Baryonic feedback measurement from KV450 cosmic shear analysis

While baryonic feedback is one of the most important astrophysical systematics that we need to address in order to achieve precision cosmology, few weak lensing studies have directly measured its impact on the matter power spectrum. We report measurement of the baryonic feedback parameter with the constraints on its lower and upper limits from cosmic shear.We use the public data from the Kilo-Degree Survey and the VISTA Kilo-Degree Infrared Galaxy Survey spanning 450 deg2. Estimating both cosmological and feedback parameters simultaneously, we obtain Ab= 1.01+ 0.80-0.85 which shows a consistency with the dark matter-only (DMO) case at the ~1.2σ level and a tendency toward positive feedback; the Ab=0 (0.81) value corresponds to the DMO (OWLS AGN) case. Despite this full constraint of the feedback parameter, our S8 (≡σ8 √m/0.3 ) measurement ( 0.739+0.036-0.035) shifts by only ~6% of the statistical error, compared to the previous measurement. When we assume the flat ΛCDM cosmology favored by the Nine-Year Wilkinson Microwave Anisotropy Probe (Planck) result, the feedback parameter is constrained to be Ab =1.21+0.61- 0.54( 1.60+0.53-0.52), which excludes the DMO case at the ~2.2σ (~3.1σ) level.