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arXiv 0804.3589astro-ph
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确认正面B/P凸起的运动学诊断

Confirmation of a Kinematic Diagnostic for Face-On B/P Bulges

J. Mendez-Abreu, E. M. Corsini, Victor P. Debattista, S. De Rijcke, J. A. L. Aguerri, A. Pizzella, .

摘要:

本文报道了NGC 98、NGC 600和NGC 1703三个正面星系的高分辨吸收线光谱研究结果,目的是寻找盒状/花生状(B/P)星系核球。这些观察测试和确认,为第一次,预测,面对B/P形凸起可以识别的两个最小值的轮廓沿酒吧的主轴的第四高斯厄米特时刻h_4的视线速度分布(LOSVD)。在NGC 98中,h_4的一个明显的双极小值出现在棒的长轴上和棒的末端之前,正如预测的那样。相比之下,在NGC 600中,它也是一个棒星系,但缺乏实质性的凸起,我们没有发现任何明显的运动学特征的B/P形凸起。在NGC 1703中,这是一个无棒控制星系,我们没有发现B/P隆起的证据。我们还直接证明了NGC 98中h_4极小值处的LOSVD比其它地方的LOSVD宽。这种更直接的方法避免了与视线速度色散测量和h_4之间的简并相关的可能的伪影。

英文摘要:

We present the results of high resolution absorption-line spectroscopy of 3 face-on galaxies, NGC 98, NGC 600, and NGC 1703 with the aim of searching for box/peanut (B/P)-shaped bulges. These observations test and confirm, for the first, time the prediction that face-on B/P-shaped bulges can be recognized by two minima in the profile along the bar's major axis of the fourth Gauss-Hermite moment h_4 of the line-of-sight velocity distribution (LOSVD). In NGC 98, a clear double minimum in h_4 is present along the major axis of the bar and before the end of the bar, as predicted. In contrast, in NGC 600, which is also a barred galaxy but lacks a substantial bulge, we do not find any significant kinematic signature for a B/P-shaped bulge. In NGC 1703, which is an unbarred control galaxy, we found no evidence of a B/P bulge. We also show directly that the LOSVD is broader at the location of the h_4 minimum in NGC 98 than elsewhere. This more direct method avoids possible artifacts associated with the degeneracy between the measurement of line-of-sight velocity dispersion and h_4.

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