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Seeing is Believing – new framework to visualize cosmic filaments

  • "A typical output from Felix: a visualization of the Large scale filaments from the Cosmogrid Simulation". Credits: Nithin Shivashankar and Vijay Natarajan

"A typical output from Felix: a visualization of the Large scale filaments from the Cosmogrid Simulation". Credits: Nithin Shivashankar and Vijay Natarajan

An international team of researchers has proposed a framework for identifying, characterizing and visualizing cosmic filaments in the universe. The proposed framework would help astronomers identify and visualise the multi-scale structure of cosmic filaments in the universe, and examine their interaction with other cosmic structures. This collaborative effort consisted of professors and student researchers from Kapteyn Astronomical Institute, University of Groningen, Netherlands, and the Indian Institute of Science, Bangalore.

The present day universe comprises of gigantic blob-like clusters of galaxies, with tenuous linear filament like arrangements of galaxies that emanate from these clusters. Also, these filaments form a coarse boundary of wall-like structures, which in turn enclose near empty three-dimensional voids. A salient aspect of this structural pattern is its fractal nature, where within clusters one expects several sub-clusters which are connected by filaments and so on. Similar patterns are expressed within the large-scale filament like regions, wall-like regions and void-like regions. Studying such multi-scale structures is essential to our understanding of the formation and evolution of galaxies. “As our insight into the complex structural pattern of the cosmic web has increased rapidly over the past years, it has become clear that the cosmic-web contains a wealth of information on a range of cosmological and astronomical aspects and processes” says the research team behind Felix.

Cosmic filaments form the most ubiquitous morphological element, and may be found in multiple density and spatial scales. Furthermore, the formation of these filaments is hypothesized to be influenced by dark matter, a kind of matter that does not interact with light or any other inter nuclear/atomic forces except gravity. Thus deciphering the structures of these filaments provide us with a wealth of information about Universe itself. Also, the precise structure of filaments and voids can potentially probe dark energy which accounts for more than two-thirds of the Universe’s energy. However, studying these mega structures, classifying and characterising them is no easy task and is an area of active research.

Here comes Felix, a framework for identification and visual exploration of multi-scale filaments in the cosmic web. Felix characterizes the different filaments available in the cosmic web using density models, making it possible to identify different classes of filaments including those which otherwise would go unnoticed due to their placement near voids or would be overshadowed by the higher density ones. This is done by performing a topology based analysis of the density field which provides a succinct structural catalogue of all detected filamentary structures, which may be efficiently browsed and queried upon to generate interactive visualizations. Felix provides the ability to extract the desired features of the filaments and study them further using interactive visualizations.

One of the exciting possibilities that presents itself using the framework is the ability to probe intra-void structural elements interactively, which helps in explaining observations like the formation of void galaxies and disappearance of dwarf galaxies. This analysis of void architecture also potentially provides a sensitive probe for dark energy/matter as well as a keen test of modified gravity theories.

About the authors

The study is a collaborative effort between six researchers across the globe. Nithin Shivashankar recently defended his PhD thesis from Department of Computer Science and Automation, Indian Institute of Science. Pratyush Pranav is working toward the PhD degree at the Kapteyn Astronomical Institute, Groningen, the Netherlands. Vijay Natarajan is an associate professor in the Indian Institute of Science. Rien van de Weygaert is a professor of cosmic structure formation in the Kapteyn Astronomical Institute, University of Groningen. E.G. Patrick Bos is working toward the PhD degree in the Kapteyn Astronomical Institute, University of Groningen. Steven Rieder is a postdoctoral researcher at RIKEN Advanced Institute for Computational Science, Japan.

The paper appeared in IEEE Transactions on Visualization and Computer Graphics  (PrePrints, doi:10.1109/TVCG.2015.2452919) on 6th July 2015.

Contact: Nithin Shivashankar

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