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arXiv 1010.3550astro-ph.CO
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局部高质量LIRG中的活动盘建造:气体、尘埃和恒星形成之间的协同作用

Active Disk Building in a local HI-Massive LIRG: The Synergy between Gas, Dust, and Star Formation

M. E. Cluver, T. H. Jarrett, R. C. Kraan-Korteweg, B. S. Koribalski, P. N. Appleton, J. Melbourne, B. Emonts, P. A. Woudt

摘要:

HIZOA J 0836 -43是HIPASS体积中发现的质量最大的HI星系(M_HI = 7.5x10^10 Msun),在光学上隐藏在银河系后面。与本星系中其他的极端HI盘有着显著的不同,它是一个亮红外星系(LIRG),有一个活跃的恒星形成盘(>50 kpc),位于其~ 130 kpc气体盘的中心,总恒星形成速率(SFR)为~20.5 Msun yr^{-1}。斯皮策光谱揭示了一个不寻常的组合,强大的多环芳烃(PAH)的排放耦合到一个相对较弱的温暖的尘埃连续,这表明光解区(PDR)为主的排放。与具有相似总红外光度(L_TIR=10^11 Lsun)的典型LIRG相比,HIZOA J 0836 -43中的多环芳烃强两倍以上,而温暖的尘埃连续体(λ> 20微米)最适合L_TIR=10^10 Lsun的恒星形成星系。Mopra CO的观测结果表明,该星系有一个扩展的分子气体成分(H_2 + He > 3.7x10^9 Msun),气体质量分数的下限约为64%;这高于本地盘系统的平均值,但与z约为1.5 BzK的星系(约为57%)相似。然而,HIZOA J 0836 -43的恒星形成效率(SFE = L_IR/L '_CO)为140 Lsun(K km s^{-1} pc^2)^{-1},与高红移的本地螺旋星系和其他盘状星系相似,与合并和强相互作用系统的SFE增加形成强烈对比。HIZOA J 0836 -43正在积极地形成恒星,并建造一个巨大的恒星盘。与更遥远的系统相比,它的恒星形成演化阶段(M_stellar,SFR,气体分数)表明它在红移z~1处被认为是典型的。这个星系提供了一个难得的机会,在附近的宇宙研究(在z~0.036)如何磁盘建设和星系演变在z~1,当类似的大气体分数可能更常见。

英文摘要:

HIZOA J0836-43 is the most HI-massive (M_HI = 7.5x10^10 Msun) galaxy detected in the HIPASS volume and lies optically hidden behind the Milky Way. Markedly different from other extreme HI disks in the local universe, it is a luminous infrared galaxy (LIRG) with an actively star forming disk (>50 kpc), central to its ~ 130 kpc gas disk, with a total star formation rate (SFR) of ~20.5 Msun yr^{-1}. Spitzer spectroscopy reveals an unusual combination of powerful polycyclic aromatic hydrocarbon (PAH) emission coupled to a relatively weak warm dust continuum, suggesting photodissociation region (PDR)-dominated emission. Compared to a typical LIRG with similar total infrared luminosity (L_TIR=10^11 Lsun), the PAHs in HIZOA J0836-43 are more than twice as strong, whereas the warm dust continuum (lambda > 20micron) is best fit by a star forming galaxy with L_TIR=10^10 Lsun. Mopra CO observations suggest an extended molecular gas component (H_2 + He > 3.7x10^9 Msun) and a lower limit of ~ 64% for the gas mass fraction; this is above average compared to local disk systems, but similar to that of z~1.5 BzK galaxies (~57%). However, the star formation efficiency (SFE = L_IR/L'_CO) for HIZOA J0836-43 of 140 Lsun (K km s^{-1} pc^2)^{-1} is similar to that of local spirals and other disk galaxies at high redshift, in strong contrast to the increased SFE seen in merging and strongly interacting systems. HIZOA J0836-43 is actively forming stars and building a massive stellar disk. Its evolutionary phase of star formation (M_stellar, SFR, gas fraction) compared to more distant systems suggests that it would be considered typical at redshift z~1. This galaxy provides a rare opportunity in the nearby universe for studying (at z~0.036) how disks were building and galaxies evolving at z~1, when similarly large gas fractions were likely more common.

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