English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

The giant molecular cloud Sagittarius B2 (hereafter SgrB2) is the mostmassive region with ongoing high-mass star formation in the Galaxy. In thesouthern region of the 40-pc large envelope of SgrB2, we encounter theSgrB2(DS) region which hosts more than 60 high-mass protostellar coresdistributed in an arc shape around an extended HII region. We use the VeryLarge Array in its CnB and D configurations, and in the frequency bands C (4--8GHz) and X (8--12 GHz) to observe the whole SgrB2 complex. Continuum and radiorecombination line maps are obtained. We detect radio continuum emission inSgrB2(DS) in a bubble-shaped structure. From 4 to 12 GHz, we derive a spectralindex between -1.2 and -0.4, indicating the presence of non-thermal emission.We decompose the contribution from thermal and non-thermal emission, and findthat the thermal component is clumpy and more concentrated, while thenon-thermal component is more extended and diffuse. The radio recombinationlines in the region are found to be not in local thermodynamic equilibrium(LTE) but stimulated by the non-thermal emission. The thermal free-freeemission is likely tracing an HII region ionized by an O7 star, while thenon-thermal emission can be generated by relativistic electrons created throughfirst-order Fermi acceleration. We have developed a simple model of theSgrB2(DS) region and found that first-order Fermi acceleration can reproducethe observed flux density and spectral index.

The physical and chemical structure of Sagittarius B2 -- V. Non-thermal emission in the envelope of Sgr B2