Hamilton’s Object – a clumpy galaxy straddling the gravitational caustic of a galaxy cluster: constraints on dark matter clumping
Hamilton’s Object – a clumpy galaxy straddling the gravitational caustic of a galaxy cluster: constraints on dark matter clumping
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DOI：
10.1093/mnras/stab1375
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发表时间：
2021-05
期刊：
影响因子：
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通讯作者：
R. Griffiths;Mitchell Rudisel;J. Wagner;T. Hamilton;Po-Chieh Huang;C. Villforth
中科院分区：
文献类型：
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作者：
R. Griffiths;Mitchell Rudisel;J. Wagner;T. Hamilton;Po-Chieh Huang;C. Villforth
我们报告了在 AGN SDSS J223010.47-081017.8（红移 0.62）附近区域的 HST 图像中发现的“折叠”引力透镜图像“汉密尔顿天体”。透镜图像源自一个光谱红移为 0.8200±0.0005 的星系，并在相应的 Pan-STARRS PS1 图像中看到的光度红移为 0.526±0.018 的前景星系团引起的焦散上形成折叠结构，并被微弱地检测为微弱的 ROSAT 全天巡天 X 射线源。透镜图像表现出与其他“折叠”类似的特性，其中源星系非常接近或横跨星系团的焦散线。折叠图像沿大致正交于临界曲线的方向拉伸，但其配置是切向尖点的配置。在形态特征、已发表的模拟和文献中类似的“折叠”观察的指导下，我们确定了第三个或“反”图像，并通过光谱学证实。由于折叠结构显示出高度独特的表面亮度特征，因此对微透镜的后续观察或以更高分辨率对各个表面亮度特征进行详细研究可以进一步揭示 kpc 尺度的暗物质特性。我们根据 Wagner 等人基于观察的镜头重建确定了多个图像位置处的局部镜头属性。 （2019）。该分析是根据质量密度进行的，该质量密度在多个倍数覆盖的区域上在弧秒尺度 (6 kpc) 上几乎没有变化
We report the discovery of a ‘folded’ gravitationally lensed image, ’Hamilton’s Object’, found in a HST image of the field near the AGN SDSS J223010.47-081017.8 (which has redshift 0.62). The lensed images are sourced by a galaxy at a spectroscopic redshift of 0.8200±0.0005 and form a fold configuration on a caustic caused by a foreground galaxy cluster at a photometric redshift of 0.526±0.018 seen in the corresponding Pan-STARRS PS1 image and marginally detected as a faint ROSAT All-Sky Survey X-ray source. The lensed images exhibit properties similar to those of other ‘folds’ where the source galaxy falls very close to or straddles the caustic of a galaxy cluster. The folded images are stretched in a direction roughly orthogonal to the critical curve, but the configuration is that of a tangential cusp. Guided by morphological features, published simulations and similar ‘fold’ observations in the literature, we identify a third or ’counter’-image, confirmed by spectroscopy. Because the fold-configuration shows highly distinctive surface brightness features, follow-up observations of microlensing or detailed investigations of the individual surface brightness features at higher resolution can further shed light on kpc-scale dark matter properties. We determine the local lens properties at the positions of the multiple images according to the observation-based lens reconstruction of Wagner et al. (2019). The analysis is in accordance with a mass density which hardly varies on an arc-second scale (6 kpc) over the areas covered by the multiple