标题： LABOCA对小麦哲伦云西南部巨型分子云的观测 显示英文标题

标题： LABOCA observations of giant molecular clouds in the south west region of the Small Magellanic Cloud

摘要： 分子气体的量是理解星系未来恒星形成的关键。 由于H2在密集且寒冷的云团中难以直接观测，因此使用了像CO这样的示踪剂。 然而，在低金属丰度的情况下，CO只能追踪云团内部被屏蔽的部分。 毫米波尘埃辐射可以作为示踪剂来揭示总密集气体的质量。 来自小型麦哲伦云（SMC）西南区域的一组巨分子云（GMCs）样本中，从连续谱SIMBA 1.2 mm发射和引力质量推算的质量之间的比较显示了一个需要解释的差异。 本研究旨在更好地评估SMC中GMCs样本中观测到的尘埃发射可能存在的不确定性，并重点关注CO检测到的GMCs最密集的部分。 使用APEX望远镜上的LABOCA相机获得了新的观测数据。 所有之前在CO中观测到的GMCs都被检测到，并将其870微米的发射与辅助数据进行了比较。 估计了次毫米波发射的不同贡献以及尘埃性质，以便精确推断分子云的质量。 在SMC西南区域的GMCs中观察到的（亚）毫米波发射主要由尘埃发射主导，对于CO检测到的每个云的部分推算了质量，并与引力质量进行了比较。 使用LABOCA观测在870微米处确认了两种方法之间的质量差异：引力质量平均比从尘埃发射推断出的密集气体质量小四倍，这与我们在银河系中观测到的等效云的情况相反。 SMC中的这种质量差异的起源仍然未知。 对该效应的直接解释是，用于计算引力质量的CO线宽没有测量气体的完整速度分布。 还讨论了几何效应和尘埃性质的不确定性。 显示英文摘要

摘要： The amount of molecular gas is a key for understanding the future star formation in a galaxy. Because H2 is difficult to observe directly in dense and cold clouds, tracers like CO are used. However, at low metallicities especially, CO only traces the shielded interiors of the clouds. mm dust emission can be used as a tracer to unveil the total dense gas masses. The comparison of masses deduced from the continuum SIMBA 1.2 mm emission and virial masses in a sample of giant molecular clouds (GMCs), in the SW region of the Small Magellanic Cloud (SMC), showed a discrepancy that is in need of an explanation. This study aims at better assessing possible uncertainties on the dust emission observed in the sample of GMCs from the SMC and focuses on the densest parts of the GMCs where CO is detected. New observations were obtained with the LABOCA camera on the APEX telescope. All GMCs previously observed in CO are detected and their emission at 870microns is compared to ancillary data. The different contributions to the sub-mmm emission are estimated, as well as dust properties, in order to deduce molecular cloud masses precisely. The (sub-)mm emission observed in the GMCs in the SW region of the SMC is dominated by dust emission and masses are deduced for the part of each cloud where CO is detected and compared to the virial masses. The mass discrepancy between both methods is confirmed at 870microns with the LABOCA observations: the virial masses are on average 4 times smaller than the masses of dense gas deduced from dust emission, contrary to what is observed for equivalent clouds in our Galaxy. The origin of this mass discrepancy in the SMC remains unkown. The direct interpretation of this effect is that the CO linewidth used to compute virial masses do not measure the full velocity distribution of the gas. Geometrical effects and uncertainties on the dust properties are also discussed.