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Session: Cosmology and Relativistic Astrophysics

Name: Dr. Konstantinos Migkas (Leiden University)
Coauthors: No coauthors were included.
Type: Poster
Title: Probing cosmic isotropy with new X-ray clusters and the first eROSITA cluster catalog
Abstract:

The isotropy of the Universe at >200 Mpc scales is a crucial assumption of LCDM. Any significant, observational deviation from this consensus can strongly challenge the standard cosmological model. Multiwavelength scaling relations of galaxy cluster properties that do or do not depend on cosmological assumptions are an excellent and powerful tool for scrutinizing cosmic isotropy. The apparent angular variation of these relations provides us with numerous independent tests of cosmic isotropy. In Migkas et al. (2021) we detected a 9% anisotropy of the local Hubble constant at a $5.4sigma$ level. This anomaly can be attributed to a 900 km/s cluster bulk flow motion extending up to 500 Mpc. These results are in strong tension with LCDM. In this work, we present for the first time the cosmic isotropy results of 1) multiple new, more precise cluster scaling relations between the core-excised X-ray luminosity, gas mass, isophotal radius, and temperature of ~300 clusters, and 2) the 1st eROSITA cluster catalog. Amazingly, we show that both the much-improved scaling relations and the independent eROSITA cluster catalog confirm the detection of a cosmic anisotropy at the <1 Gpc Universe.