The WiggleZ Dark Energy Survey: Direct constraints on blue galaxy intrinsic alignments at intermediate redshifts
Rachel Mandelbaum, Chris Blake, Sarah Bridle, Filipe B. Abdalla, Sarah Brough, Matthew Colless, Warrick Couch, Scott Croom, Tamara Davis, Michael J. Drinkwater,… 展开作者
Rachel Mandelbaum, Chris Blake, Sarah Bridle, Filipe B. Abdalla, Sarah Brough, Matthew Colless, Warrick Couch, Scott Croom, Tamara Davis, Michael J. Drinkwater, Karl Forster, Karl Glazebrook, Ben Jelliffe, Russell J. Jurek, I-hui Li, Barry Madore, Chris Martin, Kevin Pimbblet, Gregory B. Poole, Michael Pracy, Rob Sharp, Emily Wisnioski, David Woods, Ted Wyder
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18 pages, 12 figures, accepted to MNRAS; v2 has correction to one author's name, NO other changes; v3 has minor changes in explanation and calculations, no significant difference in results or conclusions; v4 has an additional footnote about model interpretation, no changes to data/calculations/results
Correlations between the intrinsic shapes of galaxy pairs, and between the intrinsic shapes of galaxies and the large-scale density field, may be induced by tidal fields. These correlations, which have been detected at low redshifts (z<0.35) for bright red galaxies in the Sloan Digital Sky Survey (SDSS), and for which upper limits exist for blue galaxies at z~0.1, provide a window into galaxy formation and evolution, and are also an important contaminant for current and future weak lensing surveys. Measurements of these alignments at intermediate redshifts (z~0.6) that are more relevant for cosmic shear observations are very important for understanding the origin and redshift evolution of these alignments, and for minimising their impact on weak lensing measurements. We present the first such intermediate-redshift measurement for blue galaxies, using galaxy shape measurements from SDSS and spectroscopic redshifts from the WiggleZ Dark Energy Survey. Our null detection allows us to place upper limits on the contamination of weak lensing measurements by blue galaxy intrinsic alignments that, for the first time, do not require significant model-dependent extrapolation from the z~0.1 SDSS observations. Also, combining the SDSS and WiggleZ constraints gives us a long redshift baseline with which to constrain intrinsic alignment models and contamination of the cosmic shear power spectrum. Assuming that the alignments can be explained by linear alignment with the smoothed local density field, we find that a measurement of σ_8 in a blue-galaxy dominated, CFHTLS-like survey would be contaminated by at most +/-0.02 (95% confidence level, SDSS and WiggleZ) or +/-0.03 (WiggleZ alone) due to intrinsic alignments. [Abridged]
Velocity Evolution and the Intrinsic Color of Type Ia Supernovae
为了了解如何最好地利用Ia型超新星（SNe Ia）的观测来获得精确和准确的距离，我们研究了SNe Ia的光谱和它们的固有颜色之间的关系。使用样本的1630光谱的255 SNe，主要是根据数据从CfA超新星计划，我们研究如何速度的演变和线强度的Si II 6355和Ca II H&K是相关的B-V颜色在峰值亮度。我们发现Si II 6355和Ca II H&K的最大光速和Si II 6355的最大光赝等效宽度与本征色相关，本征色与Si II 6355的测量值呈线性关系。Ca II H&K与固有颜色没有线性关系，但低速SNe倾向于固有蓝色。组合光谱测量并不能改善固有颜色推断。高速度超新星Ia的内在颜色散射更大-即使在去除了与速度的线性趋势之后-表明低速度超新星Ia更像是“标准蜡笔”。“利用来自SN Ia光谱的信息有可能改善对河外距离的测量以及从中推断的宇宙学性质。
Defining the intrinsic AGN infrared spectral energy distribution and measuring its contribution to the infrared output of composite galaxies
我们使用红外光谱学和光度学来凭经验定义固有的热红外光谱能量分布（即，6-100 um SED）的典型活动星系核（即，2-10 keV亮度，Lx=10^{42}-10 ^{44}尔格/秒活动星系核）。平均而言，典型AGN的红外SED最好描述为40 μ m处的破幂律<40 um that falls steeply at >（即，在远红外波长处）。尽管在长波长的这种下降，至少有3的11个活动星系核在我们的样本中观察到的SED活动星系核占主导地位，即使在60微米，表明即使在远红外波长的活动星系核的贡献占可能的重要性。我们的研究结果还表明，随着X射线光度的增加，平均内在AGN 6-100 um SED变得更蓝，这一趋势在我们的样本中以及与更明亮的类星体的内在SED进行比较时都可以看到（即，Lx>10^{44}尔格/秒）。我们比较了我们的内在AGN SED与尘埃环面模型的预测，发现它们更接近于cloudies，而不是连续的，环面模型相匹配。接下来，我们使用我们的本征AGN SED来定义一组校正因子，以将单色红外或X射线光度转换为总的本征AGN红外（即，8-1000 μ m）亮度。最后，我们概述了一个程序，使用我们新定义的内在AGN红外SED，结合选择的宿主星系模板，以适应复合星系的红外测光和测量AGN的贡献，他们的总红外输出。我们验证我们的SED拟合过程的准确性，通过比较我们的结果，两…
Optical spectroscopy of SDSS J004054.65-0915268: three possible scenarios for the classification. A z \sim 5 BL Lacertae, blue FSRQ or a weak emission line quasar
First results on the cluster galaxy population from the Subaru Hyper Suprime-Cam survey. II. Faint end color-magnitude diagrams and radial profiles of red and blue galaxies at $0.1<z<1.1$
Intensity Mapping Cross-Correlations: Connecting the Largest Scales to Galaxy Evolution
中性氢强度测绘是一种新的观测工具，它可以有效地测绘宇宙在宽红移范围内的大尺度结构。强度图的功率谱包含了关于物质分布的宇宙学信息，并通过追踪不同红移星系的HI含量和HI成团的尺度依赖性来探测星系演化。强度图与星系巡天图的互相关是一种强有力的功率谱测量方法，它减少了由仪器效应和前景去除引起的系统性。我们使用应用于Millennium模拟的半分析星系形成模型SAGE（Croton et al. 2016）的变体来检查红移z=0.9处的互相关特征，以便根据星系的恒星形成历史来模拟星系的HI气体及其光学星等。我们确定了不同类型的星系的颜色，作为他们的恒星形成活动的代理确定的互相关功率的集群。我们发现，在较小的尺度k>0.2h/Mpc下，红色静止星系的互相关系数比蓝色恒星形成星系下降得更快。此外，我们创建了一个模拟目录的高度恒星形成的星系使用的选择函数来模仿WiggleZ调查，并使用它来预测现有的和未来的GBT和帕克斯望远镜的互相关测量。我们发现，高恒星形成星系的交叉功率在小尺度上显示出比任何其他星系类型更高的聚集性，这显着改变了尺度k>0.2h/Mpc的功率谱形状。我们表明，互相关系数是不可忽略的解释宇宙学交叉功率谱。另一方面，它包含有关光选星系的HI含量的信息。
The PAU Survey: Measuring intrinsic galaxy alignments in deep wide fields as a function of colour, luminosity, stellar mass and redshift
Institute of Space Sciences (ICE, CSIC)（空间科学研究所（西班牙高等科学研究理事会））；Institut d’Estudis Espacials de Catalunya (IEEC)（加泰罗尼亚空间研究学院）；Leiden Observatory, Leiden University（莱顿大学莱顿天文台）；University of Portsmouth（朴茨茅斯大学）；Ruhr University Bochum（波鸿鲁尔大学）
