Testing the Tremaine-Weinberg Method Applied to Integral-field Spectroscopic Data Using a Simulated Barred Galaxy
Yanfei Zou, Juntai Shen, Martin Bureau, Zhao-Yu Li
备注：
24 pages, 18 figures, accepted for publication in ApJ, Figure 15 is updated to show the practical optimal phi_{bar,obs} range (black box) when selecting samples for TW measurements; Minor changes to match the published version
Tremaine and Weinberg (TW) proposed a conceptually simple procedure relying on long-slit spectroscopy to measure the pattern speeds of bars ($Ω_{\rm p}$) in disk galaxies. Using a simulated galaxy, we investigate the potential biases and uncertainties of TW measurements using increasingly popular integral-field spectrographs (IFSs), for which multiple pseudo-slits (and thus independent measurements) can be constructed with a single observation. Most important, to establish the spatial coverage required and ensure the validity of the measurements, the inferred $Ω_{\rm p}$ must asymptotically converge as the (half-)length of each pseudo-slit used is increased. The requirement for our simulation is to reach $\approx1.3$ times the half-light radius, but this may vary from galaxy to galaxy. Only those slits located within the bar region yield accurate measurements. We confirm that the position angle of the disk is the dominant source of systematic error in TW $Ω_{\rm p}$ measurements, leading to under/overestimates of tens of percents for inaccuracies of even a few degrees. Recasting the data so that the data grid aligns with the disk major axis leads to slightly reduced uncertainties. Accurate measurements are obtained only for well-defined ranges of the bar angle (relative to the galaxy major axis) $ϕ_{\rm bar}$ and the inclination angle $i$, here $10\lesssimϕ_{\rm bar}\lesssim75^{\circ}$ and $105\lesssimϕ_{\rm bar}\lesssim170^{\circ}$ and $15\lesssim i\lesssim70^{\circ}$. The adopted (pseudo-)slit widths, spatial resolution, and (unless extremely aggressive) spatial binning of IFS data have no significant impact on the measurements. Our results thus provide useful guidelines for reliable and accurate direct $Ω_{\rm p}$ measurements with IFS observations.
The Local Tremaine-Weinberg Method for Galactic Pattern Speed: Theory and its Application to IllustrisTNG
National Astronomical Observatories Chinese Academy of Sciences（中国科学院国家天文台）；School of Astronomy and Space Science University of Chinese Academy of Sciences（中国科学院大学天文与空间科学学院）；Innovation Academy for Microsatellites Chinese Academy of Sciences（中国科学院微小卫星创新研究院）
MaNGA项目已经获得了数千个邻近星系的IFU数据，包括棒星系。利用IFU提供的二维光谱和运动学信息，我们可以测量棒星系的斑图速度，它决定了棒星系的动力学。我们应用Tremaine \& Weinberg提出的非参数方法估计了53个棒星系的条形图速度，这是迄今为止以这种方式研究的最大样本。我们的样本来自MaNGA第一次公开数据发布，作为SDSS Data Release 13的一部分，主要根据杆和盘之间的轴比和位置角差，而运动学数据来自后来的SDSS Data Release 14。我们已经使用了光度图像的光度位置角和恒星速度图的运动位置角来推导图案速度。结合三个独立的酒吧长度测量和圆速度从牛仔裤各向异性建模（JAM），我们还确定了无量纲比$\cal{R}$的共转半径的酒吧长度。我们发现，星系的位置角是主要的不确定性，在确定的酒吧模式的速度。运动学位置角比光度学位置角导致更少的超快棒，这可能是由于测量运动学位置角的方法。我们研究了$\cal{R}$值对星系性质的依赖性，例如JAM模型中的暗物质分数和恒星星族合成（SPS）中的恒星年龄和金属丰度。钢筋长度与钢筋强度之间存在正相关关系：钢筋越长，钢筋强度越高。然而，没有发现其他显著的相关性，这可能是由于推导$\cal{R}$值时的误差，或者是由于星系棒复杂的形成和减速过程。
Cluster-centric trends in bar size and pattern speed: the case of Abell 2199
Indian Institute of Astrophysics（印度天体物理研究所）；Pondicherry University（本地治里大学）；Nicolaus Copernicus Astronomical Center, Polish Academy of Sciences（波兰科学院尼古拉·哥白尼天文中心）
