Shock-excited Galaxies in the Green Valley in Compact Groups: Clues to Morphology Evolution in Dense Environments

Name: Shock-excited Galaxies in the Green Valley in Compact Groups: Clues to Morphology Evolution in Dense Environments
Creator: esa.int
Published: 2013-07-03 00:00:00
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doi.org2013-07-03 更新2025-03-26 收录

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Compact groups of galaxies represent density enhancements in the Universe comparable with clusters and are dominated by early type galaxies that lie in the Green Valley between the blue and red sequence. Our observations of a sample of such groups has revealed that 10 percent of our targeted group members show unusually powerful midIR H2 emission lines relative to PAH emissionsuggesting shockexcitation. Most of these galaxies lie in the optical green valley, and exhibit specific star formation rates that lie between spirals and elliptical suggesting that they are a transition population in which shocks may play a role in their color evolution. We propose to map key farIR cooling lines [OI], [CII] and CO with the PACS and SPIRE spectrometers to both map and quantify the strength and distribution of shocks to search for clues about how they might be affected by their environment. We will also use PACS and SPIRE imaging to constrain dust SEDs to estimate SFRs and dust/gas masses to explore whether the shocks may heat the gas above the threshold for star formationhence shutting down new star formation. Alternatively, by comparison with VLA HI maps which show considerable tidal material in the groups, we will search for evidence that accretion from tidal streams is responsible for reigniting new star formationthus modifying their optical colors. This proposal will, for the first time, test whether shocks may play a transformative role in galaxy evolution. [truncated!, Please see actual data for full text] [truncated!, Please see actual data for full text]

致密星系群代表了宇宙中与星系团相当的密度增强现象，主要由位于蓝序列与红序列之间的绿谷中的早型星系所主导。对我所观察的此类星系群的样本研究揭示，目标星系成员中有10%显示出相对于富勒烯发射的异常强大的中红外H2发射线，这暗示着冲击激发。这些星系大多位于光学绿谷中，并展现出介于旋涡星系和椭圆星系之间的特定恒星形成率，这表明它们是一个过渡群体，其中冲击可能在它们的颜色演化中发挥作用。我们提议利用PACS和SPIRE光谱仪绘制关键远红外冷却线[OI]、[CII]和CO，以同时绘制和量化冲击的强度与分布，以寻找关于它们可能如何受环境影响的线索。我们还将利用PACS和SPIRE成像来约束尘埃SEDs，以估算恒星形成率以及尘埃/气体质量，以探究冲击是否可能加热气体至恒星形成的阈值以上，从而关闭新的恒星形成。或者，通过与VLA HI图进行比较，该图显示了星系群中有大量的潮汐物质，我们将寻找证据表明潮汐流的吸积是重新点燃新的恒星形成、从而改变它们光学颜色的原因。这项提议将首次检验冲击是否可能在星系演化中发挥变革性作用。[截断！请参阅实际数据以获取全文] [截断！请参阅实际数据以获取全文]

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