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NuSTAR and XMM-Newton observations of the Arches cluster in 2015: fading hard X-ray emission from the molecular cloud

Krivonos, Roman and Clavel, Maïca and Hong, JaeSub and Mori, Kaya and Ponti, Gabriele and Poutanen, Juri and Rahoui, Farid and Tomsick, John A. and Tsygankov, Sergey (2017) NuSTAR and XMM-Newton observations of the Arches cluster in 2015: fading hard X-ray emission from the molecular cloud. Monthly Notices of the Royal Astronomical Society, 468 (3). pp. 2822-2835. ISSN 0035-8711. doi:10.1093/mnras/stx585.

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We present results of long Nuclear Spectroscopic Telescope Array (NuSTAR; 200 ks) and XMM–Newton (100 ks) observations of the Arches stellar cluster, a source of bright thermal (kT ∼ 2 keV) X-rays with prominent Fe XXV Kα 6.7 keV line emission and a nearby molecular cloud, characterized by an extended non-thermal hard X-ray continuum and fluorescent Fe Kα 6.4 keV line of a neutral or low-ionization state material around the cluster. Our analysis demonstrates that the non-thermal emission of the Arches cloud underwent a dramatic change, with its homogeneous morphology, traced by fluorescent Fe Kα line emission, vanishing after 2012, revealing three bright clumps. The declining trend of the cloud emission, if linearly fitted, is consistent with half-life decay time of ∼8 yr. Such strong variations have been observed in several other molecular clouds in the Galactic Centre, including the giant molecular cloud Sgr B2, and point towards a similar propagation of illuminating fronts, presumably induced by the past flaring activity of Sgr A⋆. We also detect a significant drop of the equivalent width of the fluorescent Fe Ka line, which could mean either that the new clumps have a different position along the line of sight or that the contribution of cosmic ray has become more dominant.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Krivonos, Roman0000-0003-2737-5673
Clavel, Maïca0000-0003-0724-2742
Mori, Kaya0000-0002-9709-5389
Ponti, Gabriele0000-0003-0293-3608
Poutanen, Juri0000-0002-0983-0049
Rahoui, Farid0000-0001-7655-4120
Tomsick, John A.0000-0001-5506-9855
Additional Information:© 2017 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2017 March 7. Received 2017 March 3; in original form 2016 December 10. Published: 09 March 2017. This work has made use of data from the NuSTAR mission, a project led by the California Institute of Technology, managed by the Jet Propulsion Laboratory and funded by the National Aeronautics and Space Administration, and re-observations obtained with XMM–Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States and NASA. The research has made use of the NuSTAR Data Analysis Software (NUSTARDAS) jointly developed by the ASI Science Data Center (ASDC, Italy) and the California Institute of Technology (USA). RK acknowledges support from the Russian Basic Research Foundation (grant 16-02-00294), the Program of the President of the Russian Federation for support of leading scientific schools (project NSh- 10222.2016.2), the Basic Research Program P-7 of the Presidium of the Russian Academy of Science, the Academy of Finland (grant 300005) and hospitality of the Tuorla Observatory, and thanks Eugene Churazov for the Monte Carlo X-ray reflection model used in the paper. GP acknowledges support by the Bundesministerium für Wirtschaft und Technologie/Deutsches Zentrum für Luft- und Raumfahrt (BMWI/DLR, FKZ 50 OR 1408 and FKZ 50 OR 1604) and the Max Planck Society. The authors would like to thank the referee for valuable comments that helped to improve the paper.
Subject Keywords:ISM: clouds –X-rays: individual: Arches cluster
Issue or Number:3
Record Number:CaltechAUTHORS:20161213-111643496
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Official Citation:Roman Krivonos, Maïca Clavel, JaeSub Hong, Kaya Mori, Gabriele Ponti, Juri Poutanen, Farid Rahoui, John Tomsick, Sergey Tsygankov; NuSTAR and XMM–Newton observations of the Arches cluster in 2015: fading hard X-ray emission from the molecular cloud, Monthly Notices of the Royal Astronomical Society, Volume 468, Issue 3, 1 July 2017, Pages 2822–2835,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:72776
Deposited By: Joy Painter
Deposited On:13 Dec 2016 19:24
Last Modified:11 Nov 2021 05:06

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