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arXiv 1104.2608astro-ph.CO
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Sloan Lens ACS调查。XI。超越哈勃分辨率:中等红移时致密透镜星系的大小,光度和恒星质量

The Sloan Lens ACS Survey. XI. Beyond Hubble resolution: size, luminosity and stellar mass of compact lensed galaxies at intermediate redshift

Elisabeth R. Newton, Philip J. Marshall, Tommaso Treu, Matthew W. Auger, Raphael Gavazzi, Adam S. Bolton, Leon V. E. Koopmans, Leonidas A. Moustakas

摘要:

我们利用强大的透镜效应,探索性质的内在暗淡和紧凑的星系在中等红移,在尽可能高的分辨率在光学波长。我们的样本由斯隆透镜ACS(SLACS)巡天发现的46个强透镜发射线星系组成。星系已经在高分辨率成像与HST在三个波段(V_HST,I_814和H_160),使我们能够推断它们的大小,光度和恒星质量使用恒星星族合成模型。镜头建模是使用一个新的快速和强大的代码,klens,我们广泛测试真实和合成的非透镜星系,也模拟星系多次成像SLACS类星系尺度透镜。我们的测试表明,我们的测量星系的大小,流量和Sersic指数是强大的和准确的,即使是对象本质上小于HST点扩散函数。中位放大率为8.8,有一条长尾巴延伸到40倍以上。SLACS源的建模揭示了一群星系的颜色和Sersic指数(中位数n ~ 1)与GEMS调查中HST现场检测到的物体一致,但(通常)约2个星等较暗,表观尺寸约小5倍。最接近的类似物是由HST棱镜巡天发现的超紧凑发射线星系。在我们的样本中,质量最低的星系与恒星质量(10^7太阳质量)最亮的银河系卫星相当,并且具有确定的半光半径0。“05(~0.3千秒差距)。

英文摘要:

We exploit the strong lensing effect to explore the properties of intrinsically faint and compact galaxies at intermediate redshift, at the highest possible resolution at optical wavelengths. Our sample consists of 46 strongly-lensed emission line galaxies discovered by the Sloan Lens ACS (SLACS) Survey. The galaxies have been imaged at high resolution with HST in three bands (V_HST, I_814 and H_160), allowing us to infer their size, luminosity, and stellar mass using stellar population synthesis models. Lens modeling is performed using a new fast and robust code, klens, which we test extensively on real and synthetic non-lensed galaxies, and also on simulated galaxies multiply-imaged by SLACS- like galaxy-scale lenses. Our tests show that our measurements of galaxy size, flux, and Sersic index are robust and accurate, even for objects intrinsically smaller than the HST point spread function. The median magnification is 8.8, with a long tail that extends to magnifications above 40. Modeling the SLACS sources reveals a population of galaxies with colors and Sersic indices (median n ~ 1) consistent with the objects detected in the field with HST in the GEMS survey, but that are (typically) ~ 2 magnitudes fainter and ~ 5 times smaller in apparent size. The closest analog are ultracompact emission line galaxies identified by HST grism surveys. The lowest mass galaxies in our sample are comparable to the brightest Milky Way satellites in stellar mass (10^7 solar masses) and have well-determined half light radii of 0."05 (~0.3 kpc).

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