Abstract
We conducted an X-ray analysis of one of the twoPlanck-detected triplet-cluster systems,PLCK G334.8-38.0, with a ∼100 ks deepXMM-Newtondata. We find that the system has a redshift ofz = 0.37 ± 0.01 but the precision of the X-ray spectroscopy for two members is too low to rule out a projected triplet system, demanding optical spectroscopy for further investigation. In projection, the system looks almost like an equilateral triangle with an edge length of ∼2.0 Mpc, but masses are very unevenly distributed (M500 ∼ [2.5, 0.7, 0.3]×1014 M⊙from bright to faint). The brightest member appears to be a relaxed cool-core cluster and is more than twice as massive as both other members combined. The second brightest member appears to be a disturbed non-cool-core cluster and the third member was too faint to make any classification. None of the clusters have an overlappingR500region and no signs of cluster interaction were found; however, theXMM-Newtondata alone are probably not sensitive enough to detect such signs, and a joint analysis of X-ray and the thermal Sunyaev-Zeldovich effect is needed for further investigation, which may also reveal the presence of the warm-hot intergalactic medium within the system. The comparison with the otherPlanck-detected triplet-cluster-system (PLCK G214.6+36.9) shows that they have rather different configurations, suggesting rather different merger scenarios, under the assumption that they are both not simply projected triplet systems.
Highlights
In the standard paradigm, gravitation drives structure formation in a hierarchical process, and makes dark matter the “scaffolding” of the cosmic web
To remove the intervals of the observation contaminated by flares, a process called deflaring, we use the procedure of Kolodzig et al. This filters the light curve of an observation in three consecutive steps of histogram clipping, where the first step is tuned for the most obvious flares, the second step is tuned for weaker and longer flares using larger time bins, and the last steps is tuned for remaining flares by soft protons
Remaining flares of soft protons are detected with the light curve of the countrate ratio between the inFOV and outFOV area
Summary
Gravitation drives structure formation in a hierarchical process, and makes dark matter the “scaffolding” of the cosmic web. In the local Universe, it is expected that the vast majority of baryons ( 80%) have been heated under the action of gravity to temperatures above 105 K, and have not condensed into stars (e.g., Cen & Ostriker 1999; Roncarelli et al 2012; Kravtsov & Borgani 2012; Dolag et al 2016; Martizzi et al 2019) This makes studying the “hot” Universe a crucial step towards understanding the formation and evolution of cosmic structures. To remove the intervals of the observation contaminated by flares, a process called deflaring, we use the procedure of Kolodzig et al (in prep., hereafter KOL21) This filters the light curve of an observation in three consecutive steps of histogram clipping, where the first step is tuned for the most obvious flares, the second step is tuned for weaker and longer flares using larger time bins, and the last steps is tuned for remaining flares by soft protons. As SPB is mainly flare residuals, typically much brighter than the HEB, the deflaring procedure leads to a significant SPB reduction
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