{"id":699,"date":"2008-06-02T00:00:00","date_gmt":"2008-06-02T05:00:00","guid":{"rendered":"http:\/\/ezing.me\/transfer\/?p=699"},"modified":"2014-09-23T09:24:31","modified_gmt":"2014-09-23T14:24:31","slug":"crabpulsar","status":"publish","type":"post","link":"https:\/\/web20.olemiss.edu\/news\/wordpress\/crabpulsar\/","title":{"rendered":"LIGO Observations Probe Dynamics of the Crab Pulsar"},"content":{"rendered":"
\n\"crabnebula.jpg\"<\/p>\n
\nCrab Nebula. Courtesy photo\n<\/div>\n<\/div>\n

\nOXFORD, Miss. – The search for gravitational waves has
\nrevealed new information about the core of one of the most
\nfamous objects in the sky, providing a glimpse of the
\nspectacular discoveries that may come from the Laser
\nInterferometer Gravitational-Wave Observatory Scientific
\nCollaboration.
\n<\/span>\n<\/p>\n

\nThe LIGO collaboration, which uses huge detectors in
\nWashington and Louisiana to search for gravitational waves,
\nstudied the Crab Pulsar in the Crab Nebula, a popular
\ntarget for amateur astronomers. The analysis has shown that
\nno more than 4 percent of the pulsar’s energy loss is
\ncaused by the emission of gravitational waves, disproving
\none theory of what is slowing the pulsar’s spin rate.
\n<\/span>\n<\/p>\n

\n“The Crab Pulsar is spinning at a rate of 30 times per
\nsecond,” said Graham Woan of the University of Glasgow.
\n“However, its rotation rate is decreasing rapidly relative
\nto most pulsars, indicating that it is radiating energy at
\na prodigious rate.”
\n<\/span>\n<\/p>\n

\n\u00a0\n<\/p>\n

<\/span>
\n

Woan co-led the science group that used LIGO data to
\nanalyze the Crab Pulsar, along with Michael Landry of the
\nLIGO Hanford (Wash.) Observatory. Their findings have been
\nsubmitted to the journal Astrophysical Journal Letters.
\n<\/span><\/p>\n

\nThe LIGO Scientific Collaboration is a group of 600
\nscientists at universities around the United States and in
\n11 foreign countries. The University of Mississippi is a
\nmember of the collaboration’s Compact Binary Coalescence
\nGroup, which studies the detection of gravitational waves
\nfrom the inspiral and merger of binary compact stars and
\nblack holes. The Crab Pulsar analysis was performed by the
\ncollaboration’s Continuous Wave Group, which studies the
\ndetection of gravitational waves from rotating compact
\nobjects, such as pulsars and neutron stars.
\n<\/span>\n<\/p>\n

\nThe Crab Nebula, located 6,500 light years away in the
\nconstellation Taurus, was formed in a spectacular supernova
\nexplosion in 1054. According to ancient Chinese texts, the
\nexplosion was visible in daylight for more than three weeks
\nand may briefly have been brighter than the full moon.
\n<\/span>\n<\/p>\n

\nAt the heart of the nebula remains an incredibly rapidly
\nspinning neutron star that sweeps two narrow radio beams
\nacross the Earth each time it turns. The lighthouse-like
\nradio pulses have given the star the name “pulsar.”
\n<\/span>\n<\/p>\n

\nPulsars are almost perfect spheres made up of neutrons and
\ncontain more mass than the sun in an object only 10
\nkilometers in radius. The physical mechanisms for energy
\nloss and the accompanying braking of the pulsar spin rate
\nhave been hypothesized to be asymmetric particle emission,
\nmagnetic dipole radiation and gravitational-wave emission.
\n<\/span>\n<\/p>\n

\nGravitational waves are ripples in the fabric of space and
\ntime and are an important consequence of Einstein’s general
\ntheory of relativity. A perfectly smooth neutron star will
\nnot generate gravitational waves as it spins, but the
\nsituation changes if its shape is distorted. Gravitational
\nwaves would have been detectable even if the star were
\ndeformed by only a few meters, which could arise because
\nits semisolid crust is strained or because its enormous
\nmagnetic field distorts it.
\n<\/span>\n<\/p>\n

\n“The Crab neutron star is relatively young and therefore
\nexpected to be less symmetrical than most, which means it
\ncould generate more gravitational waves,” Woan said.
\n<\/span>\n<\/p>\n

\nUsing published timing data about the pulsar rotation rate
\nfrom the Jodrell Bank Observatory, LIGO scientists
\nmonitored the neutron star from November 2005 to August
\n2006 and looked for a synchronous gravitational-wave signal
\nusing data from the three LIGO interferometers, which were
\ncombined to create a single, highly sensitive detector.
\n<\/span>\n<\/p>\n

\nThe analysis revealed no signs of gravitational waves. But
\nthis result is itself important because it provides
\ninformation about the pulsar and its structure, said David
\nReitze, professor of physics at the University of Florida
\nand spokesperson for the LIGO Scientific Collaboration.
\n<\/span>\n<\/p>\n

\n“We can now say something definite about the role
\ngravitational waves play in the dynamics of the Crab Pulsar
\nbased on our observations,” Reitze said. “This is the first
\ntime the spin-down limit has been broken for any pulsar,
\nand this result is an important milestone for LIGO.”
\n<\/span>\n<\/p>\n

\nMichael Landry added, “These results strongly imply that no
\nmore than 4 percent of the pulsar’s energy loss is due to
\ngravitational radiation. The remainder of the loss must be
\ndue to other mechanisms, such as a combination of
\nelectromagnetic radiation generated by the rapidly rotating
\nmagnetic field of the pulsar and the emission of
\nhigh-velocity particles into the nebula.”
\n<\/span>\n<\/p>\n

\nThe LIGO project, which is funded by the National Science
\nFoundation, was designed and is operated by Caltech and the
\nMassachusetts Institute of Technology for the purpose of
\ndetecting gravitational waves and for the development of
\ngravitational-wave observations as an astronomical tool.
\n<\/span>\n<\/p>\n

\nThe collaboration’s interferometer network includes the
\nLIGO interferometers (including the 2-kilometer and
\n4-kilometer detectors in Hanford, Wash., and a 4-kilometer
\ninstrument in Livingston, La.) and the GEO600
\ninterferometer, located in Hannover, Germany, and designed
\nand operated by scientists from the Max Planck Institute
\nfor Gravitational Physics and partners in the United
\nKingdom.
\n<\/span>\n<\/p>\n

\nWork on LIGO began in the 1970s, and ground was broken on
\nthe first observatory in 1994.
\n<\/span>\n<\/p>\n

\n“After so many years of dedicated work by many scientists,
\nit is now time for scientific payoffs,” said Marco
\nCavaglia, UM assistant professor of physics and astronomy
\nand principal investigator of the Ole Miss LIGO team. “The
\nlatest result by the LIGO Scientific Collaboration is very
\nimportant because it will allow us to better understand the
\nstructure of neutron stars.”
\n<\/span>\n<\/p>\n

\nLIGO has evolved to its present capability to produce
\nsignificant scientific results, said Jay Marx of the
\nCalifornia Institute of Technology, LIGO’s executive
\ndirector.
\n<\/span>\n<\/p>\n

\n“The limit on the Crab Pulsar’s emission of gravitational
\nwaves is but one of a number of important results obtained
\nfrom LIGO’s recent two-year observing period,” Marx said.
\n“These results only serve to further our anticipation for
\nthe spectacular science that will come from LIGO in the
\ncoming years.”
\n<\/span>\n<\/p>\n

\nFor more information on LIGO, go to http:\/\/www.ligo.caltech.edu\/<\/a>.
\n<\/span>\n<\/p>\n

\nFor more information on the Ole Miss LIGO team, go to http:\/\/www.phy.olemiss.edu\/GR\/ligoteam<\/a> or contact Cavaglia at cavaglia@olemiss.edu.
\n<\/span><\/p>\n","protected":false},"excerpt":{"rendered":"

Crab Nebula. Courtesy photo OXFORD, Miss. – The search for gravitational waves has revealed new information about the core of one of the most famous objects in the sky, providing a glimpse of the spectacular discoveries that may come from the Laser Interferometer Gravitational-Wave Observatory Scientific Collaboration. The LIGO collaboration, which uses huge detectors inRead the story …<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"ngg_post_thumbnail":0,"footnotes":""},"categories":[222],"tags":[],"yoast_head":"\nLIGO Observations Probe Dynamics of the Crab Pulsar - Ole Miss News<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"http:\/\/news.olemiss.edu\/crabpulsar\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"LIGO Observations Probe Dynamics of the Crab Pulsar - Ole Miss News\" \/>\n<meta property=\"og:description\" content=\"Crab Nebula. Courtesy photo OXFORD, Miss. – The search for gravitational waves has revealed new information about the core of one of the most famous objects in the sky, providing a glimpse of the spectacular discoveries that may come from the Laser Interferometer Gravitational-Wave Observatory Scientific Collaboration. 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