I. Ruffa1,2, C. Vignali1,3, A. Mignano2 1University of Bologna, IT, 2INAF-IRA, IT, 3INAF-OABO, IT ALMA  Spherical simmetry of the CO line emitting region; median radius: 6.4 kpc  The HI mass is unknown Following Gilli et al. (2014) Nh = (8.0 ± 0.9) × 1021 cm-2 X-RAY  Flat observed photon index: intrinsic neutral absorber Using a simple, phenomenological model: Nh = (8.3 ± 2.0) × 1022 cm-2 The molecular gas (traced by the CO) may contri- bute only for a fraction to the obscuration observed in X-ray (given the assumptions adopted here) REFERENCES: Carilli & Walter 2013, ARA&A, 51, 105; Downes & Solomon 1998, ApJ, 507, 615; Garcia et al. 2010, ApJ, 718, 695; Garcia et al. 2013, ApJ, 768, 146; Gilli et al. 2014, A&A, 562, 67; Mao et al. 2014, MNRAS, 440, L31; Murphy & Yaqoob 2009, MNRAS, 397, 1549; Norris et al. 2012, MNRAS, 422, 1453; Rigopoulou et al. 1999, AJ, 118, 2625; Spoon et al. 2007, ApJ, 654, L49; Spoon et al. 2009, ApJ 693, 1223 IRAS 00183-7111 (I00183) is an Ultra Luminous Infrared Galaxy (ULIRG) at z=0.327; most of the ULIRGs are known to host a heavily obscured AGN in their nuclear regions. The de- tection of the most heavily obscured sources is crucial to shed light on the obscured accretion phase in black hole growth, the AGN/host-galaxies co-evolution issues, and eventually esti- mate the contribution of these sources to the X-ray cosmic background. We present a study of the multi-frequency properties of I00183, connecting ALMA mm/sub-mm observations with those at high energies (Ruffa et al. in prep.); one of the purposes consists in verifying at what level the gas, traced by the CO, may be responsible for the obscuration observed in X-rays (NH ≈ 2 × 1023 cm-2, Nandra & Iwasawa 2007). I00183 was selected from the top-left region of the so-called Spoon diagnostic diagram (Spoon et al. 2007, black circle in fig. 1); it compares the strength of the 9.7 μm silicate absorption feature and the equivalent width of the 6.2 μm PAH emission feature to investigate about the AGN/starburst components in ULIRGs: the top-left region is populated by the absorption- dominated sources. I00183 is one of the most powerful ULIRGs known: Lbol = 9 × 1012 Lsun, mostly in the far-IR (Spoon et al. 2009). Its K-band image (Rigopoulou et al. 1999) shows a disturbed morpology and a single nucleus, interpreted as signs of a recent merger. This property is typical of ULIRGs: their high IR luminosity is attributed to the merger of two gas-rich spirals which triggers both AGN activity and a powerful nuclear starburst. The high amount of dust accompanying the vigorous starburst activity in I00183 (≈ 220 Msun yr-1, Mao et al. 2014) causes significant extinction to its nucleus (AV≥90, Spoon et al. 2009); for this rea- son, I00183 mid-IR spectrum lacks the typical AGN tracers (e.g. the 7.65 μm [Ne IV], and the 14.3 and 24.3 μm [Ne V]). However, the presence of a powerful AGN source in its nucleus was already established by the X-ray study presented by Nandra & Iwasawa (2007). ALMA observation properties νobs (GHz) Time on target Angular resolution Spectral resolution Band 3 87 79 min 1.8” 90 km/s Band 6 270 118 min 0.8” 2 km/s 260 98 min 0.8” 2 km/s X-ray observation properties Exp. time Obs. date Instrument Chandra 22 ks 13/02/2013 ACIS-S XMM-Newton 22.2 ks 16/04/2003 EPIC PN - MOS 1/2 NuSTAR 115 ks 21/12/2015-26/04/2016 FPMA - FPMB To link the sub-mm to the X-ray properties of I00183, ALMA archival Cycle 0 data in Band 3 and Band 6 were calibrated and analyzed. The X-ray analysis was carried out using Chandra, XMM-Newton, and NuSTAR (courtesy of the PI, K. Iwasawa) data, allowing a broad-band coverage of the X-ray spectrum (0.5 − 30 keV). The multi-frequency observation properties are summarized in table 1. Fig. 1: Spoon diagnostic plot of the equivalent width of the 6.2 μm PAH emission feature versus the 9.7 μm silicate ab- sorption feature, adapted from Spoon et al. (2007). The ga- laxy spectra are classified into nine classes, identified by t