The dust-scattering component of X-ray extinction: Effects on continuum fitting and high-resolution absorption edge structure

Corrales LR, Garcia J, Wilms J, Baganoff F (2016)

Publication Status: Published

Publication Type: Journal article, Original article

Publication year: 2016

Journal

Monthly Notices of the Royal Astronomical Society Oxford University Press

Publisher: Oxford University Press

Book Volume: 458

Pages Range: 1345-1351

Journal Issue: 2

DOI: 10.1093/mnras/stw376

Abstract

Small angle scattering by dust grains causes a significant contribution to the total interstellar extinction for any X-ray instrument with sub-arcminute resolution (Chandra, Swift, XMM-Newton). However, the dust-scattering component is not included in the current absorption models: phabs, TBabs, and TBnew. We simulate a large number of Chandra spectra to explore the bias in the spectral fit and N measurements obtained without including extinction from dust scattering. We find that without incorporating dust scattering, the measured N will be too large by a baseline level of 25 per cent. This effect is modulated by the imaging resolution of the telescope, because some amount of unresolved scattered light will be captured within the aperture used to extract point source information. In high-resolution spectroscopy, dust scattering significantly enhances the total extinction optical depth and the shape of the photoelectric absorption edges. We focus in particular on the Fe-L edge at 0.7 keV, showing that the total extinction template fits well to the high-resolution spectrum of three X-ray binaries from the Chandra archive: GX 9+9, XTE J1817-330, and Cyg X-1. In cases where dust is intrinsic to the source, a covering factor based on the angular extent of the dusty material must be applied to the extinction curve, regardless of angular imaging resolution. This approach will be particularly relevant for dust in quasar absorption line systems and might constrain clump sizes in active galactic nuclei.

Authors with CRIS profile

Jörn Wilms Professur für Astronomie und Astrophysik

Involved external institutions

Massachusetts Institute of Technology (MIT) US United States (USA) (US) Harvard University US United States (USA) (US)

How to cite

APA:

Corrales, L.R., Garcia, J., Wilms, J., & Baganoff, F. (2016). The dust-scattering component of X-ray extinction: Effects on continuum fitting and high-resolution absorption edge structure. Monthly Notices of the Royal Astronomical Society, 458(2), 1345-1351. https://doi.org/10.1093/mnras/stw376

MLA:

Corrales, L. R., et al. "The dust-scattering component of X-ray extinction: Effects on continuum fitting and high-resolution absorption edge structure." Monthly Notices of the Royal Astronomical Society 458.2 (2016): 1345-1351.

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