In this study, led by myself and done in collaboration with theoreticians at the host institutions and
in Abu Dhabi, we investigated for the first time the origin of massive Low Surface Brightness (LSB)
galaxies in hydrodynamical simulations, and explored their formation mechanism: simulated LSBs
form as a result of co-planar co-rotating mergers and aligned accretion of gas at early times, while
perpendicular mergers and mis-aligned gas accretion result in higher SB galaxies by z=0.
Interestingly, the formation scenario of such `classical' LSBs differs from the one of less massive,
Ultra-Diffuse Galaxies, the latter resulting from the effects of SNae driven gas outflows: a stellar
Mass of 109 solar masses thus represents the transition regime between a feedback dominated to
an angular momentum dominated formation scenario in the LSB realm. Observational predictions
were offered regarding spatially resolved star formation rates through LSB discs: these, together
with upcoming surveys, will be used to verify the proposed emergence scenario of LSB galaxies.
On the morphology, rotation and kinematics of UDGs.
In this work, led by Master student Cardona-Barrero under my supervision, and in collaboration
with observers at host institution, we addressed the topic of kinematical properties of UDGs by
analyzing the stellar kinematics of isolated UDGs formed in the hydrodynamical simulation suite
NIHAO. We found that UDGs cover a broad distribution, ranging from dispersion to rotation
supported galaxies, with similar abundances in both regimes. We demonstrated that the alignment
of the infalling baryons into the protogalaxy at early z is the principal driver of the z=0 stellar
kinematic state: pressure supported isolated UDGs form via mis-aligned gas accretion while rotation
supported ones build-up their baryons in an ordered manner
On the dark matter content of diffuse galaxies.
In this work, coauthored by observational and theoretical researchers at the host institution and led by Dr. Trujillo,
we haved carried out a careful analysis of all existing data and showed that for this galaxy, the data
consistently indicated a much shorter distance (13 Mpc) than previously indicated (20 Mpc). With
this revised distance, the galaxy appears to be a rather ordinary low surface brightness galaxy with
plenty of room for dark matter, with a minimum halo mass >109 Msun.
On the stellar populations, age and metallicity of LSBs/UDGs.
In this observational work led by Dr. Ruiz-Lara and colleagues at the host institution, we have performed one of the most
complete characterizations of the stellar component of UDGs to date using deep optical
spectroscopic data from OSIRIS at Gran Telescopio CANARIAS (GTC). We find that their rotation
properties are compatible with dwarf galaxies. We have concluded that the UDGs in our sample are
extended dwarfs whose properties are likely the outcome of both internal processes, such as bursty
SFHs and/or high-spin haloes, as well as environmental effects within the Coma cluster.
On the environmental dependence of diffuse galaxies.
This work has been led by theoretical colleagues at The Hebrew University of Jerusalem (Dr.
Fangzhou and Dekel), with me as co-author. We studied ultra-diffuse galaxies (UDGs) in zoom in
cosmological simulations, seeking the origin of UDGs in the field versus galaxy groups. We found
that while field UDGs arise from dwarfs in a characteristic mass range by multiple episodes of
supernova feedback (as in my original paper Di Cintio et al.2017) group UDGs may also form by
tidal puffing up and they become quiescent by ram-pressure stripping.
Aside from scientific publications, the results of the DIGESTIVO project were disseminated and
presented in 12 seminars, conferences and workshops, and in several outreach activities such as
‘The Researchers Night of Macaronesia’ (La Laguna, Spain, 2018), through virtual visits to spanish
schools during the day of girls and women in science (Habla con Ellas: Mujeres en Astronomía,
2019) and at university fairs, such as the event ‘La ciencias en porciones’, (La Laguna, Spain, 2020).
Furthermore, I have organized 5 international conferences during the fellowship period, 2 of which
directly related to the project, such as ‘The Bewildering Nature of Ultra-diffuse Galaxies’, a fully
funded workshop at Lorentz Center, Leiden, in 2018.
