EWOCS ongoing project: Diffuse X-ray emission

Massive clusters such as Westerlund 1 can produce a bright X-ray diffuse emission by means of the unresolved low-mass stellar population, emission from the wind produced by the massive stars, and remnants of supernova explosions. In the past years, thanks to Chandra/ACIS-I, astronomers have been able to observe spectacular diffuse emission and outflows in massive stellar clusters such as those in the Carina Nebula.

 

Besides, the analysis of the diffuse emission in the cluster core could shade light on the accumulation of polluted material emitted by massive star. This would help us understanding the stellar formation history in globular clusters, where multiple populations are often observed (e.g. Piotto+2007), and where following generations of stars form from the polluted material emitted by massive stars. Somehow, the wind from the first generation of stars must accumulate, cool down, and become gravitationally unstable to start forming stars (D’Ercole+2008, Palouŝ+2014). In Westerlund 1 we may be witnessing the first phase of this process.

 

The analysis of the diffuse emission in Westerlund 1 is in a very preliminary stage, since a reliable source catalog is required in order to remove the contribution from point sources in the images. A preliminary map of the diffuse emission obtained from one of the observations (Obs.ID: 23288) is shown below. Sources are removed in the left panel.

 

 

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