The early-type galaxy NGC 5195 (alternatively known as M51b) possessesextended gas features detected in multi-wavelength, postulated to be associatedwith previous activities of the central supermassive black hole (SMBH). Usingintegral field spectroscopic observations from the Canada-France-HawaiiTelescope (CFHT)/SITELLE, we report on the discovery of a new large-scaleionized gas structure traced by [O III], [N II], and H$\alpha$ line emission,extending to $\sim10\rm\,kpc$ from the nucleus of NGC 5195. Its bipolarmorphology, emission line ratio diagnostics, and comparison with the X-rayimage from Chandra and low-frequency radio data from LOFAR all indicate that itis likely an outflow inflated by a past episode of elevated active galacticnucleus (AGN) activity. Assuming the ionized gas is outflowing from the centralregion of NGC 5195, the estimated mass and energy outflow rates are$\dot{M}_{\rm out} = 3.5-27.9 \rm\, M_{\odot}\, yr^{-1}$ and $\dot{E}_{\rm out}= 0.98-7.9\times10^{40}\rm\, erg\, s^{-1}$, respectively, which cannot beprovided by current star formation and the low luminosity nucleus.Alternatively, considering the history of gravitational interaction between theM51 pair and the presence of HI tidal tail, the northern large-scale ionizedgas could very likely be associated with tidally stripped material illuminatedby a luminous AGN in the past.

Context. The present study addresses a key question for our understanding ofthe relation between void galaxies and their environment: the relationshipbetween luminous and dark matter in and around voids. Aims. To explore howempty of matter local Universe voids are, we study the full (dark+luminous)matter content of seven nearby cosmic voids that are fully contained within theCosmicFlows-3 volume. Methods. The cosmic voids matter density profiles areindependently obtained using two different methods. They are built on one handfrom the galaxy redshift space 2 points-correlation function and, on the otherhand, using peculiar velocity gradients from the CosmicFlows-3 dataset.Results. The results are noticeable since when using the redshift survey, allvoids show a radial positive gradient of galaxies, while based on the dynamicalanalysis, only three of these voids display a clear underdensity of matter intheir center. Conclusions. It is the first time such a detailed observationalanalysis of voids is conducted, showing that void emptiness should be derivedfrom dynamical information. Yet, from this limited study, the Hercules void isthe best candidate for a local Universe pure "pristine volume" expanding in 3directions with no dark matter located in that void.

The existing reservoirs of neutral atomic hydrogen gas (H$\,$I) in galaxiesare insufficient to have maintained the observed levels of star formationwithout some kind of replenishment. {This refuelling of the H$\,$I reservoirs}is likely to occur at column densities an order of magnitude lower thanprevious observational limits (N$_{\rm{H\,I}\, limit} \sim 10^{19}\,$cm$^{-2}$at 30$''$ resolution over a linewidth of $20\,$km/s). In this paper, we presentrecent deep H$\,$I observations of NGC 5068, a nearby isolated star-forminggalaxy observed by MeerKAT as part of the MHONGOOSE survey. With these newdata, we are able to detect low column density H$\,$I around NGC 5068 with a$3\sigma$ detection limit of N$_{\rm{H\,I}} = 6.4 \times 10^{17}\,$cm$^{-2}$ at90$''$ resolution over a $20\,$km/s linewidth. The high sensitivity andresolution of the MeerKAT data reveal a complex morphology of the H$\,$I inthis galaxy -- a regularly rotating inner disk coincident with the mainstar-forming disk of the galaxy, a warped outer disk of low column density gas(N$_{\rm{H\,I}} < 9 \times 10^{19}\,$cm$^{-2}$), in addition to clumps of gason the north west side of the galaxy. We employ a simple two disk model thatdescribe the inner and outer disks, and are able to identify anomalous gas thatdeviates from the rotation of the main galaxy. The morphology and thekinematics of the anomalous gas suggest a possible extra-galactic origin. Weexplore a number of possible origin scenarios that may explain the anomalousgas, and conclude that fresh accretion is the most likely scenario.

Polycyclic aromatic hydrocarbons (PAHs) play a critical role in thereprocessing of stellar radiation and in balancing the heating and coolingprocesses in the interstellar medium (ISM), but appear to be destroyed in HIIregions. However, the mechanisms driving their destruction are still notcompletely understood. Using PHANGS-JWST and PHANGS-MUSE observations, weinvestigate how the PAH fraction changes in about 1500 HII regions across fournearby star-forming galaxies (NGC 628, NGC 1365, NGC 7496, IC 5332). We find astrong anti-correlation between the PAH fraction and the ionization parameter(the ratio between the ionizing photon flux and the hydrogen density) of HIIregions. This relation becomes steeper for more luminous HII regions. Themetallicity of HII regions has only a minor impact on these results in ourgalaxy sample. We find that the PAH fraction decreases with the H$\alpha$equivalent width - a proxy for the age of the HII regions - although this trendis much weaker than the one identified using the ionization parameter. Ourresults are consistent with a scenario where hydrogen-ionizing UV radiation isthe dominant source of PAH destruction in star-forming regions.

Though S0 galaxies are usually thought to be `red and dead', they oftendemonstrate weak star formation organised in ring structures and located intheir outer disks. We try to clarify the nature of this phenomenon and itsdifference from star formation in spiral galaxies. The moderate-luminositynearby S0 galaxy, UGC 4599, is studied here. By applying long-slit spectroscopyat the Russian 6m telescope, we have measured stellar kinematics for the mainbody of the galaxy and strong emission-line flux ratios in the ring. Afterinspecting the gas excitation in the ring using line ratio diagrams and havingshown that it is ionized by young stars, we have determined the gas oxygenabundance by using conventional strong-line calibration methods. We haveinspected the gas kinematics in the ring with Fabry-Perot interferometer dataobtained at the William Herschel Telescope. The pattern and properties of thebrightest star formation regions are studied with the tunable filter MaNGaL atthe 2.5m telescope of the Caucasian Mountain Observatory of the SternbergAstronomical Institute (CMO SAI MSU). The gas metallicity in the ring iscertainly subsolar, [O/H]$=-0.4 \pm 0.1$~dex, that is different from themajority of the outer starforming rings in S0s studied by us which havetypically nearly solar metallicity. The total stellar component of the galaxywhich is old in the center is less massive than its extended gaseous disk. Weconclude that probably the ring and the outer disk of UGC~4599 are a result ofgas accretion from a cosmological filament.