Journal
ASTROPHYSICAL JOURNAL
Volume 841, Issue 1, Pages -Publisher
IOP PUBLISHING LTD
DOI: 10.3847/1538-4357/aa713b
Keywords
galaxies: active; galaxies: individual (Arp 220); galaxies: interactions; X-rays: galaxies
Categories
Funding
- NASA [G04-15107X, NAS8-03060]
- National Key Program for Science and Technology Research and Development [2016YFA0400702]
- NSFC [11473021, 11522323]
- CXC
- National Science Foundation
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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 similar 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' (similar to 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 greater than or similar to 1 keV for both sources and observe 2-10 keV luminosities of similar to 2 x 1040 erg s (1) (western, W) and similar to 3 x 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) (v similar to 2000 km s(-1)) cannot be excluded. The 3 sigma upper limits on the neutral Fe-K alpha flux of the nuclear regions correspond to the intrinsic AGN 2-10 keV luminosities of < 1 x 10(42) erg s(-1) (W) and < 0.4 x 10(42) erg s(-1) (E). For typical AGN spectral energy distributions the bolometric luminosities are < 3 x 10(43) erg s (1) (W) and < 8 x 10(43) erg s (1) (E), and black hole masses of < 1 x 10(5) M circle dot (W) and < 5 x 10(5) M circle dot (E) are evaluated for Eddington limited AGNs with a standard 10% efficiency.
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