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Paper   IPM / Astronomy / 16855
School of Astronomy
  Title:   The role of thermal and non-thermal processes in the ISM of the Magellanic Clouds
  Author(s): 
1.  H . Hassani
2.  F . Tabatabaei
3.  A . Hughes
4.  J . Chastenet
5.  A. F . McLeod
6.  E . Schinnerer
7.  S . Nasiri
  Status:   Published
  Journal: MNRAS
  Vol.:  510
  Year:  2021
  Supported by:  IPM
  Abstract:
The radio continuum emission is a dust-unbiased tracer of both the thermal and non-thermal processes in the interstellar medium. We present new maps of the free-free and synchrotron emission in the Magellanic Clouds (MCs) at 0.166, 1.4, and 4.8GHz with no prior assumption about the radio non-thermal spectrum. The maps were constructed using a de-reddened H map as a template for the thermal radio emission, which we subtract from maps of the total radio continuum emission. To de-redden the H emission, it is important to know the fraction of dust surface density that attenuates the H emission along the line-of-sight, . This fraction is obtained by comparing the dust opacity obtained through the infrared emission spectrum and the Balmer decrement method. In star-forming regions, the median is about 0.1 which is by a factor of 3 lower than that in diffuse regions. We obtain a global thermal radio fraction, , of 30 per cent (35 per cent) in the LMC (SMC) at 1.4GHz. Furthermore, we present maps of the equipartition magnetic field strength with average values of G in the LMC and G in the SMC. The magnetic field is proportional to the star formation rate to a power of 0.24 and 0.20 for the LMC and SMC, respectively. This study shows that the non-thermal processes control the interstellar medium in the MCs.

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