previously known gamma ray source in the Milky Way galaxy, TeV J1930+188, which is probably due to a pulsar wind nebula, is far more complicated than originally thought. Where researchers previously identified a single gamma ray source, HAWC identified several hot spots. The United States and Mexico constructed the High Altitude Water Cherenkov (HAWC) Gamma-ray Observatory to observe some of the most energetic phenomena in the known universe--the aftermath when massive stars die, glowing clouds of electrons around rapidly spinning neutron stars, and supermassive black holes devouring matter and spitting out powerful jets of particles. These violent explosions produce high-energy gamma rays and cosmic rays, which can travel large distances--making it possible to see objects and events far outside our own galaxy. Today, scientists operating HAWC released a new survey of the sky made from the highest energy gamma rays ever observed. The new sky map, which uses data collected since the observatory began running at full capacity last March, offers a deeper understanding of high-energy processes taking place in our galaxy and beyond. "HAWC gives us a new way to see the high-energy sky," said Jordan Goodman, professor of physics at the University of Maryland, and U.S. lead investigator and spokesperson for the HAWC collaboration. "This new data from HAWC shows the galaxy in unprecedented detail, revealing new high-energy sources and previously unseen details about existing sources." HAWC researchers presented the new observation data and sky map April 18, 2016, at the American Physical Society meeting. They also participated in a press conference at the meeting. The new sky map shows many new gamma ray sources within our own Milky Way galaxy. Because HAWC observes 24 hours per day and year-round with a wide field-of-view and large area, the observatory boasts a higher energy reach especially for extended objects. In addition, HAWC can uniquely monitor for gamma ray flares by sources in our galaxy and other active galaxies, such as Markarian 421 and Markarian 501. This is a view of two-thirds of the entire sky with very-high-energy gamma rays observed by HAWC. Many sources are clearly visible in our own Milky Way galaxy, as well as two other galaxies: Markarian 421 and Markarian 501. Some well-known constellations are shown as a reference. The center of the Milky Way is located toward
Credit: HAWC Collaboration
Sagittarius. One of HAWC's new observations provides a better understanding of the high-energy nature of the Cygnus region--a northern constellation lying on the plane of the Milky Way. A multitude of neutron stars and supernova remnants call this star nursery home. HAWC scientists observed previously unknown objects in the Cygnus region and identified objects discovered earlier with sharper resolution. In a region of the Milky Way where researchers previously identified a single gamma ray source named TeV J1930+188, HAWC identified several hot spots, indicating that the region is more complicated than previously thought. "Studying these objects at the highest energies can reveal the mechanism by which they produce gamma rays and possibly help us unravel the hundred-year-old mystery of the origin of high-energy cosmic rays that bombard Earth from space," said Goodman. HAWC--located 13,500 feet above sea level on the slopes of Mexico's Volcán Sierra Negra--contains 300 detector tanks, each holding 50,000 gallons of ultrapure water with four light sensors anchored to the floor. When gamma rays or cosmic rays reach Earth's atmosphere they set off a cascade of charged particles, and when these particles reach the water in HAWC's detectors, they produce a cone-shaped flash of light known as Cherenkov radiation. The effect is much like a sonic boom produced by a supersonic jet, because the particles are traveling slightly faster than the speed of light in water when they enter the detectors. The complete array of HAWC detector tanks is seen here in Dec. 2014.
Credit: HAWC Collaboration
The light sensors record each flash of Cherenkov radiation inside the detector tanks. By comparing nanosecond differences in arrival times at each light sensor, scientists can reconstruct the angle of travel for each particle cascade. The intensity of the light indicates the primary particle's energy, and the pattern of detector hits can distinguish between gamma rays and cosmic rays. With 300 detectors spread over an area equivalent to more than three football fields, HAWC "sees" these events in relatively high resolution. "Unlike traditional telescopes, with HAWC we have now an instrument that surveys two-thirds of the sky at the highest energies, day and night," said Andrés Sandoval, Mexico spokesperson for HAWC. HAWC exhibits 15-times greater sensitivity than its predecessor--an observatory known as Milagro that operated near Los Alamos, New Mexico, and ceased taking data in 2008. In eight years of operation, Milagro found new sources of high-energy gamma rays, detected diffuse gamma rays from the Milky Way galaxy and discovered that the cosmic rays hitting earth had an unexpected non-uniformity. "HAWC will collect more data in the next few years, allowing us to reach even higher energies," said Goodman. "Combining HAWC observations with data from other instruments will allow us to extend the reach of our understanding of the most violent processes in the universe." Contacts and sources:Abby Robinson, University of Maryland (UMD) Source: http://www.ineffableisland.com/
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A Deep Look Into A Single Molecule

Credit: PTB
The quantum state of a molecular ion has been measured live and in a non-destructive fashion for the first time. The interaction of thermal energy from the environment with motional degrees of freedom is well known and often referred to as Brownian motion (also thermal motion). But in the case of polar molecules, the internal degrees of freedom - in particular the rotational quantum state - are also influenced by the thermal radiation. So far, the detection of the rotational state was only possible by destroying the molecule. However, a German research group has now demonstrated the first implementation of a non-destructive state detection technique for molecular ions. Piet Schmidt and his colleagues from the QUEST-Institute at the Physikalisch-Technische Bundesanstalt (PTB) observed changes in the rotational state of a trapped and indirectly cooled molecular ion in real time and in situ. This technique enables novel spectroscopy methods with applications ranging from chemistry to tests of fundamental physics. The results are published in the current issue of "Nature". Basic concept of the experiment: MgH+ (orange) and Mg+ (green) are trapped together in a linear ion trap. The two-ion compound is cooled to the motional ground state via the atomic ion. An oscillating dipole force changes the motional state according to the rotational state of the molecular ion. This motional excitation can be detected on the atomic ion.  Nowadays atoms can be manipulated with lasers and their spectral features can be investigated with high precision e.g. in optical clocks. In these experiments state detection plays a crucial role: the fluorescence of an atom under illumination with laser light reveals its internal quantum state. Many atoms and most molecules, however, do not fluoresce at all. Therefore, one of the standard procedures for state detection in molecules exploited the fact that molecules can be broken apart with laser light of a certain frequency, depending on their quantum state. This lets one measure the quantum state of the molecule by destroying it. Of course this detection procedure can only be applied once per molecule. Project leader Piet Schmidt has a long experience of systems in which state detection is difficult to achieve. He was involved in the development of 'quantum logic spectroscopy' in the research group of Nobel laureate David J. Wineland and extended it with his own research team to 'photon recoil spectroscopy'. Typical detection signal, where a quantum jump into the (J=1)-rotational state (from red to blue area) and a subsequent jump out of this state (blue to red) can be seen All of these novel
Credit: PTB
spectroscopy techniques are based on a common principle: beside the ion under investigation, one traps a second ion of a different species that is controllable and whose fluorescence can be used for state detection. Because of their electrical repulsion, both particles behave as if they were connected by a strong spring, such that their motion is synchronized. This is how the measurement of one particle can reveal properties of the other particle. Schmidt and his colleagues use a molecular MgH+-ion (which is the subject of the investigation) and an atomic Mg+-ion (on which the measurements will be performed). They hold both particles with electric fields in an ion trap. Then, lasers are used to cool the particles' motion to the ground state, where the synchronous motion almost comes to rest. The new trick demonstrated in this experiment relies on an additional laser, whose action is similar to an optical tweezer. It can be used to exert forces on the molecule. "The laser shakes the molecule only if the molecule is in one particular rotational state" explains Fabian Wolf, physicist in Schmidt's research group "We can detect the effect¬ -which is an excitation of the common motion of the molecule and the atom- on the atomic ion by using additional lasers. If the atom lights up, the molecule was in the state we probed. If it stays dark, the molecule was in some other state." Piet Schmidt highlights two main results of the team's findings: "Because of the non-destructive nature of our technique, we could observe the molecule jumping from one rotational state to the other. It is the first time such quantum jumps have been observed directly in an isolated molecule. Moreover, we could improve on the uncertainty of a transition frequency to an electronically excited state". He also points towards future goals: "The next step is the systematic preparation of the molecule in that quantum state instead of waiting for the thermal radiation to randomly prepare it." The researchers feel confident that their development will be important for the scientific communities that need precise methods for spectroscopy, e.g. quantum chemistry, where the inner structure of molecules is investigated, or astronomy, where spectra of cold molecules can teach us new things about the origin and the properties of the universe. Furthermore, precision molecular spectroscopy is important for the search for a variation of the fundamental constants and so far hidden properties of fundamental particles, such as the electric dipole moment of the electron. These tests of fundamental physics were Schmidt's original motivation for working on the novel detection technique."To make these applications practical, we have to push molecular spectroscopy to a level similar to that of today's optical clocks based on atoms", says Piet Schmidt, when he gets asked for his long term goal, "For this purpose we have to improve our measurement resolution by orders of magnitude, which for sure will take several years". Source: http://www.ineffableisland.com/
  • Contacts and sources: Prof. Dr. Piet O. Schmidt
  • QUEST-Institute at the Physikalisch-Technische Bundesanstalt (PTB)
  • Citation: F. Wolf, Y. Wan, J.C. Heip, F. Gebert, C. Shi, P.O. Schmidt: Non-destructive state detection for quantum logic spectroscopy of molecular ions. Nature (2016), DOI: 10.1038/nature16513
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Superluminous Supernova 20 Times Brighter Than 100 Billion Stars Wows Astronomers

Records are made to be broken, as the expression goes, but rarely are records left so thoroughly in the dust. Stunned astronomers have witnessed a cosmic explosion about 200 times more powerful than a typical supernova--events which already rank amongst the mightiest outbursts in the universe--and more than twice as luminous as the previous record-holding supernova. At its peak intensity, the explosion--called ASASSN-15lh--shone with 570 billion times the brightness of the Sun. If that statistic does not impress, consider that this luminosity level is approximately 20 times the entire output of the 100 billion stars comprising our Milky Way galaxy. The record-breaking blast is thought to be an outstanding example of a "superluminous supernova," a recently discovered, supremely rare variety of explosion unleashed by certain stars when they die. Scientists are frankly at a loss, though, regarding what sorts of stars and stellar scenarios might be responsible for these extreme supernovae. These are pseudo-color images showing the host galaxy before the explosion of ASASSN-15lh taken by the Dark Energy Camera (DECam) [Left], and the supernova by the Las Cumbres Observatory Global Telescope Network (LCOGT) 1-meter telescope network [Right]. As described in a new study published today in Science, ASASSN-15lh
Credit: The Dark Energy Survey, B. Shappee and the ASAS-SN team
is amongst the closest superluminous supernovae ever beheld, at around 3.8 billion light years away. Given its uncanny brightness and closeness, ASASSN-15lh might offer key clues in unlocking the secrets of this baffling class of celestial detonations. "ASASSN-15lh is the most powerful supernova discovered in human history," said study lead author Subo Dong, an astronomer and a Youth Qianren Research Professor at the Kavli Institute for Astronomy and Astrophysics (KIAA) at Peking University. "The explosion's mechanism and power source remain shrouded in mystery because all known theories meet serious challenges in explaining the immense amount of energy ASASSN-15lh has radiated." ASASSN-15lh was first glimpsed in June 2015 by twin telescopes with 14-centimeter diameter lenses in Cerro Tololo, Chile conducting the All Sky Automated Survey for SuperNovae (ASAS-SN), an international collaboration headquartered at The Ohio State University. (Hence ASASSN-15lh's somewhat menacing moniker.) These two tiny telescopes sweep the skies to detect suddenly appearing objects like ASASSN-15lh that are intrinsically very bright, but are too far away for human observers to notice. "ASAS-SN is the first astronomical project in history to frequently scan the entire optical sky for optical transients," said Krzysztof Stanek, professor of astronomy at the Ohio State University and the co-Principal Investigator of ASAS-SN. "Every time in science we open up a new discovery space, exciting findings should follow. The trick is not to miss them." Dong and colleagues immediately put out word about the sighting of ASASSN-15lh in order for as much data as possible to be gathered. Multiple, far larger ground-based telescopes across the globe, as well as NASA's Swift satellite, have since taken part in an intense observing campaign that continues to this day. In just the first four months after it went kablooie, so much energy beamed out of ASASSN-15lh that it would take our Sun in its current state more than 90 billion years to equal its emissions. By examining this bright, slowly fading afterglow, astronomers have gleaned a few basic clues about the origin of ASASSN-15lh. Using the 2.5-meter du Pont telescope in Chile, Dong's colleagues Ben Shappee and Nidia Morrell at the Carnegie Observatories in the United States took the first spectrum of ASASSN-15lh to identify the signatures of chemical elements scattered by the explosion. This spectrum puzzled the ASAS-SN team members, for it did not resemble any of spectra from the 200 or so supernovae the project had discovered to date. These are two of the 14-centimeter diameter lens telescopes in use for the All Sky Automated Survey for SuperNovae (ASAS-SN) that discovered ASASSN-15lh. Since this photo was taken, two more
Credit: Wayne Rosing
telescopes have been added to the ASAS-SN station in Cerro Tololo, Chile. Inspired by suggestions from Jose Prieto at Universidad Diego Portales and Millennium Institute of Astrophysics in Chile and Stanek, Dong realized that ASASSN-15lh might in fact be a superluminous supernova. Dong found a close spectral match for ASASSN-15lh in a 2010 superluminous supernova, and if they were indeed of a kind, then ASASSN-15lh's distance would be confirmable with additional observations. Nearly 10 days passed as three other telescopes, stymied by bad weather and instrument mishaps, attempted to gather these necessary spectra. Finally, the 10-meter South African Large Telescope (SALT) secured the observations of elemental signatures verifying ASASSN-15lh's distance and extreme potency. "Upon seeing the spectral signatures from SALT and realizing that we had discovered the most powerful supernova yet, I was too excited to sleep the rest of the night," said Dong, who had received word of the SALT results at 2 AM in Beijing on July 1, 2015. The ongoing observations have further revealed that ASASSN-15lh bears certain features consistent with "hydrogen-poor" (Type I) superluminous supernovae, which are one of the two main types of these epic explosions so named for lacking signatures of the chemical element hydrogen in their spectra. ASASSN-15lh has likewise shown a rate of temperature decrease and radius expansion similar to some previously discovered Type I superluminous supernova. Yet in other ways, besides its brute power, ASASSN-15lh stands apart. It is way hotter, and not just brighter, than its apparently nearest of supernova kin. The galaxy it calls home is also without precedent. Type I superluminous supernova seen to date have all burst forth in dim galaxies both smaller in size and that churn out stars much faster than the Milky Way. Noticing the pattern, astronomers hoped this specific sort of galactic environment had something to do with superluminous supernovae, either in the creation of the exotic stars that spawn them or in setting these stars off. Exceptionally, however, ASASSN-15lh's galaxy appears even bigger and brighter than the Milky Way. On the other hand, ASASSN-15lh might in fact reside in an as-yet-unseen, small, faint neighboring galaxy of its presumed, large galactic home. To clear up where exactly ASASSN-15lh is located, as well as numerous other mysteries regarding it and its hyper-kinetic ilk, the research team has been granted valuable time this year on the Hubble Space Telescope. With Hubble, Dong and colleagues will obtain the most detailed views yet of the aftermath of ASASSN-15lh's stunning explosion. Important insights into the true wellspring of its power should then come to light. One of the best hypotheses is that superluminous supernovae's stupendous energy comes from highly magnetized, rapidly spinning neutron stars called magnetars, which are the leftover, hyper-compressed cores of massive, exploded stars. But ASASSN-15lh is so potent that this compelling magnetar scenario just falls short of the required energies. Instead, ASASSN-15lh-esque supernovae might be triggered by the demise of incredibly massive stars that go beyond the top tier of masses most astronomers would speculate are even attainable. "The honest answer is at this point that we do not know what could be the power source for ASASSN-15lh," said Dong. "ASASSN-15lh may lead to new thinking and new observations of the whole class of superluminous supernova, and we look forward to plenty more of both in the years ahead." 
Contacts and sources:  Jim Cohen: The Kavli Institute for Astronomy and Astrophysics (KIAA) 

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