Project Description
Project F6 studied dust in the circumgalactic medium of galaxies and its connection to their dark-matter halos, using wide-field imaging data from the Kilo-Degree Survey (KiDS). The project was completed at the end of Phase 1 of CIM. Its main results are:- A new joint-probe analysis combining galaxy-galaxy lensing and magnification-induced magnitude shifts, which constrains the dark-matter and dust masses of galaxy halos simultaneously. It was validated on realistic simulations (MICE2) and applied to KiDS data.
- The first systematic comparison of three methods to detect dust in galaxy halos. Position-color correlation functions turned out to be robust even at high redshift, whereas the purely color-based method is affected by systematic biases at small separations.
- The detection of extended dust halos in emission out to about 20 kpc and in absorption beyond 100 kpc.
- The first direct demonstration via magnification that galaxies with high specific star-formation rates have lower dark-matter masses but up to four times higher dust-to-stellar mass ratios, showing that feedback processes enrich galaxy halos with baryonic material.
F6 contributed to the fifth data release of KiDS and to the final KiDS-Legacy cosmology analyses, and it delivered galaxy properties and halo estimates to projects A1, A2, A4 and F5. Its insights into star formation in dwarf galaxies help focus the work of project A2 in Phase 2.
