Finding and modelling gravitationally lensed quasars

寻找引力透镜类星体并对其进行建模

• 批准号: 1638336
• 金额: --
• 依托单位: University of Cambridge
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2015
• 资助国家: 英国
• 起止时间: 2015 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-1638336
• 关键词: Finding; modelling; gravitationally; lensed; quasars

Gravitationally lensed quasars are useful tools to probe cosmological parameters. However currently their contribution to making competitive constraints in cosmology is hindered by small number statistics. The proposed work would be to find many more of these systems in the Dark Energy Survey (DES) data and potentially other archived data. The systems can then be modelled and used to determine interesting cosmological and galactic astronomy. The effects of atmospheric distortion on deep astronomical images from ground-based telescopes, make classification of systems difficult. In particular large datasets must be reduced before identification of the many astronomical systems contained within them. In searching for gravitationally lensed quasars, in which you expect multiple blue quasar point sources around a red galaxy lens, it can be difficult to segment the separate parts of the image (during deblending). This means that other factors, such as their morphological structure and colours, must be considered to identify the relevant systems. Due to the large number of candidate systems identified, I will consider image invariants to help classify them, as more promising candidates are followed-up on a spectroscopic telescope.Another way to identify such systems is to look for an intrinsic variability. This is due to the variable nature of a quasar (an accreting supermassive black hole). This could be done with the DES data after more observing time. The light travel time for separate quasar images differs and hence introduces a time delay which can be measured because of the intrinsic quasar variability (matching two light curves by shifting in time and brightness). This introduces a correlation between the two light curves. Much deep data detecting these systems can be of low resolution such that the two (or more) quasar images and galaxy cannot be resolved. I will investigate how this blended lightcurve over many epochs can be used to extract relevant time delay information and also how it can be used as a candidate selection criterion for a lensed quasar. As lensed quasars are found, they can be fitted with galaxy and quasar light profiles which give accurate astrometry and photometry, which can then either be used to determine an expected time delay for the system, or if the time delay is known, parameters such as the present day Hubble constant or the dark energy equation of state may be constrained.These ideas lead on to many interesting identification techniques that can be developed. Furthermore many datasets can be probed, such as the upcoming GAIA data release.

引力透镜类星体是探测宇宙学参数的有用工具。然而，目前他们的贡献，使宇宙学中的竞争性限制是阻碍了少数统计。拟议的工作将是在暗能量调查（DES）数据和其他潜在的存档数据中找到更多的这些系统。然后，系统可以被建模并用于确定有趣的宇宙学和银河天文学。大气畸变对地面望远镜拍摄的深层天文图像的影响，使得系统分类变得困难。特别是大型数据集必须减少之前，许多天文系统包含在其中的识别。在寻找引力透镜类星体的过程中，你会发现红色星系透镜周围有多个蓝色的类星体点源，这可能很难分割图像的各个部分（在去混合过程中）。这意味着必须考虑其他因素，如其形态结构和颜色，以确定相关系统。由于已经确定了大量的候选系统，我将考虑图像不变量来帮助对它们进行分类，因为更多有希望的候选系统将在光谱望远镜上进行跟踪。这是由于类星体（一种吸积的超大质量黑洞）的可变性质。这可以在更多的观察时间后用DES数据来完成。不同类星体图像的光传播时间不同，因此引入了一个可以测量的时间延迟，因为类星体的内在可变性（通过时间和亮度的变化来匹配两个光变曲线）。这引入了两个光变曲线之间的相关性。许多探测这些系统的深层数据可能分辨率很低，以至于两个（或更多）类星体图像和星系无法分辨。我将研究如何在许多时期的混合光变曲线可以用来提取相关的时间延迟信息，以及它如何可以被用作一个透镜类星体的候选人选择标准。当透镜类星体被发现时，可以用星系和类星体的光分布拟合它们，从而得到精确的天体测量和光度测量，然后可以用来确定系统的预期时间延迟，或者如果时间延迟是已知的，可以限制诸如现在的哈勃常数或暗能量状态方程等参数。这些想法导致了许多有趣的识别技术可以发展。此外，许多数据集可以探测，例如即将发布的GAIA数据。

项目成果

VDES J2325-5229 a z=2.7 gravitationally lensed quasar discovered using morphology independent supervised machine learning

VDES J2325-5229 使用形态独立监督机器学习发现 z=2.7 引力透镜类星体

• DOI: 10.17863/cam.7974
• 发表时间: 2017
• 作者: Ostrovski F

Gravitationally lensed quasars in Gaia - II. Discoveryof 24 lensed quasars

盖亚 - II 中的引力透镜类星体。

• DOI: 10.17863/cam.27323
• 发表时间: 2018
• 作者: Lemon C

Models of the Strongly Lensed Quasar DES J0408-5354

• DOI: 10.1093/mnras/stx2242
• 发表时间: 2017-02
• 期刊: Monthly Notices of the Royal Astronomical Society
• 影响因子: 4.8
• 作者: A. Agnello;Huan Lin;L. Buckley-Geer;T. Treu;V. Bonvin;F. Courbin;C. Lemon;T. Morishita;A. Amara;M. Auger;S. Birrer;J. Chan;T. Collett;A. More;C. Fassnacht;J. Frieman;P. Marshall;R. McMahon;G. Meylan;S. Suyu;F.Castander;D. Finley;A.Howell;C. Kochanek;M. Makler;P. Martini;N. Morgan;B.Nord;F. Ostrovski;P. Schechter;D. Tucker;Risa Wechsler;T. Abbott;F. Abdalla;S. Allam;A. Benoit-Lévy;E. Bertin;D. Brooks;D. Burke;A. Rosell;M. Kind;J. Carretero;M. Crocce;C. Cunha;C. D'Andrea;L. Costa;S. Desa;J. Dietrich;T. Eifler;B. Flaugher;P. Fosalba;J. Garc'ia-Bellido;E. Gaztañaga;D. Goldstein;D. Gruen;R. Gruendl;J. Gschwend;G. Gutiérrez;K. Honscheid;D. James;K. Kuehn;N. Kuropatkin;T. Li;M. Lima;M. Maia;M. March;J. Marshall;Peter Melchior;F. Menanteau;R. Miquel;R. Ogando;A. Plazas;A. Romer;E. Sánchez;R. Schindler;M. Schubnell;I. Sevilla-Noarbe;M. Smith;R. C. Smith;F. Sobreira;E. Suchyta;M. Swanson;G. Tarlé;D. Thomas;A. Walker

A gravitationally lensed quasar discovered in OGLE

OGLE 中发现的引力透镜类星体

• DOI: 10.1093/mnras/sty259
• 发表时间: 2018
• 期刊: Monthly Notices of the Royal Astronomical Society
• 影响因子: 4.8
• 作者: Kostrzewa-Rutkowska Z

The discovery of a five-image lensed quasar at z = 3.34 using PanSTARRS1 and Gaia

使用 PanSTARRS1 和 Gaia 发现 z = 3.34 处的五图像透镜类星体

• DOI: 10.1093/mnrasl/slx173
• 发表时间: 2018
• 期刊: Letters
• 作者: Ostrovski F