Abstract
We studied physical properties of matter in 24 544 filaments ranging from 30 to 100 Mpc in length, identified in the Sloan Digital Sky Survey. We stacked the Comptonizationymap produced by the Planck Collaboration around the filaments, excluding the resolved galaxy groups and clusters above a mass of ∼3 × 1013 M⊙. We detected the thermal Sunyaev-Zel’dovich signal for the first time at a significance of 4.4σin filamentary structures on such a large scale. We also stacked thePlanckcosmic microwave background lensing convergence map in the same manner and detected the lensing signal at a significance of 8.1σ. To estimate physical properties of the matter, we considered an isothermal cylindrical filament model with a density distribution following aβ-model (β= 2/3). Assuming that the gas distribution follows the dark matter distribution, we estimate that the central gas and matter overdensityδand gas temperatureTeareδ= 19.0−12.1+27.3andTe= 1.4−0.4+0.4× 106K, which results in a measured baryon fraction of 0.080−0.051+0.116× Ωb.
Highlights
The large-scale structure of the Universe is organized in a weblike structure called the cosmic web (Bond et al 1996)
We have found that our results are consistent using these two y maps, and we show the results with the modified internal linear combination algorithm (MILCA) y map in this paper
The fitting was performed with the Markov chain Monte Carlo (MCMC) algorithm using the emcee software (Foreman-Mackey et al 2013), which is an affine-invariant ensemble sampler proposed by Goodman & Weare (2010)
Summary
The large-scale structure of the Universe is organized in a weblike structure called the cosmic web (Bond et al 1996). The formation of the cosmic-web structure is described in the standard cosmological model of structure formation (e.g., Zeldovich et al 1982). The cosmic-web structure is governed by the gravitational collapse of matter in the expanding Universe, it can be used to test cosmological models. Numerical simulations illustrate that the cosmic web consists of nodes, filaments, sheets, and voids. Nodes form in dense regions, which are interconnected by filaments and sheets, and most regions are occupied by voids with extremely low density. Galaxy clusters are prominent structures that are identified in the large-scale structure, but it is predicted that the largest fraction of matter (around 50% in mass) resides in filamentary structures (Cen & Ostriker 2006; Aragón-Calvo et al 2010a; Cautun et al 2014)
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