TY - JOUR
T1 - Search for High-excitation Emission Lines from a Quasar-scale Active Nucleus in Arp 220
AU - Goldberg, Charles E.
AU - Buiten, Victorine A.
AU - Rieke, George H
AU - Alonso-Herrero, Almudena
AU - Paggi, A.
AU - van der Werf, Paul
AU - Stone, Meredith A.
AU - Morrison, Jane E.
AU - Alberts, Stacey
AU - Dicken, Dan
AU - Wright, Gillian
N1 - Publisher Copyright:
© 2024. The Author(s). Published by the American Astronomical Society.
PY - 2024/12/1
Y1 - 2024/12/1
N2 - The late-stage galaxy merger and prototypical ultraluminous infrared galaxy (ULIRG) Arp 220 is probed using the JWST Mid Infrared Instrument medium-resolution spectrometer to search for multiple diagnostic active galactic nuclei (AGN) emission lines in the low-interstellar-opacity spectral ranges of 5.3-7.9 μm and 12.9-16.0 μm. We detect none of the characteristic high-excitation AGN emission lines. The most diagnostic nondetections are of the [Ne vi] λ 7.652 μm and [Ne v] λ 14.32 μm lines, for which the combined upper limit is ∼10-20 times fainter than the equivalent limit from Spitzer data. We also use X-ray measurements of the reflected Fe Kα line to suggest a relatively low X-ray luminosity. These results suggest that the high obscuration observed along the line of sight to the nuclei of Arp 220 is isotropic and keeps any high-excitation emission from a putative AGN from escaping. An implication is that the observed mid-infrared output of the nuclei is essentially their bolometric luminosity, i.e., no significant additional energy escapes. We utilize this result to show that any embedded AGNs are accreting at no more than ∼5% of the Eddington rate, lower than many theoretical predictions for this stage of ULIRG evolution.
AB - The late-stage galaxy merger and prototypical ultraluminous infrared galaxy (ULIRG) Arp 220 is probed using the JWST Mid Infrared Instrument medium-resolution spectrometer to search for multiple diagnostic active galactic nuclei (AGN) emission lines in the low-interstellar-opacity spectral ranges of 5.3-7.9 μm and 12.9-16.0 μm. We detect none of the characteristic high-excitation AGN emission lines. The most diagnostic nondetections are of the [Ne vi] λ 7.652 μm and [Ne v] λ 14.32 μm lines, for which the combined upper limit is ∼10-20 times fainter than the equivalent limit from Spitzer data. We also use X-ray measurements of the reflected Fe Kα line to suggest a relatively low X-ray luminosity. These results suggest that the high obscuration observed along the line of sight to the nuclei of Arp 220 is isotropic and keeps any high-excitation emission from a putative AGN from escaping. An implication is that the observed mid-infrared output of the nuclei is essentially their bolometric luminosity, i.e., no significant additional energy escapes. We utilize this result to show that any embedded AGNs are accreting at no more than ∼5% of the Eddington rate, lower than many theoretical predictions for this stage of ULIRG evolution.
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U2 - 10.3847/1538-4357/ad7eb0
DO - 10.3847/1538-4357/ad7eb0
M3 - Article
AN - SCOPUS:85210912153
SN - 0004-637X
VL - 977
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 1
M1 - 55
ER -