In the previous papers in this series, we have measured the stellar and \hicontent in a sample of edge-on galaxies. In the present paper, we perform asimultaneous rotation curve and vertical force field gradient decomposition forfive of these edge-on galaxies. The rotation curve decomposition provides ameasure of the radial dark matter potential, while the vertical force fieldgradient provide a measure of the vertical dark matter potential. We fit darkmatter halo models to these potentials. Using our \hi self-absorption results,we find that a typical dark matter halo has a less dense core($0.094\pm0.230$\,M$_\odot$/pc$^3$) compared to an optically thin \hi model($0.150\pm0.124$\,M$_\odot$/pc$^3$). The HI self-absorption dark matter halohas a longer scale length $R_c$ of $1.42\pm 3.48$\,kpc, versus $1.10\pm1.81$\,kpc for the optically thin HI model. The median halo shape is spherical,at $q=1.0\pm0.6$ (self-absorbing \hi), while it is prolate at $q=1.5\pm0.6$ forthe optically thin. Our best results were obtained for ESO\,274-G001 andUGC\,7321, for which we were able to measure the velocity dispersion in PaperIII. These two galaxies have drastically different halo shapes, with one oblateand one strongly prolate. Overall, we find that the many assumptions requiredmake this type of analysis susceptible to errors.

We present MUSE integral field spectroscopic data of the S0 galaxy NGC 3115obtained during the instrument commissioning at the ESO Very Large Telescope(VLT). We analyse the galaxy stellar kinematics and stellar populations andpresent two dimensional maps of their associated quantities. We thus illustratethe capacity of MUSE to map extra-galactic sources to large radii in anefficient manner, i.e., ~4 Re, and provide relevant constraints on its massassembly. We probe the well known set of substructures of NGC 3115 (its nucleardisc, stellar rings, outer kpc-scale stellar disc and spheroid) and show theirindividual associated signatures in the MUSE stellar kinematics and stellarpopulations maps. In particular, we confirm that NGC 3115 has a thin fastrotating stellar disc embedded in a fast rotating spheroid, and that these twostructures show clear differences in their stellar age and metallicityproperties. We emphasise an observed correlation between the radial stellarvelocity, V, and the Gauss-Hermite moment, h3, creating a "butterfly" shape inthe central 15" of the h3 map. We further detect the previously reported weakspiral and ring-like structures, and find evidence that these features can beassociated with regions of younger mean stellar ages. We provide tentativeevidence for the presence of a bar, despite the fact that the V-h3 correlationcan be reproduced by a simple axisymmetric dynamical model. Finally, we presenta reconstruction of the two dimensional star formation history of NGC 3115 andfind that most of its current stellar mass was formed at early epochs (>12Gyrago), while star formation continued in the outer (kpc-scale) stellar discuntil recently. Since z~2, and within ~4 Re, we suggest that NGC 3115 has beenmainly shaped by secular processes.

We investigate the dust energy balance for the edge-on galaxy IC 2531, one ofthe seven galaxies in the HEROES sample. We perform a state-of-the-artradiative transfer modelling based, for the first time, on a set of optical andnear-infrared galaxy images. We show that taking into account near-infraredimaging in the modelling significantly improves the constraints on theretrieved parameters of the dust content. We confirm the result from previousstudies that including a young stellar population in the modelling is importantfor explaining the observed stellar energy distribution. However, thediscrepancy between the observed and modelled thermal emission at far-infraredwavelengths, the so-called dust energy balance problem, is still present: themodel underestimates the observed fluxes by a factor of about two. We comparetwo different dust models, and find that dust parameters and thus the spectralenergy distribution in the infrared domain are sensitive to the adopted dustmodel. In general, the THEMIS model reproduces the observed emission in theinfrared wavelength domain better than the popular Zubko et al. BARE-GR-Smodel. Our study of IC 2531 is a pilot case for detailed and uniform radiativetransfer modelling of the entire HEROES sample, which will shed more light onthe strength and origins of the dust energy balance problem.

We study the spatially resolved excitation properties of the ionised gas in asample of 646 galaxies using integral field spectroscopy data from SDSS-IVMaNGA. Making use of Baldwin-Philips-Terlevich diagnostic diagrams wedemonstrate the ubiquitous presence of extended (kpc scale) low ionisationemission-line regions (LIERs) in both star forming and quiescent galaxies. Instar forming galaxies LIER emission can be associated with diffuse ionised gas,most evident as extra-planar emission in edge-on systems. In addition, weidentify two main classes of galaxies displaying LIER emission: `central LIER'(cLIER) galaxies, where central LIER emission is spatially extended, butaccompanied by star formation at larger galactocentric distances, and `extendedLIER' (eLIER) galaxies, where LIER emission is extended throughout the wholegalaxy. In eLIER and cLIER galaxies, LIER emission is associated with radiallyflat, low H$\alpha$ equivalent width of line emission ($<$ 3 \AA) and stellarpopulation indices demonstrating the lack of young stellar populations,implying that line emission follows tightly the continuum due to the underlyingold stellar population. The H$\alpha$ surface brightness radial profiles arealways shallower than $\rm 1/r^{2}$ and the line ratio[OIII]$\lambda$5007/[OII]$\lambda$3727,29 (a tracer of the ionisation parameterof the gas) shows a flat gradient. This combined evidence strongly supports thescenario in which LIER emission is not due to a central point source but todiffuse stellar sources, the most likely candidates being hot, evolved(post-asymptotic giant branch) stars. Shocks are observed to play a significantrole in the ionisation of the gas only in rare merging and interacting systems.