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We report results of soft gamma-ray observations of the ultraluminousinfrared galaxies Arp 220, Mrk 273, and Mrk 231 in order to test whether theinfrared radiation from these sources originates from buried active galacticnuclei (AGNs). Only upper limits are measured, implying that the emergent softgamma-ray luminosities are 1-2 orders of magnitude smaller than the infraredluminosities. Monte Carlo simulations of radiation transport through tori areused to infer the minimum column densities $N_H$ required to block transmissionof soft gamma-rays from a buried AGN, assuming that spectra of AGNs in suchsources are similar to those of radio-quiet quasars. Lack of measured gamma-rayemission provides no supporting evidence for the existence of buried AGNs inthese galaxies, but is consistent with an origin of the infrared luminosityfrom starburst activity.Comment: 12 pages; Latex; 2 encapsulated postscript figures. To appear in  Astrophysical Journal Letter

OSSE Observations of the Ultraluminous Infrared Galaxies Arp 220, Markarian 273, and Markarian 231