High-resolution mapping of dust via extinction in the M31 bulge

摘要: We map the dust distribution in central 180" (~680 pc) region of M31 bulge, based on HST/WFC3 and ACS observations ten bands from near-ultraviolet (2700 A) to near-infrared (1.5 micron). This large wavelength coverage gives us great leverage detect not only dense dusty clumps, but also diffuse molecular gas. fit a pixel-by-pixel spectral energy distributions construct high-dynamic-range extinction with unparalleled angular resolution (~0.5" , i.e., ~2 sensitivity (the uncertainty, \delta A_V~0.05). In particular, data allow directly fractions starlight obscured by individual hence their radial distances bulge. Most these clumps seem be located thin plane, which is tilted respect disk appears face-on. convert into mass surface density compare it that derived emission as observed Herschel . The masses two maps are consistent each other, except low-extinction regions, where inferred tends underestimated. Further, we use simulations show our method can used measure Virgo cluster early-type galaxies an accuracy within factor ~2.