A1 Vertaisarvioitu alkuperäisartikkeli tieteellisessä lehdessä
NuSTAR and XMM-Newton observations of the Arches cluster in 2015: fading hard X-ray emission from the molecular cloud
Tekijät: Krivonos R, Clavel M, Hong J, Mori K, Ponti G, Poutanen J, Rahoui F, Tomsick J, Tsygankov S
Kustantaja: OXFORD UNIV PRESS
Julkaisuvuosi: 2017
Journal: Monthly Notices of the Royal Astronomical Society
Tietokannassa oleva lehden nimi: MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
Lehden akronyymi: MON NOT R ASTRON SOC
Vuosikerta: 468
Numero: 3
Aloitussivu: 2822
Lopetussivu: 2835
Sivujen määrä: 14
ISSN: 0035-8711
eISSN: 1365-2966
DOI: https://doi.org/10.1093/mnras/stx585
Verkko-osoite: https://academic.oup.com/mnras/article-lookup/doi/10.1093/mnras/stx585
Rinnakkaistallenteen osoite: https://research.utu.fi/converis/portal/detail/Publication/23346022
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 similar to 2 keV) X-rays with prominent Fe XXV K alpha 6.7 keV line emission and a nearby molecular cloud, characterized by an extended non-thermal hard X-ray continuum and fluorescent Fe K alpha 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 K alpha 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 similar to 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(star). 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.
Ladattava julkaisu This is an electronic reprint of the original article. |  |
