Discovery of "Warm Dust" Galaxies in Clusters at z~0.3: Evidence for Stripping of Cool Dust in the Dense Environment?
T. D. Rawle, M. Rex, E. Egami, S. M. Chung, P. G. Pérez-González, I. Smail, G. Walth, B. Altieri, P. Appleton, A. Berciano Alba, A. W. Blain, M. Dessauges-Zavad… 展开作者
T. D. Rawle, M. Rex, E. Egami, S. M. Chung, P. G. Pérez-González, I. Smail, G. Walth, B. Altieri, P. Appleton, A. Berciano Alba, A. W. Blain, M. Dessauges-Zavadsky, D. Fadda, A. H. Gonzalez, M. J. Pereira, I. Valtchanov, P. P. van der Werf, M. Zemcov
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25 pages, 13 figures, accepted for publication in ApJ
Using far-infrared imaging from the "Herschel Lensing Survey", we derive dust properties of spectroscopically-confirmed cluster member galaxies within two massive systems at z~0.3: the merging Bullet Cluster and the more relaxed MS2137.3-2353. Most star-forming cluster sources (~90%) have characteristic dust temperatures similar to local field galaxies of comparable infrared (IR) luminosity (T_dust ~ 30K). Several sub-LIRG (L_IR < 10^11 L_sun) Bullet Cluster members are much warmer (T_dust > 37K) with far-infrared spectral energy distribution (SED) shapes resembling LIRG-type local templates. X-ray and mid-infrared data suggest that obscured active galactic nuclei do not contribute significantly to the infrared flux of these "warm dust" galaxies. Sources of comparable IR-luminosity and dust temperature are not observed in the relaxed cluster MS2137, although the significance is too low to speculate on an origin involving recent cluster merging. "Warm dust" galaxies are, however, statistically rarer in field samples (> 3sigma), indicating that the responsible mechanism may relate to the dense environment. The spatial distribution of these sources is similar to the whole far-infrared bright population, i.e. preferentially located in the cluster periphery, although the galaxy hosts tend towards lower stellar masses (M_* < 10^10 M_sun). We propose dust stripping and heating processes which could be responsible for the unusually warm characteristic dust temperatures. A normal star-forming galaxy would need 30-50% of its dust removed (preferentially stripped from the outer reaches, where dust is typically cooler) to recover a SED similar to a "warm dust" galaxy. These progenitors would not require a higher IR-luminosity or dust mass than the currently observed normal star-forming population.
Simulating the impact of dust cooling on the statistical properties of the intracluster medium
从恒星和星系形成的第一阶段开始，非引力过程，如冲压压力剥离、超新星、星系风、活动星系核、星系-星系合并等。导致IGM中的恒星，金属以及尘埃的富集，通过星系物质喷射到IGM中。我们现在知道，这些过程与引力一起形成了结构的形成和演化。我们在这里提出的结构形成的流体动力学模拟实施的效果，由尘埃冷却大尺度结构的形成。我们关注星系团的尺度，研究星系团的统计性质。在这里，我们提出了我们的结果上的$T_X-M$和$L_X-M$标度关系，表现出的斜率和归一化的变化时，由尘埃冷却的标准辐射冷却模型。例如，对于包括尘埃冷却的模型，在$M=10^{14}$ M $_\odot$处，$T_X-M$关系的归一化仅改变最大2%，而在$T_X=1$ keV处，$L_X-T_X$的归一化改变多达10%。我们的研究表明，尘埃是一个额外的非引力过程，有助于塑造热ICM气体的物理状态。
