Abstract: The recently identified tension between primary CMB and cluster counts constraints on cosmological parameters, specially on σ₈, encountered by the Planck collaboration have risen the question about the possible incompleteness of the cluster detected samples. In this work, we search for very extended X-ray galaxy cluster on the ROSAT All-Sky Survey (RASS) that might have been missed in previous works. We use a state of-the-art source detection and classification algorithm. To optimise the cluster detection efficiency of our algorithm, we first setup ROSAT X-ray image simulations. Then, we use the same procedure on the RASS data. We obtain a list of possible X-ray extended cluster candidates, for which we use 2MASS/SDSS observations for visual inspection. In our work, hundreds of new X-ray galaxy clusters are found, which might provide us one way to constrain cosmological parameters further. 

Weiwei X u obtained her bachelor degree at Shandong University/Weihai in 2011, and her master degree of science at the NAOC in 2014. She's since been a PhD candidate of the NAOC, and became a visiting student at the University of Bonn with a CAS-DAAD scholarship. Her research interest focus on X-ray studies of galaxy clusters, AGN and X-ray binaries.