Optical Emission Lines Research Articles

Properties of Interstellar Medium in the S0 Galaxy NGC 1222: Evidence for Shock-enhanced Line Emission

Abstract In this paper, we present a comprehensive study on the properties of the interstellar medium in NGC 1222, a star-forming early-type merging galaxy that forms a triple system, using optical and far-infrared spectroscopic, and multiband photometric data. The fit to the spectral energy distribution reveals a high dust content in the galaxy, with a dust-to-stellar mass ratio of M dust/M ⋆ ∼ 3.3 × 10−3 that is 40–90 times larger than the mean value of local S0 galaxies. By comparing the observed optical emission line ratios to shock models, we suggest that a merger-induced shock, which is further supported by the higher-than-average [O i] 63 μm- and [C ii] 158 μm-to-PAH ratios, plays a role in heating the gas in NGC 1222. We also show evidence for gas inflow by analyzing the kinematic properties of NGC 1222.

A merging pair of massive quiescent galaxies at z = 3.44 in the Cosmic Vine

We report the spectroscopic confirmation of a merging pair of massive quiescent galaxies at z = 3.44. Using JWST observations, we confirm that the two galaxies lie at a projected separation of 4.5 kpc with a velocity offset of ∼680 km s−1 (δz ∼ 0.01). The pair resides in the core of a known rich overdensity of galaxies, dubbed the “Cosmic Vine”. For both pair members, modeling of the spectral energy distributions and faint rest-frame optical emission lines indicate high stellar masses (log(M⋆/M⊙) ∼ 10.9) and suppressed star formation (log(sSFR/yr−1) < −10), more than an order of magnitude below the level of the star formation main sequence at this redshift. We then explore the Illustris-TNG simulation and the GAEA and SHARK semi-analytical models to examine whether they produce a pair of massive quiescent galaxies akin to that of the Cosmic Vine. While all models produce close pairs of massive quiescent galaxies at 2 < z < 4 with comparable separations and velocity offsets, their predicted number densities are 10–80 times lower than our observational constraint. This discrepancy cannot be fully explained by coarse time sampling in these models or the general challenge of forming early massive quiescent galaxies in simulations. Given that > 90% of simulated pairs in the models that we analyzed merge by z = 0, our findings suggest that our observed pair will likely coalesce into a single massive galaxy. The merger, occurring in the dense core of a large-scale structure, might represent a critical event in the formation of a brightest cluster galaxy and the morphological transformation of high-redshift disky quiescent galaxies into early-type ellipticals.

Shining a Light on the Connections between Galactic Outflows Seen in Absorption and Emission Lines

Abstract Galactic outflows provide important feedback effects to regulate the evolution of host galaxies. Two primary diagnostics of outflows are broad and/or blueshifted emission and absorption lines. Even though well-established methods exist to analyze these outflow signatures, connections between them are rarely studied and largely unknown. In this paper, we conduct such a study in a sample of 33 low-redshift starburst galaxies. Their UV absorption lines are detected by the Hubble Space Telescope, and optical emission lines are observed by Keck or the Very Large Telescope. We find that the outflow properties derived from emission and absorption lines are tightly correlated. These include outflow maximum velocity, line width, and radial extent. On average, in the same galaxy, the maximum velocity and line width of outflows measured from emission lines reach only 60%–70% of those from the absorption lines. We also find outflow rates derived from emission lines are consistently lower than those from absorption lines by 0.2–0.5 dex. These findings can be explained by a radial decline in density and a corresponding increase in outflow velocity, combined with the fact that emission line luminosity scales with the square of the density while absorption line depth scales linearly. We test both spherical and biconical outflow models and find that the same radial outflow velocity and density distributions can explain the observed correlations. These results provide novel calibration between galactic outflow properties measured from the two diagnostics and underscore the need for high-fidelity UV and optical spectra to accurately assess galactic feedback effects in high-z galaxies.

A Multiwavelength Autopsy of the Interacting Type IIn Supernova 2020ywx: Tracing Its Progenitor Mass-loss History for 100 Yr Before Death

Abstract While the subclass of interacting supernovae (SNe) with narrow hydrogen emission lines (Type IIn supernovae (SNe IIn)) consists of some of the longest-lasting and brightest supernovae (SNe) ever discovered, their progenitors are still not well understood. Investigating SNe IIn as they emit across the electromagnetic spectrum is the most robust way to understand the progenitor evolution before the explosion. This work presents X-ray, optical, infrared, and radio observations of the strongly interacting Type IIn supernova, SN 2020ywx, covering a period >1200 days after discovery. Through multiwavelength modeling, we find that the progenitor of 2020ywx was losing mass at ∼10−2–10−3 M ⊙ yr−1 for at least 100 yr pre-explosion using the circumstellar medium (CSM) speed of 120 km s−1 measured from optical and near-infrared (NIR) spectra. Despite the similar magnitude of mass loss measured in different wavelength ranges, we find discrepancies between the X-ray and optical/radio-derived mass-loss evolution, which suggest asymmetries in the CSM. Furthermore, we find evidence for dust formation due to the combination of a growing blueshift in optical emission lines and NIR continuum emission which we fit with blackbodies at ∼1000 K. Based on the observed elevated mass loss over more than 100 yr and the configuration of the CSM inferred from the multiwavelength observations, we invoke binary interaction as the most plausible mechanism to explain the overall mass-loss evolution. SN 2020ywx is thus a case that may support the growing observational consensus that SNe IIn mass loss is explained by binary interaction.

GA-NIFS: High number of dual active galactic nuclei at z ∼ 3

Context. Merger events can trigger gas accretion onto supermassive black holes (SMBHs) located at the centre of galaxies and form close pairs of active galactic nuclei (AGNs). The fraction of AGNs in pairs offers critical insights into the dynamics of galaxy interactions, SMBH growth, and their co-evolution with host galaxies. However, the identification of dual AGNs is difficult, as it requires high-quality spatial and spectral data; hence, very few pairs have been found in the distant Universe so far. Aims. This study is aimed at providing a first observational estimate of the fraction of dual AGNs at 2 < z < 6 by analysing a sample of 16 AGNs observed with the JWST Near-InfraRed Spectrograph (NIRSpec) in integral field mode, as part of the GA-NIFS survey. For two AGNs in our sample, we also incorporated archival VLT/MUSE data to expand the search area. Methods. We searched for nearby companion galaxies and emission-line sources within the ∼20 × 20 kpc field of view of the NIRSpec data cubes, extending up to ∼50 kpc using the MUSE data cubes. We analysed the spectra of such emitters to determine their physical and kinematic properties. Results. We report the serendipitous discovery of a triple AGN system and four dual AGNs (two of which had been considered as candidates), with projected separations in the range 3−28 kpc. The results of this study more than double the number of known multiple AGNs at z > 3 at these separations. Their AGN classification is mainly based on standard optical emission line flux ratios, as observed with JWST/NIRSpec, and complemented with additional multi-wavelength diagnostics. The identification of these 3−5 multiple AGNs out of the 16 AGN systems in the GA-NIFS survey (i.e. ∼20−30%) suggests they might be more common than previously thought from other observational campaigns. Moreover, our inferred fraction of dual AGN moderately exceeds predictions from cosmological simulations that mimic our observational criteria (∼10%). Conclusions. This work highlights the exceptional capabilities of NIRSpec for detecting distant dual AGNs, prompting new investigations to constrain their fraction across cosmic time.

JADES: A large population of obscured, narrow-line active galaxtic nuclei at high redshift

We present the identification of 41 narrow-line active galactic nuclei (type-2 AGN) candidates in the two deepest observations of the JADES spectroscopic survey with JWST/NIRSpec. The spectral coverage and the depth of our observations allowed us to select narrow-line AGN based on both rest-frame optical and UV emission lines up to z=10. Due to the metallicity decrease of galaxies, at z>3, the standard optical diagnostic diagrams (N2-BPT or S2-VO87) become unable to distinguish many AGN from other sources of photoionisation. Therefore, we also used high ionisation lines, such as and also in combination with other UV transitions, to trace the presence of AGN. Out of a parent sample of 209 galaxies, we identified 42 type-2 AGN (although ten of them are tentative), making the fraction of galaxies in JADES hosting type-2 AGN about $20±5$%, which does not evolve significantly in the redshift range between 2 and 10. The selected type-2 AGN have estimated bolometric luminosities of 10^41.3-44.9 erg s^-1 and host-galaxy stellar masses of 10^7.2-9.3 M_⊙. The star formation rates of the selected AGN host galaxies are consistent with those of the star-forming main sequence. The AGN host galaxies at z=4-6 contribute ∼18-30 % to the UV luminosity function across different UV luminosity bins, increasing slightly with UV luminosity.

Estimating Black Hole Masses in Obscured Active Galactic Nuclei from X-Ray and Optical Emission Line Luminosities

Abstract We test a novel method for estimating black hole masses (M BH) in obscured active galactic nuclei (AGN) that uses proxies to measure the FWHM of broad Hα (FWHMbHα ) and the accretion disk luminosity at 5100 Å (λL 5100 Å). Using a published correlation, we estimate FWHMbHα from the narrow optical emission line ratio L [O iii]/L nHβ . Using a sample of 99 local obscured AGN from the Swift Burst Alert Telescope AGN Spectroscopic Survey (BASS), we assess the agreement between estimating λL 5100 Å from the intrinsic 2 to 10 keV X-ray luminosity and from narrow optical emission lines. We find a mean offset of 0.32 ± 0.68 dex between these methods, which propagates to a factor of ∼2 uncertainty when estimating M BH using a virial mass formula where L [O iii]/L nHβ serves as a proxy of FWHMbHα (M BH,[O iii]/nHβ ). We compare M BH,[O iii]/nHβ with virial M BH measurements from broad Paschen emission lines. For the 14 (12) BASS AGN with broad Paα (Paβ) detections, we find M BH,[O iii]/nHβ to be systematically higher than M BH,Paα (M BH,Paβ ) by a factor of 0.39 ± 0.44 dex (0.48 ± 0.51 dex). Since these offsets are within the scatter, more data are needed to assess whether M BH,[O iii]/nHβ is biased high. For 151 BASS AGN with measured stellar velocity dispersions (σ *), we find that the σ *-derived M BH agrees with M BH,[O iii]/nHβ to within 0.08 dex, albeit with wide scatter (0.74 dex). The method tested here can provide estimates of M BH in thousands of obscured AGN in spectroscopic surveys when other diagnostics are not available, though with an uncertainty of ∼3–5.

Identification of M1 lines of Ca-like Ge12+ and Se14+ ions at electron beam ion traps

Abstract Optical emission lines within the 200–750 nm range of the Ca-like ions Ge12+ and Se14+ are measured using electron beam ion traps. Six previously unreported spectral lines emitted by these ions are obtained. The multiconfiguration Dirac-Hartree–Fock (MCDHF) methods are employed to calculate the energy levels and transition rates, accounting for Breit interaction, QED effects, and significant valence-valence, core-valence, and core-core correlations. By comparing with the theoretical calculations, three lines each for Ge12+ and Se14+ ions are successfully identified. Along the isoelectronic sequence of the Ca-like ions from Fe6+ to Kr16+, the transition energy scaling with nuclear charge Z is investigated.

Insight into the starburst nature of Galaxy GN-z11 with JWST MIRI spectroscopy

This paper presents a deep MIRI/JWST medium-resolution spectroscopy (MRS) covering the rest-frame optical spectrum of the GN-z11 galaxy. The [O III] 5008 Å and Hα emission lines are detected and spectroscopically resolved. The line profiles are well modeled by a narrow Gaussian component with intrinsic full widths at half maximum of 189 ± 25 and 231 ± 52 km s−1, respectively. We do not find any evidence of a dominant broad Hα emission line component tracing a broad-line region in a type 1 active galactic nucleus (AGN). The existence of an accreting black hole dominating the optical continuum and emission lines of GN-z11 is not compatible with the measured Hα and [O III] 5008 Å luminosities. If the well-established relations for low-z AGNs apply in GN-z11, the [O III] 5008 Å and Hα luminosities would imply extremely high super-Eddington ratios (λE > 290), and bolometric luminosities ∼20 times those derived from the UV/optical continuum. However, a broad (∼430–470 km s−1) and weak (< 20–30%) Hα line component, tracing a minor AGN contribution in the optical, cannot be completely ruled out with the sensitivity of the current data. The physical and excitation properties of the ionized gas are consistent with a low-metallicity starburst with a star formation rate of 24 ± 3 M⊙ yr−1. The electron temperature of the ionized gas is Te (O++) = 14 000 ± 2100 K, while the direct-Te gas-phase metallicity is 12 + log(O/H) = 7.91 ± 0.07 (Z = 0.17 ± 0.03 Z⊙). The optical line ratios locate GN-z11 in the starburst or AGN region, but they are more consistent with those of local low-metallicity starbursts and high-z luminous galaxies detected at redshifts similar to GN-z11. We conclude that the MRS optical spectrum of GN-z11 is consistent with that of a massive, compact, and low-metallicity starburst galaxy. Its high star formation and stellar mass surface densities are close to those of the densest stellar clusters, and we therefore speculate that GN-z11 might undergo a feedback-free, highly efficient starburst phase. Additional JWST data are needed to validate this scenario and other recently proposed alternatives to explain the existence of bright compact galaxies in the early Universe.

Spectral insights and evolutionary pathways of globular cluster ULX in NGC 1399: a two-decade X-ray and optical study

ABSTRACT We present new multiwavelength observations of two ultraluminous X-ray sources (ULXs) hosted by globular clusters (GCs) in the giant elliptical NGC 1399, focusing on CXO J0338318−352604 (GCU7), only the second GC ULX known to have luminous optical emission lines. Notably, only [N ii] and [O iii] emission is observed in the optical spectra, suggesting H-poor material. Previous work suggested the possibility that the properties of GCU7 could be explained by the tidal disruption of a horizontal branch star by an intermediate-mass black hole. We use new data to show that the lack of evolution in the X-ray or optical properties of the source over the last 20 yr rules out this scenario. Instead, we use cloudy simulations to demonstrate that the optical emission lines are consistent with an outflow from an ultracompact X-ray binary where a compact object – likely a neutron star (NS) – is accreting above the Eddington limit from a helium white dwarf (He WD). This binary would have dynamically formed from a direct collision between a NS and a red giant, or else via an exchange interaction. The ULX is predicted to evolve to lower mass transfer rates over time and eventually become a doppelganger to the well-studied ultracompact X-ray binaries in Galactic GCs such as 4U 1820–30. These results show the utility of using extragalactic GCs to study short-lived phases in dynamical binary evolution that occur too rarely to be observed in Galactic clusters.

Late-time Optical and X-Ray Emission Evolution of the Oxygen-rich SN 1996cr

Abstract When the ejecta of a supernova (SN) interact with the progenitor star's circumstellar environment, a strong shock is driven back into the ejecta, causing the material to become bright optically and in X-rays. Most notably, as the shock traverses the H-rich envelope, it begins to interact with metal-rich material. Thus, continued monitoring of bright and nearby SNe provides valuable clues about both the progenitor structure and its pre-SN evolution. Here we present late-time, multiepoch optical and Chandra X-ray spectra of the core-collapse SN, SN 1996cr. Magellan IMACS optical spectra taken in 2017 July and 2021 August show a very different spectrum from that seen in 2006 with broad, double-peaked optical emission lines of oxygen, argon, and sulfur with expansion velocities of ±4500 km s−1. Redshifted emission components are considerably fainter compared to the blueshifted components, presumably due to internal extinction from dust in the SN ejecta. Broad ±2400 km s−1 Hα is also seen, which we infer is shocked progenitor pre-SN, mass-loss, H-rich material. Chandra data indicate a slow but steady decline in the overall X-ray luminosity, suggesting that the forward shock has broken through any circumstellar shell or torus, which is inferred from prior deep Chandra ACIS-S/HETG observations. The X-ray properties are consistent with what is expected from a shock breaking out into a lower-density environment. Though originally identified as a Type IIn SN, based upon late-time optical emission-line spectra, we argue that the SN 1996cr progenitor was partially or highly stripped, suggesting a Type IIb/Ib SN.

Mapping the Active Galactic Nucleus Effects on the Stellar and Gas Properties of NGC 5806

Abstract It is commonly accepted that active galactic nuclei (AGNs) have a strong impact upon the evolution of their host galaxies, but the processes by which they do so are not fully understood. We aim to further the understanding of AGN feeding and feedback by examining an active galaxy using spatially resolved spectroscopy. We analyze integral field spectroscopy of the active galaxy NGC 5806, obtained using the Very Large Telescope Multi-Unit Spectroscopic Explorer. We map the dynamics of gas and stars, as well as gas optical emission line fluxes throughout the central 8 × 8 kpc2 of the galaxy. We use emission line ratios to map gas metallicity and identify regions of gas excitation dominated by AGN/shocks or star formation. We also determine the average stellar population age and metallicity, and model the rotation and dynamics of the galaxy. We find that NGC 5806 has a star-forming circumnuclear ring, with a projected radius of ~400 pc. The dynamics of this galaxy are driven by a large-scale bar, which transports gas from the spiral arm to the central ring and potentially fuels the AGN. We also observe AGN-dominated gas excitation up to 3.3 kpc away from the center of the galaxy, showing the extended AGN effect on the gas in the central regions of the galaxy.

GA-NIFS: A galaxy-wide outflow in a Compton-thick mini-broad-absorption-line quasar at z = 3.5 probed in emission and absorption

Context. Studying the distribution and properties of ionised gas in outflows driven by active galactic nuclei (AGN) is crucial for understanding the feedback mechanisms at play in extragalactic environments. These outflows provide key insights into the regulation of star formation and the growth of supermassive black holes. Aims. In this study, we explore the connection between ionised outflows traced by rest-frame ultra-violet (UV) absorption and optical emission lines in GS133, a Compton thick AGN at z = 3.47. We combine observations from the James Webb Space Telescope (JWST) NIRSpec Integral Field Spectrograph (IFS) with archival Very Large Telescope (VLT) VIMOS long-slit spectroscopic data, as part of the ‘Galaxy Assembly with NIRSpec IFS’ (GA-NIFS) project. Methods. We performed a multi-component kinematic decomposition of the UV and optical line profiles to derive the physical properties of the absorbing and emitting gas in GS133. Results. Our kinematic decomposition reveals two distinct components in the optical emission lines. The first component likely traces a rotating disc with a dynamical mass of 2 × 1010 M⊙. The second component corresponds to a galaxy-wide, bi-conical outflow, with a velocity of ∼ ± 1000 km s−1 and an extension of ∼3 kpc. The UV absorption lines show two outflow components, with bulk velocities vout ∼ −900 km s−1 and ∼ − 1900 km s−1, respectively. This characterises GS133 as a mini-broad absorption line (mini-BAL) system. Balmer absorption lines with similar velocities are tentatively detected in the NIRSpec spectrum. Both photoionisation models and outflow energetics suggest that the ejected absorbing gas is located at 1–10 kpc from the AGN. We use 3D gas kinematic modelling to infer the orientation of the [O III] bi-conical outflow, and find that a portion of the emitting gas resides along our line of sight, suggesting that [O III] and absorbing gas clouds are partially mixed in the outflow. The derived mass-loading factor (i.e. the mass outflow rate divided by the star formation rate) of 1–10, and the kinetic coupling efficiency (i.e. the kinetic power divided by LAGN) of 0.1–1% suggest that the outflow in GS133 provides significant feedback on galactic scales.

HCG 57: Evidence for Shock-heated Intergalactic Gas from X-Rays and Optical Emission Line Spectroscopy

Abstract We present Chandra and XMM-Newton X-ray observations of the compact group HCG 57, and optical integral field spectroscopy of the interacting galaxy pair HCG 57A/D. These two spiral galaxies recently suffered an off-axis collision with HCG 57D passing through the disk of A. We find evidence of a gas bridge linking the galaxies, containing ∼108 M ⊙ of hot, ∼1 keV thermal plasma and warm ionized gas radiating in Hα, Hβ, [O iii] and [N ii] lines. The optical emission lines in the central regions of HCG 57D show excitation properties consistent with H ii-regions, while the outer rim of HCG 57D parts of the bridge and the outer regions of HCG 57A show evidence of shocked gas consistent with shock velocities of 200–300 km s−1. In contrast, the X-ray emitting gas requires a collision velocity of 650–750 km s−1 to explain the observed temperatures. These different shock velocities can be reconciled by considering the contributions of rotation to collision velocity in different parts of the disks, and the clumpy nature of the preshock medium in the galaxies, which likely lead to different shock velocities in different components of the turbulent postshocked gas. We examine the diffuse X-ray emission in the group members and their associated point sources, identifying X-ray active galactic nuclei in HCG 57A, B, and D. We also confirm the previously reported ∼1 keV intra-group medium and find it to be relaxed with a low central entropy (18.0 ± 1.7 keV cm2 within 20 kpc) but a long cooling time (5.9 ± 0.8 Gyr).

The ALPINE-ALMA [CII] Survey: Modelling ALMA and JWST lines to constrain the interstellar medium of z∼ 5 galaxies

Aims. We have devised a model for estimating the ultraviolet (UV) and optical line emission (i.e. CIII] 1909 Å, Hβ, [OIII] 5007 Å, Hα, and [NII] 6583 Å) that traces HII regions in the interstellar medium (ISM) of a subset of galaxies at z ~ 4-6 from the ALMA large programme ALPINE. The aim is to investigate the combined impact of binary stars in the stellar population and an abrupt quenching in the star formation history (SFH) on the line emission. This is crucial for understanding the ISM’s physical properties in the Universe’s earliest galaxies and identifying new star formation tracers in high-z galaxies. Methods. The model simulates HII plus PhotoDissociation Region (PDR) complexes by performing radiative transfer through 1D slabs characterised by gas density (n), ionisation parameter (U), and metallicity (Z). The model also takes into account (a) the heating from star formation, whose spectrum has been simulated with Starburst99 and Binary Population and Spectral Synthesis (BPASS) to quantify the impact of binary stars; and (b) a constant, exponentially declining, and quenched SFH. For each galaxy, we selected from our CLOUDY models the theoretical ratios between the [CII] line emission that trace PDRs and nebular lines from HII regions. These ratios were then used to derive the expected optical/UV lines from the observed [CII]. Results. We find that binary stars have a strong impact on the line emission after quenching, by keeping the UV photon flux higher for a longer time. This is relevant in maintaining the free electron temperature and ionised column density in HII regions unaltered up to 5 Myr after quenching. Furthermore, we constrained the ISM properties of our subsample, finding a low ionisation parameter of log U≈ − 3.8 ± 0.2 and high densities of log(n/cm−3)≈2.9 ± 0.6. Finally, we derive UV/optical line luminosity-star formation rate relations (log(Lline/erg s−1) = α log(SFR/M⊙ yr−1) + β) for different burstiness parameter (ks) values. We find that in the fiducial BPASS model, the relations have a negligible SFH dependence but depend strongly on the ks value, while in the SB99 case, the dominant dependence is on the SFH. We propose their potential use for characterising the burstiness of galaxies at high z.

How do supernova remnants cool?

Context. About 15%-60% of all supernova remnants are estimated to interact with dense molecular clouds. In these high-density environments, radiative losses are significant. The cooling radiation can be observed in forbidden lines at optical wavelengths. Aims. We aim to determine whether supernovae at different positions within a molecular cloud (with or without magnetic fields) can be distinguished based on their optical emission (e.g. Hα (λ 6563), Hβ (λ 4861), [O III] (λ 5007), [S II] (λ 6717, 6731), and [N II] (λ 6583)) using machine learning (e.g. principle component analysis and k-means clustering). Methods. We have conducted a statistical analysis of the optical line emission of simulated supernovae interacting with molecular clouds that formed from the multi-phase interstellar medium modelled in the SILCC-Zoom simulations with and without magnetic fields. This work is based on the post-processing of simulations that have been carried out with the 3D (magneto)hydrodynamic code FLASH. Our dataset consists of 22 simulations. The supernovae were placed at a distance of either 25 pc or 50 pc from the molecular cloud’s centre of mass. First, we calculated optical synthetic emission maps (taking into account dust attenuation within the simulation sub-cube) with a post-processing code based on MAPPINGS V cooling tables. Second, we analysed the dataset of synthetic observations using principle component analysis to identify clusters with the k-means algorithm. In addition, we made use of BPT diagrams as a diagnostic of shock-dominated regions. Results. We find that the presence or absence of magnetic fields has no statistically significant effect on the optical line emission. However, the ambient density distribution at the site of the supernova changes the entire evolution and morphology of the supernova remnant. Due to the different ambient densities in the 25 pc and 50 pc simulations, we are able to distinguish them in a statistically significant manner. Although, optical line attenuation within the supernova remnant can mimic this result depending on the attenuation model that is used. That is why, multi-dimensional analysis of optical emission line ratios in this work does not give extra information about the environmental conditions (ambient density and ambient magnetic field) of supernova remnant.

Correction to: Determining star formation rates in AGN hosts from strong optical emission lines

Correction to: Determining star formation rates in AGN hosts from strong optical emission lines

A Case Study of Gas Impacted by Black-hole Jets with the JWST: Outflows, Bow Shocks, and High Excitation of the Gas in the Galaxy IC 5063

We present James Webb Space Telescope MIRI data of the inner ∼3 × 2 kpc2 of the galaxy IC 5063, in which the jets of a supermassive black hole interact with the gaseous disk they are crossing. Jet-driven outflows were known to be initiated along or near the jet path and to modify the stability of molecular clouds, possibly altering their star formation properties. The MIRI data, of unprecedented resolution and sensitivity in the infrared, now reveal that there are more than 10 discrete regions with outflows, nearly doubling the number of such known regions. Outflows exist near the radio lobes, at the nucleus, in a biconical structure perpendicular to the jet, and in a bubble moving against the disk. In some of them, velocities above escape velocity are observed. Stratification is also observed, with higher ionization or excitation gas attaining higher velocities. More outflows and bow shocks, found further away from the nucleus than the radio lobes, in regions without significant radio emission, reveal the existence of past or weak radio jets that interacted with the interstellar medium. The coincidence of the bow shocks with the optical extended emission line region (EELR) suggests that the jets also contributed to the gas ionization. Maps of the H2 gas excitation temperature, T ex, indicate that the molecular gas is most excited in regions with radio emission. There, T ex is >100 K higher than in the EELR interior. We argue that a combination of jet-related shocks and cosmic rays is likely responsible for this excess molecular gas excitation.

A MUSE source-blind survey for emission from the circumgalactic medium.

The recent detection of optical emission lines from the circumgalactic medium (CGM) in combined, large samples of low-redshift, normal galaxy spectra hints at the potential to map the cool (∼104 kelvin) CGM in individual, representative galaxies. Using archival data from a forefront instrument (MUSE) on the VLT, we present a source-blind, wide-redshift-range (z ∼ 0 to 5) narrowband imaging survey for CGM emission. Our detected, resolved emission line sources are cataloged and include a 30-kiloparsec-wide Hα source likely tracing the CGM of a low-mass galaxy (stellar mass ∼ 108.78±0.42 solar mass) at z = 0.1723, a 60-kiloparsec-wide Ly α structure associated with a galaxy at z = 3.9076, and a 130-kiloparsec (∼rvir)-wide [O II] feature revealing an interaction between a galaxy pair at z = 1.2480. The Hα velocity field for the low-mass galaxy suggests that the CGM is more chaotic or turbulent than the galaxy disk, while that for the interacting galaxies shows large-scale (∼50 kiloparsec) coherent motions.

Emission line velocity, metallicity, and extinction maps of the Small Magellanic Cloud

ABSTRACT Optical emission lines across the Small Magellanic Cloud (SMC) have been measured from multiple fields using the Australian National University 2.3m telescope with the wide-field spectrograph. Interpolated maps of the gas-phase metallicity, extinction, H $\alpha$ radial velocity, and H $\alpha$ velocity dispersion have been made from these measurements. There is a metallicity gradient from the centre to the north of the galaxy of $\sim$−0.095 dex kpc−1 with a shallower metallicity gradient from the centre to the south of the galaxy of $\sim$−0.013 dex kpc−1. There is an extinction gradient of $\sim$−0.086 E(B − V)/kpc from the centre going north and shallower going from the centre to the south of $\sim$−0.0089 E(B − V)/kpc. The SMC eastern arm has lower extinction than the main body. The radial velocity of the gas from the H $\alpha$ line and the H i line have been compared across the SMC. In general there is good agreement between the two measurements, though there are a few notable exceptions. Both show a region that has different radial velocity to the bulk motion of the SMC in the southern western corner by at least 16 km s$^{-1}$. The velocity dispersion from H $\alpha$ and H i across the SMC have also been compared, with the H $\alpha$ velocity dispersion usually the higher of the two. The eastern arm of the SMC generally has lower velocity dispersion than the SMC’s main body. These measurements enable a detailed examination of the SMC, highlighting its nature as a disrupted satellite galaxy.