The Fundamental Plane in RX J0142.0+2131: A Galaxy Cluster Merger at z = 0.28
The Fundamental Plane in RX J0142.0+2131: A Galaxy Cluster Merger at z = 0.28
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RX J0142.0 2131 中的基本平面：z = 0.28 处的星系团合并
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发表时间：
2006
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影响因子：
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通讯作者：
M. Bergmann
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作者：
J. Barr;I. Jørgensen;K. Chiboucas;R. Davies;M. Bergmann
我们展示了 z = 0.28 星系团 RX J0142.0+2131 中的基本平面 (FP)。尽管内部散射更大，但没有证据表明 FP 的斜率与后发星团相比存在差异。平均而言，RX J0142.0+2131 中的恒星群的静止框架 V 波段质光比 (M/LV) 比后发区低 0.29 ± 0.03 dex。这明显低于 zf = 2 时形成的被动演化星团的预期。透镜状星系的平均 M/LV 较低，并且 M/LV 分布比椭圆星系具有更大的散射。较低的质光比并不是由于最近的恒星形成造成的：我们之前对 RX J0142.0+2131 E/S0 星系的光谱观测表明，在过去约 4 Gyr 内没有明显的恒星形成的证据。然而，簇成员的 α 元素丰度比有所提高，这可能会降低 M/LV。 RX J0142.0+2131 FP 中散射的增加反映了 M/LV 中的大散射，这意味着星系在一系列历元内经历了恒星形成的爆发。最东边的7个星系团，包括第二亮的成员，其M/LV与被动演化一致，zf = 2。我们推测RX J0142.0+2131是一个星团-星团合并，其中东部的星系尚未落入星团主体或因合并而没有经历恒星形成。
We present the fundamental plane (FP) in the z = 0.28 cluster of galaxies RX J0142.0+2131. There is no evidence for a difference in the slope of the FP when compared with the Coma Cluster, although the internal scatter is larger. On average, stellar populations in RX J0142.0+2131 have rest-frame V-band mass-to-light ratios (M/LV) 0.29 ± 0.03 dex lower than in Coma. This is significantly lower than expected for a passively evolving cluster formed at zf = 2. Lenticular galaxies have lower average M/LV and a distribution of M/LV with larger scatter than ellipticals. Lower mass-to-light ratios are not due to recent star formation: our previous spectroscopic observations of RX J0142.0+2131 E/S0 galaxies showed no evidence for significant star formation within the past ~4 Gyr. However, cluster members have enhanced α-element abundance ratios, which may act to decrease M/LV. The increased scatter in the RX J0142.0+2131 FP reflects a large scatter in M/LV implying that galaxies have undergone bursts of star formation over a range of epochs. The seven easternmost cluster galaxies, including the second brightest member, have M/LV consistent with passive evolution and zf = 2. We speculate that RX J0142.0+2131 is a cluster-cluster merger where the galaxies to the east are yet to fall into the main cluster body or have not experienced star formation as a result of the merger.