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arXiv 1406.2872astro-ph.GAastro-ph.CO
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3C 220.3:射电星系对亚毫米星系的透镜作用

3C 220.3: a radio galaxy lensing a submillimeter galaxy

Martin Haas, Christian Leipski, Peter Barthel, Belinda J. Wilkes, Simona Vegetti, R. Shane Bussmann, S. P. Willner, Christian Westhues, Matthew L. N. Ashby, Rol… 展开作者

Martin Haas, Christian Leipski, Peter Barthel, Belinda J. Wilkes, Simona Vegetti, R. Shane Bussmann, S. P. Willner, Christian Westhues, Matthew L. N. Ashby, Rolf Chini, David L. Clements, Christopher D. Fassnacht, Assaf Horesh, Ulrich Klaas, Leon V. E. Koopmans, Joanna Kuraszkiewicz, David J. Lagattuta, Klaus Meisenheimer, Daniel Stern, Dominika Wylezalek

摘要:

赫歇尔空间天文台的测光和广泛的多波长跟踪显示,z=0.685的强大射电星系3C 220.3充当了z=2.221的背景亚毫米星系(SMG)的引力透镜。在1 mm的观测波长下,SMG被透镜化为三个不同的图像。在观测到的近红外线中,这些图像由半径为1.8”的圆弧连接,形成一个以射电星系为中心的爱因斯坦半环。在可见光下,只有电弧是明显的。3C 220.3是唯一一个已知的由强大的射电星系引起的星系尺度透镜效应的例子,该星系不位于星系团中,因此它提供了探测射电星系宿主的暗物质含量的可能性。透镜模型拒绝了单个透镜,但以射电星系宿主A和伴星B为中心的两个透镜,相隔1.5”,提供了与所有数据一致的拟合,并揭示了预测的第四和第五张图像的微弱候选者。该模型不需要一个扩展的共同暗物质晕,与我们的钱德拉图像上没有扩展的明亮X射线发射相一致。在爱因斯坦半径A(1.02”)和B(0.61”)内的投影暗物质分数约为0.4 +/- 0.3和0.55 +/- 0.3。在CASTLES、LSD和SL 2S样品中,A和B的质量与i波段光的比值M/L ~ 8 +/- 4 Msun/Lsun与射电宁静透镜星系的质量与i波段光的比值M/L ~ 8 +/- 4 Msun/Lsun相当。透镜SMG非常明亮,由于放大因子μ ~10,观察到f(250 μ m)= 440 mJy。SMG的光谱显示出明亮的窄CIV 154.9nm发射,揭示了SMG除了猛烈的星暴之外还有一个隐藏的类星体。多色图像重建的SMG表明双极形态的发射的紫外线(UV)光暗示锥,通过它的UV光逃脱尘埃笼罩的核。

英文摘要:

Herschel Space Observatory photometry and extensive multiwavelength followup have revealed that the powerful radio galaxy 3C 220.3 at z=0.685 acts as a gravitational lens for a background submillimeter galaxy (SMG) at z=2.221. At an observed wavelength of 1mm, the SMG is lensed into three distinct images. In the observed near infrared, these images are connected by an arc of 1.8" radius forming an Einstein half-ring centered near the radio galaxy. In visible light, only the arc is apparent. 3C 220.3 is the only known instance of strong galaxy-scale lensing by a powerful radio galaxy not located in a galaxy cluster and therefore it offers the potential to probe the dark matter content of the radio galaxy host. Lens modeling rejects a single lens, but two lenses centered on the radio galaxy host A and a companion B, separated by 1.5", provide a fit consistent with all data and reveal faint candidates for the predicted fourth and fifth images. The model does not require an extended common dark matter halo, consistent with the absence of extended bright X-ray emission on our Chandra image. The projected dark matter fractions within the Einstein radii of A (1.02") and B (0.61") are about 0.4 +/- 0.3 and 0.55 +/- 0.3. The mass to i-band light ratios of A and B, M/L ~ 8 +/- 4 Msun/Lsun, appear comparable to those of radio-quiet lensing galaxies at the same redshift in the CASTLES, LSD, and SL2S samples. The lensed SMG is extremely bright with observed f(250um) = 440mJy owing to a magnification factor mu~10. The SMG spectrum shows luminous, narrow CIV 154.9nm emission, revealing that the SMG houses a hidden quasar in addition to a violent starburst. Multicolor image reconstruction of the SMG indicates a bipolar morphology of the emitted ultraviolet (UV) light suggestive of cones through which UV light escapes a dust-enshrouded nucleus.

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