archive-edu.com » EDU » C » CALTECH.EDU

Total: 352

Choose link from "Titles, links and description words view":

Or switch to "Titles and links view".
  • LIGO General Computing Information
    home LIGO Highlights of Computer Use Policy Contacts webmaster LIGO is supported by the National Science Foundation nsf gov

    Original URL path: http://www.ligo.caltech.edu/LIGO_web/GC/ (2015-06-02)
    Open archived version from archive


  • Many gamma-ray bursts go undetected, MIT mathematician estimates
    a method totally independent of the supernova association involving spectral characteristics of the gamma ray emissions themselves To derive their figure van Putten and Regimbau assumed the now standard collapsar model of GRBs In that model the core of an especially massive star undergoes a gravitational collapse likely resulting in a black hole producing a massive pressure wave that blasts out of the star in a particular direction The blast wave collides with dust and gas in the surrounding interstellar medium at velocities near that of light producing gamma ray emissions The type of star used in the collapsar model is also the type of star that ends its life in a supernova SUPERNOVAE EVIDENCE What was missing was observational evidence linking GRBs to supernovae That evidence was provided by a burst detected on March 29 2003 and therefore dubbed GRB 030329 by the HETE satellite one of the main GRB seeking satellites That burst was so close in astronomical terms roughly 2 billion light years away that astronomers were able to study the afterglow light of progressively less energetic radiation What astronomers saw in the spectral analysis of the light curves was the unmistakable signature of a supernova including the presence of oxygen emission lines excited in the blast This information provided powerful support to a previous even closer blast on April 25 1998 that had provided a less conclusive link between supernovae and GRBs Once the GRB supernovae link was established van Putten and Regimbau used a very precious sample of 33 GRBs whose distances unlike most are well known to establish a mathematical relationship between how bright a given burst is and the rate at which the massive stars form and die They could do this because the massive stars involved in GRBs and supernovae live for only a few tens of millions of years as opposed to billions of years This fact van Putten said means such massive stars essentially die at their place of birth One aspect of the collapsar model is that the burst which precedes the actual supernova explosion occurs along a particular axis in both directions as opposed to a symmetric radial one Since axes of stars are oriented randomly throughout the universe we detect only those bursts along or near whose axis the Earth happens to lie This effect is known as beaming and it means the angle through which the blast of energy is seen is relatively small for most observed blasts no more than a few degrees of sky Van Putten said this beaming effect is factored into their figure because the relationship is based on peak brightness A BOON TO WAVE SEARCH Van Putten said the confirmation that there are so many more GRBs than we actually detect is potentially a boon in the quest to find gravitational waves These minute waves in space time are thought to be produced by massive objects undergoing extreme events such as the formation of new black holes or collision coalescence of

    Original URL path: http://www.ligo.caltech.edu/LIGO_web/gsfc_mit/ (2015-06-02)
    Open archived version from archive

  • Einstein's GWs May Set Speed Limit For Pulsar Spin - July 2, 2003
    star pulsar or if there is enough mass a black hole The surface layers of the star blast outward forming the colorful patterns typical of supernova remnants Credit for animations Dana Berry High Resolution image of Animation Still 1 High Resolution image of Animation Still 2 High Resolution image of Animation Still 3 High Resolution image of Animation Still 4 The Top Story Archive listing can be found by clicking on this link All stories found on a Top Story page or the front page of this site have been archived from most to least current on this page For a list of recent press releases click here July 2 2003 date of web publication EINSTEIN S GRAVITATIONAL WAVES MAY SET SPEED LIMIT FOR PULSAR SPIN Animation 1 Gravitational radiation ripples in the fabric of space predicted by Albert Einstein may serve as a cosmic traffic enforcer protecting reckless pulsars from spinning too fast and blowing apart according to a report published in the July 3 issue of Nature Pulsars the fastest spinning stars in the Universe are the core remains of exploded stars containing the mass of our Sun compressed into a sphere about 10 miles across Some pulsars gain speed by pulling in gas from a neighboring star reaching spin rates of nearly one revolution per millisecond or almost 20 percent light speed These millisecond pulsars would fly apart if they gained much more speed Using NASA s Rossi X ray Timing Explorer scientists have found a limit to how fast a pulsar spins and speculate that the cause is gravitational radiation The faster a pulsar spins the more gravitational radiation it might release as its exquisite spherical shape becomes slightly deformed This may restrain the pulsar s rotation and save it from obliteration Animation 2 Nature has set a speed limit for pulsar spins said Prof Deepto Chakrabarty of the Massachusetts Institute of Technology lead author on the journal article Just like cars speeding on a highway the fastest spinning pulsars could technically go twice as fast but something stops them before they break apart It may be gravitational radiation that prevents pulsars from destroying themselves Chakrabarty s co authors are Drs Edward Morgan Michael Muno and Duncan Galloway of MIT Rudy Wijnands University of St Andrews Scotland Michiel van der Klis University of Amsterdam and Craig Markwardt NASA Goddard Space Flight Center Wijnands also leads a second Nature letter complementing this finding Animation 3 Gravitational waves analogous to waves upon an ocean are ripples in four dimensional spacetime These exotic waves predicted by Einstein s theory of relativity are produced by massive objects in motion and have not yet been directly detected Created in a star explosion a pulsar is born spinning perhaps 30 times per second and slows down over millions of years Yet if the dense pulsar with its strong gravitational potential is in a binary system it can pull in material from its companion star This influx can spin up the pulsar to

    Original URL path: http://www.ligo.caltech.edu/LIGO_web/gsfc/ (2015-06-02)
    Open archived version from archive

  • AAAS Annual Meeting and Science Innovation Exposition - LIGO
    on the Universe Rita Colwell NSF animations Gravity Studying the Fabric of the Universe Barry Barish CIT The LIGO Interferometers How They Work and How Well They Work Rainer Weiss MIT First Searches with the LIGO Interferometers Preliminary Results from

    Original URL path: http://www.ligo.caltech.edu/LIGO_web/aaas0203/ (2015-06-02)
    Open archived version from archive

  • The LIGO-TAMA Kyoto Accord
    of coincident data taken during LIGO s S1 and TAMA s DT7 runs in August September 2002 This data set constitutes a testbed for prototyping joint analysis approaches Plans are also being made to run simultaneously during the upcoming two month long LIGO S2 and TAMA DT8 runs in February April 2003 To promote close cooperation and exchange of information and ideas for this activity a small working group of five individuals each from the LSC and TAMA has been established The working group includes the following people Masaki Ando University of Tokyo Patrick Brady University of Wisconsin Milwaukee Sam Finn Pennsylvania State University Nobuyuki Kanda Osaka City University Erik Katsavounidis MIT Albert Lazzarini Caltech Hideyuki Tagoshi Osaka University Ryutaro Takahashi National Astronomical Observatory of Japan Daisuke Tatsumi National Astronomical Observatory of Japan Peter Saulson Syracuse University The initial searches to be conducted in collaboration will target unmodeled signals from bursts or transient sources explosive gravitational wave signals from sources unexpected or unpredicted a particularly challenging signal to hunt and chirps from binary inspiral coalescences the much sought collisions of neutron stars or black holes that spiral into one another as their orbits decay with the emission of gravitational waves

    Original URL path: http://www.ligo.caltech.edu/LIGO_web/kyoto.html (2015-06-02)
    Open archived version from archive

  • Barry Barish Nominated to National Science Board
    on the basis of their eminence in basic medical or social sciences engineering agriculture education research management or public affairs The Board also functions as national science policy advisor to the President and the Congress A graduate of U C Berkeley in 1963 Dr Barish has been a member of Caltech since that time In addition to being the LIGO Director and Principal Investigator he is a member of the

    Original URL path: http://www.ligo.caltech.edu/LIGO_web/barish.html (2015-06-02)
    Open archived version from archive

  • The S2 Science Run Schedule
    work prior to S2 has been developed and it is being implemented The LSC has just held an important teleconference to display the status of the data analysis effort with the S1 data and to define the program leading to reports of the results near the end of the year The S1 run also involved coincidence running with the GEO 600 interferometer and the TAMA300 detector This coincidence running also promises additional results and early experience in running a network of detectors across the globe We have consulted with our partners in these efforts as well regarding accomplishments and plans for the future Our overarching mission is to accomplish the scientific reach planned for the LIGO interferometer system and to exploit the system with the LSC to accomplish the science Our approach has been defined in the memos listed above The next step is the S2 run Following the S2 run we have a plan for additional commissioning including the important installation of the Livingston seismic preisolation system An extended S3 run will follow that commissioning interval marking the beginning of true search running Given that scientific analysis should be completed near the end of the year and that the

    Original URL path: http://www.ligo.caltech.edu/LIGO_web/s2.html (2015-06-02)
    Open archived version from archive

  • E7 Engineering Run
    of data from sustained operation that will now be used to develop and exercise the LIGO data analysis pipeline Of course work is still underway to tune up the LIGO interferometers to their design sensitivities and much remains to do Still the data recorded during E7 is vital in that it will provide LIGO Scientific Collaboration LSC scientists with real interferometer data needed for perfecting and tuning gravitational wave search algorithms Fig 2 The control room at LLO The four kilometer long interferometer at the LIGO Livingston Observatory LLO was operated in a recombined but not recycled configuration While we have demonstrated the operation of the LLO interferometer in a power recycled configuration we are able to operate for longer time periods in the non recycled mode Seismic noise is significantly higher at Livingston than at Hanford and use of the non recycled mode reduces seismic sensitivity In addition a newly installed active compensation system was used to filter the large microseism present at LLO At Hanford the two kilometer long interferometer was operated in a power recycled configuration while the site s second instrument the four kilometer long interferometer was operated in a recombined but not recycled configuration A new system to compensate for the tidal distortion of the earth s crust by the sun and moon was used to allow for extended continuous locking of the instruments Large levels of vibration were present at Hanford each weekday from approximately 7 00 am to 3 30 pm due to a building construction approximately 700 feet from the corner station Our machines were unavailable during these periods as expected There were also some high wind conditions and when wind speeds exceeded 25 30 miles per hour we were able to observe effects in our data The four kilometer interferometer used

    Original URL path: http://www.ligo.caltech.edu/LIGO_web/news/e7.html (2015-06-02)
    Open archived version from archive



  •