{"id":729,"date":"2014-08-19T12:25:19","date_gmt":"2014-08-19T10:25:19","guid":{"rendered":"http:\/\/oldblogs.uct.ac.za\/blog\/big-bytes\/2014\/08\/19\/evolution-of-linear-perturbations-in-spherically-symmetric-dust-spacetime"},"modified":"2015-08-14T10:16:10","modified_gmt":"2015-08-14T08:16:10","slug":"evolution-of-linear-perturbations-in-spherically-symmetric-dust-spacetime","status":"publish","type":"post","link":"https:\/\/ucthpc.uct.ac.za\/index.php\/2014\/08\/19\/evolution-of-linear-perturbations-in-spherically-symmetric-dust-spacetime\/","title":{"rendered":"Evolution of linear perturbations in spherically symmetric dust spacetime"},"content":{"rendered":"Sean Febuary completed his PhD in Applied Mathematics at the University of Cape Town.\r\n\r\nBrief description of his work: The growth of cosmic structure (e.g. galaxies,\r\nclusters thereof) is poorly understood in inhomogeneous cosmological\r\nmodels. Such models were originally proposed in the literature as an\r\nattempt to explain observations (e.g. distances to type Ia supernova)\r\nwithout dark energy. In this work, we solved - for the first time - the\r\nfull set of coupled partial differential equations that describe the\r\nevolution of linear perturbations about a large spherically symmetric\r\nunderdense region of spacetime (i.e. a void). We showed that the\r\nevolution of the density\r\ncontrast is well approximated by the previously studied decoupled\r\nevolution only on very large scales. However, the evolution of the\r\ngravitational potentials within the void is inaccurate at more than the\r\n10% level, and is even worse on small scales.\r\n\r\nHis paper can be found at <a href=\"http:\/\/iopscience.iop.org\/0264-9381\/31\/17\/175008\/\">http:\/\/iopscience.iop.org\/0264-9381\/31\/17\/175008\/<\/a> or <a href=\"http:\/\/hex.uct.ac.za\/Citations\/PhD_Sean_Febraury.pdf\">Evolution of linear perturbations in spherically symmetric dust spacetime<\/a>\r\n\r\nComputation work was delivered by the University of Cape Town HPC Facilities and the eResearch Center.\r\n\r\n<img src=\"https:\/\/ucthpc.uct.ac.za\/wp-content\/uploads\/2015\/07\/Spacetime_evolution_of_perturbations.png\" alt=\"\" width=\"325\" height=\"480\" border=\"0\" \/>\r\n\r\n&nbsp;","protected":false},"excerpt":{"rendered":"<p>    Sean Febuary completed his PhD in Applied Mathematics at the University of Cape Town.Brief description of his work: The growth of cosmic structure (e.g. galaxies,<br \/>\nclusters thereof) is poorly understood in inhomogeneous cosmological<br \/>\nmodels. Such &#8230;<\/p>\n","protected":false},"author":3,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":[],"categories":[4],"tags":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v21.4 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>Evolution of linear perturbations in spherically symmetric dust spacetime - UCT HPC<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/ucthpc.uct.ac.za\/index.php\/2014\/08\/19\/evolution-of-linear-perturbations-in-spherically-symmetric-dust-spacetime\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Evolution of linear perturbations in spherically symmetric dust spacetime - UCT HPC\" \/>\n<meta property=\"og:description\" content=\"Sean Febuary completed his PhD in Applied Mathematics at the University of Cape Town.Brief description of his work: The growth of cosmic structure (e.g. galaxies,  clusters thereof) is poorly understood in inhomogeneous cosmological  models. Such ...\" \/>\n<meta property=\"og:url\" content=\"https:\/\/ucthpc.uct.ac.za\/index.php\/2014\/08\/19\/evolution-of-linear-perturbations-in-spherically-symmetric-dust-spacetime\/\" \/>\n<meta property=\"og:site_name\" content=\"UCT HPC\" \/>\n<meta property=\"article:published_time\" content=\"2014-08-19T10:25:19+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2015-08-14T08:16:10+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/ucthpc.uct.ac.za\/wp-content\/uploads\/2015\/07\/Spacetime_evolution_of_perturbations.png\" \/>\n<meta name=\"author\" content=\"Timothy Carr\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"Timothy Carr\" \/>\n\t<meta name=\"twitter:label2\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"1 minute\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"Article\",\"@id\":\"https:\/\/ucthpc.uct.ac.za\/index.php\/2014\/08\/19\/evolution-of-linear-perturbations-in-spherically-symmetric-dust-spacetime\/#article\",\"isPartOf\":{\"@id\":\"https:\/\/ucthpc.uct.ac.za\/index.php\/2014\/08\/19\/evolution-of-linear-perturbations-in-spherically-symmetric-dust-spacetime\/\"},\"author\":{\"name\":\"Timothy Carr\",\"@id\":\"https:\/\/ucthpc.uct.ac.za\/#\/schema\/person\/41f6cd039836d7741f2b82a7b7cfe8d0\"},\"headline\":\"Evolution of linear perturbations in spherically symmetric dust spacetime\",\"datePublished\":\"2014-08-19T10:25:19+00:00\",\"dateModified\":\"2015-08-14T08:16:10+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\/\/ucthpc.uct.ac.za\/index.php\/2014\/08\/19\/evolution-of-linear-perturbations-in-spherically-symmetric-dust-spacetime\/\"},\"wordCount\":193,\"publisher\":{\"@id\":\"https:\/\/ucthpc.uct.ac.za\/#organization\"},\"articleSection\":[\"hpc\"],\"inLanguage\":\"en-ZA\"},{\"@type\":\"WebPage\",\"@id\":\"https:\/\/ucthpc.uct.ac.za\/index.php\/2014\/08\/19\/evolution-of-linear-perturbations-in-spherically-symmetric-dust-spacetime\/\",\"url\":\"https:\/\/ucthpc.uct.ac.za\/index.php\/2014\/08\/19\/evolution-of-linear-perturbations-in-spherically-symmetric-dust-spacetime\/\",\"name\":\"Evolution of linear perturbations in spherically symmetric dust spacetime - 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