标题： 具有无法解释的极端速度偏移的宽线类星体：激波后外流？ 显示英文标题

标题： A broad-line quasar with unexplained extreme velocity offsets: post-shock outflow?

摘要： 类星体 SDSS 0956+5128 展现出三个具有明显偏移的发射速度组分：[O II]、[O III] 和 [Ne III] 窄线的系统速度红移为$z=0.7142$；宽 Mg II 线相对于窄线偏移了$-1200$km s$^{-1}$；宽 H$\alpha$、H$\beta$线位于$-4100$km s$^{-1}$。 我们展示了新的哈勃太空望远镜观测到的Lyman α$\alpha$和 C IV 发射线的光谱以及类星体的高分辨率图像。这些发射线的偏移量与巴耳末发射线的速度分量一致，并且光学和近红外波段的测光数据没有显示出宿主星系中近期合并或类星体位置异常的迹象。数据并未证实之前最有可能涉及类星体盘特殊取向和形态的假设（如黑洞反冲情景）的预测，也不支持吸积盘风的一致性。相反，根据累积证据，我们提出了一个新的情景，即宽线区处于由强激波引发的外流状态，其中超新星可能是产生激波抛射物的可能事件。 显示英文摘要

摘要： The quasar SDSS 0956+5128 exhibits three distinct velocity components with large offsets in emission: the systemic velocity of [O II], [O III] and [Ne III] narrow lines have redshift $z=0.7142$; broad Mg II line is shifted by $-1200$ km s$^{-1}$ with respect to the narrow lines; broad H$\alpha$, H$\beta$ lines are at $-4100$ km s$^{-1}$. We present new Hubble Space Telescope spectra of Ly$\alpha$ and C IV emission lines and high-resolution images of the quasar. The offsets of these lines are consistent with the velocity component of the Balmer emission, and the photometry in optical and near-infrared wavelengths does not show any signs of recent mergers in the host galaxy or irregularities in the location of the quasar. The data do not confirm predictions of the previous most-likely hypotheses involving a special orientation and morphology of the quasar disk, such as in the recoiling black hole scenario, neither it is consistent with accretion disk winds. Instead, based on the cumulative evidence, we propose a new scenario, in which the broad line region is in the state of outflow caused by a strong shock wave, with a supernova as a possible event for producing the shock ejecta.