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<i>Hitomi</i> Constraints on the 3.5 keV Line in the Perseus Galaxy Cluster [electronic resource].

Published:
Washington, D.C. : United States. Dept. of Energy, 2017.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy
Physical Description:
Article numbers L15 : digital, PDF file
Additional Creators:
SLAC National Accelerator Laboratory, United States. Department of Energy, Nihon Gakujutsu Shinko?kai, National Aeronautics and Space Administration Announcement, and United States. Department of Energy. Office of Scientific and Technical Information
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Summary:
High-resolution X-ray spectroscopy with Hitomi was expected to resolve the origin of the faint unidentified $E\approx 3.5\,\mathrm{keV}$ emission line reported in several low-resolution studies of various massive systems, such as galaxies and clusters, including the Perseus cluster. We have analyzed the Hitomi first-light observation of the Perseus cluster. The emission line expected for Perseus based on the XMM-Newton signal from the large cluster sample under the dark matter decay scenario is too faint to be detectable in the Hitomi data. However, the previously reported 3.5 keV flux from Perseus was anomalously high compared to the sample-based prediction. We find no unidentified line at the reported high flux level. Taking into account the XMM measurement uncertainties for this region, the inconsistency with Hitomi is at a 99% significance for a broad dark matter line and at 99.7% for a narrow line from the gas. We do not find anomalously high fluxes of the nearby faint K line or the Ar satellite line that were proposed as explanations for the earlier 3.5 keV detections. We do find a hint of a broad excess near the energies of high-n transitions of S xvi ($E\simeq 3.44\,\mathrm{keV}$ rest-frame)—a possible signature of charge exchange in the molecular nebula and another proposed explanation for the unidentified line. While its energy is consistent with XMM pn detections, it is unlikely to explain the MOS signal. In conclusion, a confirmation of this interesting feature has to wait for a more sensitive observation with a future calorimeter experiment.
Report Numbers:
E 1.99:slac-pub-17171
slac-pub-17171
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Other Subject(s):
Note:
Published through SciTech Connect.
03/03/2017.
"slac-pub-17171"
The Astrophysical Journal. Letters 837 1 ISSN 2041-8213 AM
Aharonian, F.; Akamatsu, H.; Akimoto, F.; Allen, S.; Angelini, L.; Arnaud, K.; Audard, M.; Awaki, H.; Axelsson, M.; Bamba, A.; Bautz, M.; Blandford, R.; Bulbul, E.; Brenneman, L.; Brown, G.; Cackett, E.; Chernyakova, M.; Chiao, M.; Coppi, P.; Costantini, E.; Plaa, J.; Herder, J.; Done, C.; Dotani, T.; Ebisawa, K.; et al.
Canadian Space Agency
Funding Information:
AC02-76SF00515
NNX15AM19G
AC52-07NA27344
15H02070
15K05107
23340071
26109506
24103002
25400236
25800119
25400237
25287042
24540229
25105516
23540280
25400235
25247028
26800095
25400231
26220703
24105007
23340055
15H00773
23000004
15H02090
15K17610
15H05438
15H00785
24540232
ST/J003697/2
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