For over two decades, there has been a discrepancy between the number of predicted sub-haloes in CDM simulations and those actually observed around the Milky Way. Gravitational lensing provides a clean method for probing directly the projected matter density distribution of galaxies, even at low mass-scales, as a sub-halo can significantly modify the image magnifications, and hence their observed flux-ratios. Therefore, anomalous flux-ratios are a key method in exploring the sub-halo population in distant massive galaxies, but this method is currently limited by the small number of systems (only seven) with reliable flux-ratio measurements. Here, we request 60 h of HSA time to image 5 radio-quiet gravitational lenses where we have previously detected faint radio emission with the VLA. These follow-up observations will i) test the detectability of faint radio emission at VLBI-scales, ii) use the observed magnifications of the lensed images to search for deviations from a smooth lensing mass model, and iii) combine the results with our current sample to constrain the thermal relic mass of the dark matter particle.
Name | Institution |
---|---|
Di Wen | Kapteyn Astronomical Institute |
Simona Vegetti | Max-Planck-Institut für Astrophysik |
Hannah Stacey | Kapteyn Astronomical Institute; Max-Planck-Institut für Astrophysik |
John McKean * | Netherlands Institute for Radio Astronomy; Kapteyn Astronomical Institute |
GBT Operator | Green Bank Observatory |
* indicates the PI