Exploring the Nature of the Hard X-ray/ Soft Gamma-ray Emission of Cen A James Rodi1, Elisabeth Jourdain2,3, Jean-Pierre Roques2,3 1INAF-IAPS, Rome, Italy; 2Universite de Toulouse, Toulouse; 3CNRS, Toulouse Above: Cen A 20—40 keV and 100- 200 keV light curves on revolution timescale. SPI (black) and ISGRI (red). Sides: Photon index vs 50 keV flux for obs close in time with SPI (left) and ISGRI (right). Best-fit to a constant photon index shown as red dashed line. Centaurus A Introduction: As one of the brightest radio-loud active galactic nuclei (AGNs) in the hard X-ray sky (Beckmann et al. 2009), Centarus A (Cen A) has been observed by numerous missions since its first detection in 1969 (Bowyer et al. 1970). Results have shown that the spectral shape does not vary with flux (Jourdain et al. 1993; Rothschild et al. 2006; Beckmann et al. 2011; Rothschild et al. 2011; Burke et al. 2014). Consequently, one would expect reported spectral parameters for Cen A to be similar across time and instruments. Yet that has not been the case as there has been a lack of consistency in the values, which has made interpreting the origin of the hard X-ray/soft gamma-ray emission difficult. From the past ∼30 years, the main disagreement is over the presence of spectral curvature at high energies. In general, X-ray analyses favor models without spectral curvature below ~1 MeV (Rothschild et al. 2006, Rothschild et al. 2011, Furst et al. 2016). However, analyses up to soft gamma-rays show evidence of curvature, though where the curvature is varies (Jourdain et al. 1993, Steinle et al. 1998, Beckmann et al., 2011, Burke et al. 2014). The existence of curvature and where it is is critical to understanding the emission process at work in Cen A. Additionally, recent Swift/BAT results show spectral variability after 2013 with the source spectrum steeper when the source is brighter and harder when the flux is lower (Rani et al. 2022). Data Analyses: We analyzed SPI and ISGRI archival data and observations from the current AO to span the full INTEGRAL mission, revolution 48- 2539 in the ~20 keV – 2 MeV energy range using SPIDAI and the most recent version of OSA, respectively, for a total exposure time of ~ 5 Ms each. During this time, Cen A underwent a range of fluxes that enable searches for spectral-flux variability and also investigate the presence of high-energy spectral curvature. ABSTRACT: Despite decades of observations, the nature of the hard X-ray/soft gamma-ray emission of Cena, the brightest radio-loud AGN in the hard X-ray sky, is still unclear. The two main competing models are thermal Comptonization and synchrotron self-Compton emission. They predict a spectral cutoff of roughly 300 keV or > 1 MeV, respectively, and require spectral coverage to the MeV region to differentiate. Using archival data and observations from the current INTEGRAL AO, we investigate Cen A's spectrum using both SPI and IBIS/ISGRI to better understand the soft gamma-ray emission and the process at work in that energy range. Also, we search for spectral variability in light of recent results from Swift/BAT. We find that INTEGRAL spectra can be described by either a cutoff power law model with Ecut~550 keV or by a log parabola model. Results & Future Work Results: To start we looked for spectral variability by fitting observations close in time to power-law models in the 25-70 keV energy range for SPI and 30-70 keV for ISGRI. The results for each instrument are shown in plots above. Each set of photon indexes were fit to a constant value to test for spectral variability. The best-fit constant for each instrument is plotted as a red dashed line. For SPI the best-fit photon index is 1.70 +/- 0.03 for SPI and 1.83 +/- 0.01 for ISGRI with red. chi2 values less than 1 for each with all the data points within 3-sigma from the average value thus the data are consistent with a constant photon index. However the best-fit indexes for each instrument are significantly different. T