  Sagittarius B2 (Sgr B2) is a giant molecular cloud complex in the central
molecular zone of our Galaxy hosting several sites of high-mass star formation.
The two main centers of activity are Sgr B2(M) and Sgr B2(N), which contain 27
and 20 continuum sources, respectively. Our analysis aims to be a comprehensive
modeling of each core spectrum, where we take the complex interaction between
molecular lines, dust attenuation, and free-free emission arising from HII
regions into account. In this work, we determine the dust and, if HII regions
are contained, the parameters of the free-free thermal emission of the ionized
gas for each core, and derive a self-consistent description of the continuum
levels of each core. Using the high sensitivity of ALMA, we characterize the
physical and chemical structure of these continuum sources and gain better
insight into the star formation process within the cores. We used ALMA to
perform an unbiased spectral line survey of all 47 sources in ALMA band 6 with
a frequency coverage from 211 GHz to 275 GHz. In order to model the free-free
continuum contribution of a specific core, we fit the contained recombination
lines (RRLs) to obtain the electron temperatures and the emission measures,
where we use an extended XCLASS program to describe RRLs and free-free
continuum simultaneously. In contrast to previous analyses, we derived the
corresponding parameters here not only for each core, but also for their local
surrounding envelope, and determined their physical properties. The
distribution of RRLs we found in the core spectra closely fits the distribution
of HII regions described in previous analyses. For the cores we determine
average dust temperatures of around 236 K (Sgr B2(M)) and 225 K (Sgr B2(N)),
while the electronic temperatures are located in a range between 3800 K and
23800 K.
