# Features of Structure and Absorption in the Jet-Launching Region of M87
## 3 Results
### Transverse Jet Structure  
In this part, we use intensity slices to extract details of the jet and to analyze the transverse jet structure evolving with core distance \(d\). To improve the angular resolution in the direction transverse to the jet with the least distortion of the images, in advance of slicing, we restored the images with circular Gaussian beams whose diameter equal to the geometric mean of the length of major and minor axis of their synthesized beams, which is 0.65, 0.36 and 0.17 mas for the image at 22, 43 and 86 GHz respectively. The restored images are shown as contours in the left panels of Figure 3. Then we slice the restored images in a direction perpendicular to the approximate overall jet axis, which is \(-67^{\circ}\) respect to the north (referred as \"jet axis\" hereafter). For the 22 GHz image, we made slices between \(d=2.00\) and 10.00 mas, at an interval of 0.05 mas; for the 43 GHz image, we made slices between \(d=0.10\) and 3.00 mas, at an interval of 0.05 mas; for the 86 GHz image, we made slices between \(d=0.10\) and 1.40 mas, at an interval of 0.01 mas. The right panels of Figure 3 present the sample slices, showing the intensity as a function of position angles referring to the jet axis (PAs, the northern limb is at positive values, while its southern counterpart is at negative values). Locations of these sample slices are presented as lines superimposed on the contours in the left panels of Figure 3. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Frequency** & **Flux Density \({}^{a}\)** & **Radius \({}^{b}\)** & **Theta \({}^{c}\)** & **Theta \({}^{c}\)** & **Major Axis \({}^{d}\)** & **Axial Ratio \({}^{e}\)** & **Phi \({}^{f}\)** & **Brightness Temperature \({}^{g}\)** \\
**(GHz)** & **(mJy)** & **(\(\mu\)as)** & **(deg)** & **(\(\mu\)as)** & **Axial Ratio \({}^{e}\)** & **(deg)** & **(10\({}^{10}\)K)** \\ \hline
22 & \(1605\pm 195\) & \(19.9\pm 2.1\) & \(-80.8\pm 6.1\) & 479.2 \(\pm\) 1.1 & 0.84 & 43.4 & 3.1 \\
43 & \(1016\pm 122\) & \(3.6\pm 0.4\) & \(-142.8\pm 5.8\) & 261.2 \(\pm\) 0.2 & 0.62 & 20.2 & 2.3 \\
86 & \(580\pm 58\) & \(3.6\pm 0.3\) & \(-44.7\pm 4.4\) & 73.0 \(\pm\) 0.2 & 0.52 & 31.8 & 5.0 \\ \hline \hline \end{tabular}  
* Notes: \({}^{a}\) Integral flux density of Gaussians. \({}^{b}\) Distance of Gaussians to the center of the images. \({}^{c}\) Position angle of Gaussians referring to the north. \({}^{d}\) Size of Major axis of Gaussians. \({}^{e}\) Axial ratio of Gaussians. \({}^{f}\) Position angle of major axis of Gaussians referring to the north. \({}^{g}\) Brightness temperature of Gaussians.  
\end{table} 
Table 2: Core Component. Figure 2: 86 GHz contour plot overlapping with pseudo-color image of the same frequency of M87; contours are from (\(-1\), 1, 2, 4, 8...) \(\times\) 0.60 mJy beam\({}^{-1}\). The synthesized beam of 0.24 \(\times\) 0.12 mas at a position angle of \(-17.7^{\circ}\) is shown at the top-left corner. Figure 3: The left panels shows the images restored with circular beams as contours. The restored beams are shown at the top-left corner of each panel. Locations of sample slices are presented as lines superimposed on the contours. The ridgeline is presented as red curves superimposed on the contour plots. The right panels present sample slices, showing the intensity as functions of position angles PAs referring to the jet axis. The northern limb is at positive values, while its southern counterpart is at negative values. The blue horizontal lines represent \(5\sigma\) of the restored images. In our intensity slices, at 43 and 86 GHz, the northern limb represents as a well defined hump since \(d\) = 0.65 and 0.50 mas respectively, while its southern counterpart since \(d\) = 0.45 and 0.24 mas respectively. The counter jet emission also seems bifurcated on the restored 43 GHz image, and a slice at \(d\) = 0.60 mas shows this bifurcated structure clearly (see the cyan line in the second row of Figure 3). We also recover the ridgeline of the limb-brightened jet in M87 with the intensity slices.