Damped and Sub-damped Lyman-alpha Absorbers: What Are They, and What Do They Tell Us About Galaxy Evolution?

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。库尔卡尼博士将通过观察更遥远的明亮类星体光谱中的吸收线来研究星系之间和新生星系周围的气体。 一般来说，在阻尼莱曼-α吸收器中的氘气已经在形成恒星。 如果这些吸收体代表年轻的星系，我们可以预期重元素的丰度会从较低的值上升到今天的太阳水平，因为垂死的恒星会将这些元素返回到气体中。 相反，大多数这样的气体云是贫金属的。 Kulkarni博士和她的合作者已经证明，密度稍低的“亚阻尼莱曼α超导体”确实会像预期的那样随着时间的推移变得更加富含金属。 这表明许多恒星形成活动发生在这些密度较低的云层中。 Kulkarni博士将对阻尼和亚阻尼莱曼α吸收器进行进一步研究。她将对更大的样品进行光谱分析，以阐明低金属含量和高金属含量系统之间的物理和化学差异。 利用双子座和凯克望远镜的自适应光学技术，她将在近红外波段获得它们恒星形成区域的深层图像。 与欧洲合作者，她将获得空间分辨光谱在甚大望远镜，以跟踪运动的气体电离的年轻恒星和检查梯度的气体属性。 利用麦哲伦望远镜对双星类星体和引力透镜类星体进行光谱学研究，将探测吸收气体的空间范围。 Kulkarni博士将继续在当地学校和组织进行外展讲座，并在校园天文台举行公众观察会议。 她在指导研究中代表性不足的群体的学生方面有着很好的记录，她将继续这样做。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).Dr Kulkarni will study the gas between galaxies and around nascent galaxies by observing its absorption lines in the spectra of more distant bright quasars. Generally, the densest gas, in the damped Lyman-alpha absorbers, is already forming stars. If these absorbers represented young galaxies, we would expect the abundance of heavy elements to rise from a low value towards roughly the solar levels at the present day, as dying stars return these elements to the gas. Instead, most such gas clouds are metal-poor. Dr Kulkarni and her collaborators have shown that 'sub-damped Lyman-alpha absorbers', of slightly lower density, do become more metal-rich over time as expected. This suggests that much star-forming activity happens in these less-dense clouds. Dr Kulkarni will conduct further studies of both damped and sub-damped Lyman-alpha absorbers. She will take spectra for a larger sample, to elucidate the physical and chemical differences between systems of low and high metal content. Using adaptive-optics techniques at the Gemini and Keck telescopes, she will obtain deep images of their star-forming regions in the near infrared. With European collaborators, she will obtain spatially resolved spectroscopy at the Very Large Telescope, to trace the motions of gas ionized by the young stars and examine gradients in gas properties. Spectroscopy of binary quasars and gravitationally lensed quasars with the Magellan telescopes will probe the spatial extent of the absorbing gas.A graduate student will be trained by participating in the research. Dr Kulkarni will continue her outreach talks at local schools and organizations, and public observing sessions at the campus observatory. She has a strong record of mentoring students from under-represented groups in research, which she will continue.