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arXiv 1002.4991astro-ph.CO
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QSO:SDSS J0013 +1523在z = 0.120时的强引力透镜现象

First case of strong gravitational lensing by a QSO : SDSS J0013+1523 at z = 0.120

F. Courbin, M. Tewes, S. G. Djorgovski, D. Sluse, A. Mahabal, F. Rerat, G. Meylan

摘要:

本文报道了第一个类星体SDSS J 0013 +1523(z = 0.120)的强引力透镜现象。这一发现是在SDSS数据第7版的22298个光谱中系统搜索类星体后面红移的发射线的结果。除了前景类星体的z = 0.120光谱特征外,SDSS J 0013 +1523的光谱还显示了OII和H β发射线以及OIII双重线,它们都在相同的红移z = 0.640。使用尖锐的凯克自适应光学K波段图像获得的激光导星,我们揭示了两个对象的半径为2角秒的类星体。深凯克光谱学清楚地证实了其中一个物体在z = 0.640处,并显示了第二个物体的OIII发射线的痕迹,也是在z = 0.640处。透镜模型表明,它们代表了同一个z = 0.640发射线星系的两个图像。我们的凯克光谱也使我们能够测量一个位于z = 0.394的中间星系的红移,该星系位于距离类星体视线3.2角秒的地方。若将z = 0.120的类星体宿主星系模拟为奇异等温球,则其在爱因斯坦半径内的质量为M_E(r < 1 kpc)= 2.16e 10 M_Sun,速度色散为sigma_SIS = 169 km/s。这与根据类星体Hbeta发射线的宽度估算的速度色散σ_*(M_BH)= 124 +/- 47 km/s相差约1 σ。深度光学HST成像将是必要的,以限制总的径向质量档案的类星体宿主星系使用的详细形状的透镜源。这是类星体作为强透镜作用于更远天体的第一个案例,为类星体宿主星系的研究开辟了新的方向。

英文摘要:

We present the first case of strong gravitational lensing by a QSO : SDSS J0013+1523, at z = 0.120. The discovery is the result of a systematic search for emission lines redshifted behind QSOs, among 22298 spectra of the SDSS data release 7. Apart from the z = 0.120 spectral features of the foreground QSO, the spectrum of SDSS J0013+1523 also displays the OII and Hbeta emission lines and the OIII doublet, all at the same redshift, z = 0.640. Using sharp Keck adaptive optics K-band images obtained using laser guide stars, we unveil two objects within a radius of 2 arcsec from the QSO. Deep Keck optical spectroscopy clearly confirms one of these objects at z = 0.640 and shows traces of the OIII, emission line of the second object, also at z = 0.640. Lens modeling suggests that they represent two images of the same z = 0.640 emission-line galaxy. Our Keck spectra also allow us to measure the redshift of an intervening galaxy at z = 0.394, located 3.2 arcsec away from the line of sight to the QSO. If the z = 0.120 QSO host galaxy is modeled as a singular isothermal sphere, its mass within the Einstein radius is M_E(r < 1 kpc) = 2.16e10 M_Sun and its velocity dispersion is sigma_SIS = 169 km/s. This is about 1 sigma away from the velocity dispersion estimated from the width of the QSO Hbeta emission line, sigma_*(M_BH) = 124 +/- 47 km/s. Deep optical HST imaging will be necessary to constrain the total radial mass profile of the QSO host galaxy using the detailed shape of the lensed source. This first case of a QSO acting as a strong lens on a more distant object opens new directions in the study of QSO host galaxies.

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