Universe Structure

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Galaxies in the Early Universe Last Updated on 2009-11-11 00:00:00 About ten years ago, astronomers using new submillimeter wavelength facilities discovered the existence of a new class of very distant galaxies. These objects are located so far away that their light has been traveling towards us for over ten billion years - more than 70% of the lifetime of the universe. Although today they are old, we see them as they were only a few billion years after they formed, when they were relatively young. These galaxies were undetected in the visible but emit strongly at submillimeter wavelengths because they have an abundance of warm dust. What heats the dust is still controversial - probably either massive star formation, or an active black hole at the galactic nucleus, or perhaps both. Our Milky Way galaxy, or at least the region where the sun resides, probably formed between seven and ten billion years ago, and so understanding these remote systems... More »
LIGO Listens for Gravitational Echoes of the Birth of the Universe Last Updated on 2009-08-19 00:00:00 Caltech, Pasadena, CA (Aug. 19. 2009) – An investigation by the LIGO (Laser Interferometer Gravitational-Wave Observatory) Scientific Collaboration and the Virgo Collaboration has significantly advanced our understanding of the early evolution of the universe. Analysis of data taken over a two-year period, from 2005 to 2007, has set the most stringent limits yet on the amount of gravitational waves that could have come from the Big Bang in the gravitational wave frequency band where LIGO can observe. In doing so, the gravitational-wave scientists have put new constraints on the details of how the universe looked in its earliest moments. Much like it produced the cosmic microwave background, the Big Bang is believed to have created a flood of gravitational waves—ripples in the fabric of space and time—that still fill the universe and carry information about the universe as it was... More »
Researchers Interpret Asymmetry in Early Universe Last Updated on 2008-12-16 00:00:00 Caltech, Pasadena, CA (Dec. 16, 2008) – The Big Bang is widely considered to have obliterated any trace of what came before. Now, astrophysicists at the California Institute of Technology (Caltech) think that their new theoretical interpretation of an imprint from the earliest stages of the universe may also shed light on what came before. FIGURE CAPTION – The Cosmic Microwave Background Courtesy NASA/WMAP Science Team. "It's no longer completely crazy to ask what happened before the Big Bang," comments Marc Kamionkowski, Caltech's Robinson Professor of Theoretical Physics and Astrophysics. Kamionkowski joined graduate student Adrienne Erickcek and senior research associate in physics Sean Carroll to propose a mathematical model explaining an anomaly in what is supposed to be a universe of uniformly distributed radiation and matter. Their investigations turn on a phenomenon called... More »
Notes from the Astronomy Underground- Astropalooza Last Updated on 2008-09-28 00:00:00   According to the tagline in Ridley Scott’s 1979 blockbuster Alien, “In space, no one can hear you scream.” It’s true that sound waves, unlike light, need a medium- some kind of substance to carry their energy across a distance. And space is a vacuum, which, save the occasional solar system, fuzzy nebula, or bizarre stellar end product, is devoid of any respectable amount of matter. No matter, no sound, right?   Well, almost. Space is not completely empty. There are about one or two hydrogen molecules per square centimeter in the sparsest of regions. It beats our clumsy, terrestrial vacuum chambers handedly, but it’s not a vacuum in the strictest connotation of the word. Sound waves can still propagate through space, but so slowly and ineffectively that it would be pointless for aerophilic humans to do anything about it. Unless of course, we had ears many millions... More »
A Dark Matter Disk In Our Galaxy Last Updated on 2008-09-18 00:00:00 Royal Astronomical Society, London (Sept. 18, 2008) – An international team of scientists predict that our Galaxy, the Milky Way, contains a disk of ‘dark matter’. In a paper published in Monthly Notices of the Royal Astronomical Society, astronomers Dr Justin Read, Professor George Lake and Oscar Agertz of the University of Zurich, and Dr Victor Debattista of the University of Central Lancashire use the results of a supercomputer simulation to deduce the presence of this disk. They explain how it could allow physicists to directly detect and identify the nature of dark matter for the first time. FIGURE CAPTION – A composite image of the dark matter disk (red contours) and the Atlas image mosaic of the Milky Way obtained as part of the Two Micron All Sky Survey (2MASS). (Credit: J. Read and O. Agertz) Unlike the familiar ‘normal’ matter that makes up stars, gas and dust,... More »