Investigating the origin of the faint non-thermal emission of the Arches cluster using the 2015-2016 NuSTAR and XMM-Newton X-ray observations
arXiv:1901.03121 · doi:10.1093/mnras/stz119
Abstract
Recent NuSTAR and XMM-Newton observations of the molecular cloud around the Arches stellar cluster demonstrate a dramatic change both in morphology and intensity of its non-thermal X-ray emission, similar to that observed in many molecular clouds of the Central Molecular Zone at the Galactic Center. These variations trace the propagation of illuminating fronts, presumably induced by past flaring activities of Sgr A. In this paper we present results of a long NuSTAR observation of the Arches complex in 2016, taken a year after the previous XMM+NuSTAR observations which revealed a strong decline in the cloud emission. The 2016 NuSTAR observation shows that both the non-thermal continuum emission and the Fe K 6.4~keV line flux are consistent with the level measured in 2015. No significant variation has been detected in both spectral shape and Fe K equivalent width EW, which may be interpreted as the intensity of the Arches non-thermal emission reaching its stationary level. At the same time, the measured 2016 non-thermal flux is not formally in disagreement with the declining trend observed in 2007-2015. Thus, we cannot assess whether the non-thermal emission has reached a stationary level in 2016, and new observations, separated by a longer time period, are needed to draw stringent conclusions. Detailed spectral analysis of three bright clumps of the Arches molecular cloud performed for the first time showed different EW and absorption. This is a strong hint that the X-ray emission from the molecular cloud is a mix of two components with different origins.
arXiv comment10 pages, 8 figures, 6 tables. Accepted to MNRAS
References in corpus (30)
- The SIMBAD astronomical database
- The Nuclear Spectroscopic Telescope Array (NuSTAR) Mission
- HST/NICMOS Observations of Massive Stellar Clusters Near the Galactic Center
- Massive Stars in the Arches Cluster
- Discovery of a superluminal Fe K echo at the Galactic Center: The glorious past of Sgr A* preserved by molecular clouds
- Hard X-ray view of the past activity of Sgr A* in a natural Compton mirror
- Fading hard X-ray emission from the Galactic Centre molecular cloud Sgr B2
- Equivalent width, shape and proper motion of the iron fluorescent line emission from the molecular clouds as an indicator of the illuminating source X-ray flux history
- Echoes of multiple outbursts of Sagittarius A* revealed by Chandra
- Detection of X-ray Emission from the Arches Cluster Near the Galactic Center
- The Interplay between Star Formation and the Nuclear Environment of our Galaxy: Deep X-ray Observations of the Galactic Center Arches and Quintuplet Clusters
- ASCA Observations of the Sgr B2 Cloud: An X-Ray Reflection Nebula
- Traces of past activity in the Galactic Centre
- Nonthermal X-rays from low-energy cosmic rays: Application to the 6.4 keV line emission from the Arches cluster region
- X-ray Echo from the Sagittarius C Complex and 500-year Activity History of Sagittarius A*
- NuSTAR Hard X-ray Survey of the Galactic Center Region II: X-ray Point Sources
- X-ray Observations of Stellar Clusters Near the Galactic Center
- Hard X-ray Morphological and Spectral Studies of The Galactic Center Molecular Cloud Sgr B2: Constraining Past Sgr A* Flaring Activity
- Not that long time ago in the nearest galaxy: 3D slice of molecular gas revealed by a 110 years old flare of Sgr A*
- Glimpses of the past activity of Sgr A* inferred from X-ray echoes in Sgr C
- First hard X-ray detection of the non-thermal emission around the Arches cluster: morphology and spectral studies with NuSTAR
- An X-ray survey of the central molecular zone: variability of the Fe Ka emission line
- Fe Ka line emission from the Arches cluster region - evidence for ongoing particle bombardment?
- Suzaku Spectroscopy Study of Hard X-Ray Emission in the Arches Cluster
- Variation of the X-ray non-thermal emission in the Arches cloud
- Can Sgr A* flares reveal the molecular gas density PDF?
- NuSTAR and XMM-Newton observations of the Arches cluster in 2015: fading hard X-ray emission from the molecular cloud
- Discovery of X-ray flaring activity in the Arches cluster
- On the Origin of the 6.4 keV Line in the Galactic Center Region
- Time-Variability of equivalent width of 6.4 keV line from the Arches Complex: reflected X-rays or charged particles?
Cited by in corpus (7)
- The Galactic LMXB Population and the Galactic Centre Region
- SRG/eROSITA view of X-ray reflection in the Central Molecular Zone: a snapshot in September-October 2019
- Sgr B2 hard X-ray emission with INTEGRAL after 2009: still detectable?
- X-ray emission from Westerlund 2 detected by SRG/ART-XC and Chandra: search for radiation of TeV leptons
- 25 years of XMM-Newton observations of the Sgr A complex: 3D distribution and internal structure of the clouds
- X-raying molecular clouds with a short flare: probing statistics of gas density and velocity fields
- High Energy Emission from the Galactic Center