Volume 643, November 2020
|Number of page(s)||7|
|Section||Letters to the Editor|
|Published online||06 November 2020|
Letter to the Editor
First detection of stacked X-ray emission from cosmic web filaments
Université Paris-Saclay, CNRS, Institut d’Astrophysique Spatiale, Bâtiment 121, 91405 Orsay, France
Accepted: 1 September 2020
We report the first statistical detection of X-ray emission from cosmic web filaments in ROSAT data. We selected 15 165 filaments at 0.2 < z < 0.6 ranging from 30 Mpc to 100 Mpc in length, identified in the Sloan Digital Sky Survey survey. We stacked the X-ray count-rate maps from ROSAT around the filaments, excluding resolved galaxy groups and clusters above the mass of ∼3 × 1013 M⊙ as well as the detected X-ray point sources from the ROSAT, Chandra, and XMM-Newton observations. The stacked signal results in the detection of the X-ray emission from the cosmic filaments at a significance of 4.2σ in the energy band of 0.56−1.21 keV. The signal is interpreted, assuming the Astrophysical Plasma Emission Code model, as an emission from the hot gas in the filament-core regions with an average gas temperature of 0.9−0.6+1.0 keV and a gas overdensity of δ ∼ 30 at the center of the filaments. Furthermore, we show that stacking the SRG/eROSITA data for ∼2000 filaments only would lead to a ≳5σ detection of their X-ray signal, even with an average gas temperature as low as ∼0.3 keV.
Key words: cosmology: observations / large-scale structure of Universe / diffuse radiation / X-rays: diffuse background
© H. Tanimura et al. 2020
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