Constraints on the optical polarization source in the luminous non-blazar quasar 3C 323.1 (PG 1545+210) from the photometric and polarimetric variability
Constraints on the optical polarization source in the luminous non-blazar quasar 3C 323.1 (PG 1545+210) from the photometric and polarimetric variability
复制标题
光度和偏振变化对发光非耀变类星体 3C 323.1 (PG 1545 210) 中光学偏振源的限制
DOI：
10.1093/mnras/stx080
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发表时间：
2017
影响因子：
4.8
通讯作者：
Mitsuru Kokubo
中科院分区：
文献类型：
--
作者：
中村伸;長尾遼;野口巧;Mitsuru Kokubo
我们研究了发光的1型非耀变体类星体3C 323.1（PG 1545+210）的光学光度和偏振变化。1996-1998年和2003年的两次光谱偏振测量结合2002年的aV波段成像偏振测量表明：（1）如文献所述，3C 323.1的偏振仅限于连续谱发射，即宽谱区的发射是非偏振的;（2）偏振通量谱表明在巴尔末连续谱和其它复合谱线的波长范围内存在时变的宽吸收特征;（3）偏振位置角（PA）在4-6年的时间尺度上有大约0.4 °的弱变率;波段总通量和偏振通量在1年的时间尺度上表现出高度相关的变化。考虑到上述的光度和偏振变化特性以及前人的研究结果，我们提出了3C 323.1中偏振源的几何模型，其中赤道吸收区和轴不对称的赤道电子散射区位于吸积盘和宽线区之间.散射/吸收区域可能归因于吸积盘风或耀斑盘表面，但需要对3C 323.1和其他具有连续限制偏振的类星体进行进一步的偏振监测观测，以探索这些区域的真正物理起源。
We examine the optical photometric and polarimetric variability of the luminous type 1 non-blazar quasar 3C 323.1 (PG 1545+210). Two optical spectropolarimetric measurements taken during the periods 1996–1998 and 2003 combined with aV-band imaging-polarimetric measurement taken in 2002 reveal that (1) as noted in the literature, the polarization of 3C 323.1 is confined only to the continuum emission, i.e. the emission from the broad-line region is unpolarized; (2) the polarized flux spectra show evidence of a time-variable broad absorption feature in the wavelength range of the Balmer continuum and other recombination lines; (3) weak variability in the polarization position angle (PA) of ∼4°over a time-scale of 4–6 yr is observed and (4) theV-band total flux and the polarized flux show highly correlated variability over a time-scale of 1 yr. Taking the above-mentioned photometric and polarimetric variability properties and the results from previous studies into consideration, we propose a geometrical model for the polarization source in 3C 323.1, in which an equatorial absorbing region and an axi-asymmetric equatorial electron-scattering region are assumed to be located between the accretion disc and the broad-line region. The scattering/absorbing regions can perhaps be attributed to the accretion disc wind or flared disc surface, but further polarimetric monitoring observations for 3C 323.1 and other quasars with continuum-confined polarization are needed to probe the true physical origins of these regions.