Comprehensive Search for BAL Velocity Shifts in Quasars with Multi-Epoch SDSS Observations

However, the scarcity of measured cases of BAL velocity shifts still limits further research. To gain a deeper understanding of outflowing absorption line velocity shifts, it is essential to search for more observed cases. This study aims to comprehensively search for BAL velocity shifts from quasars with multi-epoch observations by the Sloan Digital Sky Survey (SDSS) and conduct in-depth research on the physical mechanism behind the BAL velocity shift.

This article is structured as follows: Section 2 provides details on the sample selection and outlines the methods used for spectral analysis, identification of BALs, and measurement of relevant properties. Section 3 presents the detected BALs in the 25 quasar sample, one by one. Section 4 presents our statistical analysis results and discusses possible causes of the EW variability and velocity shifts of the BALs in our sample. Section 5 concludes our work.