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标题：Detection of intercluster gas in superclusters using the thermal Sunyaev–Zel’dovich effect
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作者：H. Tanimura ; N. Aghanim ; M. Douspis 等
期刊名称：Astronomy & Astrophysics
印刷版ISSN：0004-6361
电子版ISSN：1432-0746
出版年度：2019
卷号：625
DOI：10.1051/0004-6361/201833413
语种：English
出版社：EDP Sciences
摘要：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 Comptonizationymap produced by thePlanckCollaboration 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 thePlancktSZ, ROSAT X-ray, and SDSS optical surveys down to a total mass of 1013 M⊙. We report the first detection of intercluster gas in superclusters withy = (3.5 ± 1.4) × 10−8at a significance of 2.5σ. Assuming a simple isothermal and flat density distribution of intercluster gas over superclusters, the estimated baryon density is (Ωgas/Ωb)×(Te/8 × 106 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.
关键词：encosmology: observationslarge-scale structure of Universe