J/A+A/671/A55 GC and inner disc XMM-Newton observations (Anastasopoulou+, 2023)
Study of the excess Fe XXV line emission in the central degrees of the Galactic
centre using XMM-Newton data.
Anastasopoulou K., Ponti G., Sormani M.C., Locatelli N., Haberl F.,
Morris M.R., Churazov E.M., Schoedel R., Maitra C., Campana S.,
Di Teodoro E.M., Jin C., Khabibullin I., Mondal S., Sasaki M., Zhang Y.,
Zheng X.
<Astron. Astrophys. 671, A55 (2023)>
=2023A&A...671A..55A 2023A&A...671A..55A (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Galactic center ; X-ray sources
Keywords: Galaxy: bulge - Galaxy: centre - Galaxy: disc - X-rays: general -
X-rays: ISM
Abstract:
The diffuse Fe XXV (6.7keV) 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 ∼7keV
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 (-10deg<l<10deg,
-2deg<b<2deg). 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=±1deg and
b=±0.25deg the 6.7keV emission is 1.3 to 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*1040erg/s 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=±0.3deg and b=±0.15deg,
corresponding to a thermal energy of ∼2*1052erg, 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.
Description:
All XMM-Newton observations covering the GC and inner disc except
those already presented in Ponti et al. (2015MNRAS.453..172P 2015MNRAS.453..172P). We
report the OBSID number, the total and clean exposure time for each
camera (in seconds), as well as the custom cut-offs (in counts per
second) used for the background filtering after visual inspection of
the background light curves. For observations where the threshold
column is empty, the standard values of 2.5ct/s and 8.0ct/s for the
EPIC MOS and EPIC pn exposures were used respectively.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tableb1.dat 69 258 XMM-Newton observations
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See also:
B/xmm : XMM-Newton Observation Log (XMM-Newton Science Operation Center, 201
IX/65 : XMM-Newton Serendipitous Source Catalogue 4XMM-DR11 (Webb+, 2022)
Byte-by-byte Description of file: tableb1.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- ObsID Observation ID
14- 19 I6 s Exp-pn EPIC-pn exposure time
21- 26 I6 s Exp-MOS1 EPIC-MOS1 exposure time
28- 33 I6 s Exp-MOS2 EPIC-MOS2 exposure time
35- 40 I6 s Exp-pn-clean EPIC-pn clean exposure time
42- 47 I6 s Exp-MOS1-clean EPIC-MOS1 clean exposure time
49- 54 I6 s Exp-MOS2-clean EPIC-MOS2 clean exposure time
56- 59 F4.1 ct/s threshold-pn ? EPIC-pn background threshold
61- 64 F4.1 ct/s threshold-MOS1 ? EPIC-MOS1 background threshold
66- 69 F4.1 ct/s threshold-MOS2 ? EPIC-MOS2 background threshold
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Acknowledgements:
Konstantina Anastasopoulou, konstantina.anastasopoulou(at)inaf.it
(End) Patricia Vannier [CDS] 11-Jan-2023