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Abstract: We report the results from our analysis of {\it Suzaku} XIS 0.5-10 keV andHXD-PIN 15-40 keV observations of five well-known local ULIRGs: {\em IRAS}F05189-2524, {\em IRAS} F08572+3915, Mrk 273, PKS 1345+12, and Arp 220. The XISobservations of F05189-2524 and Mrk 273 reveal strong iron lines consistentwith Fe K$\alpha$ and changes in spectral shapes with respect to previous {\itChandra} and {\it XMM-Newton} observations. Mrk 273 is also detected by theHXD-PIN at $\sim$1.8-$\sigma$. For F05189-2524, modeling of the data from thedifferent epochs suggests that the change in spectral shape is likely due tothe central source switching off, leaving behind a residual reflectionspectrum, or an increase in the absorbing column. An increase in the coveringfraction of the absorber can describe the spectral variations seen in Mrk 273,although a reduction in the intrinsic AGN luminosity cannot be formally ruledout. The {\it Suzaku} spectra of Mrk 273 are well fit by a ~94% coveringfraction model with a column density of $\sim10^{24}$ cm$^{-2}$. Theabsorption-corrected log$L { m 2-10 keV}$ - $L { m IR}$ ratio is consistentwith those found in PG Quasars. The 0.5-10 keV spectrum of PKS 1345+12 and Arp220 seem unchanged from previous observations and their hard X-ray emission isnot convincingly detected by the HXD-PIN. The large column density derived fromCO observations and the large equivalent width of an ionized Fe line in Arp 220can be reconciled by an ionized reflection model. F08572+3915 is undetected inboth the XIS and HXD-PIN, but the analysis of unpublished {\em Chandra} dataprovides a new measurement at low energies.

Autor: Stacy H. Teng, Sylvain Veilleux, Naohisa Anabuki, Charles D. Dermer, Luigi C. Gallo, Takao Nakagawa, Christopher S. Reynolds, D.B


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