Data di Pubblicazione:
2017
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) (\upsilon ̃ 2000 {{km}} {{{s}}}-1) cannot be excluded. The 3σ 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.
Tipologia CRIS:
03A-Articolo su Rivista
Keywords:
galaxies: active; galaxies: individual (Arp 220); galaxies: interactions; X-rays: galaxies; Astronomy and Astrophysics; Space and Planetary Science
Elenco autori:
Paggi, Alessandro; Fabbiano, Giuseppina; Risaliti, Guido; Wang, Junfeng; Karovska, Margarita; Elvis, Martin; Maksym, W. Peter; Mcdowell, Jonathan; Gallagher, Jay
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