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tokens: strong enough, it will be difficult to detect them in low resolution spectra especially when the data is noisy. Unfortunately, the Ly β spectral region in most of our spectra has low SNR. This limits our ability to accurately measure the H i column density in individual systems. We, therefore, try to stack these spectra to increase the SNR. The higher SNR of the stacked spectrum would in principle allow us to determine the H i column density by fitting the damping wings of the Ly β absorption. If the majority of the systems have high H i column density, the damping wings of the Ly β absorption should be clearly and prominently visible in the stacked spectrum. In order to increase the chances of clearly detecting the damping wings of the Ly β absorption in the stacked spectrum, we carefully choose the quasar spectra that are used in the construction of the stacked spectrum using the following procedure. We first create a synthetic Ly β absorption line with H i column density of N (H i ) = 10 21 cm −2 and b -value of 100 km s −1 . We then exclude quasar spectra whose Ly β absorption are narrower than this synthetic absorption line. For example, in the lower panel (upper panel) of Figure 8 , we show two quasar spectra with their Ly β absorption being narrower (broader) than the synthetic one. This conservative approach ensures that only spectra of the absorbers with relatively higher H i column density and stronger damping wings contribute in the construction of the stacked spectrum. Applying this constraint on the S β sample leaves us with 21 spectra. We then median-stack these spectra following the method described in Paper I . Figure 8. Ly β spectral regions of four ghostly absorbers. In each panel, the red curve shows a synthetic Ly β absorption line with log N (H i ) = 21.0 and b -value of 100 km s −1 . The upper panels (lower panels) show Ly β absorption that are broader (resp. narrower) than the synthetic spectrum. Figure 9 shows the resulting stacked spectrum around the Ly α , Ly β , and Ly γ spectral regions. The Voigt profile fit for log N (H i ) = 21.5 and b -value of 50 km s −1 is overplotted on the observed spectrum as the red curve. This column density is 0.5 dex higher than the H i column density derived from the stacked spectrum of Paper I . As shown in Figure 9 , the damping wings (especially the red wing) of the Ly β absorption is clearly visible in the spectrum. This implies that the majority of the ghostly absorbers whose spectra are used in the stacked spectrum, are DLAs. Follow-up observation with higher resolution and SNR are needed to precisely measure the H i column density in the individual systems, and confirm which of them are indeed DLAs. Figure 9. Voigt profile fit (red curves), with log N (H i ) = 21.5 and b -value of 50 km s −1 , on the Ly β and Ly γ absorption lines in the stacked spectrum of the ghostly absorbers with strong Ly β absorption lines (see the text). The H i column density is constrained by the strong