It is well established that SNe Ia are caused by the thermonuclear explosion of CO white dwarfs. However, there is still a lot of uncertainty about their progenitor channel(s) and explosion mechanism(s). "Bumps" in the early light curves of SN Ia were predicted to occur when the SN ejecta shocks the non-degenerate binary companion (Kasen 2010), thus providing evidence for the single-degenerate (SD) progenitor channel. However, after several examples of these bumps were found, it is still debated if this is indeed evidence for the SD channel, or whether other progenitor channels and explosion mechanism can also cause such bumps.

Massive early-type galaxies (ETGs) represent the final stages of galaxy evolution within the hierarchical formation framework. They typically host central super-massive black holes (BHs), which co-evolve with their galaxies and offer an excellent opportunity to study their joint growth. Using integral-field spectroscopic data (MUSE, SINFONI) and a combined approach of stellar population modelling and triaxial Schwarzschild orbit-based modelling, we investigated the BH masses and stellar orbital structures of four massive ETGs. Our models account for radially varying stellar mass-to-light ratios driven by gradients in the initial mass function (IMF). From stellar population analysis, we detect super-Salpeter IMFs in galaxy centers and find that IMF variations can change BH mass estimates by 10–30% compared to constant-IMF assumptions. In this talk, I will present our results on stellar populations and SMBHs in ETGs, highlighting how they are linked. I will also discuss how different orbital families shape observed kinematics, trace the assembly histories of ETGs, and reveal the impact of central SMBHs.

Isotope/Isotopologue ratios have been claimed as
good indicators of planet formation scenarios and
atmospheric evolution. They have been widely studied in
our Solar System, providing information on the planet
formation conditions and the atmospheric compositions that
are currently observed. In contrast, very little is
known about isotope/isotopologue ratios in exoplanets, with
scarce observational studies having been conducted to
date. In this context, during my PhD I developed an
isotopologue-sensitive cross-correlation technique that has leaded to
the detection of molecules in JWST/NIRSpec transmission spectra at
medium spectral resolution, including novel hints of detection of
isotopologues. Studies of isotope/isotopologue ratios in
exoplanets are still in their infancy, but this is
now an emerging field with a lot of potentials
providing an observational constraint on when, where and
how an exoplanet formed in the primordial protoplanetary
disk.

The surface brightness fluctuations (SBF) technique is among the most precise distance indicators across a

range from a few to several hundred Mpc. In this informal discussion, I will highlight the key features of the SBF

methodology, focusing on the origin of the SBF signal and its standardization for distance measurements.

Modern surveys of the transient sky catch stellar explosions as early as a few hours after shock emergence. In Type II supernovae (SNe) from

red-supergiant star explosions, these early spectra sometimes show narrow lines broadened by electron scattering rather than the expected Doppler-broadened

profiles from fast expanding ejecta, indicating the presence of dense and extended circumstellar material (CSM) around the exploding star. In such cases,

prompt high-cadence high-resolution and high S/N observations can catch the rapid evolution of this CSM prior to being shocked, revealing its acceleration

by the SN radiation from its original velocity to thousands of km/s. In this discussion, I will show recent observations that revealed this process and numerical

simulations that support this interpretation. Future high cadence UV surveys will allow for considerable progress on that topic and help reveal the surface

properties of red supergiants.

White dwarf binaries are expected to be the most numerous sources in LISA. Models predict that about 10 000 sources will be

individually resolved and that millions of others will combine into an unresolved foreground.  The shape and amplitude of the background

as well as the orbital frequencies of the individual detections will be very informative on the evolution of low mass binary stars and also the

shape of the Milky Way. It was recently shown that extragalactic white dwarfs will also create a background. In thediscussion I will show what

we currently know about these signals and how their combined information can help us understand binary evolution.

With the simple mind of a mathematician, I almost ran away from the lab when I started coding my SED fitter and encountered the "beautiful mess" of: magnitudes, photometric systems and filters (exact same name for two filters with remarkably different transmission curves), photon vs energy counting, etc. And even when finally the fluxes were in physical units... here comes the debate on what is the suitable lambda to use (for plotting!! :-)) and the strong opinions regarding fluxes and
density fluxes... Little did I understand at that point that it is not that astrophysicist like to complicate their lives (don't we?), but that there is a fascinating combination of historical and technical reasons that prevent having a "clean" and homogeneous way to go from what is observable to SI traceable flux measurements. In this ID I will go
briefly on how we calibrate now, why it is not enough for some cases and interesting initiatives in this context like the Landolt Satellite Project.

The shaping of planetary nebulae on their evolution from asymptotic giant branch (AGB) circumstellar envelopes (CSE)

to their final, most often axisymmetrical, form is still a process with many unknown details. For this, the study of the transition

objects, pre-planetary nebulae (pPNe), is key to understand the whole shaping process. After creating a detailed 3-D

morpho-kinematical model of M1–92, a pPN with one of the richest chemistry, we obtain a full description of the nebula’s

physical and chemical properties, finding robust discrepancies in the 12C/13C isotopic ratio across structures depending on

their age and linking it to its ongoing shaping process.

The number of applications to graduate programs is growing extremely fast without a significant increase in the number of available positions, making it harder to run an admissions process that is fair and efficient. Last week, the AAS Graduate Admissions Task Force (GATF) released a summary of their final report, which includes recommendations aimed at improving the current state of graduate admissions in astronomy. One of the topics they addressed is the use of recommendation letters, which were also the focus of a recent open letter from early-career researchers to the GATF. In this ID, I’ll summarise the key points from both documents, focusing on the role of recommendation letters, with the aim to discuss together whether, in their current form, they are truly effective tools for evaluating students fairly and equitably.

The Epoch of Reionization (EoR) marks a critical phase in the evolution of the universe, yet remains poorly understood. While star-forming galaxies are acknowledged as key contributors to ionized bubble formation, the extent of contribution from alternative sources such as shock-heated ISM or emission from X-ray binaries remains unclear. In this study, we employ cosmological radiative transfer simulations to explore the impact of diverse sources on intergalactic medium (IGM) properties. Our focus is not merely data fitting, but rather understanding whether the interpretation of Lyman-ɑ forest observations is changed by using theoretical models incorporating non-stellar sources.

Moving beyond the EoR, the study explores the Epoch of Helium Reionization (HeEoR), when HeII transitions to HeIII (𝑧 ≲ 4), predominantly driven by quasar-produced ionizing photons. Using the parametrization of the quasar luminosity function (QLF) proposed by Shen et al. (2020), we examine its implications for recent observations suggesting an extended HeEoR.

Finally, the study delves into the origin of UV luminosity function (UVLF) variability, potentially explaining the unexpectedly high abundance of UV-bright galaxies at extreme redshifts observed by JWST. By exploring the stochasticity of star formation and dust attenuation driven by different implementations of supernova feedback, we provide insights into the UVLF's evolution and its link to early galaxy morphologies. This presentation will highlight these findings and their broader implications for our understanding of cosmic reionization.

Type Ia and other peculiar supernovae (SNe) are thought to originate from the thermonuclear explosions of white dwarfs (WDs). Some of the proposed channels involve the ejection of a partly exploded WD (e.g. Iax SN remnant) or the companion of an exploding WD at extremely high velocities (>400 km s^-1). Characterization of such hyper-runaway/hypervelocity (HVS) WDs might therefore shed light on the physics and origins of SNe. Here we analyse the Gaia DR3 data to search for HVS WDs candidates and peculiar sub-main-sequence (sub-MS) objects. We retrieve the previously identified HVSs and find 46 new HVS candidates. Among these we identify two new unbound WDs and two new unbound sub-MS candidates. The remaining stars are hyper-runaway WDs and hyper-runaway sub-MS stars. The numbers and properties of the HVS WD and sub-MS candidates suggest that extreme velocity ejections (>1000 km s^-1) can accompany at most a small fraction of type Ia SNe, disfavouring a significant contribution of the D6-scenario to the origin of Ia SNe. The rate of HVS ejections following the hybrid WD reverse-detonation channel could be consistent with the identified HVSs. The numbers of lower-velocity HVS WDs could be consistent with type Iax SNe origin and/or contribution from dynamical encounters. We also searched for HVS WDs related to known SN remnants but identified only one such candidate ( https://ui.adsabs.harvard.edu/abs/2023MNRAS.518.6223I/abstract).

I will describe an extended, ongoing observational effort aimed at discovering and studying the properties of a large sample of dual and strongly lensed QSOs at sub-arcsec separations. With these data, we will be able to address numerous scientific questions, including testing several previously untested predictions of galaxy/SMBH evolution models, developing more accurate predictions of massive BH merger rates and LISA GW event rates, and studying dark matter distribution in the central kpc of lensing galaxies. We select candidates using Gaia and Euclid data and follow up on targets with various space- and ground-based telescopes, including an ESO large program with VLT/MUSE, to obtain spatially resolved spectroscopy. This has produced, for the first time, a substantial sample of confirmed dual AGN beyond the local universe, and the most compact quadruply lensed QSO ever discovered.

The Gaia mission has recently completed its last scientific observations. This is a good time to reflect on why this is a great mission, with one of the worst data access policy. I will provide a biased view on some of the revolutionary results it led to and provide a brief overview of what is still planned for the young and patient people in the audience.

Galaxies don’t just form stars—they continuously exchange gas with their surroundings. This circumgalactic medium (CGM) is a turbulent, magnetized mix of gas shaping how galaxies evolve. Observations reveal a multiphase CGM, but capturing this complexity in simulations is a major challenge due to small lengthscales involved. 

In this talk, I will explore:

- Why small-small effects in multiphase astrophysical gas are important?

- How turbulence & magnetic field shape CGM structure?

- How a new subgrid model can bring these small-scale effects to large-scale cosmological simulations?

By improving how we model the CGM, we can better interpret observational data and refine our understanding of galaxy evolution. Let's talk about how we can make that happen.

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The Informal Discussion is in-person only, and held in the ESO library.

At around 10:30, we will continue in the discussion at science coffee.

Fellowship selection processes in academia are designed to reward scientific excellence, yet research suggests that bias—especially unconscious bias—can subtly influence evaluation outcomes, often disadvantaging underrepresented groups. In this informal discussion, we will first explore the impact of bias on selection processes, with a particular focus on hidden, unconscious biases that shape decision-making without evaluators even realizing it We will then examine how prestigious fellowship programs, including Marie Skłodowska-Curie Actions (MSCA), the European Research Council (ERC), and other major astronomy and astrophysics fellowships, attempt to mitigate these biases. Using insights from peer-reviewed studies and official funding reports, we will analyze how different selection panels confront issues such as Halo bias, linguistic bias, and cognitive bias.

I will summarize 3 recent papers about galaxies at z>=10, and the Ho tension. I will then discuss, without offering solutions, whether such results place the standard Cosmological model en course towards the rocky shores of a funtamental(s) crisis.