Low-mass "dwarf" galaxies are the most common types of galaxies in the Universe. The terminology "dwarf" is perhaps confusing: low-mass galaxies represent the norm in the cosmos, while giant spirals and ellipticals are much more rare (albeit easier to find and study!). For historical reasons, the dwarf galaxy classification spans a very vast range in stellar mass, from a few billions down to a few thousands solar masses. Despite this huge range in physical properties, dwarf galaxies can be separated in three basic families: (1) dwarf spheroidals or dwarf ellipticals that have no on-going star formation, (2) dwarf irregulars that have a low level of star formation, and (3) starbust dwarfs or blue compact dwarfs that are copiously forming new stars at an enhanced rate.
Several properties of dwarf galaxies (such as their abundance, phase-space distribution, and internal dynamics) are difficult to reproduce within the standard cosmological model LCDM, so dwarf galaxies represent a key tool to understand galaxy evolution and constrain the nature of dark matter!
GAS DYNAMICS IN STARBURST DWARFS
Starburst dwarf galaxies in the Local Universe are the ideal laboratory to study supernovae feedback and its effects on the interstellar medium. The picture shows, on a common physical scale, the optical appearance of 18 starburst dwarfs that I have studied during my PhD work. For some of these galaxies, we are currently analysing integral-field spectroscopic data from VLT/MUSE to investigate the properties of ionized gas and the occurrence of gas outflows and AGN activity.
THE CENTAURUS-A GALAXY GROUP
The majority of dwarf satellite galaxies around the Milky Way are arranged in a planar, co-rotating structure. A similar configuration of dwarf satellites is observed around our nearest neighbour, the Andromeda galaxy. These kinematically coherent configurations, however, are expected to be very rare (<1%) in a LCDM cosmology. This constitutes the "planes of satellites problem".
Is this problem a peculiarity of the Local Group? Do we live in a special location? The Centaurus-A galaxy group, one of the richest and nearest group to us, is the ideal laboratory to investigate this problem!
GAS AND STAR FORMATION IN DWARF AND LOW-SURFACE-BRIGHTNESS GALAXIES
Bright spiral galaxies follow a relationship between stellar mass and star-formation rate, the so-called the "star-forming main sequence". Are dwarf galaxies following a similar relation? We think so but it's a steeper one (see plot). "Thriving dwarfs" are extremely gas rich and may continue forming stars at a constant rate for several Hubble times, whereas spiral galaxies are "weary giants" on the verge of consuming their gas reservoir.