J/A+A/671/A55  GC and inner disc XMM-Newton observations (Anastasopoulou+, 2023)
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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        (SIMBAD/NED BibCode)
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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*10^40^erg/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*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.

Description:
    All XMM-Newton observations covering the GC and inner disc except
    those already presented in Ponti et al. (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

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(End)                                        Patricia Vannier [CDS]  11-Jan-2023