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1. GOALS-JWST: Resolving the Circumnuclear Gas Dynamics in NGC 7469 in the Mid-infrared

   https://doi.org/10.3847/2041-8213/ac961c  

   U, Vivian ; Lai, Thomas ; Bianchin, Marina ; Remigio, Raymond P. ; Armus, Lee ; Larson, Kirsten L. ; Díaz-Santos, Tanio ; Evans, Aaron ; Stierwalt, Sabrina ; Law, David R. ; et al ( November 2022 , The Astrophysical Journal Letters)

   The nearby, luminous infrared galaxy NGC 7469 hosts a Seyfert nucleus with a circumnuclear star-forming ring and is thus the ideal local laboratory for investigating the starburst–AGN (active galactic nucleus) connection in detail. We present integral-field observations of the central 1.3 kpc region in NGC 7469 obtained with the JWST Mid-InfraRed Instrument. Molecular and ionized gas distributions and kinematics at a resolution of ∼100 pc over the 4.9–7.6μm region are examined to study the gas dynamics influenced by the central AGN. The low-ionization [Feii]λ5.34μm and [Arii]λ6.99μm lines are bright on the nucleus and in the starburst ring, as opposed to H₂S(5)λ6.91μm, which is strongly peaked at the center and surrounding ISM. The high-ionization [Mgv] line is resolved and shows a broad, blueshifted component associated with the outflow. It has a nearly face-on geometry that is strongly peaked on the nucleus, where it reaches a maximum velocity of −650 km s⁻¹, and extends about 400 pc to the east. Regions of enhanced velocity dispersion in H₂and [Feii] ∼ 180 pc from the AGN that also show highL(H₂)/L(PAH) andL([Feii])/L(Pfα) ratios to the W and N of the nucleus pinpoint regions where the ionized outflow is depositing energy, via shocks, into themore »dense interstellar medium between the nucleus and the starburst ring. These resolved mid-infrared observations of the nuclear gas dynamics demonstrate the power of JWST and its high-sensitivity integral-field spectroscopic capability to resolve feedback processes around supermassive black holes in the dusty cores of nearby luminous infrared galaxies.

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2. A Nascent Tidal Dwarf Galaxy Forming within the Northern H i Streamer of M82

   https://doi.org/10.3847/2041-8213/ac3ca6  

   Pasha, Imad ; Lokhorst, Deborah ; van Dokkum, Pieter G. ; Chen, Seery ; Abraham, Roberto ; Greco, Johnny ; Danieli, Shany ; Miller, Tim ; Lippitt, Erin ; Polzin, Ava ; et al ( December 2021 , The Astrophysical Journal Letters)

   Abstract We identify a ∼600 pc wide region of active star formation located within a tidal streamer of M82 via H α emission ( F H α ∼ 6.5 × 10 −14 erg s −1 cm −2 ), using a pathfinder instrument based on the Dragonfly Telephoto Array. The object is kinematically decoupled from the disk of M82 as confirmed via Keck/LRIS spectroscopy and is spatially and kinematically coincident with an overdensity of H i and molecular hydrogen within the “northern H i streamer” induced by the passage of M81 several hundred Myr ago. From H i data, we estimate that ∼5 × 10 7 M ⊙ of gas is present in the specific overdensity coincident with the H α source. The object’s derived metallicity (12+ log ( O / H ) ≃ 8.6 ), position within a gas-rich tidal feature, and morphology (600 pc diameter with multiple star-forming clumps), indicate that it is likely a tidal dwarf galaxy in the earliest stages of formation.
3. Excitation mechanisms in the intracluster filaments surrounding brightest cluster galaxies

   https://doi.org/10.1051/0004-6361/202039730  

   Polles, F. L. ; Salomé, P. ; Guillard, P. ; Godard, B. ; Pineau des Forêts, G. ; Olivares, V. ; Beckmann, R. S. ; Canning, R. E. ; Combes, F. ; Dubois, Y. ; et al ( July 2021 , Astronomy & Astrophysics)

   Context. The excitation of the filamentary gas structures surrounding giant elliptical galaxies at the center of cool-core clusters, also known as brightest cluster galaxies (BCGs), is key to our understanding of active galactic nucleus (AGN) feedback, and of the impact of environmental and local effects on star formation. Aims. We investigate the contribution of thermal radiation from the cooling flow surrounding BCGs to the excitation of the filaments. We explore the effects of small levels of extra heating (turbulence), and of metallicity, on the optical and infrared lines. Methods. Using the C LOUDY code, we modeled the photoionization and photodissociation of a slab of gas of optical depth A V  ≤ 30 mag at constant pressure in order to calculate self-consistently all of the gas phases, from ionized gas to molecular gas. The ionizing source is the extreme ultraviolet (EUV) and soft X-ray radiation emitted by the cooling gas. We tested these models comparing their predictions to the rich multi-wavelength observations from optical to submillimeter, now achieved in cool core clusters. Results. Such models of self-irradiated clouds, when reaching sufficiently large A V , lead to a cloud structure with ionized, atomic, and molecular gas phases. These models reproduce most ofmore »the multi-wavelength spectra observed in the nebulae surrounding the BCGs, not only the low-ionization nuclear emission region like optical diagnostics, [O  III ] λ 5007 Å/H β , [N  II ] λ 6583 Å/H α , and ([S  II ] λ 6716 Å+[S  II ] λ 6731 Å)/H α , but also the infrared emission lines from the atomic gas. [O  I ] λ 6300 Å/H α , instead, is overestimated across the full parameter space, except for very low A V . The modeled ro-vibrational H 2 lines also match observations, which indicates that near- and mid-infrared H 2 lines are mostly excited by collisions between H 2 molecules and secondary electrons produced naturally inside the cloud by the interaction between the X-rays and the cold gas in the filament. However, there is still some tension between ionized and molecular line tracers (i.e., CO), which requires optimization of the cloud structure and the density of the molecular zone. The limited range of parameters over which predictions match observations allows us to constrain, in spite of degeneracies in the parameter space, the intensity of X-ray radiation bathing filaments, as well as some of their physical properties like A V or the level of turbulent heating rate. Conclusions. The reprocessing of the EUV and X-ray radiation from the plasma cooling is an important powering source of line emission from filaments surrounding BCGs. C LOUDY self-irradiated X-ray excitation models coupled with a small level of turbulent heating manage to simultaneously reproduce a large number of optical-to-infrared line ratios when all the gas phases (from ionized to molecular) are modeled self-consistently. Releasing some of the simplifications of our model, like the constant pressure, or adding the radiation fields from the AGN and stars, as well as a combination of matter- and radiation-bounded cloud distribution, should improve the predictions of line emission from the different gas phases.« less
4. The Active Galactic Nuclei in the Hobby–Eberly Telescope Dark Energy Experiment Survey (HETDEX). III. A Red Quasar with Extremely High Equivalent Widths Showing Powerful Outflows

   https://doi.org/10.3847/1538-4357/ac9af2  

   Liu, Chenxu ; Gebhardt, Karl ; Kollatschny, Wolfram ; Ciardullo, Robin ; Cooper, Erin Mentuch ; Davis, Dustin ; Farrow, Daniel J. ; Finkelstein, Steven L. ; Gawiser, Eric ; Gronwall, Caryl ; et al ( November 2022 , The Astrophysical Journal)

   We report an active galactic nucleus (AGN) with an extremely high equivalent width (EW), EW_{Lyα+N V,rest}≳921Å, in the rest frame, atz∼ 2.24 in the Hobby–Eberly Telescope Dark Energy Experiment Survey (HETDEX), as a representative case of the high-EW AGN population. The continuum level is a nondetection in the HETDEX spectrum; thus the measured EW is a lower limit. The source is detected with significant emission lines (>7σ) at Lyα+ Nvλ1241, Civλ1549, and a moderate emission line (∼4σ) at Heiiλ1640 within the wavelength coverage of HETDEX (3500–5500 Å). Ther-band magnitude is 24.57 from the Hyper Suprime-Cam-HETDEX joint survey with a detection limit ofr= 25.12 at 5σ. The Lyαemission line spans a clearly resolved region of ∼10″ (85 kpc) in diameter. The Lyαline profile is strongly double peaked. The spectral decomposed blue gas and red gas Lyαemission are separated by ∼1.″2 (10.1 kpc) with a line-of-sight velocity offset of ∼1100 km s⁻¹. This source is probably an obscured AGN with powerful winds.
5. Observing the influence of the youngest super star clusters in NGC 1569: Keck Brackett α spectroscopy

   https://doi.org/10.1093/mnras/stab643  

   Cohen, Daniel P ; Turner, Jean L ; Beck, Sara C ; Consiglio, S Michelle ( March 2021 , Monthly Notices of the Royal Astronomical Society)

   ABSTRACT We report Keck–NIRSPEC observations of the Brackett α 4.05 μm recombination line across the two candidate embedded super star clusters (SSCs) in NGC 1569. These SSCs power a bright H ii region and have been previously detected as radio and mid-infrared sources. Supplemented with high-resolution VLA mapping of the radio continuum along with IRTF–TEXES spectroscopy of the [S iv] 10.5 μm line, the Brackett α data provide new insight into the dynamical state of gas ionized by these forming massive clusters. Near-infrared sources detected in 2 μm images from the slit-viewing Camera are matched with Gaia sources to obtain accurate celestial coordinates and slit positions to within ∼0${_{.}^{\prime\prime}}$1. Br α is detected as a strong emission peak powered by the less luminous infrared source, MIR1 (LIR ∼ 2 × 107 $\rm L_\odot$). The second candidate SSC MIR2 is more luminous (LIR ≳ 4 × 108 $\rm L_\odot$) but exhibits weak radio continuum and Br α emission, suggesting the ionized gas is extremely dense (ne ≳ 105 cm−3), corresponding to hypercompact H ii regions around newborn massive stars. The Br α and [S iv] lines across the region are both remarkably symmetric and extremely narrow, with observed line widths Δv ≃ 40 $\rm km\, s^{-1}$, full width at half-maximum. This result is the first clear evidence thatmore »feedback from NGC 1569’s youngest giant clusters is currently incapable of rapid gas dispersal, consistent with the emerging theoretical paradigm in the formation of giant star clusters.« less