透镜模型和源重建揭示冷螺旋LIRG SGAS J143845 .1 $+$ 145407的形态和恒星形成分布
Lens Model and Source Reconstruction Reveal the Morphology and Star Formation Distribution in the Cool Spiral LIRG SGAS J143845.1$+$145407
摘要：
我们提出了$Hubble\ Space\ Telescope$（$HST$）成像和棱镜光谱的强透镜LIRG在$z=0.816$，SGAS 143845.1 $+$ 145407，并使用引力透镜放大率的提升，研究整个星系的恒星形成的分布。基于$HST$成像数据，我们建立了该系统的透镜模型，我们计算了$z=0.237$前景透镜的质量分布和放大率图。我们发现透镜星系的放大率介于$2$和$10$之间，总放大率（在源的所有图像上测量）为$μ=11.8^{+4.6}_{-2.4}$。我们发现最亮的星系团在$\sim34$ kpc内的总投影质量密度为$6.0^{+0.3}_{-0.7}\times10^{12}\,M_{\odot}$。使用透镜模型，我们创建了一个源重建SGAS 143845.1 $+$ 145407，这与一个微弱的检测H $α$的棱镜光谱配对，使我们能够最终直接评论在$z\sim1$ LIRG恒星形成的分布。我们在这个星系中发现了广泛的恒星形成，这与目前对这些物体的理解一致。然而，我们注意到在SGAS 143845.1 $+$ 145407的核中H $α$发射的缺陷，可能是由于尘埃消光。
英文摘要：
We present $Hubble\ Space\ Telescope$ ($HST$) imaging and grism spectroscopy of a strongly lensed LIRG at $z=0.816$, SGAS 143845.1$+$145407, and use the magnification boost of gravitational lensing to study the distribution of star formation throughout this galaxy. Based on the $HST$ imaging data, we create a lens model for this system; we compute the mass distribution and magnification map of the $z=0.237$ foreground lens. We find that the magnification of the lensed galaxy ranges between $2$ and $10$, with a total magnification (measured over all the images of the source) of $μ=11.8^{+4.6}_{-2.4}$. We find that the total projected mass density within $\sim34$ kpc of the brightest cluster galaxy is $6.0^{+0.3}_{-0.7}\times10^{12}\,M_{\odot}$. Using the lens model we create a source reconstruction for SGAS 143845.1$+$145407, which paired with a faint detection of H$α$ in the grism spectroscopy, allows us to finally comment directly on the distribution of star formation in a $z\sim1$ LIRG. We find widespread star formation across this galaxy, in agreement with the current understanding of these objects. However, we note a deficit of H$α$ emission in the nucleus of SGAS 143845.1$+$145407, likely due to dust extinction.
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