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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. Unravelling the physics of multiphase AGN winds through emission line tracers

   https://doi.org/10.1093/mnras/stab556  

   Richings, Alexander J ; Faucher-Giguère, Claude-André ; Stern, Jonathan ( March 2021 , Monthly Notices of the Royal Astronomical Society)

   ABSTRACT Observations of emission lines in active galactic nuclei (AGNs) often find fast (∼1000 km s−1) outflows extending to kiloparsec scales, seen in ionized, neutral atomic and molecular gas. In this work we present radiative transfer calculations of emission lines in hydrodynamic simulations of AGN outflows driven by a hot wind bubble, including non-equilibrium chemistry, to explore how these lines trace the physical properties of the multiphase outflow. We find that the hot bubble compresses the line-emitting gas, resulting in higher pressures than in the ambient interstellar medium or that would be produced by the AGN radiation pressure. This implies that observed emission line ratios such as [O iv]$_{25 \, \rm {\mu m}}$ / [Ne ii]$_{12 \, \rm {\mu m}}$, [Ne v]$_{14 \, \rm {\mu m}}$ / [Ne ii]$_{12 \, \rm {\mu m}}$, and [N iii]$_{57 \, \rm {\mu m}}$ / [N ii]$_{122 \, \rm {\mu m}}$ constrain the presence of the bubble and hence the outflow driving mechanism. However, the line-emitting gas is under-pressurized compared to the hot bubble itself, and much of the line emission arises from gas that is out of pressure, thermal and/or chemical equilibrium. Our results thus suggest that assuming equilibrium conditions, as commonly done in AGN line emission models, is not justifiedmore »if a hot wind bubble is present. We also find that ≳50 per cent of the mass outflow rate, momentum flux, and kinetic energy flux of the outflow are traced by lines such as [N ii]$_{122 \, \rm {\mu m}}$ and [Ne iii]$_{15 \, \rm {\mu m}}$ (produced in the 10$^{4} \, \rm {K}$ phase) and [C ii]$_{158 \, \rm {\mu m}}$ (produced in the transition from 10$^{4} \, \rm {K}$ to 100 K).« less
3. RESOLVE and ECO: Finding Low-metallicity z ∼ 0 Dwarf AGN Candidates Using Optimized Emission-line Diagnostics

   https://doi.org/10.3847/1538-4357/ac6595  

   Polimera, Mugdha S. ; Kannappan, Sheila J. ; Richardson, Chris T. ; Bittner, Ashley S. ; Ferguson, Carlynn ; Moffett, Amanda J. ; Eckert, Kathleen D. ; Bellovary, Jillian M. ; Norris, Mark A. ( May 2022 , The Astrophysical Journal)

   Existing star-forming vs. active galactic nucleus (AGN) classification schemes using optical emission-line diagnostics mostly fail for low-metallicity and/or highly star-forming galaxies, missing AGN in typicalz∼ 0 dwarfs. To recover AGN in dwarfs with strong emission lines (SELs), we present a classification scheme optimizing the use of existing optical diagnostics. We use Sloan Digital Sky Survey emission-line catalogs overlapping the volume- and mass-limited REsolved Spectroscopy Of a Local VolumE (RESOLVE) and Environmental COntex (ECO) surveys to determine the AGN percentage in SEL dwarfs. Our photoionization grids show that the [Oiii]/Hβversus [Sii]/Hαdiagram (Siiplot) and [Oiii]/Hβversus [Oi]/Hαdiagram (Oiplot) are less metallicity sensitive and more successful in identifying dwarf AGN than the popular [Oiii]/Hβversus [Nii]/Hαdiagnostic (Niiplot or “BPT diagram”). We identify a new category of “star-forming AGN” (SF-AGN) classified as star-forming by the Niiplot but as AGN by the Siiand/or Oiplots. Including SF-AGN, we find thez∼ 0 AGN percentage in dwarfs with SELs to be ∼3%–16%, far exceeding most previous optical estimates (∼1%). The large range in our dwarf AGN percentage reflects differences in spectral fitting methodologies between catalogs. The highly complete nature of RESOLVE and ECO allows us to normalize strong emission-line galaxy statistics to the full galaxy population, reducing the dwarfmore »AGN percentage to ∼0.6%–3.0%. The newly identified SF-AGN are mostly gas-rich dwarfs with halo mass <10^11.5M_⊙, where highly efficient cosmic gas accretion is expected. Almost all SF-AGN also have low metallicities (Z≲ 0.4Z_⊙), demonstrating the advantage of our method.

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4. PHANGS–JWST First Results: Variations in PAH Fraction as a Function of ISM Phase and Metallicity

   https://doi.org/10.3847/2041-8213/acadd7  

   Chastenet, Jérémy ; Sutter, Jessica ; Sandstrom, Karin ; Belfiore, Francesco ; Egorov, Oleg V. ; Larson, Kirsten L. ; Leroy, Adam K. ; Liu, Daizhong ; Rosolowsky, Erik ; Thilker, David A. ; et al ( February 2023 , The Astrophysical Journal Letters)

   We present maps tracing the fraction of dust in the form of polycyclic aromatic hydrocarbons (PAHs) in IC 5332, NGC 628, NGC 1365, and NGC 7496 from JWST/MIRI observations. We trace the PAH fraction by combining the F770W (7.7μm) and F1130W (11.3μm) filters to track ionized and neutral PAH emission, respectively, and comparing the PAH emission to F2100W, which traces small, hot dust grains. We find the averageR_PAH= (F770W + F1130W)/F2100W values of 3.3, 4.7, 5.1, and 3.6 in IC 5332, NGC 628, NGC 1365, and NGC 7496, respectively. We find that Hiiregions traced by MUSE Hαshow a systematically low PAH fraction. The PAH fraction remains relatively constant across other galactic environments, with slight variations. We use CO+Hi+Hαto trace the interstellar gas phase and find that the PAH fraction decreases above a value of${\mathrm{I}}_{\mathrm{H}\alpha }/{\mathrm{\Sigma }}_{\mathrm{H}\mathrm{I}+{\mathrm{H}}_2}\sim {10}^{37.5}\mathrm{erg}{\mathrm{s}}^{-1}{\mathrm{kpc}}^{-2}{(M_{\odot }{\mathrm{pc}}^{-2})}^{-1}$in all four galaxies. Radial profiles also show a decreasing PAH fraction with increasing radius, correlated with lower metallicity, in line with previous results showing a strong metallicity dependence to the PAH fraction. Our results suggest that the process of PAH destruction in ionized gas operates similarlymore »across the four targets.

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5. ALMA Reveals Extended Cool Gas and Hot Ionized Outflows in a Typical Star-forming Galaxy at Z = 7.13

   https://doi.org/10.3847/1538-4357/ac795b  

   Akins, Hollis B. ; Fujimoto, Seiji ; Finlator, Kristian ; Watson, Darach ; Knudsen, Kirsten K. ; Richard, Johan ; C. Bakx, Tom J. L. ; Hashimoto, Takuya ; Inoue, Akio K. ; Matsuo, Hiroshi ; et al ( July 2022 , The Astrophysical Journal)

   We present spatially resolved morphological properties of [CII] 158μm, [OIII] 88μm, dust, and rest-frame ultraviolet (UV) continuum emission for A1689-zD1, a strongly lensed, sub-L* galaxy atz= 7.13, by utilizing deep Atacama Large Millimeter/submillimeter Array (ALMA) and Hubble Space Telescope (HST) observations. While the [OIII] line and UV continuum are compact, the [CII] line is extended up to a radius ofr∼ 12 kpc. Using multi-band rest-frame far-infrared continuum data ranging from 52 to 400μm, we find an average dust temperature and emissivity index of$T_{\mathrm{dust}}={41}_{-14}^{+17}$K and$\beta ={1.7}_{-0.7}^{+1.1}$, respectively, across the galaxy. We find slight differences in the dust continuum profiles at different wavelengths, which may indicate that the dust temperature decreases with distance. We map the star formation rate (SFR) via IR and UV luminosities and determine a total SFR of 37 ± 1M_⊙yr⁻¹with an obscured fraction of 87%. While the [OIII] line is a good tracer of the SFR, the [CII] line shows deviation from the localL_[CII]-SFR relations in the outskirts of the galaxy. Finally, we observe a clear difference in the line profile between [CII] and [OIII], with significant residuals (∼5σ) in the [OIII] line spectrum after subtracting a single Gaussian model. This suggestsmore »a possible origin of the extended [CII] structure from the cooling of hot ionized outflows. The extended [CII] and high-velocity [OIII] emission may both contribute in part to the highL_[OIII]/L_[CII]ratios recently reported inz> 6 galaxies.

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