When researchers in Japan conducted an experiment with slime mold that mirrored the Tokyo railway system back in 2010, it sparked the emergence of a theory known as biologically inspired adaptive network design. A New Mexico State University graduate student used the slime mold model as part of his Ph.D. thesis to improve the way astronomers identify the largest scale structures in the universe, the “cosmic web.”
Measuring the environmental density of galaxies isn’t new, but the paper “Filaments of the Slime Mold Cosmic Web and How they Affect Galaxy Evolution,” published in August’s “Astrophysical Journal,” outlines how Hasan changed one step in the existing research framework combining it with a new method using an algorithm based on the slime mold model.
“I didn't know how well it was going to work or not work, but I had a hunch the slime mold method could tell us much more detailed information about how density is structured in the universe, so I decided to give it a try,” said Farhanul Hasan, lead author on the paper who subsequently earned his Ph.D. in astronomy at NMSU. “As it turned out, it produced a lot more detailed discrete structures than the old method.”
NMSU assistant astronomy professor Joe Burchett co-authored the paper with Hasan and eight other authors. Burchett introduced the slime mold method to astrophysical application at the University of California, Santa Cruz as a post-doctoral fellow. With Burchett’s help, Hasan took this research a major step further at NMSU.
“We were looking for a way to visualize the cosmic web, the large-scale structure of the universe, and in particular, the gas that sort of permeates through it,” Burchett said. “Working with an expert on graphics rendering, Oskar Elek, we came across this algorithm that was designed to mimic slime mold and its ability to find food sources by reforming itself to kind of look a lot like the cosmic web. That was our inspiration for setting off on this whole path. We’ve worked on that now for several years. Farhan's work has taken it to new heights that we'd only dreamed of back then.”
Scientists have known since the eighties that a galaxy's environment impacts its growth and evolution; however, there is still debate over this connection's exact nature. Hasan’s research demonstrates how galaxies evolve depending on their proximity to dense cosmic structures.
“These filaments are highways of space and just as highways affect cities in real life; these filaments affect galaxies differently,” Hasan said. “But another thing I want to highlight is that this connection completely depends on what era of universe you're looking at.”
Hasan’s research found that earlier times saw galaxies’ growth stimulated by close proximity to larger structures while currently they are stymied by being near these larger structures.
“One big takeaway here is if we can map out gas around real universes at different times it's easier building consistent pictures,” Hasan said.“If we collect data from earlier times where things looked different and later times; we can get physical pictures showing how gas distributes largely affecting whether galaxies grow because or hindered by them."
“We have very fundamental questions about how galaxies effectively live and die," Burchett added.“The data collected for nearly century suggests where galaxy lives impacts lifespan hugely; basically having harder time surviving ‘big cities’ universes."
“What Farhanul has done is look state-of-art models available regarding galaxy formation/evolution via large-scale computer simulations trying understanding local/large-scale environments impacting evolutions."
After earning his Ph.D., Hasan began post-doctoral fellowship September Space Telescope Science Institute continuing research applying theory real NASA Hubble Space Telescope data planning present results couple years.
“We’re applying observational data actually mapping filamentary structure real universe using Hubble identifying distributed gases testing many theories galaxy/structure formations largely bringing whole thing full circle," Hasan concluded.
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CUTLINE: From Left: New Mexico State University astronomy assistant professor Joe Burchett and Ph.D. graduate Farhanul Hasan at Astronomy Hall (NMSU photo by Josh Bachman)
CUTLINE: This image from Farhanul Hansan’s paper shows large-scale matter distribution/cosmic “filaments” captured better slime mold model than existing standard framework (Image courtesy Farhanul Hasan)