论文标题
Z〜3的类星时候的光谱特征
Spectral Signatures of Quasar Ages at z~3
论文作者
论文摘要
可以从近端效应中获得对类星体年龄的见解，但到目前为止，只有有限数量的明亮类星体。基于2.5 <= z <= 3.5的〜2600 sdss quasar光谱，搜索ly-alpha森林线之间的光谱空隙可在较大的径向距离上找到接近区。大多数区域尺寸小于5 MPC，其数量降低了较大的距离。通过亮度归一化后，与预期值相比，区域大小分布为0.64。选择一组类星体，以> 〜10 mpc的较大接近区域。它们的复合频谱在LY-Alpha和其他主要的紫外线发射线中显示出强狭窄的核心和较大的等效宽度。如果视线沿线的接近区域表示类星体年龄，则这些特征可能是旧类星体的签名。选择了另一组类星体，因为它们没有显示邻近区域，并且在z_ {ab}> z_ {em}处显示了内在的吸收线。它们可能是年轻的类星体，并且表现出较弱的窄发射线组件。两组之间的光谱特征的显着差异可能反映了类星体寿命的演化模式。
Insight into quasar ages may be obtained from the proximity effect, but so far only in a limited number of bright quasars. Based on ~2600 SDSS quasar spectra at 2.5 <= z <= 3.5, a search for spectral voids between Ly-alpha forest lines finds proximity zones over a wide range of radial distances. The majority of zone sizes are less than 5 Mpc, with their numbers decreasing exponentialy towards larger distances. After normalization by luminosities, the zone sizes are distributed an e-folding scale of 0.64 as compared with the anticipated values. A group of quasars are selected for their large proximity zones of >~ 10 Mpc. Their composite spectrum displays strong narrow cores and large equivalent widths in Ly-alpha and other major UV emission lines. If the proximity zones along lines of sight are indicative of quasar ages, these features may be the signatures of old quasars. Another group of quasars are selected as they show no proximity zone and exhibit intrinsic absorption lines at z_{ab} > z_{em}. They are likely young quasars and exhibit weaker narrow emission-line components. The significant difference of spectral features between the two groups may reflect an evolution pattern over quasars' lifetimes.
