High-resolution X-Ray Spectroscopy of Interstellar Iron toward Cygnus X-1 and GX 339-4
We present a high-resolution spectral study of Fe L -shell extinction by the diffuse interstellar medium (ISM) in the direction of the X-ray binaries Cygnus X-1 and GX 339–4, using the XMM-Newton reflection grating spectrometer. The majority of interstellar Fe is suspected to condense into dust grai...
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| Format: | Article |
| Language: | English |
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IOP Publishing
2024-01-01
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| Series: | The Astrophysical Journal |
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| Online Access: | https://doi.org/10.3847/1538-4357/ad2939 |
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| author | Lía Corrales Eric V. Gotthelf Efrain Gatuzz Timothy R. Kallman Julia C. Lee Michael Martins Frits Paerels Ioanna Psaradaki Stefan Schippers Daniel Wolf Savin |
| author_facet | Lía Corrales Eric V. Gotthelf Efrain Gatuzz Timothy R. Kallman Julia C. Lee Michael Martins Frits Paerels Ioanna Psaradaki Stefan Schippers Daniel Wolf Savin |
| author_sort | Lía Corrales |
| collection | DOAJ |
| description | We present a high-resolution spectral study of Fe L -shell extinction by the diffuse interstellar medium (ISM) in the direction of the X-ray binaries Cygnus X-1 and GX 339–4, using the XMM-Newton reflection grating spectrometer. The majority of interstellar Fe is suspected to condense into dust grains in the diffuse ISM, but the compounds formed from this process are unknown. Here, we use the laboratory cross sections from Kortright & Kim ( 2000 ) and Lee et al. ( 2005 ) to model the absorption and scattering profiles of metallic Fe, and the crystalline compounds fayalite (Fe _2 SiO _4 ), ferrous sulfate (FeSO _4 ), hematite ( α -Fe _2 O _3 ), and lepidocrocite ( γ -FeOOH), which have oxidation states ranging from Fe ^0 to Fe ^3+ . We find that the observed Fe L -shell features are systematically offset in energy from the laboratory measurements. An examination of over two dozen published measurements of Fe L -shell absorption finds a 1–2 eV scatter in energy positions of the L -shell features. Motivated by this, we fit for the best energy-scale shift simultaneously with the fine structure of the Fe L -shell extinction cross sections. Hematite and lepidocrocite provide the best fits (≈ + 1.1 eV shift), followed by fayalite (≈ + 1.8 eV shift). However, fayalite is disfavored, based on the implied abundances and knowledge of ISM silicates gained by infrared astronomical observations and meteoritic studies. We conclude that iron oxides in the Fe ^3+ oxidation state are good candidates for Fe-bearing dust. To verify this, new absolute photoabsorption measurements are needed on an energy scale accurate to better than 0.2 eV. |
| first_indexed | 2024-04-24T08:09:13Z |
| format | Article |
| id | doaj.art-3f6b80f85041429aa5106dda332b6cfc |
| institution | Directory Open Access Journal |
| issn | 1538-4357 |
| language | English |
| last_indexed | 2024-04-24T08:09:13Z |
| publishDate | 2024-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal |
| spelling | doaj.art-3f6b80f85041429aa5106dda332b6cfc2024-04-17T08:21:26ZengIOP PublishingThe Astrophysical Journal1538-43572024-01-01965217210.3847/1538-4357/ad2939High-resolution X-Ray Spectroscopy of Interstellar Iron toward Cygnus X-1 and GX 339-4Lía Corrales0https://orcid.org/0000-0002-5466-3817Eric V. Gotthelf1https://orcid.org/0000-0003-3847-3957Efrain Gatuzz2https://orcid.org/0000-0002-3252-9633Timothy R. Kallman3https://orcid.org/0000-0002-5779-6906Julia C. Lee4https://orcid.org/0000-0002-7336-3588Michael Martins5https://orcid.org/0000-0002-1228-5029Frits Paerels6Ioanna Psaradaki7https://orcid.org/0000-0002-1049-3182Stefan Schippers8https://orcid.org/0000-0002-6166-7138Daniel Wolf Savin9https://orcid.org/0000-0002-1111-6610Astronomy Department, University of Michigan , Ann Arbor, MI 48109, USA ; liac@umich.eduColumbia Astrophysics Laboratory, Columbia University , 550 West 120th Street, New York, NY 10027-6601, USA ; eric@astro.columbia.edu, dws26@columbia.eduMax-Planck-Institut für extraterrestrische Physik , Giessenbachstrasse 1, D-85748 Garching, GermanyNASA/GSFC , Code 662, Greenbelt MD 20771, USAHarvard University , John A. Paulson School of Engineering & Applied Science, 29 Oxford Street, Cambridge, MA 02138, USAInstitut für Experimentalphysik, Universität Hamburg , Luruper Chaussee 149, 22761 Hamburg, Germany; Center for Free-Electron Laser Science , Notkestrasse 85, 22607 Hamburg, GermanyColumbia Astrophysics Laboratory and Department of Astronomy, Columbia University , 550 West 120th Street, New York, NY 10027, USAAstronomy Department, University of Michigan , Ann Arbor, MI 48109, USA ; liac@umich.eduI. Physikalisches Institut, Justus-Liebig-Universität Giessen , Heinrich-Buff-Ring 16, 35392 Giessen, GermanyColumbia Astrophysics Laboratory, Columbia University , 550 West 120th Street, New York, NY 10027-6601, USA ; eric@astro.columbia.edu, dws26@columbia.eduWe present a high-resolution spectral study of Fe L -shell extinction by the diffuse interstellar medium (ISM) in the direction of the X-ray binaries Cygnus X-1 and GX 339–4, using the XMM-Newton reflection grating spectrometer. The majority of interstellar Fe is suspected to condense into dust grains in the diffuse ISM, but the compounds formed from this process are unknown. Here, we use the laboratory cross sections from Kortright & Kim ( 2000 ) and Lee et al. ( 2005 ) to model the absorption and scattering profiles of metallic Fe, and the crystalline compounds fayalite (Fe _2 SiO _4 ), ferrous sulfate (FeSO _4 ), hematite ( α -Fe _2 O _3 ), and lepidocrocite ( γ -FeOOH), which have oxidation states ranging from Fe ^0 to Fe ^3+ . We find that the observed Fe L -shell features are systematically offset in energy from the laboratory measurements. An examination of over two dozen published measurements of Fe L -shell absorption finds a 1–2 eV scatter in energy positions of the L -shell features. Motivated by this, we fit for the best energy-scale shift simultaneously with the fine structure of the Fe L -shell extinction cross sections. Hematite and lepidocrocite provide the best fits (≈ + 1.1 eV shift), followed by fayalite (≈ + 1.8 eV shift). However, fayalite is disfavored, based on the implied abundances and knowledge of ISM silicates gained by infrared astronomical observations and meteoritic studies. We conclude that iron oxides in the Fe ^3+ oxidation state are good candidates for Fe-bearing dust. To verify this, new absolute photoabsorption measurements are needed on an energy scale accurate to better than 0.2 eV.https://doi.org/10.3847/1538-4357/ad2939Interstellar mediumDust compositionX-ray binary stars |
| spellingShingle | Lía Corrales Eric V. Gotthelf Efrain Gatuzz Timothy R. Kallman Julia C. Lee Michael Martins Frits Paerels Ioanna Psaradaki Stefan Schippers Daniel Wolf Savin High-resolution X-Ray Spectroscopy of Interstellar Iron toward Cygnus X-1 and GX 339-4 The Astrophysical Journal Interstellar medium Dust composition X-ray binary stars |
| title | High-resolution X-Ray Spectroscopy of Interstellar Iron toward Cygnus X-1 and GX 339-4 |
| title_full | High-resolution X-Ray Spectroscopy of Interstellar Iron toward Cygnus X-1 and GX 339-4 |
| title_fullStr | High-resolution X-Ray Spectroscopy of Interstellar Iron toward Cygnus X-1 and GX 339-4 |
| title_full_unstemmed | High-resolution X-Ray Spectroscopy of Interstellar Iron toward Cygnus X-1 and GX 339-4 |
| title_short | High-resolution X-Ray Spectroscopy of Interstellar Iron toward Cygnus X-1 and GX 339-4 |
| title_sort | high resolution x ray spectroscopy of interstellar iron toward cygnus x 1 and gx 339 4 |
| topic | Interstellar medium Dust composition X-ray binary stars |
| url | https://doi.org/10.3847/1538-4357/ad2939 |
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