Galactic Archaeology in the Triangulum System (M33) [M33 DAS-2]

Triangulum is a dwarf spiral galaxy, believed to be the largest satellite of Andromeda (M31). Due to its morphological characteristics, it can be classified as a low surface brightness (LSB) galaxy, visible at a low inclination angle.Although considered in scientific literature to be a galaxy free of disturbances due to tidal interactions, upon closer analysis, it exhibits an unmistakable morphology attributable to past events.According to some less than convincing interpretations, M33 experienced a close passage to M31. This event, dating back between 6 and 8 billion years, is attributed to the evident distortions in the outer arms, particularly the northern one, as well as the subtraction of its family of dwarf satellite galaxies and a significant number of globular clusters.Kinematic considerations make this scenario unlikely. According to recent models and evidence, Triangulum is instead falling for the first time into the gravitational pull of M31 and, more generally, the Local Group, with little likelihood of future interaction and merger.The signs of interaction exhibited, demonstrated beyond doubt in this new analysis, are therefore attributable to past minor merger events involving the capture, disruption, and absorption of some of its gas-rich satellites, with evidence of an outflow of ionized hydrogen. The presence of at least three ultrafaint satellite galaxies (Andromeda XXII, Pisces VII, and Triangulum IV) supports this hypothesis.Note how some of the detected structures perfectly superimpose on the asymmetric neutral gas halo, which has been known for some time.