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Galaxy evolution in the metric of the Cosmic Web

2017-09-05
  • Speaker : Dr. Katarina Kraljic (The university of Edinburgh, UK)
  • Date : 2017-11-15 16:00 ~ 17:00
  • Location : JYS 331-1
  • Host : Dr. Rory Smith

I will present recent results on the role of the cosmic web in shaping galaxy properties in the GAMA spectroscopic survey in the redshift range  0.03 < z < 0.25. The stellar mass, u - r dust corrected colour and  specific star formation rate (sSFR) of galaxies are analysed as a function of their distances to the 3D cosmic web features, such as nodes, filaments and walls.  Significant mass and type/colour gradients are found for the whole population, with more massive and/or passive  galaxies being located closer to the filament and wall than their less massive and/or star-forming counterparts. The red fraction of galaxies  is found to increase when closing in on nodes, and on filaments regardless of the distance to nodes. Similarly, the star-forming population reddens (or lowers its sSFR) at fixed mass when closing in on filament, implying that some quenching takes place. Comparable trends are also found in the state-of-the-art hydrodynamical simulation HORIZON-AGN. I will argue that these results suggest that on top of stellar mass and large-scale density, the traceless component of the tides from the anisotropic large-scale environment also shapes galactic properties. I will also show that an extension of excursion theory accounting for filamentary tides provides a qualitative explanation in terms of anisotropic assembly bias, and it also explains the absence of type/colour gradients in the data on smaller, non-linear scales.


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