Oxygen, neon, and iron X-ray absorption in the local interstellar medium

¹ Max-Planck-Institut für Astrophysik, 85741 Garching bei München, Germany
e-mail: egatuzz@mpa-garching.mpg.de
² Escuela de Física, Facultad de Ciencias, Universidad Central de Venezuela, PO Box 20632, 1020A Caracas, Venezuela
³ Centro de Física, Instituto Venezolano de Investigaciones Científicas (IVIC), PO Box 20632, 1020A Caracas, Venezuela
⁴ Harvard-Smithsonian Center for Astrophysics, Cambridge, MA, 02138, USA
⁵ NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA

Received: 16 November 2015
Accepted: 15 February 2016

Abstract

Aims. We present a detailed study of X-ray absorption in the local interstellar medium by analyzing the X-ray spectra of 24 galactic sources obtained with the Chandra High Energy Transmission Grating Spectrometer and the XMM-Newton Reflection Grating Spectrometer.

Methods. By modeling the continuum with a simple broken power-law and by implementing the new ISMabs X-ray absorption model, we have estimated the total H, O, Ne, and Fe column densities towards the observed sources.

Results. We have determined the absorbing material distribution as a function of source distance and galactic latitude–longitude.

Conclusions. Direct estimates of the fractions of neutrally, singly, and doubly ionized species of O, Ne, and Fe reveal the dominance of the cold component, thus indicating an overall low degree of ionization. Our results are expected to be sensitive to the model used to describe the continuum in all sources.