Imaging and Nulling with the SPACE INTERFEROMETER MISSION

We present numerical simulations for a possible synthesis imaging mode of theSpace Interferometer Mission (SIM). We summarize the general techniques thatSIM offers to perform imaging of high surface brightness sources, and discusstheir strengths and weaknesses. We describe an interactive software packagethat is used to provide realistic, photometrically correct estimates of SIMperformance for various classes of astronomical objects. In particular, wesimulate the cases of gaseous disks around black holes in the nuclei ofgalaxies, and zodiacal dust disks around young stellar objects. Regarding thefirst, we show that a Keplerian velocity gradient of the line-emitting gaseousdisk -- and thus the mass of the putative black hole -- can be determined withSIM to unprecedented accuracy in about 5 hours of integration time for objectswith H_alpha surface brigthness comparable to the prototype M 87. Detectionsand observations of exo-zodiacal dust disks depend critically on the diskproperties and the nulling capabilities of SIM. Systems with similar disk sizeand at least one tenth of the dust content of beta Pic can be detected by SIMat distances between 100 pc and a few kpc, if a nulling efficiency of 1/10000is achieved. Possible inner clear regions indicative of the presence of massiveplanets can also be detected and imaged. On the other hand, exo-zodiacal diskswith properties more similar to the solar system will not be found inreasonable integration times with SIM.Comment: 28 pages, incl. 8 postscript figures, excl. 10 gif-figures Submitted to Ap