The Correlation between Dispersion Measure and X-ray Column Density from Radio Pulsars
Mar 21, 2013Citations per year
Abstract: (IOP)
Pulsars are remarkable objects that emit across the entire electromagnetic spectrum, providing a powerful probe of the interstellar medium. In this study, we investigate the relation between dispersion measure (DM) and X-ray absorption column density N (H) using 68 radio pulsars detected at X-ray energies with the Chandra X-Ray Observatory or XMM-Newton. We find a best-fit empirical linear relation of NH(1020cm−2)=0.30−0.09+0.13DM(pccm−3), which corresponds to an average ionization of 10−3+4%, confirming the ratio of one free electron per 10 neutral hydrogen atoms commonly assumed in the literature. We also compare different N (H) estimates and note that some N (H) values obtained from X-ray observations are higher than the total Galactic H I column density along the same line of sight, while the optical extinction generally gives the best N (H) predictions.Note:
- 4 figures, accepted for publication in ApJ
- dust, extinction
- ISM: general
- pulsars: general
- X-rays: ISM
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