The LMC geometry and outer stellar populations from early DES data

摘要: The Dark Energy Camera has captured a large set of images as part Science Verification (SV) for the Survey. SV footprint covers lar ge portion outer Large Magellanic Cloud (LMC), providing photometry 1.5 magnitudes fainter than main sequence turn-off oldest LMC stel population. We derive geometrical and structural parameters various stellar populations in disk. For distribution all stars, we find an inclination $i=-38.14^{\circ}\pm0.08^{\circ}$ (near side North) position angle line nodes $\theta_0=129.51^{\circ}\pm0.17^{\circ}$. that stars younger $\sim 4$ Gyr are more centrally concentrated older stars. Fitting projected exponential disk shows scale radius old is $R_{>4 Gyr}=1.41\pm0.01$ kpc, while population $R_{<4 Gyr}=0.72\pm0.01$ kpc. Howe ver, spatial deviates significantly from model. suggests truncation $R_{t}=13.5\pm0.8$ If this dominated by tidal field Galaxy, $\simeq 24^{+9}_{-6}$ times less massive encircled Galactic mass. By measuring Red Clump peak magnitude comparing with best-fit LM C model, warped thicker regions north centre. Our findings may either be interpreted flared outskirts, or evidence spheroidal halo component