Letters of Intent received in 2016

LoI 2018-1922
GA Symposium: 21st Century Astrometry: crossing the Dark and Habitable frontiers

Topics

• Dwarf Galaxies: internal dynamics of Milky Way companions;
• HVS: probing the triaxiality of the Milky Way DM Halo;
• Disc perturbations due to DM clumps;
• Exoplanet detection: from long period Jupiters to Habitable Exo-earths;
• Exoplanet characterisation: dynamics, chaos and orbital determination;
• Astrometric signatures of Black Holes: microlensing, shadows, hot-spots, and gravitational effects;
• Equation of state of NS: probing the most extreme states of matter;
• Trigonometric parallaxes for H0 determination: Cepheids, RR-Lyraes and other steps of the distance ladder;
• New astrometric instruments and technologies: space mission concepts and ground based astrometry in the age of the ELTs;
• Modern Statistical Methods for astrophysical information extraction from Astrometric data: signal processing, bayesian methods, optimization strategies.

Rationale

Astrometry is facing new challenges and crossing new frontiers in its exploration of the  Universe, thanks to an increased level of precision and accuracy. Building on the ESA/Gaia space mission’s legacy, new space missions capable of performing astrometry measurements in the micro-arcsecond regime would bring the faint Universe at our fingertips.  Armed with such a level of astrometry precision, ground-breaking dark matter studies will become feasible while an exhaustive census of exoplanets will be finally doable. Astrometry, dark matter and exoplanets will thus become increasingly hot topics in astronomy and cosmology in the forthcoming future. It is therefore timely to organize an IAU Symposium that can bridge these communities, to address some of the most profound questions of modern Science together.

About 80% of the matter in our Universe is made of Dark Matter (DM). Its physical properties are unknown but astrometry could provide new insights by probing its kinematical and dynamical signatures. Astrometric surveys such as ESA/Gaia may detect new ultra-faint dwarf galaxies. Future astrometric space missions, such as Theia, will be able to probe the internal proper motions in faint and ultra-faint dwarf galaxies and reveal the nature of dark matter by measuring its distribution in their cores. Measurements performed with such experiments will provide new means to test inflation models, thanks to the gravitational perturbations that primordial objects (black holes, DM lumps) imprint on other objects characteristics (whether it is perturbations of the Milky Way disk or the light from stars). Astrometry will be key to reveal the darkest and smallest objects, a few years from now.

Astrometry is also the least biased technique for exoplanet detection and for orbital characterisation. ESA/Gaia astrometry will enable the detection of thousands of Jupiter-like exoplanets far from us, and very long period planets. It is also unique in providing 3D orbits of systems, irrespectively of their inclination, providing an unbiased picture of the three dimensional architectures of planetary systems, like no other approach. The next generation of space-based astrometric observatories is expected to cross the microarcsecond barrier, towards the hundreds of nano-arcseconds regime. This will enable a complete detection-census of 1 MEarth planets inside the habitable zone of our nearest FGK stars. Moreover, for these planetary systems, future astrometric missions will allow reliable inferences on the planetary masses, and its full characterization (period, inclination, semi-major axis, eccentricity, angles and ephemeris), thus paving the way for future exobiology missions.

The creation of strong ties between the Dark Matter, Exoplanets and Astrometry communities will ensure progress and increase fundamental knowledge. With forthcoming ESA/Gaia data releases and exciting new space mission proposals, such as Theia, the timing is opportune to organize a joint Symposium between these three different communities. We propose an IAU Symposium to shape the community through the use of one of the most rigorous area of Astronomy, Astrometry, to answer the most fundamental questions that modern Science is facing: What is the nature of Dark Matter? Is there life elsewhere in the Universe and, in particular, near us?

NOTE: Although there is only one field in the IAU/UAI webform to declare the coordinating division, Division A and F wish to be the coordinating divisions for the present proposal.