南方基地知识库

光谱观测显示类星体SDSS J091613.60+292106.1 (简称J0916+2921,系统红移zem=1.1418±0.0018)中有特殊的2175?尘埃消光特征,其强度显著大于银河系平均强度.光谱同时探测到与尘埃成协的丰富气体吸收线,确定吸收线系统红移为zabs=1.1413±0.0002,和类星体红移一致.气态金属离子柱密度相对太阳丰度的比例为[Al/Zn]=-1.68±0.10,[Cr/Zn]=-0.49±0.10,[Fe/Zn]=-0.81±0.18.尘埃耗散作用显著,说明该系统中尘埃十分丰富,与观测的强尘埃消光特征吻合.类银河系的2175?尘埃消光特征在类星体光谱中多见于中间插入吸收线系统,至今未明确认证内禀吸收线系统出现该特征,类星体SDSS J0916+2921是目前仅有的数个候选者之一.该类星体X射线辐射相较一般类星体更强,后续可用作研究2175?尘埃在强高能射线照射条件下的形成与离解平衡,以揭示2175?尘埃的化学成分、物理性质和起源. 

We report a Milky–Way–like 2715 ˚A dust extinction feature observed toward the quasar SDSS J091613.60+292106.1 (J0916+2921) (system redshift zem = 1.1418 ± 0.0018) spectroscopically, whose strength is greater than the average Galactic value obviously. Plenty of metal absorption lines were detected at a redshift of zabs =1.1413 ± 0.0002, which is associated with the quasar emissions. The ratios of column densities of gaseous metal ions relative to Solar metallicities are [Al/Zn] = −1.68±0.10, [Cr/Zn] = −0.49±0.10, and [Fe/Zn] = −0.81±0.18, showing significant dust depletions. The pattern indicates that the absorber is heavily dusty, supporting the detection of 2175 ˚A dust extinction feature. The Milky–Way–like dust extinction was usually observed in the intervening quasar absorbers, but its existence in the quasar intrinsic absorbers has never been confirmed. The associated dusty absorber toward the quasar SDSS J0916+2921 is on of the several intrinsic 2175 ˚A absorber candidates. The X–ray radiation of the quasar is greater than the average value. This might provide a natural laboratory for further studying the equilibrium of formation and destruction of 2175 ˚A dust grains in the harsh radiation field, so that their chemical compositions, physical structures, and origins are revealed.