我们展示了对一个模拟分子云的合成谱线观测,采用了动力学与时间相关化学演化的自洽处理方法。我们研究了三种最常见的CO同位素分子($^{12}$CO、$^{13}$CO、C$^{18}$O)和六种被认为示踪致密气体的分子(NH$_3$、HCN、N$_2$H$^+$、HCO$^+$、CS、HNC)的谱线发射。我们的模拟产生了一系列与实际分子云中观测结果一致的谱线强度。HCN与CO的强度比随柱密度变化相对不敏感,这使得HCN(以及化学性质相似的物种如CS)成为云中高密度物质的较差示踪剂。另一方面,N$_2$H$^+$与HCN或CO的比值对柱密度高于$10^{22} \, {\ m cm^{-2}}$的区域具有高度选择性,并且N$_2$H$^+$谱线是高体积密度($>10^4 \, {\ m cm^{-3}}$)物质动力学的非常好的示踪剂。聚焦于模拟云中形成的核,我们发现其谱线强度与一个前恒星核观测样本的谱线强度吻合良好,包括在硫元素丰度未耗尽的条件下再现了观测到的CS谱线强度。然而,模拟中形成的核与具有其他方面可比性质的孤立核模型之间的一致性较差。来自大尺度环境的形成过程及其与环境的相互作用对核的谱线发射性质有显著影响,使得孤立模型不适合用于解释观测数据。
英文摘要:
We present synthetic line observations of a simulated molecular cloud, utilising a self-consistent treatment of the dynamics and time-dependent chemical evolution. We investigate line emission from the three most common CO isotopologues ($^{12}$CO, $^{13}$CO, C$^{18}$O) and six supposed tracers of dense gas (NH$_3$, HCN, N$_2$H$^+$, HCO$^+$, CS, HNC). Our simulation produces a range of line intensities consistent with that observed in real molecular clouds. The HCN-to-CO intensity ratio is relatively invariant with column density, making HCN (and chemically-similar species such as CS) a poor tracer of high-density material in the cloud. The ratio of N$_2$H$^+$ to HCN or CO, on the other hand, is highly selective of regions with densities above $10^{22} \, {\rm cm^{-2}}$, and the N$_2$H$^+$ line is a very good tracer of the dynamics of high volume density ($>10^4 \, {\rm cm^{-3}}$) material. Focusing on cores formed within the simulated cloud, we find good agreement with the line intensities of an observational sample of prestellar cores, including reproducing observed CS line intensities with an undepleted elemental abundance of sulphur. However, agreement between cores formed in the simulation, and models of isolated cores which have otherwise-comparable properties, is poor. The formation from and interaction with the large-scale environment has a significant impact on the line emission properties of the cores, making isolated models unsuitable for interpreting observational data.
NEATH V: the relationship between line emission from dense gas tracers and the star formation rate
Cardiff University(卡迪夫大学);Universität Heidelberg, Zentrum für Astronomie, Institut für Theoretische Astrophysik(海德堡大学天文学中心理论天体物理研究所);National Astronomical Observatory of Japan, National Institute of Natural Sciences(日本国立天文台 国立自然科学研究院);Universität Heidelberg, Interdisziplinäres Zentrum für Wissenschaftliches Rechnen(海德堡大学跨学科科学计算中心)
The Neutral Atomic Hydrogen in the solar neighborhood (NeAtHood) project I. Ghost in the shell: Neutral atomic hydrogen in the extended Orion nebula
University of Vienna(维也纳大学);Max-Planck Institute for Astronomy(马克斯·普朗克天文学研究所);Universität Heidelberg(海德堡大学);National Radio Astronomy Observatory(美国国家射电天文台);Deutsches Zentrum for Astrophysics(德国天体物理中心);Stanford University(斯坦福大学);Jet Propulsion Laboratory, California Institute of Technology(加州理工学院喷气推进实验室)
A comparison of UV and optical metallicities in star-forming galaxies
我们研究最早期星系中星际介质特性的能力将依赖于静止帧紫外(UV)波长的发射线诊断。在这项工作中,我们确定使用UV发射线的金属敏感的诊断。我们比较紫外衍生的金属丰度与标准的,完善的光学金属丰度使用一个样本的星系与休息帧紫外光谱和光学光谱。我们发现He 2-O3 C3诊断(He II 1640 / C III 1906,1909 vs. O III 1666 / C III 1906,1909)是一个可靠的金属丰度示踪剂,特别是在低金属丰度(12+log(O/H)< 8)时,恒星贡献最小。我们发现,Si 3-O3 C3诊断(Si III 1883 / C III 1906,1909 vs. O III 1666 / C III 1906,1909)是一个可靠的金属丰度示踪剂,虽然有大的散射(0.2-0.3 dex),我们认为这是由气相丰度的变化驱动。我们发现,C4-O3 C3诊断(C IV 1548,1550/ O III 1666 vs. O III 1666 / C III 1906,1909)与光学衍生金属丰度相关性较差。我们讨论了这些不一致的金属丰度测定,包括电离光谱的硬度,恒星风排放的贡献,和非太阳尺度的气相丰度可能的解释。最后,我们提供了两个新的UV氧丰度诊断,计算多项式拟合的模型网格表面的He 2-O3 C3和Si 3-O3 C3图。
Breathless BEARS: [O$_{\rm \,III}$] 88$μ$m Emission of Dusty Star-Forming Galaxies at $z = 3-4$
Chalmers University of Technology(查尔姆斯理工大学);Academia Sinica(中央研究院);Universität zu Köln(科隆大学);Max-Planck-Institut für Radioastronomie(马克斯·普朗克射电天文研究所);University of Manchester(曼彻斯特大学);Institut de Radioastronomie Millimétrique (IRAM)(毫米波射电天文学研究所);Universidad de Oviedo(奥维耶多大学);Instituto Universitario de Ciencias y Tecnologas Espaciales de Asturias (ICTEA)(阿斯图里亚斯空间科学与技术大学研究所);Sorbonne Université(索邦大学);CNRS(法国国家科学研究中心)
Blowing Star Formation Away in AGN Hosts (BAH) -- III. Serendipitous discovery of a $z\sim2.9$ star-forming galaxy lensed by the galactic bulge of CGCG 012-070 using JWST NIRSpec
Catching the Nebular Needle in a Polluted Haystack: Line-emission Signatures from Population III-forming Pockets around Massive Galaxies at the End of Reionization
University of Texas at Austin(德克萨斯大学奥斯汀分校);Cosmic Frontier Center, The University of Texas at Austin(德克萨斯大学奥斯汀分校宇宙前沿中心);Sapienza, Università di Roma(罗马第一大学);INFN, Sezione di Roma I(意大利国家核物理研究所罗马第一分部);INAF-Osservatorio Astronomico di Roma(意大利国家天体物理研究所罗马天文台);Weinberg Institute for Theoretical Physics, University of Texas at Austin(德克萨斯大学奥斯汀分校温伯格理论物理研究所)
PRUSSIC III -- ALMA and NOEMA survey of dense gas in high-redshift star-forming galaxies
Leiden University(莱顿大学);Delft University of Technology(代尔夫特理工大学);SRON - Netherlands Institute for Space Research(荷兰空间研究所);Universität zu Köln(科隆大学);European Southern Observatory (ESO)(欧洲南方天文台);Cosmic Dawn Center (DAWN)(宇宙黎明中心);Technical University of Denmark(丹麦技术大学);University College London(伦敦大学学院)
Herschel far-infrared photometry of the Swift Burst Alert Telescope active galactic nuclei sample of the local universe - III. Global star-forming properties and the lack of a connection to nuclear activity
A framework for modelling Population III stars in cosmological simulations
Max-Planck-Institut für Astronomie(马克斯·普朗克天文学研究所);Indian Institute of Science Education and Research - Kolkata(印度科学教育与研究学院-加尔各答分院);Universidad de Granada(格拉纳达大学);York University(约克大学)
MEGATRON: The environments of Population III stars at Cosmic Dawn and their connection to present day galaxies
University of Oxford(牛津大学);University of Chicago(芝加哥大学);Kavli Institute for Cosmological Physics, University of Chicago(芝加哥大学卡弗里宇宙物理学研究所);Institut d’Astrophysique de Paris, Sorbonne Université, CNRS(巴黎天体物理研究所,索邦大学,法国国家科学研究中心);University of Bath(巴斯大学);Lund University(隆德大学);Yonsei University(延世大学)
Relations of stellar mass between electron temperature-based metallicity of star-forming galaxies in a wide mass range
We select 947 star-forming galaxies from SDSS-DR7 with [O~{ \sc iii}] $λ$ 4363 emission lines detected at a signal-to-noise {ratio }larger than 5 $σ$ . Their electron temperatures and direct oxygen abundances are {then }determined. {W}e compare the results from different methods. $t_2$ {, the} electron temperature in {the }low ionization region{,} estimated from $t_3$ {, that} in {the }high ionization region{,} {is} compared {using} three analysis relations between $t_2-t_3$ {. These} show obvious differences, which result in some different ionic oxygen abundances. The results of $t_3$ , $t_2$…
A Multiwavelength Assessment Disfavoring the X-ray Binary Origin of He III Regions in Metal-Poor Star-Forming Dwarf Galaxies
University of Nevada, Reno(内华达大学雷诺分校);Nevada Center for Astrophysics(内华达天体物理中心);INAF - Osservatorio Astrofisico di Torino(意大利国家天体物理研究所都天文台);The University of Sydney(悉尼大学);Greenhill Observatory(格林希尔天文台);University of Michigan(密歇根大学);Université de Strasbourg(斯特拉斯堡大学);Catholic University of America(美国天主教大学)
The DESIRED electron temperature relations in star-forming regions of the local Universe
Instituto de Astrofísica de Canarias(加那利天体物理研究所);Universidad de La Laguna(拉帕尔马大学);Universidad Nacional Autónoma de México(墨西哥国立自治大学);University of Edinburgh(爱丁堡大学);Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas (CIEMAT)(能源、环境与技术研究中心);Instituto Nacional de Astrofísica, Óptica y Electrónica (INAOE-CONAHCyT)(国家天体物理学、光学和电子学研究所)
Illuminating the Dark Side of Cosmic Star Formation III: Building the largest homogeneous sample of Radio-Selected Dusty Star-Forming Galaxies in COSMOS with PhoEBO