THE CORRELATION BETWEEN DISPERSION MEASURE AND X-RAY COLUMN DENSITY FROM RADIO PULSARS

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 sub(H) using 68 radio pulsars detected at X-ray...

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Bibliographic Details
Published in:The Astrophysical journal 2013-05, Vol.768 (1), p.1-8
Main Authors: HE, C, Ng, C-Y, Kaspi, V M
Format: Article
Language:English
Subjects:
ABSORPTION
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
DENSITY
DISPERSIONS
FORECASTING
HYDROGEN
Ionization
PROBES
PULSARS
Radio
SPECTRA
Texts
X RADIATION
X-rays
XMM (spacecraft)
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Summary: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 sub(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 N sub(H) (ProQuest: Formulae and/or non-USASCII text omitted) DM (pc cm super(-3)), which corresponds to an average ionization of (ProQuest: Formulae and/or non-USASCII text omitted), confirming the ratio of one free electron per 10 neutral hydrogen atoms commonly assumed in the literature. We also compare different N sub(H) estimates and note that some N sub(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 sub(H) predictions.
ISSN:0004-637X
1538-4357
DOI:10.1088/0004-637X/768/1/64