Detection of intercluster gas in superclusters using the thermal Sunyaev–Zel’dovich effect

Abstract

Using a thermal Sunyaev-Zel'dovich (tSZ) signal, we search for hot gas in superclusters identified using the Sloan Digital Sky Survey Data Release 7 (SDSS/DR7) galaxies. We stack a Comptonization y map produced by the Planck Collaboration around the superclusters and detect the tSZ signal at a significance of 6.4σ. We further search for an intercluster component of gas in the superclusters. For this, we remove the intracluster gas in the superclusters by masking all galaxy groups/clusters detected by the Planck tSZ, ROSAT X-ray, and SDSS optical surveys down to a total mass of 10 13 M . We report the first detection of intercluster gas in superclusters with y = (3.5 ± 1.4) × 10 −8 at a significance of 2.5σ. Assuming a simple isothermal and flat density distribution of intercluster gas over superclusters, the estimated baryon density is (Ω gas /Ω b ) × (T e /8 × 10 6 K) = 0.067 ± 0.006 ± 0.025. This quantity is inversely proportional to the temperature, therefore taking values from simulations and observations, we find that the gas density in superclusters may account for 17 -52% of missing baryons at low redshifts. A better understanding of the physical state of gas in the superclusters is required to accurately estimate the contribution of our measurements to missing baryons.

Density and temperature of cosmic-web filaments on scales of tens of megaparsecs

“…In order to remove the contribution from foreground/background galaxy groups and clusters, the objects listed in Tanimura et al (2019a) (Rykoff et al 2014), 158103 WHL clusters (Wen et al 2012;Wen & Han 2015) and 46,479 AMF clusters (Banerjee et al 2018) detected from SDSS galaxies. Mass and redshift distributions of the groups and clusters are shown in Tanimura et al (2019a) and the mass distribution in the union catalogue reaches down to 10 13 M .…”

Low Surface Brightness Optical Emission as a Probe of Cosmic Ray Reservoirs

“…Typical conditions in the intracluster medium of a rich cluster of galaxies are n e = 3 × 10 −3 cm −3 , B = 1µG and the CMB is the dominant radiation energy density. Recent work on the gas density between clusters [8] in superclusters suggests a much lower intercluster density of n e 10 −5 cm −3 . Plotting the loss timescales for those conditions ( figure 2) shows that the longest lived intracluster particles are those with γ e 500 and lifetimes of only a few Billion years.…”

“…In the outer regions of X-ray emitting rich clusters where radio relics have been found, the thermal gas pressure is typically ∼ 10 eV cm −3 . In the intercluster medium of a supercluster, pressure estimates using the thermal Sunyaev-Zeldovich effect [8] indicate a substantially lower thermal gas pressure of ∼ 10 −2 eV cm −3 .…”

Multiwavelength cross-correlation analysis of the simulated cosmic web

“…Botteon et al 2018;Vacca et al 2018;Govoni et al 2019). More recently, Tanimura et al (2019b) and de Graaff et al (2019) have presented the possible first detection of the coldest part of the coldest part of the WHIM in the cosmic web, by stacking the thermal SZ signal of pairs of galaxies or pairs of galaxy groups.…”