The HI absorption line and anomalous dispersion in pulsar emission

Jiang, Jinchen

We use FAST baseband data to measure the HI emission and absorption lines around 1420 MHz for PSR B1937+21. We estimate the kinematic distance of PSR B1937+21 using Doppler shifted emission and absorption lines. We also measure the anomalous dispersion of the pulse profile around the absorption line， where the group velocity can be faster than the light speed.