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arXiv 0709.3304astro-ph
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局部莱曼破裂星系类似物的HST形态I:合并触发的星爆证据

HST morphologies of local Lyman break galaxy analogs I: Evidence for starbursts triggered by merging

Roderik A. Overzier, Timothy M. Heckman, Guinevere Kauffmann, Mark Seibert, R. Michael Rich, Antara Basu-Zych, Jennifer Lotz, Alessandra Aloisi, Stephane Charlo… 展开作者

Roderik A. Overzier, Timothy M. Heckman, Guinevere Kauffmann, Mark Seibert, R. Michael Rich, Antara Basu-Zych, Jennifer Lotz, Alessandra Aloisi, Stephane Charlot, Charles Hoopes, D. Christopher Martin, David Schiminovich, Barry Madore

摘要:

Heckman等人(2005)利用星系演化探测器(GALEX)的紫外成像巡天显示,附近存在着一个罕见的紧凑紫外发光星系(UVLG),它们非常类似于高红移的莱曼破裂星系(LBG)。我们目前的HST图像中的UV,光学,和Ha,并reimulate他们的深度和分辨率的货物/UDF字段显示UVLG的形态也是类似的LBG。因此,我们的8个LBG类似物的样本提供了详细的洞察恒星形成和LBG形态之间的联系。在所有的静止帧光学图像中都可以看到微弱的潮汐特征或伴星,这表明星爆是合并或相互作用的结果。紫外光/可见光主要由未解析(~100 - 300 pc)的超级星爆区域(SSB)组成。与z = 0.02的Haro 11和VV 114星系的详细比较表明,SSB本身由漫射星和(超)星团组成。新的HST图像所揭示的结构特征发生在非常小的物理尺度上,因此在高红移LBG的图像中无法检测到,除非在少数情况下,它们被引力透镜放大。因此,我们认为LBG是由富含气体、质量相对较低(~10^10 Msun)的系统合并而成的,合并触发了SSB的形成。如果星系在高红移是由SSB主导的,那么光度函数的暗端斜率被预测为斜率α~2。我们的研究结果是迄今为止最直接的确认模型,该模型预测早期宇宙中恒星形成的主要模式是高度碰撞。

英文摘要:

Heckman et al. (2005) used the Galaxy Evolution Explorer (GALEX) UV imaging survey to show that there exists a rare population of nearby compact UV-luminous galaxies (UVLGs) that closely resembles high redshift Lyman break galaxies (LBGs). We present HST images in the UV, optical, and Ha, and resimulate them at the depth and resolution of the GOODS/UDF fields to show that the morphologies of UVLGs are also similar to those of LBGs. Our sample of 8 LBG analogs thus provides detailed insight into the connection between star formation and LBG morphology. Faint tidal features or companions can be seen in all of the rest-frame optical images, suggesting that the starbursts are the result of a merger or interaction. The UV/optical light is dominated by unresolved (~100-300 pc) super starburst regions (SSBs). A detailed comparison with the galaxies Haro 11 and VV 114 at z=0.02 indicates that the SSBs themselves consist of diffuse stars and (super) star clusters. The structural features revealed by the new HST images occur on very small physical scales and are thus not detectable in images of high redshift LBGs, except in a few cases where they are magnified by gravitational lensing. We propose, therefore, that LBGs are mergers of gas-rich, relatively low-mass (~10^10 Msun) systems, and that the mergers trigger the formation of SSBs. If galaxies at high redshifts are dominated by SSBs, then the faint end slope of the luminosity function is predicted to have slope alpha~2. Our results are the most direct confirmation to date of models that predict that the main mode of star formation in the early universe was highly collisional.

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