Speaker：Xinnan Du (杜辛楠；PhD candidate, University of California, Los Angeles；天文系09级系友）

　　Title：The Kinematics of CIV in Star-forming Galaxies at z~1.2

　　Time：Sep. 29th (Tuesday), 10:00am

　　Place：Room 402, Astronomy Building

　　Abstract：We present the first statistical sample of rest-frame far-UV spectra of CIVλλ1548,1550 absorption measurements in star-forming galaxies at z ~1. One unique aspect of these spectra is that they trace the highly-ionized phase of circumgalactic gas flows. We also detect low-ionization features such as SiIIλ1527, FeIIλ1608, AlIIλ1670, NiII λλ1741,1751 and SiIIλ1808, and intermediate-ionization features of AlIIIλλ1854,1862. Our sample is drawn from the DEEP2 survey and spans the redshift range 1.01 ≤ z ≤ 1.35 ( = 1.25). By isolating the interstellar CIV absorption from the stellar P-Cygni wind profile we find that a marginally larger fraction (69%) of the CIV absorption shows blueshifted absorption, and CIV is more blueshifted (-71km/s median) than other near-UV FeII resonance absorption lines. At the same time, the CIV blueshift is comparable to that of MgIIλλ2796,2803. The larger blueshift of CIV absorption may be caused by either the faster motions of highly-ionized gas relative to gas traced by FeII, or else filling in on the red side from resonant CIV emission. We investigate how far-UV interstellar absorption kinematics correlate with other galaxy properties using stacked spectra. Both the blueshift and equivalent width of CIV increase with star formation rate (SFR), but neither varies significantly with stellar mass, luminosity, U-B color or specific SFR. Our results provide a quantitative understanding of the multi-phase structure and geometry of gas flows at z ~1.

欢迎各位老师、同学参加！

　　                                         南京大学天文与空间科学学院