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arXiv 0905.3349astro-ph.CO
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11个Seyfert 2星系中心kpc的OASIS积分场谱

OASIS integral-field spectroscopy of the central kpc in 11 Seyfert 2 galaxies

Ivana Stoklasová, Pierre Ferruit, Eric Emsellem, Bruno Jungwiert, Emmanuel Pécontal, Sebastian F. Sánchez

摘要:

我们映射窄线区域(NLR)的11个附近的塞弗特2星系的光学积分场光谱仪OASIS安装在CFHT。我们模拟了5个禁线双峰和2个巴耳末线的发射线轮廓,通过合成演化恒星星族模型重建恒星光谱来校正潜在的恒星吸收。对于11个目标中的每一个,我们提出了在观测到的发射线,诊断线强度比,气体运动学(平均视线速度和速度色散),电子密度和星际红化的表面亮度的二维地图,我们绘制空间分辨光谱诊断图。恒星的数据表示的平均视线(LOS)速度和年轻的恒星星族的相对质量分数的地图。80%的样品中的气体速度场呈现扭曲的S形等速线,这是非圆轨道的特征,表明非轴对称的引力势,气体运动出银道面,或可能的流出和流入。根据运动学测量,我们确定了NGC 262(Mrk 348)中可能存在的核环或径向气体流。11个观测对象中有8个表现出强烈的不对称或多成分的发射线轮廓,在大多数情况下,局限于通过银河系中心的细长区域,垂直于发射主轴。

英文摘要:

We map narrow-line regions (NLRs) of 11 nearby Seyfert 2 galaxies with the optical integral-field spectrograph OASIS mounted at CFHT. We model emission-line profiles of 5 forbidden-line doublets and 2 Balmer lines, correcting for the underlying stellar absorption by reconstructing stellar spectra with synthetic evolutionary stellar population models. For each of the 11 targets, we present 2D maps of surface brightness in the observed emission lines, diagnostic line intensity ratios, gas kinematics (mean line-of-sight velocity and velocity dispersion), electron density, and interstellar reddening, and we plot spatially resolved spectral-diagnostic diagrams. The stellar data are represented by maps of mean line-of-sight (LOS) velocities and of the relative mass fractions of the young stellar populations. The gas velocity fields in 80% of the sample exhibit twisted S-shaped isovelocity contours, which are signatures of non-circular orbits and indicate non-axisymmetric gravitational potentials, gas motions out of the galactic plane, or possible outflows and inflows. Based on the kinematic measurements, we identified a possible nuclear ring or radial gas flow in NGC 262 (Mrk 348), not reported before. Eight of the eleven observed objects exhibit strongly asymmetric or multi-component emission-line profiles, in most cases confined to an elongated region passing through the galactic centre, perpendicular to the major axis of emission.

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