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Register a new userRevising the merger scenario of the galaxy cluster Abell 1644: a new gas poor structure discovered by weak gravitational lensing
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Added by
Rog\\'erio Monteiro-Oliveira
Publication date
2020
fields
Physics
and research's language is
English
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The galaxy cluster Abell 1644 ($bar{z}=0.047$) is known for its remarkable spiral-like X-ray emission. It was previously identified as a bimodal system, comprising the subclusters, A1644S and A1644N, each one centered on a giant elliptical galaxy. In this work, we present a comprehensive study of this system, including new weak-lensing and dynamical data and analysis plus a tailor-made hydrodynamical simulation. The lensing and galaxy density maps showed a structure in the North that could not be seen on the X-ray images. We, therefore, rename the previously known northern halo as A1644N1 and the new one as A1644N2. Our lensing data suggests that those have fairly similar masses: $M_{200}^{rm N1}=0.90_{-0.85}^{+0.45} times10^{14}$ and $M_{200}^{rm N2}=0.76_{-0.75}^{+0.37} times10^{14}$ M$_odot$, whereas the southern structure is the main one: $M_{200}^{rm S}=1.90_{-1.28}^{+0.89}times 10^{14}$ M$_odot$. Based on the simulations, fed by the observational data, we propose a scenario where the remarkable X-ray characteristics in the system are the result of a collision between A1644S and A1644N2 that happened $sim$1.6 Gyr ago. Currently, those systems should be heading to a new encounter, after reaching their maximum separation.
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We present two weak lensing reconstructions of the nearby ($z_{cl}=0.055$) merging cluster Abell 3667, based on observations taken $sim 1$ year apart under different seeing conditions. This is the lowest redshift cluster with a weak lensing mass reconstruction to date. The reproducibility of features in the two mass maps demonstrate that weak lensing studies of low-redshift clusters are feasible. These data constitute the first results from an X-ray luminosity-selected weak lensing survey of 19 low-redshift ($z< 0.1$) southern clusters.
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