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Dark Matter and Stars in the Dark Ages

Final Report Summary - DAMIDA (Dark matter and stars in the dark ages)

The DAMIDA project aimed to understand the effects of a popular class of dark matter (DM) candidates, the weakly interacting massive particles (WIMPs) over the first generation of stars (population III) formed in the Universe, after the cosmological epochs. The main planned goals were to properly model the effects of WIMP DM over the first stars in order to gain higher insight on the behaviour of the resulting, exotic population of objects, in order to use them as possible probes of the WIMP DM parameter space. Planned goals have been achieved within the timescales, and several spin-off activities have been carried on in addition to the planned ones.

During the DAMIDA project, started in November 2009, the following scientific goals, as proposed in the original DAMIDA workplan proposal, have been achieved:

- The population III protostellar phase, sensible only to self-annihilation of WIMPs (and therefore to the self-annihilation cross section) has been addressed through one-dimensional simulations of the collapsing gas cloud.
- The observational signatures of both DM-sustained proto-stellar cores, and DM-fuelled star (the latter sensitive to the scattering cross section between WMPs and baryons) have been addressed, as well as the feasibility of observational campaigns aimed at finding such objects. The properties potentially observable through the James Webb Space Telescope (JWST, recently fully funded by the United-States congress) have been studied.
- Three-dimensional (3D) simulations to explore the proto-stellar phase lead by the annihilation of DM have been set-up, in collaboration with groups of expertise in this field.

Research on themes connected to the DAMIDA project have been carried on at the same time:

- DM and stars:
The effects of non-annihilating, yet weakly interacting particles (e.g. asymmetric DM) have been addressed: constraints on DM parameters from the induced neutrino flux modification from the Sun have been obtained, constraints of astrophysical nature competitive with the ones from direct detection on the Earth. In the currently submitted paper, we have studied the behaviour of main sequence (amongst them massive ones, such as Population III stars) stars in environments richer of DM than our Sun's. This leads to very strong signatures on the star's evolution and observational properties, and could be used to place even more stringent constraints on ADM properties.

- DM in the CMB:
The strongest astrophysical constraints on DM annihilation properties come from signature on the cosmic microwave background (CMB). Such strong constraints have been updated in light of the recent seventh data release of the WMAP experiment. Forecasts have been drawn in light of the forthcoming PLANCK satellite data release.
- Gravitational signatures of DM:
Using the most up-to-date microlensing observations, it is possible to accurately measure the stellar mass in the region of our Galaxy innermost of the Sun. In best constraints on the distribution of DM in our Galaxy, as well as on the DM density at the Sun's location, have been obtained by combining microlensing observations with those of the rotation curve of the Milky Way.