The [CII]158um line is one of the dominant cooling lines in star-forming active regions. The commonly assumed clumpy UV-penetrated cloud models predict a [CII] line profile similar to that of CO. However, recent spectral-resolved observations show th
at they are often very different, indicating a more complex origin of the line emission including the dynamics of the source region. The aim of our study is to investigate the physical properties of the star-forming ISM in the Large Magellanic Cloud (LMC) by separating the origin of the emission lines spatially and spectrally. In this paper, we focus on the spectral characteristics and the origin of the emission lines, and the phases of carbon-bearing species in the N159 star-forming region in the LMC. We mapped a 4x(3-4) region in N159 in [CII]158um and [NII]205um with the GREAT on board SOFIA, and in CO(3-2), (4-3), (6-5), 13CO(3-2), and [CI]3P1-3P0 and 3P2-3P1 with APEX. The emission of all transitions observed shows a large variation in the line profiles across the map and between the different species. At most positions the [CII] emission line profile is substantially wider than that of CO and [CI]. We estimated the fraction of the [CII] integrated line emission that cannot be fitted by the CO line profile to be 20%-50%. We derived the relative contribution from C+, C, and CO to the column density in each velocity bin. The contribution from C+ dominates the velocity range far from the velocities traced by the dense molecular gas, and the region located between the CO cores of N159 W and E. We estimate the contribution of the ionized gas to the [CII] emission using the ratio to the [NII] emission to be < 19% to the [CII] emission at its peak position, and <15% over the whole observed region. Using the integrated line intensities, we present the spatial distribution of I([CII])/I(FIR). (abridged for arXiv)
Supernova remnants (SNRs) are considered as being the sources of galactic cosmic rays. In order to understand the origin, acceleration, and composition of these cosmic rays, detailed knowledge of the physical conditions in the local interstellar medi
um is needed. The shock interaction of SNRs with molecular clouds that gives rise to strong molecular emission in the far-IR and sub-mm wavelength regimes can be used as a highly valuable tracer of these conditions. The application of MHD shock models in the interpretation of the resulting line emission can yield information on the energetic and chemical impact of supernova remnants. We have mapped two regions in the supernova remnant W44 with the APEX telescope in ${}^{12}$CO (3-2), (4-3), (6-5), (7-6) and ${}^{13}$CO (3-2). The extraction of integrated intensities on five different positions, corresponding to local maxima of CO emission, allows to compare these intensities to the outputs of a grid of models, which combine an MHD shock code with a radiative transfer module based on the large velocity gradient approximation. We find that the observed CO line emission is compatible with non-stationary shocks and a pre-shock density of $10^4$ cm${}^{-3}$. Our models furthermore allow to constrain shock ages, velocities, the pre-shock magnetic field strength components perpendicular to the line-of-sight, and the full ladder of CO transitions. Finally, our analysis can be used to estimate the contribution of such SNRs to, e.g. the galactic energy balance and the momentum-injection into the surrounding interstellar medium.
We investigate the gas dynamics and the physical properties of photodissociation regions (PDRs) in IC1396A, which is an illuminated bright-rimmed globule with internal structures created by young stellar objects. Our mapping observations of the [CII]
emission in IC1396A with GREAT onboard SOFIA revealed the detailed velocity structure of this region. We combined them with observations of the [CI] 3P_1 - 3P_0 and CO(4-3) emissions to study the dynamics of the different tracers and physical properties of the PDRs. The [CII] emission generally matches the IRAC 8 micron, which traces the polycyclic aromatic hydrocarbon (PAH) emissions. The CO(4-3) emission peaks inside the globule, and the [CI] emission is strong in outer regions, following the 8 micron emission to some degree, but its peak is different from that of [CII]. The [CII] emitting gas shows a clear velocity gradient within the globule, which is not significant in the [CI] and CO(4-3) emission. Some clumps that are prominent in [CII] emission appear to be blown away from the rim of the globule. The observed ratios of [CII]/[CI] and [CII]/CO(4-3) are compared to the KOSMA-tau PDR model, which indicates a density of 10^4-10^5 cm-3.
