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Dust and gas absorption in the high mass X-ray binary IGR J16318−4848

Ballhausen, Ralf and Lorenz, Maximilian and Fürst, Felix and Pottschmidt, Katja and Corrales, Lia and Tomsick, John A. and Bissinger né Kühnel, Matthias and Kretschmar, Peter and Kallman, Timothy R. and Grinberg, Victoria and Hell, Natalie and Psadaraki, Ioanna and Rogantini, Daniele and Wilms, Jörn (2020) Dust and gas absorption in the high mass X-ray binary IGR J16318−4848. Astronomy and Astrophysics, 641 . Art. No. A65. ISSN 0004-6361. doi:10.1051/0004-6361/202038317.

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Context. With an absorption column density on the order of 10²⁴ cm⁻², IGR J16318−4848 is one of the most extreme cases of a highly obscured high mass X-ray binary. In addition to the overall continuum absorption, the source spectrum exhibits a strong iron and nickel fluorescence line complex at 6.4 keV. Previous empirical modeling of these features and comparison with radiative transfer simulations raised questions about the structure and covering fraction of the absorber and the profile of the fluorescence lines. Aims. We aim at a self-consistent description of the continuum absorption, the absorption edges, and the fluorescence lines to constrain the properties of the absorbing material, such as ionization structure and geometry. We further investigate the effects of dust absorption on the observed spectra and the possibility of fluorescence emission from dust grains. Methods. We used XMM-Newton and NuSTAR spectra to first empirically constrain the incident continuum and fluorescence lines. Next we used XSTAR to construct a customized photoionization model where we vary the ionization parameter, column density, and covering fraction. In the third step we modeled the absorption and fluorescence in a dusty olivine absorber and employed both a simple analytical model for the fluorescence line emission and a Monte Carlo simulation of radiative transfer that generates line fluxes, which are very close to the observational data. Results. Our empirical spectral modeling is in agreement with previous works. Our second model, the single gas absorber does not describe the observational data. In particular, irrespective of the ionization state or column density of the absorber, a much higher covering fraction than previously estimated is needed to produce the strong fluorescence lines and the large continuum absorption. A dusty, spherical absorber (modeled as consisting of olivine dust, although the nature of dust cannot be constrained) is able to produce the observed continuum absorption and edges. Conclusions. A dense, dusty absorber in the direct vicinity of the source consisting of dust offers a consistent description of both the strong continuum absorption and the strong emission features in the X-ray spectrum of IGR J16318−4848. In particular, for low optical depth of individual grains, which is the case for typical volume densities and grain size distribution models, the dust will contribute significantly to the fluorescence emission.

Item Type:Article
Related URLs:
URLURL TypeDescription
Ballhausen, Ralf0000-0002-1118-8470
Lorenz, Maximilian0000-0001-6553-9590
Fürst, Felix0000-0003-0388-0560
Pottschmidt, Katja0000-0002-4656-6881
Corrales, Lia0000-0002-5466-3817
Tomsick, John A.0000-0001-5506-9855
Bissinger né Kühnel, Matthias0000-0002-8709-8236
Kretschmar, Peter0000-0001-9840-2048
Kallman, Timothy R.0000-0002-5779-6906
Grinberg, Victoria0000-0003-2538-0188
Hell, Natalie0000-0003-3057-1536
Rogantini, Daniele0000-0002-5359-9497
Wilms, Jörn0000-0003-2065-5410
Additional Information:© ESO 2020. Received 1 May 2020 / Accepted 2 July 2020. We thank the anonymous referee for constructive comments that helped to improve the manuscript. We thank Jakob Stierhof, Daniel Stern, and Stefan Licklederer for extensive and fruitful discussions. R.B. acknowledges partial funding by the Bundesministerium für Wirtschaft under Deutsches Zentrum für Luft- und Raumfahrt contract 50 OR 1410. V.G. is supported through the Margarete von Wrangell fellowship by the ESF and the Ministry of Science, Research and the Arts Baden-Württemberg. Work at LLNL is conducted under the auspices of the US DOE under Contract DE-AC52-07NA27344. This research is based on observations obtained with XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States and NASA and has made use of data obtained with NuSTAR, a project led by the California Institute of Technology, managed by the Jet Propulsion Laboratory, and funded by NASA. We acknowledge the use of the NuSTAR Data Analysis Software (NuSTARDAS) jointly developed by the ASI Science Data Center (ASDC, Italy) and the California Institute of Technology (USA). This work has made use of a collection of ISIS functions (ISISscripts) provided by ECAP/Remeis observatory and MIT (
Group:Space Radiation Laboratory, NuSTAR
Funding AgencyGrant Number
Deutsches Zentrum für Luft- und Raumfahrt (DLR)50 OR 1410
European Social FundUNSPECIFIED
Baden-Württemberg Ministry of Science, Research and the ArtsUNSPECIFIED
Department of Energy (DOE)DE-AC52-07NA27344
Subject Keywords:X-rays: binaries / dust, extinction / X-rays: individuals: IGR J16318-4848 / circumstellar matter
Record Number:CaltechAUTHORS:20200915-115017424
Persistent URL:
Official Citation:Dust and gas absorption in the high mass X-ray binary IGR J16318−4848 Ralf Ballhausen, Maximilian Lorenz, Felix Fürst, Katja Pottschmidt, Lia Corrales, John A. Tomsick, Matthias Bissinger né Kühnel, Peter Kretschmar, Timothy R. Kallman, Victoria Grinberg, Natalie Hell, Ioanna Psadaraki, Daniele Rogantini and Jörn Wilms A&A, 641 (2020) A65 DOI:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:105385
Deposited By: George Porter
Deposited On:15 Sep 2020 20:18
Last Modified:16 Nov 2021 18:42

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