X-ray analysis of the galaxy group UGC03957 beyond R200 with Suzaku

TL;DR

This study analyzes the gas properties of galaxy group UGC03957 up to 1.4 times its R200 radius using Suzaku and Chandra data, revealing temperature decline, flat metal abundance, and entropy behavior consistent with simulations, suggesting galactic winds and deviations from equilibrium.

Contribution

First detailed X-ray analysis of UGC03957 beyond R200, showing unique entropy and gas fraction profiles compared to other clusters and groups.

Findings

Temperature drops by a factor of ~3 from center to outskirts.

Metal abundance profile is flat at large radii.

Gas mass fraction exceeds cosmic mean beyond R200.

Abstract

We investigated the gas properties of the galaxy group UGC03957 up to $1.4R_{200} \approx 1.4$Mpc in four azimuthal directions with the Suzaku satellit and performed a spectral analysis of five Suzaku observations of UGC03957 with 138ks good exposure time in total and five Chandra snapshot observations for point source detection. We found a temperature drop of a factor of ${\sim} 3$ from the center to the outskirts that is consistent with previous results for galaxy clusters. The metal abundance profile shows a flat behavior towards large radii, which is a hint for galactic winds as the primary ICM enrichment process. The entropy profile is consistent with numerical simulations after applying a gas mass fraction correction. Previous analyses for clusters and groups often showed an entropy flattening or even a drop around ${\sim} R_{200}$, which can be an indication of clumping or non-equilibrium states in the outskirts. Such entropy behavior is absent in UGC03957. The gas mass fraction is well below the cosmic mean but rises above this value beyond $R_{200}$, which could be a hint for deviations from hydrostatic equilibrium at these large radii. We determined the relative number of different supernovae types and found that the abundance pattern can be described by a relative contribution of 80% - 100% of core-collapse supernovae. This result is in agreement with previous measurements for galaxy groups.