Browsing by Author "Paillas, Enrique"

Now showing 1 - 2 of 2
  • No Thumbnail Available
    Item
    Optimal void finders in weak lensing maps
    (2021) Davies, Christopher T.; Paillas, Enrique; Cautun, Marius; Li, Baojiu
    Cosmic voids are a key component of the large-scale structure that contain a plethora of cosmological information. Typically, voids are identified from the underlying galaxy distribution, which is a biased tracer of the total matter field. Previous works have shown that 2D voids identified in weak lensing (WL) maps - WL voids - correspond better to true underdense regions along the line of sight. In this work, we study how the properties of WL voids depend on the choice of void finder, by adapting several popular void finders. We present and discuss the differences between identifying voids directly in the convergence maps, and in the distribution of WL peaks. Particular effort has been made to test how these results are affected by galaxy shape noise (GSN), which is a dominant source of noise in WL observations. By studying the signal-to-noise ratios (S/N) for the tangential shear profile of each void finder, we find that voids identified directly in the convergence maps have the highest S/N but are also the ones most affected by GSN. Troughs are least affected by noise, but also have the lowest S/N. The tunnel algorithm, which identifies voids in the distribution of WL peaks, represents a good compromise between finding a large tangential shear S/N and mitigating the effect of GSN.
  • No Thumbnail Available
    Item
    Revealing the properties of void galaxies and their assembly using the EAGLE simulation
    (2022) Rosas-Guevara, Yetli; Tissera, Patricia; Lagos, Claudia del P.; Paillas, Enrique; Padilla, Nelson
    We explore the properties of central galaxies living in voids using the EAGLE, cosmological hydrodynamic simulations. Based on the minimum void-centric distance, we define four galaxy samples: inner void, outer void, wall, and skeleton. We find that inner void galaxies with host halo masses < 10(12) M-circle dot have lower stellar mass and stellar mass fractions than those in denser environments, and the fraction of galaxies with star formation (SF) activity and atomic hydrogen (H I) gas decreases with increasing void-centric distance, in agreement with observations. To mitigate the influence of stellar (halo) mass, we compare inner void galaxies to subsamples of fixed stellar (halo) mass. Compared to denser environments, inner void galaxies with M-* = 10([9.0-9.5]) M-circle dot have comparable SF activity and H I gas fractions, but the lowest quenched galaxy fraction. Inner void galaxies with M-* = 10([9.0-10.5]) M-circle dot have the lowest H I gas fraction, the highest quenched fraction and the lowest gas metallicities. On the other hand, inner void galaxies with M-* > 10(10.5) M-circle dot have comparable SF activity and H I gas fractions to their analogues in denser environments. They retain the highest metallicity gas that might be linked to physical processes that act with lower efficiency in underdense regions such as AGN (active galaxy nucleus) feedback. Furthermore, inner void galaxies have the lowest fraction of positive gas-phase metallicity gradients, which are typically associated with external processes or feedback events, suggesting they have more quiet merger histories than galaxies in denser environments. Our findings shed light on how galaxies are influenced by their large-scale environment.