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Understanding the star formation efficiency in dense gas: Initial results from the CAFFEINE survey with ArTéMiS★
Astronomy & Astrophysics ( IF 5.4 ) Pub Date : 2024-08-20 , DOI: 10.1051/0004-6361/202449908
M. Mattern , Ph. André , A. Zavagno , D. Russeil , H. Roussel , N. Peretto , F. Schuller , Y. Shimajiri , J. Di Francesco , D. Arzoumanian , V. Revéret , C. De Breuck

Context. Despite recent progress, the question of what regulates the star formation efficiency (SFE) in galaxies remains one of the most debated problems in astrophysics. According to the dominant picture, star formation (SF) is regulated by turbulence and feedback, and the SFE is ~1–2% or less per local free-fall time on all scales from Galactic clouds to high-redshift galaxies. In an alternate scenario, the star formation rate (SFR) in galactic disks is linearly proportional to the mass of dense gas above some critical density threshold ~104 cm–3.Aims. We aim to discriminate between these two pictures thanks to high-resolution submillimeter and mid-infrared imaging observations, which trace both dense gas and young stellar objects (YSOs) for a comprehensive sample of 49 nearby massive SF complexes out to a distance of d ~ 3 kpc in the Galactic disk.Methods. We used data from CAFFEINE, a complete 350/450 µm survey with APEX/ArTéMiS of the densest portions of all southern molecular clouds at d ≲ 3 kpc, in combination with Herschel data to produce column density maps at a factor of ~4 higher resolution (8") than standard Herschel column density maps (36″). Our maps are free of any saturation effect around luminous high-mass pro-tostellar objects and resolve the structure of dense gas and the typical ~0.1 pc width of molecular filaments out to 3 kpc, which is the most important asset of the present study and is impossible to achieve with Herschel data alone. Coupled with SFR estimates derived from Spitzer mid-infrared observations of the YSO content of the same clouds, this allowed us to study the dependence of the SFE on density in the CAFFEINE clouds. We also combine our findings with existing SF efficiency measurements in nearby clouds to extend our analysis down to lower column densities.Results. Our results suggest that the SFE does not increase with density above the critical threshold and support a scenario in which the SFE in dense gas is approximately constant (independent of free-fall time). However, the SF efficiency measurements traced by Class I YSOs in nearby clouds are more inconclusive, since they are consistent with both the presence of a density threshold and a dependence on density above the threshold. Overall, we suggest that the SF efficiency in dense gas is primarily governed by the physics of filament fragmentation into protostellar cores.

中文翻译:


了解稠密气体中的恒星形成效率:ArTéMiS 咖啡因调查的初步结果★



语境。尽管最近取得了进展,但调节星系中恒星形成效率(SFE)的问题仍然是天体物理学中最具争议的问题之一。根据主要图像,恒星形成 (SF) 受到湍流和反馈的调节,从银河云到高红移星系的所有尺度上,每个局部自由落体时间的 SFE 约为 1-2% 或更少。在另一种情况下,星系盘中的恒星形成率 (SFR) 与高于某个临界密度阈值 ~104 cm–3 的致密气体质量成线性比例。我们的目标是通过高分辨率亚毫米和中红外成像观测来区分这两张图片,这些观测追踪致密气体和年轻恒星物体(YSO),以获取 d ~ 距离附近 49 个巨大 SF 复合体的综合样本。 3 kpc 在银河盘中。方法。我们使用来自 CAFFEINE 的数据,这是使用 APEX/ArTéMiS 对 d ≲ 3 kpc 处所有南方分子云最密集部分进行的完整 350/450 µm 调查,结合 Herschel 数据以约 4 倍的高分辨率生成柱密度图(8") 比标准赫歇尔柱密度图 (36")。我们的地图在发光的高质量原恒星物体周围没有任何饱和效应,并解析了致密气体的结构和分子丝的典型 ~0.1 pc 宽度到 3 kpc,这是本研究最重要的资产,仅靠赫歇尔数据是不可能实现的,再加上从斯皮策对同一云中 YSO 含量的中红外观测得出的恒星形成率估计,这使我们能够研究SFE 对咖啡因云密度的依赖性。 我们还将我们的发现与附近云中现有的 SF 效率测量相结合,将我们的分析扩展到较低的柱密度。结果。我们的结果表明,SFE 不会随着密度高于临界阈值而增加,并且支持稠密气体中的 SFE 近似恒定(与自由落体时间无关)的情况。然而,附近云中 I 类 YSO 追踪的 SF 效率测量结果更加不确定,因为它们与密度阈值的存在以及对阈值以上密度的依赖性一致。总体而言,我们认为致密气体中的超场效应效率主要受细丝分裂成原恒星核心的物理原理的影响。
更新日期:2024-08-21