Complex AGN feedback in the Teacup galaxy. A powerful ionised galactic outflow, jet-ISM interaction, and evidence for AGN-triggered star formation in a giant bubble

Venturi, G.; Treister, E.; Finlez, C.; D'Ago, G.; Bauer, F.; Harrison, C. M.; Ramos Almeida, C.; Revalski, M.; Ricci, F.; Sartori, L. F.; Girdhar, A.; Keel, W. C.; Tubín, D.
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Astronomy and Astrophysics

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Context. The z ∼ 0.1 type-2 QSO J1430+1339, known as the "Teacup", is a complex galaxy showing a loop of ionised gas ∼10 kpc in diameter, co-spatial radio bubbles, a compact (∼1 kpc) jet, and outflow activity. Its closeness offers the opportunity to study in detail the intricate interplay between the central supermassive black hole (SMBH) and the material in and around the galaxy, both the interstellar medium (ISM) and circumgalactic medium (CGM).
Aims: We characterise the spatially resolved properties and effects of the galactic ionised gas outflow and compare them with those of the radio jet and with theoretical predictions to infer its acceleration mechanism.
Methods: We used VLT/MUSE optical integral field spectroscopic observations to obtain flux, kinematic, and excitation maps of the extended (up to ∼100 kpc) ionised gas and to characterise the properties of stellar populations. We built radial profiles of the outflow properties as a function of distance from the active nucleus, from kiloparsec up to tens of kiloparsec scales, at ∼1 kpc resolution.
Results: We detect a velocity dispersion enhancement (≳300 km s−1) elongated over several kiloparsecs perpendicular to the radio jet, the active galactic nucleus (AGN) ionisation lobes, and the fast outflow, similar to what is found in other galaxies hosting compact, low-power jets, indicating that the jet strongly perturbs the host ISM during its passage. We observe a decreasing trend with distance from the nucleus for the outflow properties (mass outflow rate, kinetic rate, momentum rate). The mass outflow rate drops from around 100 M⊙ yr−1 in the inner 1-2 kpc to ≲0.1 M⊙ yr−1 at 30 kpc. The mass outflow rate of the ionised outflow is significantly higher (∼1-8 times) than the molecular one, in contrast with what is often quoted in AGN. Based on energetic and morphological arguments, the driver of the multi-phase outflow is likely a combination of AGN radiation and the jet, or AGN radiation pressure on dust alone. The outflow mass-loading factor is ∼5-10 and the molecular gas depletion time due to the multi-phase outflow is ≲108 yr, indicating that the outflow can significantly affect the star formation and the gas reservoir in the galaxy. However, the fraction of the ionised outflow that is able to escape the dark matter halo potential is likely negligible. We detect blue-coloured continuum emission co-spatial with the ionised gas loop. Here, stellar populations are younger (≲100-150 Myr) than in the rest of the galaxy (∼0.5-1 Gyr). This constitutes possible evidence for star formation triggered at the edge of the bubble due to the compressing action of the jet and outflow ("positive feedback"), as predicted by theory. All in all, the Teacup constitutes a rich system in which AGN feedback from outflows and jets, in both its negative and positive flavours, co-exist.

Based on observations made with ESO Telescopes at the La Silla Paranal Observatory under programme ID 0102.B-0107.

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