Abstract We present an imaging and spectral analysis of the nuclear region of the ultraluminous infrared galaxy merger of Arp 220, using deep Chandra-ACIS observations summing up to ∼ 300 ks . Narrowband imaging with subpixel resolution of the innermost nuclear region reveals two distinct Fe–K emitting sources, coincident with the infrared and radio nuclear clusters. These sources are separated by 1′ (∼380 pc). The X-ray emission is extended and elongated in the eastern (E) nucleus, like the disk emission observed in millimeter radio images, suggesting a starburst dominance in this region. We estimate an Fe–K equivalent width of ≳ 1 keV for both sources and observe 2–10 keV luminosities of ∼ 2 × 10 40 erg s − 1 (western, W) and ∼ 3 × 10 40 erg s − 1 (E). In the 6–7 keV band the emission from these regions is dominated by the 6.7 keV Fe xxv line, suggesting a contribution from collisionally ionized gas. The thermal energy content of this gas is consistent with the kinetic energy injection in the interstellar medium by SNe II. However, nuclear winds from a hidden active galactic nucleus (AGN) ( υ ∼ 2000 km s − 1 ) cannot be excluded. The 3 σ upper limits on the neutral Fe–Kα flux of the nuclear regions correspond to the intrinsic AGN 2–10 keV luminosities of < 1 × 10 42 erg s − 1 (W) and < 0.4 × 10 42 erg s − 1 (E). For typical AGN spectral energy distributions the bolometric luminosities are < 3 × 10 43 erg s − 1 (W) and < 8 × 10 43 erg s − 1 (E), and black hole masses of < 1 × 10 5 M ☉ (W) and < 5 × 10 5 M ☉ (E) are evaluated for Eddington limited AGNs with a standard 10% efficiency.