Dark galaxies: Probing the ΛCDM cosmological model on unprecedented scales

Projektbeschreibung

Neue Erkenntnisse über dunkle Materie und die Entstehung von Zwerggalaxien

Das Lambda-Modell der kalten dunklen Materie (Lambda-CDM) ist die jüngste Version unseres Wissensstands über den Kosmos. Es besagt, dass unser Universum hauptsächlich aus dunkler Materie besteht. Zudem liefert es eine vernünftige Erklärung für die Menge, die Struktur und die Anhäufung von Halos aus dunkler Materie, jenen Regionen, in denen sich Galaxien bilden. Ungeachtet seines Erfolgs ist jedoch immer noch unklar, ob das Modell die Entstehung von Zwerggalaxien genau beschreiben kann. Das EU-finanzierte Projekt DarkGalaxies wird nun das Lambda-CDM-Modell in bislang noch nie erreichten kleinen Größenordnungen untersuchen, wobei eine fundamentale Vorhersage des Modells zugrunde gelegt wird: die Existenz naher dunkler Galaxien. Das Verständnis der Beschaffenheit der dunklen Materie und der Strukturbildung in kleinen kosmischen Maßstäben könnte anhand der Projektergebnisse verbessert werden.

Ziel

The currently favoured Lambda-Cold-Dark-Matter (ΛCDM) cosmological model makes specific predictions about the
abundance, structure and clustering of dark matter halos (DMHs), the sites where galaxies form. These predictions are
accurate at describing large scale observations. On smaller scales, the agreement between ΛCDM and observations of
dwarf galaxies is unclear because (i) the structure of DMHs depends on particularities of different galaxy formation models,
and (ii) observations of dwarfs suffer from sizable uncertainties. Is ΛCDM successful on small scales? A definite answer to
this major open question may either reveal the nature of DM or change dramatically our understanding of structure formation
in the Universe. My research will deliver the foundations to probe ΛCDM on unprecedented small scales by exploiting a
fundamental prediction of the model: the existence of nearby DM-dominated “dark” galaxies (so-called RELHICs). RELHICs
are pristine collapsed DMHs that contain sufficient gas leftover from the epoch of reionization to recombine and emit
radiation that can be observed in 21 cm (or recombination lines) but without becoming self-shielding and forming stars.

Firstly, I will develop and analyse high-resolution hydrodynamical simulations performed with state-of-the-art numerical
codes that include cutting-edge galaxy formation and radiative-transfer (RT) models to predict the abundance and clustering
of RELHICs. Secondly, I will design robust survey strategies targeted at detecting RELHICs with current and upcoming
observing facilities (e.g. ALMA, FAST, MEERKAT, WALLABY). The detection and characterization of REHICs will offer an
unprecedented and clean probe to ΛCDM on scales that have not yet been probed.

My extensive expertise in numerical simulations, cosmology and galaxy formation, combined with that of Prof. Michele
Fumagalli in RT and physics of the interstellar medium will enable me to materialize my predictions into observational probes.