CO Disk Research Articles

The Arizona Molecular ISM Survey with the SMT: Survey Overview and Public Data Release

The CO(1–0) line has been carefully calibrated as a tracer of molecular gas mass. However, recent studies often favor higher J transitions of the CO molecule, which are brighter and accessible for redshift ranges where CO(1–0) is not. These lines are not perfect analogs for CO(1–0), owing to their more stringent excitation conditions, and must be calibrated for use as molecular gas tracers. Here, we introduce the Arizona Molecular ISM Survey with the SMT, a multi-CO line survey of z ∼ 0 galaxies conducted to calibrate the CO(2–1) and CO(3–2) lines. The final survey includes CO(2–1) spectra of 176 galaxies and CO(3–2) spectra for a subset of 45. We supplement these with archival CO(1–0) spectra from xCOLD GASS for all sources and additional CO(1–0) observations with the Kitt Peak 12 m Telescope. Targets were selected to be representative of the 109 M ⊙ ≤ M * ≤ 1011.5 M ⊙ galaxy population. Our project emphasized careful characterization of statistical and systematic uncertainties to enable studies of trends in CO line ratios. We show that optical and CO disk sizes are on average equal, for both the CO(1–0) and CO(2–1) line. We measure the distribution of CO line luminosity ratios, finding medians (16th–84th percentile) of 0.71 (0.51–0.96) for the CO(2–1)-to-CO(1–0) ratio, 0.39 (0.24–0.53) for the CO(3–2)-to-CO(1–0) ratio, and 0.53 (0.41–0.74) for the CO(3–2)-to-CO(2–1) ratio. A companion paper presents our study of CO(2–1)'s applicability as a molecular gas mass tracer and search for trends in the CO(2–1)-to-CO(1–0) ratio. Our catalog of CO line luminosities is publicly available.

Cloud Collision Signatures in the Central Molecular Zone

Molecular cloud collisions are a prominent theory for the formation of stars. Observational studies into cloud collisions identify the collision via a bridging feature: a continuous strip of line emission that connects two intensity peaks that are related in position space and separated in velocity space. Currently, most observations of collisions and these bridging features take place in the Milky Way disc. They are also theorized to take place in the Central Molecular Zone (CMZ), where temperatures and densities are both significantly higher than in the disc. For studies in the Milky Way Disc, the most commonly-used tracer tends to be CO. However, for studies in the CMZ, where the density and temperature are significantly higher, CO becomes so abundant that it loses its ability to adequately highlight the bridging feature of cloud collisions. As a result, studies have begun using other tracers, whose physical and chemical behavior has not been studied under CMZ conditions. We perform combined hydrodynamical, chemical and radiative transfer simulations of cloud collisions under both disc- and CMZ-like conditions, and investigate collision signatures in a number of commonly-observed molecular lines. Under the Milky Way disc conditions ( ) has the standard bridging feature; however, the other tracers, CS, HCO +, N 2H + only emit in the intermediate-velocity bridge region, making the feature itself non-existent. In the CMZ, the higher density and temperature make the bridging feature far more indistinct for CO, but the other tracers have morphologically similar bridging features to the CO disc model, validating their use as tracers of cloud collisions under these conditions.

JWST study of the DG Tau B disk-wind candidate

Context. The origin of outflows and their impact on protoplanetary disk evolution and planet-formation processes are still crucial open questions. DG Tau B is a Class I protostar associated with a structured disk and a rotating conical CO outflow and was recently identified by ALMA as one of the best CO disk wind candidate. It is therefore a perfect target for studying these questions. Aims. We aim to map and study any outflow component intermediate between the axial jet and the CO outflow in order to constrain the origin (irradiated or shocked disk wind or swept-up material) of the redshifted molecular outflows in DG Tau B. Methods. We analyzed observations obtained with James Webb Space Telescope NIRSpec-IFU and NIRCam, supplemented with IFU data from the SINFONI/VLT instrument. We investigated the morphology, kinematics, and excitation conditions of the ro-vibrational H2 emission lines and their relation with the atomic jet and CO outflow. We focus our analysis on the redshifted outflow lobe. Results. We observe a global layered structure of the redshifted outflows in DG Tau B, with the atomic jet inside the H2 cavity, which in turn is nested inside the CO conical outflow. We also find temperature, velocity, and collimation to be increasing towards the axis of the flow. The redshifted H2 emission traces a narrow conical cavity (semi-opening angle of 9.4°) that is wider than the axial jet but nested just inside the CO outflow. Both the jet and the H2 cavity originate from the innermost regions of the disk (r0 < 6 au). The redshifted H2 cavity flows with a constant vertical velocity of Vz = 22.5 ± 0.8 km s−1, twice faster than the conical CO flow. The excitation conditions imply a hot H2 gas (Tex ≃ 2200 K) with an average mass flux of Ṁ(H2) = 3 × 10−11 M⊙ yr−1, which is significantly lower than the jet and CO values. Conclusions. The global layered H2-CO structure in temperature, velocity, and collimation in the DG Tau B redshifted lobe is consistent with a magneto-hydrodynamic disk wind scenario. The hot H2 could trace the inner, dense photodissociation layer in the wind. An H2 launching region at disk radii of 0.2−0.4 au combined with a large ejection efficiency (ξ ≃ 1) would account for the mass flux and kinematics. Alternatively, the near-IR ro-vibrational H2 could be emitted in the interaction layer driven by successive jet bow shocks into an outer disk wind or envelope. Further constraints on both scenarios will be obtained from the analysis of MIRI observations.

Chromatically modeling the parsec-scale dusty structure in the center of NGC 1068

Context. The Very Large Telescope Interferometer (VLTI) has been providing breakthrough images of the dust in the central parsecs of active galactic nuclei (AGNs), which is thought to be a key component of the AGN unification scheme and AGN host galaxy interaction. In single infrared bands, these images can enjoin multiple interpretations, some of which could challenge the unification scheme. This is the case for the archetypal type 2 AGN of NGC 1068, whereby the degeneracy is reduced by multi-band temperature maps that are hindered by an ambiguity in the alignment between different single-band images. Aims. We aim to solve this problem by creating a chromatic model capable of simultaneously explaining the VLTI GRAVITY+MATISSE 2 μm–13 μm observations of AGNs hosted by NGC 1068. Methods. We employed a simple disk and wind geometry populated by spherical black-body emitters and dust obscuration to create a versatile multi-wavelength modelling method for chromatic IR interferometric data of dusty objects. Results. This simple geometry is capable of reproducing the spectro-interferometric data of NGC 1068 from the K through N bands. It explains the complex single band images with obscuration and inclination effects, and it solves the alignment problem between bands. We find that the resulting model disk and wind geometry is consistent with previous studies of comparable and larger scales. For example, compared to molecular gas emission, our model wind position angle (PA) of 2322° is close to the mas-scale outflowing CO(6–5) PA of ∼33° seen with ALMA. The equivalent 90° offset model disk PA is also consistent with the CO(6–5) disk axis of 112° as well as the mas-scale disk axis from CO(2–1), CO(3–2), and HCO+(4–3) of 115 ± 5°. Furthermore, the resulting model images visually resemble the multiple achromatic image reconstructions of the same data when evaluated at the same wavelengths. We conclude that the IR emitting structure surrounding the AGN within NGC 1068 can indeed be explained by the clumpy disk+wind iteration of the AGN unification scheme. Within the scheme, we find that it is best explained as a type 2 AGN and the obscuring dust chemistry can be explained by a mix of olivine silicates and 16 ± 1% amorphous carbon.

PRODIGE – planet-forming disks in Taurus with NOEMA

Context. The physics and chemistry of planet-forming disks are far from being fully understood. To make further progress, both broad line surveys and observations of individual tracers in a statistically significant number of disks are required. Aims. Our aim is to perform a line survey of eight planet-forming Class II disks in Taurus with the IRAM NOrthern Extended Millimeter Array (NOEMA), as a part of the MPG-IRAM Observatory Program PRODIGE (PROtostars and DIsks: Global Evolution; PIs: P. Caselli and Th. Henning). Methods. Compact and extended disks around T Tauri stars CI, CY, DG, DL, DM, DN, IQ Tau, and UZ Tau E are observed in ~80 lines from > 20 C-, O,- N-, and S-bearing species. The observations in four spectral settings at 210–280 GHz with a 1σ rms sensitivity of ~8–12 mJy beam−1 at a 0.9″ and 0.3 km s−1 resolution will be completed in 2024. The uv visibilities are fitted with the DiskFit model to obtain key stellar and disk properties. Results. In this first paper, the combined 12CO, 13CO, and C18O J = 2–1 data are presented. We find that the CO fluxes and disk masses inferred from dust continuum tentatively correlate with the CO emission sizes. We constrained dynamical stellar masses, geometries, temperatures, the CO column densities, and gas masses for each disk. The best-fit temperatures at 100 au are ~ 17–37 K, and decrease radially with the power-law exponent q ~ 0.05–0.76. The inferred CO column densities decrease radially with the power-law exponent p ~ 0.2–3.1. The gas masses estimated from 13CO (2–1) are ~0.001–0.2 M⊙. Conclusions. Using NOEMA, we confirm the presence of temperature gradients in our disk sample. The best-fit CO column densities point to severe CO freeze-out in these disks. The DL Tau disk is an outlier, and has either stronger CO depletion or lower gas mass than the rest of the sample. The CO isotopologue ratios are roughly consistent with the observed values in disks and the low-mass star-forming regions. The high 13CO/C18O ratio of ~23 in DM Tau could be indicative of strong selective photodissociation of C18O in this disk.

The SUPERCOLD-CGM Survey. I. Probing the Extended CO(4–3) Emission of the Circumgalactic Medium in a Sample of 10 Enormous Lyα Nebulae at z ∼ 2

To understand how massive galaxies at high z coevolve with enormous reservoirs of halo gas, it is essential to study the coldest phase of the circumgalactic medium (CGM), which directly relates to stellar growth. The SUPERCOLD-CGM survey is the first statistical survey of cold molecular gas on CGM scales. We present Atacama Large Millimeter Array and Atacama Compact Array observations of CO(4–3) and continuum emission from 10 enormous Lyα nebulae (ELANe) around ultraluminous type I quasi-stellar objects (QSOs) at z ∼ 2. We detect CO(4–3) in 100% of our targets, with 60% showing extended CO on scales of 15–100 kpc. Q1228+3128 reveals the most extended CO(4–3) reservoir of ∼100 kpc and is the only radio-loud target in our sample. The CO reservoir is located along the radio axis, which could indicate a link between the inner radio jet and cold halo gas. For the other five radio-quiet ELANe, four of them show extended CO(4–3) predominantly in the direction of their companions. These extended CO(4–3) reservoirs identify enrichment of the CGM and may potentially contribute to widespread star formation. However, there is no evidence from CO(4–3) for diffuse molecular gas spread across the full extent of the Lyα nebulae. One target in our sample (Q0107) shows significant evidence for a massive CO disk associated with the QSO. Moreover, 70% of our QSO fields contain at least one CO companion, two of which reveal extended CO emission outside the ELANe. Our results provide insight into roles of both the cold CGM and companions in driving the early evolution of massive galaxies.

Resolving a merger in a hyperluminous submillimeter galaxy at z = 2.82

ABSTRACT We present the resolved properties of the z = 2.82 hyperluminous infrared Galaxy (HyLIRG) HS1700.850.1, the brightest 850 $\mu$m source found in the SCUBA-2 followup to the Keck Baryonic Structure Survey fields (S850$\mu$m =19.5 mJy), and amongst the most luminous starbursts known at any redshift.- Using the IRAM-NOEMA interferometer in the highest resolution A-configuration, we resolve the source into two components separated by ∼8 kpc, visible as blue shifted and red shifted 12CO(5–4) lines, exhibiting the expected kinematic properties of a major merger between two gas rich Galaxies. The combined merger system is traced over 2.3 arcsec or 18.4 kpc. Each component of the merger shows ordered gas motions suggestive of a massive turbulent disc. We measure the dynamical masses of the blue and red discs as (1.5 ± 0.2) × 1011 and (0.71 ± 0.22) × 1011 M⊙, respectively. The more massive disc component shows broad wings in the CO line, offset by ∼3 kpc from the disc centroid along the major axis, and extending to velocities ∼±1000 km $\rm {s^{-1}}$ from systemic velocity. We interpret this as either a possible bipolar outflowing component, or more likely a warping or tidal structure in the CO disc. Comparing the properties of HS1700.850.1 to other submillimeter detected galaxies with comparably bright 850 $\mu$m luminosities suggests that ongoing gas-rich mergers, or at least a clustered/group environment lead to these most extreme starburst phases.

Hydrostatic Equilibrium Does Not Solve the C18O Flux Problem in Protoplanetary Disks

ALMA observations have shown that there is discrepancy between the disk mass estimate from CO emission and disk masses estimated from other tracers. This discrepancy has been interpreted as lower than expected CO abundance in the warm, surface layers of the disk. Recent work by Ruaud et al. claims that the low observed C18O fluxes can be explained with a ISM abundance of CO, that is 10−4 w.r.t. H2 by including hydrostatic equilbrium in the model density setup. We show that the Ruaud et al. low CO fluxes are due to an unrealistic temperature structure in the outer disk, due to an interaction of their dust model and hydrostatic equilibrium at their inner model edge. Furthermore, we show with our own modeling that a parametric model does a better job at matching the measured outer disk temperature structure.

CO Line Emission Surfaces and Vertical Structure in Midinclination Protoplanetary Disks

High spatial resolution CO observations of midinclination (≈30°–75°) protoplanetary disks offer an opportunity to study the vertical distribution of CO emission and temperature. The asymmetry of line emission relative to the disk major axis allows for a direct mapping of the emission height above the midplane, and for optically thick, spatially resolved emission in LTE, the intensity is a measure of the local gas temperature. Our analysis of Atacama Large Millimeter/submillimeter Array archival data yields CO emission surfaces, dynamically constrained stellar host masses, and disk atmosphere gas temperatures for the disks around the following: HD 142666, MY Lup, V4046 Sgr, HD 100546, GW Lup, WaOph 6, DoAr 25, Sz 91, CI Tau, and DM Tau. These sources span a wide range in stellar masses (0.50–2.10 M ⊙), ages (∼0.3–23 Myr), and CO gas radial emission extents (≈200–1000 au). This sample nearly triples the number of disks with mapped emission surfaces and confirms the wide diversity in line emitting heights (z/r ≈ 0.1 to ≳0.5) hinted at in previous studies. We compute the radial and vertical CO gas temperature distributions for each disk. A few disks show local temperature dips or enhancements, some of which correspond to dust substructures or the proposed locations of embedded planets. Several emission surfaces also show vertical substructures, which all align with rings and gaps in the millimeter dust. Combining our sample with literature sources, we find that CO line emitting heights weakly decline with stellar mass and gas temperature, which, despite large scatter, is consistent with simple scaling relations. We also observe a correlation between CO emission height and disk size, which is due to the flared structure of disks. Overall, CO emission surfaces trace ≈2–5× gas pressure scale heights (Hg) and could potentially be calibrated as empirical tracers of Hg.

Gas Disk Sizes from CO Line Observations: A Test of Angular Momentum Evolution

The size of a disk encodes important information about its evolution. Combining new Submillimeter Array observations with archival Atacama Large Millimeter/submillimeter Array data, we analyze millimeter continuum and CO emission line sizes for a sample of 44 protoplanetary disks around stars with masses of 0.15–2 M ⊙ in several nearby star-forming regions. Sizes measured from 12CO line emission span from 50 to 1000 au. This range could be explained by viscous evolution models with different α values (mostly of 10−4–10−3) and/or a spread of initial conditions. The CO sizes for most disks are also consistent with MHD wind models that directly remove disk angular momentum, but very large initial disk sizes would be required to account for the very extended CO disks in the sample. As no CO size evolution is observed across stellar ages of 0.5–20 Myr in this sample, determining the dominant mechanism of disk evolution will require a more complete sample for both younger and more evolved systems. We find that the CO emission is universally more extended than the continuum emission by an average factor of 2.9 ± 1.2. The ratio of the CO to continuum sizes does not show any trend with stellar mass, millimeter continuum luminosity, or the properties of substructures. The GO Tau disk has the most extended CO emission in this sample, with an extreme CO-to-continuum size ratio of 7.6. Seven additional disks in the sample show high size ratios (≳4) that we interpret as clear signs of substantial radial drift.

The diverse cold molecular gas contents, morphologies, and kinematics of type-2 quasars as seen by ALMA

We present CO(2−1) and adjacent continuum observations of seven nearby radio-quiet type-2 quasars (QSO2s) obtained with ALMA at ∼0.2″ resolution (370 pc at z ∼ 0.1). These QSO2s are luminous (L[OIII] > 108.5 L⊙ ∼ MB < −23), and their host galaxies massive (M* ∼ 1011 M⊙). The CO morphologies are diverse, including disks and interacting systems. Two of the QSO2s are red early-type galaxies with no CO(2–1) detected. In the interacting galaxies, the central kiloparsec contains 18–25% of the total cold molecular gas, whereas in the spirals it is only ∼5–12%. J1010+0612 and J1430+1339 show double-peaked CO flux maps along the major axis of the CO disks that do not have an optical counterpart at the same angular resolution. Based on our analysis of the ionized and molecular gas kinematics and millimeter continuum emission, these CO morphologies are most likely produced by active galactic nucleus (AGN) feedback in the form of outflows, jets, and/or shocks. The CO kinematics of the QSO2s with CO(2−1) detections are dominated by rotation but also reveal noncircular motions. According to our analysis, these noncircular motions correspond to molecular outflows that are mostly coplanar with the CO disks in four of the QSO2s, and either to a coplanar inflow or vertical outflow in the case of J1010+0612. These outflows represent 0.2–0.7% of the QSO2s’ total molecular gas mass and have maximum velocities of 200–350 km s−1, radii from 0.4 to 1.3 kpc, and outflow mass rates of 8–16 M⊙ yr−1. These outflow properties are intermediate between those of the mild molecular outflows measured for Seyfert galaxies and the fast and energetic outflows shown by ultra-luminous infrared galaxies. This suggests that it is not only AGN luminosity that drives massive molecular outflows. Other factors such as jet power, coupling between winds, jets, and/or ionized outflows and the CO disks, and amount or geometry of dense gas in the nuclear regions might also be relevant. Thus, although we do not find evidence for a significant impact of quasar feedback on the total molecular gas reservoirs and star formation rates, it appears to be modifying the distribution of cold molecular gas in the central kiloparsec of the galaxies.

Physical Characterization of Serendipitously Uncovered Millimeter-wave Line-emitting Galaxies at z ∼ 2.5 behind the Local Luminous Infrared Galaxy VV 114

Abstract We present a detailed investigation of millimeter-wave line emitters ALMA J010748.3-173028 (ALMA-J0107a) and ALMA J010747.0-173010 (ALMA-J0107b), which were serendipitously uncovered in the background of the nearby galaxy VV 114 with spectral scan observations at λ = 2–3 mm. Via Atacama Large Millimeter/submillimeter Array (ALMA) detection of CO(4–3), CO(3–2), and [C i](1–0) lines for both sources, their spectroscopic redshifts are unambiguously determined to be z = 2.4666 ± 0.0002 and z = 2.3100 ± 0.0002, respectively. We obtain the apparent molecular gas masses M gas of these two line emitters from [C i] line fluxes as (11.2 ± 3.1) × 1010 M ⊙ and (4.2 ± 1.2) × 1010 M ⊙, respectively. The observed CO(4–3) velocity field of ALMA-J0107a exhibits a clear velocity gradient across the CO disk, and we find that ALMA-J0107a is characterized by an inclined rotating disk with a significant turbulence, that is, a deprojected maximum rotation velocity to velocity dispersion ratio v max / σ v of 1.3 ± 0.3. We find that the dynamical mass of ALMA-J0107a within the CO-emitting disk computed from the derived kinetic parameters, (1.1 ± 0.2) × 1010 M ⊙, is an order of magnitude smaller than the molecular gas mass derived from dust continuum emission, (3.2 ± 1.6) × 1011 M ⊙. We suggest this source is magnified by a gravitational lens with a magnification of μ ≳ 10, which is consistent with the measured offset from the empirical correlation between CO-line luminosity and width.

Interaction of the galactic-centre super bubbles with the gaseous disc

ABSTRACT The interaction of Galactic centre (GC) super bubbles (GSBs) with the gaseous disc and halo of the Milky Way is investigated using radio continuum, X-ray, H i, and CO line surveys. The radio North Polar Spur (NPS) constitutes the brightest eastern ridge of GSB, brightening towards the galactic plane and reaching l = 22○, b = +2○ at the sharpest end, where it intersects the tangential direction of the 3-kpc-expanding ring and crater. Examination of the spur ridges reveals that the entire GSB, including the NPS and its counter spurs, constitutes a GC-symmetrical Ω/ Ʊ shape. The thickness and gas density of the H i and CO discs are shown to increase sharply from the inside (lower longitude) to the outside the 3-kpc crater. Formation of crater is explained by the sweeping of the upper layer of disc gas by the shock wave from the GC by the explosion ∼10 My ago with the emitted energy of several 1055 erg. Based on the discussion, a unified view on the structure and formation mechanism of GSB is presented.

Resolved molecular line observations reveal an inherited molecular layer in the young disk around TMC1A

Context.Physical processes that govern the star and planet formation sequence influence the chemical composition and evolution of protoplanetary disks. Recent studies allude to an early start to planet formation already during the formation of a disk. To understand the chemical composition of protoplanets, we need to constrain the composition and structure of the disks from whence they are formed.Aims.We aim to determine the molecular abundance structure of the young disk around the TMC1A protostar on au scales in order to understand its chemical structure and any possible implications for disk formation.Methods.We present spatially resolved Atacama Large Millimeter/submillimeter Array observations of CO, HCO+, HCN, DCN, and SO line emission, as well as dust continuum emission, in the vicinity of TMC1A. Molecular column densities are estimated both under the assumption of optically thin emission from molecules in local thermodynamical equilibrium (LTE) as well as through more detailed non-LTE radiative transfer calculations.Results.Resolved dust continuum emission from the disk is detected between 220 and 260 GHz. Rotational transitions from HCO+, HCN, and SO are also detected from the inner 100 au region. We further report on upper limits to vibrational HCNυ2= 1, DCN, and N2D+lines. The HCO+emission appears to trace both the Keplerian disk and the surrounding infalling rotating envelope. HCN emission peaks toward the outflow cavity region connected with the CO disk wind and toward the red-shifted part of the Keplerian disk. From the derived HCO+abundance, we estimate the ionization fraction of the disk surface, and find values that imply that the accretion process is not driven by the magneto-rotational instability. The molecular abundances averaged over the TMC1A disk are similar to its protostellar envelope and other, older Class II disks. We meanwhile find a discrepancy between the young disk’s molecular abundances relative to Solar System objects.Conclusions.Abundance comparisons between the disk and its surrounding envelope for several molecular species reveal that the bulk of planet-forming material enters the disk unaltered. Differences in HCN and H2O molecular abundances between the disk around TMC1A, Class II disks, and Solar System objects trace the chemical evolution during disk and planet formation.

WISDOM project – VI. Exploring the relation between supermassive black hole mass and galaxy rotation with molecular gas

ABSTRACT Empirical correlations between the masses of supermassive black holes (SMBHs) and properties of their host galaxies are well established. Among these is the correlation with the flat rotation velocity of each galaxy measured either at a large radius in its rotation curve or via a spatially integrated emission-line width. We propose here the use of the deprojected integrated CO emission-line width as an alternative tracer of this rotation velocity, which has already been shown useful for the Tully–Fisher (luminosity–rotation velocity) relation. We investigate the correlation between CO line widths and SMBH masses for two samples of galaxies with dynamical SMBH mass measurements, with spatially resolved and unresolved CO observations, respectively. The tightest correlation is found using the resolved sample of 25 galaxies as $\log (M_\mathrm{BH}/\mathrm{M_\odot })=(7.5\pm 0.1)+(8.5\pm 0.9)[\log (W_\mathrm{50}/\sin i \, \mathrm{km\, s}^{-1})-2.7]$, where MBH is the central SMBH mass, W50 is the full width at half-maximum of a double-horned emission-line profile, and i is the inclination of the CO disc. This relation has a total scatter of $0.6\,$ dex, comparable to those of other SMBH mass correlations, and dominated by the intrinsic scatter of $0.5\,$ dex. A tight correlation is also found between the deprojected CO line widths and the stellar velocity dispersions averaged within one effective radius. We apply our correlation to the COLD GASS sample to estimate the local SMBH mass function.

The AGN fuelling/feedback cycle in nearby radio galaxies – III. 3D relative orientations of radio jets and CO discs and their interaction

ABSTRACT This is the third paper of a series exploring the multifrequency properties of a sample of eleven nearby low-excitation radio galaxies (LERGs) in the southern sky. We are conducting an extensive study of different galaxy components (stars, dust, warm and cold gas, radio jets) with the aim of better understanding the AGN fuelling/feedback cycle in LERGs. Here, we present new, deep, sub-kpc resolution Karl G. Jansky Very Large Array (JVLA) data for five sample sources at 10 GHz. Coupling these data with previously acquired Atacama Large Millimetre/submillimetre Array (ALMA) CO(2–1) observations and measurements of comparable quality from the literature, we carry out for the first time a full 3D analysis of the relative orientations of jet and disc rotation axes in six FR I LERGs. This analysis shows (albeit with significant uncertainties) that the relative orientation angles span a wide range (≈30○–60○). There is no case where both axes are accurately aligned and there is a marginally significant tendency for jets to avoid the disc plane. Our study also provides further evidence for the presence of a jet-CO disc interaction (already inferred from other observational indicators) in at least one source, NGC 3100. In this case, the limited extent of the radio jets, along with distortions in both the molecular gas and the jet components, suggest that the jets are young, interacting with the surrounding matter and rapidly decelerating.

Spatial power spectra of dust across the Local Group: No constraint on disc scale height

ABSTRACT We analyse the 1D spatial power spectra of dust surface density and mid to far-infrared emission at $24\!-\!500\, \mu$m in the LMC, SMC, M31, and M33. By forward-modelling the point spread function (PSF) on the power spectrum, we find that nearly all power spectra have a single power-law and point source component. A broken power-law model is only favoured for the LMC 24 μm MIPS power spectrum and is due to intense dust heating in 30 Doradus. We also test for local power spectrum variations by splitting the LMC and SMC maps into 820 pc boxes. We find significant variations in the power-law index with no strong evidence for breaks. The lack of a ubiquitous break suggests that the spatial power spectrum does not constrain the disc scale height. This contradicts claims of a break where the turbulent motion changes from 3D to 2D. The power spectrum indices in the LMC, SMC, and M31 are similar (2.0–2.5). M33 has a flatter power spectrum (1.3), similar to more distant spiral galaxies with a centrally-concentrated H2 distribution. We compare the power spectra of H i, CO, and dust in M31 and M33, and find that H i power spectra are consistently flatter than CO power spectra. These results cast doubt on the idea that the spatial power spectrum traces large scale turbulent motion in nearby galaxies. Instead, we find that the spatial power spectrum is influenced by (1) the PSF on scales below ∼3 times the FWHM, (2) bright compact regions (30 Doradus), and (3) the global morphology of the tracer (an exponential CO disc).

The AGN fuelling/feedback cycle in nearby radio galaxies – II. Kinematics of the molecular gas

ABSTRACT This is the second paper of a series exploring the multicomponent (stars, warm and cold gas, and radio jets) properties of a sample of 11 nearby low-excitation radio galaxies, with the aim of better understanding the active galactic nuclei (AGN) fuelling/feedback cycle in these objects. Here, we present a study of the molecular gas kinematics of six sample galaxies detected in 12CO(2-1) with the Atacama Large Millimeter/submillimeter Array (ALMA). In all cases, our modelling suggests that the bulk of the gas in the observed (sub-)kpc CO discs is in ordered rotation. Nevertheless, low-level distortions are ubiquitous, indicating that the molecular gas is not fully relaxed into the host galaxy potential. The majority of the discs, however, are only marginally resolved, preventing us from drawing strong conclusions. NGC 3557 and NGC 3100 are special cases. The features observed in the CO velocity curve of NGC 3557 allow us to estimate a supermassive black hole (SMBH) mass of (7.10 ± 0.02) × 108 M⊙, in agreement with expectations from the MSMBH–σ* relation. The rotation pattern of NGC 3100 shows distortions that appear to be consistent with the presence of both a position angle and an inclination warp. Non-negligible radial motions are also found in the plane of the CO disc, likely consistent with streaming motions associated with the spiral pattern found in the inner regions of the disc. The dominant radial motions are likely to be inflows, supporting a scenario in which the cold gas is contributing to the fuelling of the AGN.

Powerful AGN jets and unbalanced cooling in the hot atmosphere of IC 4296

Abstract We present new Karl G. Jansky Very Large Array (VLA, 1.5 GHz) radio data for the giant elliptical galaxy IC 4296, supported by archival radio, X-ray (Chandra, and XMM–Newton) and optical (SOAR, and HST) observations. The galaxy hosts powerful radio jets piercing through the inner hot X-ray emitting atmosphere, depositing most of the energy into the ambient intracluster medium (ICM). Whereas the radio surface brightness of the A configuration image is consistent with a Fanaroff–Riley Class I system, the D configuration image shows two bright, relative to the central region, large (${\sim } 160\, \rm {kpc}$ diameter), well-defined lobes, previously reported by Killeen et al., at a projected distance $r\gtrsim 230\, \rm {kpc}$. The XMM–Newton image reveals an X-ray cavity associated with one of the radio lobes. The total enthalpy of the radio lobes is ${\sim }7\times 10^{59}\, \rm {erg}$ and the mechanical power output of the jets is ${\sim } 10^{44}\, \rm {erg\, s}^{-1}$. The jets are mildly curved and possibly rebrightened by the relative motion of the galaxy and the ICM. The lobes display sharp edges, suggesting the presence of bow shocks, which would indicate that they are expanding supersonically. The central entropy and cooling time of the X-ray gas are unusually low and the nucleus hosts a warm Hα + [$\rm{N\,{\small II}}$] nebula and a cold molecular CO disc. Because most of the energy of the jets is deposited far from the nucleus, the atmosphere of the galaxy continues to cool, apparently feeding the central supermassive black hole and powering the jet activity.

ALMA study of the HD 100453 AB system and the tidal interaction of the companion with the disk

Context. The complex system HD 100453 AB with a ring-like circumprimary disk and two spiral arms, one of which is pointing to the secondary, is a good laboratory in which to test spiral formation theories. Aims. We aim to resolve the dust and gas distribution in the disk around HD 100453 A and to quantify the interaction of HD 100453 B with the circumprimary disk. Methods. Using ALMA band 6 dust continuum and CO isotopologue observations we have studied the HD 100453 AB system with a spatial resolution of 0′′.09 × 0′′.17 at 234 GHz. We used smoothed particle hydrodynamics (SPH) simulations and orbital fitting to investigate the tidal influence of the companion on the disk. Results. We resolve the continuum emission around HD 100453 A into a disk between 0′′.22 and 0′′.40 with an inclination of 29.5° and a position angle of 151.0°, an unresolved inner disk, and excess mm emission cospatial with the northern spiral arm which was previously detected using scattered light observations. We also detect CO emission from 7 au (well within the disk cavity) out to 1′′.10, overlapping with HD 100453 B at least in projection. The outer CO disk position angle (PA) and inclination differ by up to 10° from the values found for the inner CO disk and the dust continuum emission, which we interpret as due to gravitational interaction with HD 100453 B. Both the spatial extent of the CO disk and the detection of mm emission at the same location as the northern spiral arm are in disagreement with the previously proposed near co-planar orbit of HD 100453 B. Conclusions. We conclude that HD 100453 B has an orbit that is significantly misaligned with the circumprimary disk. Because it is unclear whether such an orbit can explain the observed system geometry we highlight an alternative scenario that explains all detected disk features where another, (yet) undetected, low mass close companion within the disk cavity, shepherds a misaligned inner disk whose slowly precessing shadows excite the spiral arms.