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Study of the excess Fe XXV line emission in the central degrees of the Galactic centre using XMM-Newton data

The diffuse Fe XXV (6.7 keV) line emission observed in the Galactic ridge is widely accepted to be produced by a superposition of a large number of unresolved X-ray point sources. In the very central degrees of our Galaxy, however, the existence of an extremely hot (~7 keV) diffuse plasma is still u...

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Hauptverfasser: Anastasopoulou, Konstantina (VerfasserIn) , Ponti, G. (VerfasserIn) , Sormani, Mattia C. (VerfasserIn) , Locatelli, N. (VerfasserIn) , Haberl, F. (VerfasserIn) , Morris, M. R. (VerfasserIn) , Churazov, E. M. (VerfasserIn) , Schödel, R. (VerfasserIn) , Maitra, C. (VerfasserIn) , Campana, S. (VerfasserIn) , Teodoro, E. M. Di (VerfasserIn) , Jin, C. (VerfasserIn) , Khabibullin, I. (VerfasserIn) , Mondal, S. (VerfasserIn) , Sasaki, M. (VerfasserIn) , Zhang, Y. (VerfasserIn) , Zheng, X. (VerfasserIn)
Dokumenttyp: Article (Journal)
Sprache:Englisch
Veröffentlicht: 07 March 2023
In: Astronomy and astrophysics
Year: 2023, Jahrgang: 671, Pages: 1-17
ISSN:1432-0746
DOI:10.1051/0004-6361/202245001
Online-Zugang:Verlag, lizenzpflichtig, Volltext: https://doi.org/10.1051/0004-6361/202245001
Verlag, lizenzpflichtig, Volltext: https://www.aanda.org/articles/aa/abs/2023/03/aa45001-22/aa45001-22.html
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Verfasserangaben:K. Anastasopoulou, G. Ponti, M.C. Sormani, N. Locatelli, F. Haberl, M.R. Morris, E.M. Churazov, R. Schödel, C. Maitra, S. Campana, E.M. Di Teodoro, C. Jin, I. Khabibullin, S. Mondal, M. Sasaki, Y. Zhang, and X. Zheng
Beschreibung
Zusammenfassung:The diffuse Fe XXV (6.7 keV) line emission observed in the Galactic ridge is widely accepted to be produced by a superposition of a large number of unresolved X-ray point sources. In the very central degrees of our Galaxy, however, the existence of an extremely hot (~7 keV) diffuse plasma is still under debate. In this work we measure the Fe XXV line emission using all available XMM-Newton observations of the Galactic centre (GC) and inner disc (−10° < ℓ < 10°, −2° < b < 2°). We use recent stellar mass distribution models to estimate the amount of X-ray emission originating from unresolved point sources, and find that within a region of ℓ = ±1° and b = ±0.25° the 6.7keV emission is 1.3-1.5 times in excess of what is expected from unresolved point sources. The excess emission is enhanced towards regions where known supernova remnants are located, suggesting that at least a part of this emission is due to genuine diffuse very hot plasma. If the entire excess is due to very hot plasma, an energy injection rate of at least ~6 × 10 40 erg s−1 is required, which cannot be provided by the measured supernova explosion rate or past Sgr A* activity alone. However, we find that almost the entire excess we observe can be explained by assuming GC stellar populations with iron abundances ~1.9 times higher than those in the bar/bulge, a value that can be reproduced by fitting diffuse X-ray spectra from the corresponding regions. Even in this case, a leftover X-ray excess is concentrated within ℓ = ±0.3° and b = ±0.15°, corresponding to a thermal energy of ~2 × 10 52 erg, which can be reproduced by the estimated supernova explosion rate in the GC. Finally we discuss a possible connection to the observed GC Fermi-LAT excess.
Beschreibung:Gesehen am 27.11.2023
Beschreibung:Online Resource
ISSN:1432-0746
DOI:10.1051/0004-6361/202245001

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