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- Title
JWST detection of extremely excited outflowing CO and H<sub>2</sub>O in VV 114 E SW: A possible rapidly accreting IMBH.
- Authors
González-Alfonso, Eduardo; García-Bernete, Ismael; Pereira-Santaella, Miguel; Neufeld, David A.; Fischer, Jacqueline; Donnan, Fergus R.
- Abstract
Mid-infrared (mid-IR) gas-phase molecular bands are powerful diagnostics of the warm interstellar medium. We report the James Webb Space Telescope detection of the CO v = 1 − 0 (4.4 − 5.0 μm) and H2O ν2 = 1 − 0 (5.0 − 7.8 μm) ro-vibrational bands, both in absorption, toward the "s2" core in the southwest nucleus of the merging galaxy VV 114 E. All ro-vibrational CO lines up to Jlow = 33 (Elow ≈ 3000 K) are detected, as well as a forest of H2O lines up to 130, 13 (Elow ≈ 2600 K). The highest-excitation lines are blueshifted by ∼180 km s−1 relative to the extended molecular cloud, which is traced by the rotational CO (J = 3 − 2) 346 GHz line observed with the Atacama Large Millimeter/submillimeter Array. The bands also show absorption in a low-velocity component (blueshifted by ≈30 km s−1) with lower excitation. The analysis shows that the bands are observed against a continuum with an effective temperature of Tbck ∼ 550 K extinguished with τ6 μmext ∼ 2.5−3 τ 6 μ m ext ∼ 2.5 − 3 $ \tau_{{6\,{\upmu}\mathrm{m}}}^{\mathrm{ext}}\sim 2.5{-}3 $ (Ak ∼ 6.9 − 8.3 mag). The high-excitation CO and H2O lines are consistent with v = 0 thermalization with Trot ≈ 450 K and column densities of NCO ≈ (1.7 − 3.5)×1019 cm−2 and NH2O ≈ (1.5 − 3.0)×1019 cm−2. Thermalization of the v = 0 levels of H2O requires either an extreme density of nH2 ≳ 109 cm−3, or radiative excitation by the mid-IR field in a very compact (< 1 pc) optically thick source emitting ∼1010 L⊙. The latter alternative is favored, implying that the observed absorption probes the very early stages of a fully enshrouded active black hole (BH). On the basis of a simple model for BH growth and applying a lifetime constraint to the s2 core, an intermediate-mass BH (IMBH, MBH ∼ 4.5 × 104 M⊙) accreting at super-Eddington rates is suggested, where the observed feedback has not yet been able to break through the natal cocoon.
- Subjects
JAMES Webb Space Telescope (Spacecraft); INTERSTELLAR medium; MOLECULAR clouds; SPACE telescopes; BLACK holes; GALACTIC evolution
- Publication
Astronomy & Astrophysics / Astronomie et Astrophysique, 2024, Vol 682, p1
- ISSN
0004-6361
- Publication type
Article
- DOI
10.1051/0004-6361/202348469