Galaxy Cluster Mashups -The Most Violent Events in the Universe Since the Big Bang

Clustercolli This composite image shows the effects of a collision between two small galaxy clusters in the northern part of the galaxy cluster Abell 1758, located about 3.2 billion light years from Earth.

Galaxy clusters are the largest structures in the Universe that are bound together by gravity. They form when smaller clusters or groups of galaxies collide and merge. Collisions between galaxy clusters, such as this one in Abell 1758 and its more famous cousin the Bullet Cluster, are the most energetic events in the Universe since the Big Bang. Their growth rate over the last 7 billion years is believed to have been slowed by the effects of dark energy.


Do Jupiter’s Radio Emissions Hint that Dark Energy May Not Exist? (Today’s Most Popular)

Utane Sawangwit and Tom Shanks of Durham University believe that errors on the “gold standard” cosmic microwave background results from the WMAP satellite that includes dark matter, dark energy and the exponential expansion after the big bang known as inflation may be larger than previously supposed. 

6a00d8341bf7f753ef0133f0f831c9970b.jpg It is the pattern of ripples detected by microwave background telescopes such as WMAP that underpin the idea that the Universe is composed of 22% dark exotic particles and 74% dark energy with the remaining 4% being the atoms in the ordinary material that we see around us. 

This model produces a largest ripple size of about 1 degree on the microwave sky and this is well matched by the ripples seen in the WMAP data. So these WMAP ripples have a size that is roughly twice the size of the Full Moon as they appear on the sky. Models that don’t have dark energy or dark matter tend to produce CMB ripples that are smaller, only about half the standard model size and so just about the size of the Full Moon.   

Sawangwit and Shanks have used point-like radio sources to test how much the WMAP telescope smoothes these CMB ripples and have found evidence that this ”beam smoothing” is much larger than suggested from WMAP’s observations of the planet Jupiter. 


Extraterrestrial Water Sources of the Milky Way Mapped

Herschel_sc_artist-instruments_L The Herschel Space Observatory's  HIFI instrument was designed to follow the water trail in the Universe over a wide range of scales, from the Solar System out to extragalactic sources. Early results, presented this week at the Herschel First Results Symposium, demonstrate how HIFI uses water to probe the physical and chemical conditions in different regions of the cosmos.

Water is crucial in the processes of star formation, because this molecule contributes to the cooling of the gas and dust mixture from which stars are born. Early results demonstrated the detection of water in various proto-stellar systems. Along with upcoming data from star-forming clouds throughout the Milky Way, these data will help astronomers understand the mechanisms of star formation in great detail. Beyond our Galaxy, water signatures have been found in nearby galaxies which are known to be undergoing intense bursts of star formation.

Water trails go all the way from vast star-forming clouds down to stars and planets on much smaller scales. In the proto-planetary discs surrounding stars in the process of forming, water vapour may in fact freeze onto dust grains; these cold grains would then condense into icy planetesimals, the seeds of planet formation.


Neutrino Discovery Could Reveal Why Antimatter Failed to Dominate the Universe

Neutrino_event A team of physicists, including some from MIT, has found surprising differences between the flavor-switching behavior of neutrinos and antineutrinos. If confirmed, the finding could help explain why matter, and not antimatter, dominates our universe.  Neutrinos, elementary particles generated by nuclear reactions in the sun, "suffer from an identity crisis as they cross the universe, morphing between three different flavors.” Their antimatter counterparts do the same thing.

“People are very excited about it because it suggests that there are differences between neutrinos and antineutrinos,” says Georgia Karagiorgi, an MIT graduate student and one of the leaders of the analysis of experimental data produced by the Booster Neutrino Experiment (MiniBooNE) at the Fermi National Accelerator Laboratory.

The new results appear to be one of the first observed violations of CP symmetry: the theory that matter and antimatter should behave in the same way. CP symmetry violation has been seen before in quarks, but never in neutrinos or electrons. CP symmetry means in the words of Roger Penrose (The Road to Reality), "CP sends a particle's zig into its antiparticle's zag, and vice versa."


Image of the Day: A Massive Jet of Color from a Black Hole 100,000 Light Years Long


A new image from NASA's Hubble, Chandra and Spitzer space telescopes shows a giant jet of particles that has been shot out from the vicinity of a type of supermassive black hole called a quasar. The jet is enormous, stretching across more than 100,000 light-years of space – a size comparable to the entire Milky Way galaxy.



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