A search for warm/hot gas filaments between pairs of SDSS Luminous Red Galaxies. Issue 1 (16th November 2018)

• Record Type: Journal Article
• Authors: Tanimura, Hideki; Hinshaw, Gary; McCarthy, Ian G; Van Waerbeke, Ludovic; Aghanim, Nabila; Ma, Yin-Zhe; Mead, Alexander; Hojjati, Alireza; Tröster, Tilman
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 483:Issue 1(2019)
• Page Start: 223
• Page End: 234
• Publication Date: 2018-11-16
• Subjects: galaxies: clusters: general -- galaxies: groups: general -- galaxies: haloes -- large-scale structure of Universe; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/sty3118
• Languages: English
• ISSNs: 0035-8711

Abstract

Abstract: We search the Planck data for a thermal Sunyaev–Zel'dovich (tSZ) signal due to gas filaments between pairs of Luminous Red Galaxies (LRGs) taken from the Sloan Digital Sky Survey Data Release 12 (SDSS/DR12). We identify ∼260 000 LRG pairs in the DR12 catalogue that lie within 6–10 $h^{-1} \, \mathrm{Mpc}$ of each other in tangential direction and within 6 $h^{-1} \, \mathrm{Mpc}$ in radial direction. We stack pairs by rotating and scaling the angular positions of each LRG so they lie on a common reference frame, then we subtract a circularly symmetric halo from each member of the pair to search for a residual signal between the pair members. We find a statistically significant (5.3σ) signal between LRG pairs in the stacked data with a magnitude Δ y = (1.31 ± 0.25) × 10 −8 . The uncertainty is estimated from two Monte Carlo null tests which also establish the reliability of our analysis. Assuming a simple, isothermal, cylindrical filament model of electron overdensity with a radial density profile proportional to r c / r (as determined from simulations), where r is the perpendicular distance from the cylinder axis and r c is the core radius of the density profile, we constrain the product of overdensity and filament temperature to be $\delta _\mathrm{ c} \times (T_{\rm e}/10^7 \, {\rm K}) \times (r_\mathrm{ c}/0.5h^{-1} \, {\rm Mpc}) = 2.7 \pm 0.5$ . To our knowledge, this is the first detection of filamentary gas at overdensities typical of cosmological large-scale structure. We compare our result to the BAHAMAS suite of cosmological hydrodynamic simulations (McCarthy et al. 2017 ) and find a slightly lower, but marginally consistent Comptonization excess, Δ y = (0.84 ± 0.24) × 10 −8 .