COLDz: A High Space Density of Massive Dusty Starburst Galaxies ~1 Billion Years after the Big Bang
Dominik A. Riechers, Jacqueline A. Hodge, Riccardo Pavesi, Emanuele Daddi, Roberto Decarli, Rob J. Ivison, Chelsea E. Sharon, Ian Smail, Fabian Walter, Manuel A… 展开作者
Dominik A. Riechers, Jacqueline A. Hodge, Riccardo Pavesi, Emanuele Daddi, Roberto Decarli, Rob J. Ivison, Chelsea E. Sharon, Ian Smail, Fabian Walter, Manuel Aravena, Peter L. Capak, Christopher L. Carilli, Pierre Cox, Elisabete da Cunha, Helmut Dannerbauer, Mark Dickinson, Roberto Neri, Jeff Wagg
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30 pages, 15 figures, 8 tables, to appear in ApJ (accepted April 21, 2020) [v2: fixed one latex issue and a few typos, no content changes]
We report the detection of CO($J$=2$\to$1) emission from three massive dusty starburst galaxies at $z$$>$5 through molecular line scans in the NSF's Karl G. Jansky Very Large Array (VLA) CO Luminosity Density at High Redshift (COLDz) survey. Redshifts for two of the sources, HDF 850.1 ($z$=5.183) and AzTEC-3 ($z$=5.298), were previously known. We revise a previous redshift estimate for the third source GN10 ($z$=5.303), which we have independently confirmed through detections of CO $J$=1$\to$0, 5$\to$4, 6$\to$5, and [CII] 158 $μ$m emission with the VLA and the NOrthern Extended Milllimeter Array (NOEMA). We find that two currently independently confirmed CO sources in COLDz are "optically dark", and that three of them are dust-obscured galaxies at $z$$>$5. Given our survey area of $\sim$60 arcmin$^2$, our results appear to imply a $\sim$6-55 times higher space density of such distant dusty systems within the first billion years after the Big Bang than previously thought. At least two of these $z$$>$5 galaxies show star-formation rate surface densities consistent with so-called "maximum" starbursts, but we find significant differences in CO excitation between them. This result may suggest that different fractions of the massive gas reservoirs are located in the dense, star-forming nuclear regions - consistent with the more extended sizes of the [CII] emission compared to the dust continuum and higher [CII]-to-far-infrared luminosity ratios in those galaxies with lower gas excitation. We thus find substantial variations in the conditions for star formation between $z$$>$5 dusty starbursts, which typically have dust temperatures $\sim$57%$\pm$25% warmer than starbursts at $z$=2-3 due to their enhanced star formation activity.
The CO Luminosity Density at High-z (COLDz) Survey: A Sensitive, Large Area Blind Search for Low-J CO Emission from Cold Gas in the Early Universe with the Karl G. Jansky Very Large Array
ALMA Imaging of Gas and Dust in a Galaxy Protocluster at Redshift 5.3: [CII] Emission in "Typical" Galaxies and Dusty Starbursts ~1 Billion Years after the Big Bang
Upper limit on HF(1-0) absorption in a dusty star-forming galaxy at $z = 6$: Constraints on early fluorine enrichment
Institute of Astronomy, Graduate School of Science, The University of Tokyo（东京大学理学研究科天体物理学研究所）；Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo Institutes for Advanced Study, The University of Tokyo（东京大学前沿研究院宇宙物理与数学研究所（WPI）卡弗里研究所）；Centre for Astrophysics Research, Department of Physics, Astronomy and Mathematics, University of Hertfordshire（赫特福德大学物理、天文与数学系天体物理学研究中心）；Research Center for the Early Universe, Graduate School of Science, The University of Tokyo（东京大学理学研究科早期宇宙研究中心）；Faculty of Engineering, Hokkai-Gakuen University（北海道学园大学工学部）；Research Center for Physics and Mathematics, Osaka Electro-Communication University（大阪电通大学理数研究中心）；Institute for Advanced Research, Nagoya University（名古屋大学高等研究院）
REMAP: Determination of the inner edge of the dust torus in AGN by measuring time delays
活动星系核（AGN）是由位于星系中心的SMBH吸积物质提供动力的高光度源。SMBH周围是一个广泛的发射线区（BLR）和尘埃环面。由于活动星系核的中心区域无法用现有的任何常规成像技术分辨，因此很难研究尘埃环的范围。虽然目前的红外干涉技术在原理上可以分辨出活动星系核附近的环面，但是它非常昂贵，并且仅限于少数明亮的活动星系核。一个更可行的替代干涉测量技术来确定活动星系核中尘埃环的范围是混响映射（RM）技术。REMAP（Reverberation Mapping of AGN Program）是一个长期的光度监测计划，由印度班加罗尔的IIA运行，目的是利用RM技术测量许多活动星系核的环面尺寸。它涉及在光学和近红外波段中积累适当长且采样良好的光变曲线，以测量不同波段中光变曲线之间的时间延迟。这些延迟被用来确定尘埃环内边缘的半径。REMAP于2016年启动，从那时起，HCT每五天（天气允许）分配一次约一小时的观测时间。我们为该计划精心选择的初始样本包括使用HCT可观察到的总共8个源。REMAP的结果是确定了一个活动星系核H0507+164的尘埃环内缘的范围。第二个源的数据积累已经完成，第三个源的观测正在进行中。我们将概述该观测计划的动机，遵循的观测策略，这项工作所采用的分析程序以及迄今为止从该计划获得的结果。
Taking Census of Massive, Star-Forming Galaxies formed <1 Gyr After the Big Bang
20年的努力已经投入到单碟和干涉毫米波巡天中，以推断宇宙时间内尘埃恒星形成星系（DSFG，SFR> 100 M $_\odot$ yr $^{-1}$）的体积密度。虽然遮蔽星系在$z\sim2$的宇宙恒星形成高峰附近占主导地位，但这种严重遮蔽的星系对宇宙恒星形成的贡献在$z\sim2.5$之外是未知的，这与通过深空和地基近红外笔形光束调查研究的莱曼破裂星系（LBG）的人口形成鲜明对比。解开$z>3$以外的DSFG的体积密度，特别是在大爆炸后的第一个1 Gyr内，对于解决有关早期宇宙星系形成的关键开放问题至关重要：（1）在最初几个Gyr中，宇宙的综合恒星形成率密度是多少？（例如莱曼破裂星系）和大质量星系（例如DSFG和类星体宿主星系）？(2)第一个大质量星系是如何以及在哪里聚集的？(3)关于大爆炸后<1 Gyr的尘埃产生机制（例如超新星、AGB星、ISM中的晶粒生长），最极端的DSFG能告诉我们什么？我们总结了未来十年解决这些问题所需的观测类型。
A Census of the 200 Most Massive Galaxies Spectroscopically Observed with JWST at zspec $\sim$3-15
University of Geneva（日内瓦大学）；Cosmic Dawn Center (DAWN)（黎明宇宙中心）；Niels Bohr Institute, University of Copenhagen（哥本哈根大学尼尔斯·玻尔研究所）；University of Sussex（萨塞克斯大学）；Université Paris-Saclay（巴黎萨克雷大学）；Université Paris Cité（巴黎西岱大学）；CEA（法国原子能和替代能源委员会）；CNRS（法国国家科学研究中心）
The Diversity of Metal-Enrichment and Abundance Patterns at High Redshift: A Magellan Survey of Gas-rich Galaxies Traced by Damped Lyman-alpha Absorbers at z~5
本研究通过 Magellan 巡天分析10个 z≈4.2–5.0 的 DLA 元素丰度，揭示高红移金属丰度的显著离散、C/α元素增丰及 Pop III 贡献，并证实早期富金属多尘埃系统的存在。
