We present first results from Multi Unit Spectroscopic Explorer (MUSE)observations at the Very Large Telescope in the MUSE Ultra Deep Field (MUDF), a$\approx 1.2\times 1.4$ arcmin$^2$ region for which we are collecting$\approx$200 hours of integral field spectroscopy. The $\approx 40$-hourobservation completed to date reveals the presence of a group of threeLy$\alpha$ nebulae associated with a bright quasar pair at $z\simeq3.23$ withprojected separation of $\approx 500\rm~kpc$. Two of the nebulae are physicallyassociated with the quasars which are likely powering the Ly$\alpha$ emission,and extend for $\gtrsim 100~\rm kpc$ at a surface brightness level of $\approx6\times 10^{-19}~\rm erg~s^{-1}~cm^{-2}~arcsec^{-2}$. A third smaller($\approx$35 kpc) nebula lies at a velocity offset of $\approx 1550$ kms$^{-1}$. Despite their clustered nature, the two large nebulae have propertiessimilar to those observed in isolated quasars and exhibit no sharp decline influx at the current depth, suggesting an even more extended distribution of gasaround the quasars. We interpret the shape and the alignment of the twobrighter nebulae as suggestive of the presence of an extended structureconnecting the two quasar host galaxies, as seen for massive galaxies formingwithin gas-rich filaments in cosmological simulations.

We present a set of treatment techniques for GMOS/IFU data cubes, including:correction of the differential atmospheric refraction; Butterworth spatialfiltering, to remove high spatial-frequency noise; instrumental fingerprintremoval; Richardson-Lucy deconvolution, to improve the spatial resolution ofthe observations. A comparison with HST images shows that the treatmenttechniques preserve the morphology of the spatial structures in the data cubes,without introducing distortions or ghost features. The treatment procedureapplied to the data cube of the central region of the late-type galaxy NGC 2835allowed the detection of a nuclear emitting region with emission-line ratiosindicating a probable LINER, although the classifications of Transition Objector Seyfert galaxy cannot be discarded. Such a detection was not possiblewithout the data treatment. This shows that the benefits provided by thistreatment procedure are not merely cosmetic, but actually affect the quality ofdifferent types of analyses, like the determination of the fraction ofgalaxies, of different morphological types, with a centralSeyfert/LINER/Transition object emission.

The Milky Way, when viewed in the neutral hydrogen line emission, presentslarge structures called Galactic supershells (GSs). The origin of thesestructures is still a subject of debate. The most common scenario invoked isthe combined action of strong winds from massive stars and their subsequentexplosion as supernova. The aim of this work is to determine the origin of 490GSs that belong to the Catalog of HI supershell candidates in the outer part ofthe Galaxy. To know the physical processes that took place to create theseexpanding structures, it is necessary to determine their kinetic energies. Toobtain all the GS masses, we developed and used an automatic algorithm, whichwas tested on 95 GSs whose masses were also estimated by hand. The estimatedkinetic energies of the GSs vary from $1\times10^{47}$ to $3.4\times10^{51}$erg. Considering an efficiency of 20% for the conversion of mechanical stellarwind energy into the kinetic energy of the GSs, the estimated values of the GSenergies could be reached by stellar OB associations. For the GSs located athigh Galactic latitudes, the possible mechanism for their creation could beattributed to collision with high velocity clouds (HVC). We have also analysedthe distribution of GSs in the Galaxy, showing that at low Galactic latitudes,$|b|<2^\circ$, most of the structures in the third Galactic quadrant seem to beprojected onto the Perseus Arm. The detection of GSs at very high distancesfrom the Galactic centre may be attributed to diffuse gas associated with thecircumgalactic medium of M31 and to intra-group gas in the Local Groupfilament.

We present a sample of 91 HI galaxies with little or no star formation anddiscuss the analysis of the integral field unit (IFU) spectra of 28 of thesegalaxies. We identified HI galaxies from the HI Parkes All-Sky Survey Catalog(HICAT) with Wide-field Infrared Survey Explorer (WISE) colours consistent withlow specific star formation (< 10$^{-10.4}$ yr$^{-1}$), and obtained opticalIFU spectra with the Wide-Field Spectrograph (WiFeS). Visual inspection of thePanSTARRS, Dark Energy Survey, and Carnegie-Irvine imaging of 62 galaxiesreveals that at least 32 galaxies in the sample have low levels of starformation, primarily in arms/rings. New IFU spectra of 28 of these galaxiesreveal 3 galaxies with central star formation, 1 galaxy with low-ionisationnuclear emission-line regions (LINERs), 20 with extended low-ionisationemission-line regions (LIERs) and 4 with high excitation Seyfert (Sy) emission.From the spectroscopic analysis of HI-selected galaxies with little starformation, we conclude that 75% of this population are LINERs/LIERs.