Dynamical Tracers of the Nature of Dark Matter

18 Feb 2025, 10:00 → 19 Feb 2025, 19:00 Europe/Rome

María Benito, Oscar Straniero (Istituto Nazionale di Astrofisica (INAF))

This online workshop is intended for extensive discussions on the distinctive features in galactic dynamics that imprint the different empirically allowed properties of dark matter, such as its mass (e.g., ultra-light, axions, WDM-like, WIMP-like, PBHs) or interaction type (FDM, SIDM, CDM). Our goal is to further investigate the possibility of leveraging galactic dynamics as a tool to probe the nature of dark matter, with a special emphasis on understanding how particular dynamical tracers in galaxies can be used to constrain specific general properties of dark matter.

The workshop will last two days, each with three invited talks (30 minutes per talk). Each day will conclude with a one-hour discussion session, bringing the total duration per day to 2.5 hours.

Tuesday 18 February

10:00 → 10:30 Is gravity the only dark matter interaction that matters in the physics of galaxies?

One of the most relevant problems in Physics is to identify new particles beyond the Standard Model, which can fit the properties of the cosmological dark matter. Despite decades of searching for candidates, the nature of dark matter remains a mystery even though its role in explaining cosmic structure formation has become progressively more fundamental. Analysing the properties of the galaxy population is arguable among the most promising short-term avenues to look for clues to solve the dark matter enigma. In this talk, I will present a broad overview of the status of the allowed impact of new dark matter physics (i.e., beyond its gravity) in the physics of galaxies.

Speaker: Jesús Zavala

JesusZavala_DMtracers_2025.pdf

10:30 → 11:00 Dark matter density profiles on galactic and sub-galactic scales

The less massive galaxies, such as dwarf galaxies are ideal laboratories for exploring the fundamental nature of dark matter because they are largely dark matter-dominated systems. Their structural and dynamical properties provide unique opportunities to place constraints on dark matter distributions on small scales. However, uncovering their dark matter distributions requires detailed kinematic data from plenty of stellar samples and a robust understanding of the systematic uncertainties in dynamical modeling.
In this talk, I will present current efforts to constrain the dark matter profiles of the dwarf galaxies using dynamical analyses of the available data. I will also discuss future prospects for these studies, highlighting anticipated advances in data quality and dynamical modeling.

Speaker: Kohei Hayashi

11:00 → 11:30 Gravitational dynamical probes of the nature of dark matter in galaxies

The hypothesis of dark matter was introduced to address observations associated with gravitational dynamics in cosmology and in galaxies. It seems natural to seek new observables that could shed light on dark matter within the same ballpark of minimal gravitational interactions, in dark matter-dominated systems. I will discuss some attempts of this type focusing on galaxies, and covering lines of research including gravitational lensing, stellar kinematics, and globular cluster dynamics.

Speaker: Kfir Blum

11:30 → 12:30 OPEN DISCUSSION

Questions for the speakers from, comments, suggestions, perspectives....

Wednesday 19 February

15:30 → 16:00 Tidal stripping and the fate of dark substructures of the Milky Way

Measurements of the presence or the absence of dark substructures of the Milky Way -- e.g. through their impact on stellar streams -- are a powerful probe of the nature of dark matter. However, the necessary theoretical predictions are tricky, since subhaloes of the Milky Way get significantly diminished through tidal stripping -- which depends on aspects that may be unresolved or unmodelled in most cosmological simulations.
In this talk, I will give an overview over the theory, the modelling and the pitfalls of tidal stripping and tidal shocks. Further, I will discuss a novel analytical approach, based on the conservation of actions, that allows to predict the long-term fate of substructures from first principles.

Speaker: Jens Stücker (Universität Wien)

JensStuecker_2025_dyntracers.pdf

16:00 → 16:30 What can dwarf galaxies reveal about the nature of dark matter?

I will review constraints on dark matter (DM) properties from dwarf galaxy luminosity function and stellar velocity dispersion measurements. These data constrain DM models that affect halo abundances (e.g. warm, fuzzy, and interacting DM) and density profiles (e.g. fuzzy, self-interacting, and primordial black hole DM). I will conclude with forecasts for upcoming dwarf galaxy surveys, including from the Vera C. Rubin Observatory, highlighting the potential to combine with strong lensing observations from JWST.

Speaker: Ethan O. Nadler

Nadler Dynamical Tracers 2025.pdf

16:30 → 17:00 Motivations for self-interacting dark matter and its viable signatures

This talk will summarize the motivations for self-interacting dark matter models from galactic-scale observations, current constraints from Milky Way satellites and galaxy clusters, and end with signatures of viable models in gravitational lensing images.

Speaker: Manoj Kaplinghat

Kaplinghat-Dyn-Tracers-Feb2025.pdf

17:00 → 18:00 OPEN DISCUSSION