arXiv subjects

M. W. L. Smith

Publications and source records attributed to M. W. L. Smith.

At least 19 recordsLinked to original sources

arXiv2026

DustPedia: Multiwavelength Photometry and Imagery of 875 Nearby Galaxies in 42 Ultraviolet--Microwave Bands

The DustPedia project is capitalising on the legacy of the Herschel Space Observatory, using cutting-edge modelling techniques to study dust in the 875 DustPedia galaxies - representing the vast majority of extended galaxies within 3000 km s$^{-1}$ that were observed by Herschel. This work requires a database of multiwavelength imagery and photometry that greatly exceeds the scope (in terms of wavelength coverage and number of galaxies) of any previous local-Universe survey. We constructed a database containing our own custom Herschel reductions, along with standardised archival observations from GALEX, SDSS, DSS, 2MASS, WISE, Spitzer, and Planck. Using these data, we performed consistent aperture-matched photometry, which we combined with external supplementary photometry from IRAS and Planck. We present our multiwavelength imagery and photometry across 42 UV-microwave bands for the 875 DustPedia galaxies. Our aperture-matched photometry, combined with the external supplementary photometry, represents a total of 21,857 photometric measurements. A typical DustPedia galaxy has multiwavelength photometry spanning 25 bands. We also present the Comprehensive & Adaptable Aperture Photometry Routine (CAAPR), the pipeline we developed to carry out our aperture-matched photometry. CAAPR is designed to produce consistent photometry for the enormous range of galaxy and observation types in our data. In particular, CAAPR is able to determine robust cross-compatible uncertainties, thanks to a novel method for reliably extrapolating the aperture noise for observations that cover a very limited amount of background. Our rich database of imagery and photometry is being made available to the community

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arXiv2026

Spatially-resolved interstellar dust properties in the face-on spiral galaxy M 99 as observed by NIKA2

Large dust grains in thermal equilibrium dominate the far-infrared and contribute to the millimetre continuum of star-forming galaxies, but constraining their properties is difficult due to free-free and synchrotron contamination. We study spatial variations in the dust spectral index, mass, and grain properties in the nearby face-on spiral galaxy M 99. We use new 1.15 and 2 mm continuum observations from NIKA2 on the IRAM 30 m telescope (IMEGIN Guaranteed Time Large Programme) combined with multiwavelength data from UV to radio. The infrared-to-radio SED is decomposed into dust, free-free, and synchrotron components using the hierarchical Bayesian code HerBIE. Dust is modelled via a modified blackbody (MBB) with variable millimetre spectral index beta and the THEMIS dust model with fixed beta. We perform spatially-resolved analysis at scales ~1.75 kpc (~25''), covering the centre, spiral arms, and inter-arm regions. MBB fits reveal beta variations from ~1.6-1.7 in diffuse regions to ~2.3-2.5 in dense star-forming areas, likely due to grain coagulation and changes in silicate-to-carbonaceous ratios. Dust masses from variable beta are up to ~4x higher than fixed-beta models, which systematically bias dust-to-stellar and dust-to-gas ratios. The small grain fraction rises from ~10% in the centre to ~15% in the diffuse disc, anti-correlated with the interstellar radiation field; gas-phase metallicity plays a minor role within 8 kpc. Synchrotron spectral index ranges from ~0.6-0.7 in star-forming regions to ~1.2 in the diffuse medium, consistent with cosmic-ray electron ageing.

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arXiv2026

Resolved ISM properties and scaling relations in the barred galaxy NGC 3627: constraints from NIKA2 observations

We investigate the interplay between star formation, interstellar medium (ISM) components, and dust properties in NGC 3627 using new NIKA2 1.15 and 2 mm observations from the IMEGIN Large Program. Our goal is to analyze dust and radio emission, decompose contributions in the millimeter-centimeter regime, and explore ISM properties within the galaxy. We perform spectral energy distribution fitting, at both global and spatial scales, using the THEMIS dust model within the HerBIE code, applied to data from 3.4 $μ$m to 6 cm. We decompose emission into dust, free-free, and synchrotron components, and examine correlations with gas surface density and star formation activity. Additionally, we analyze the small dust grain fraction and its variation across the galaxy. We find $\sim$10% radio emission at 2 mm, peaking at 18% in the southern bar-end, which hosts the highest star formation activity. However, an isolated star-forming region beyond this bar-end is the most efficient, as indicated by its elevated dust production efficiency and effective yield, predicted by our simplistic dust evolution model. The 160 $μ$m emission shows the strongest correlation with molecular gas, while 1.15 mm better traces the dust mass surface density. Small grains, which make up $\sim$13% of dust mass (2 $\times$ 10$^{7}$ M$_{\odot}$), are depleted in intense radiation fields, with a notable deficit in the southern tidal tail. ISM properties and chemical evolution indicate that dynamical processes, such as bar-driven gas flows and tidal interactions, are crucial in shaping the galactic structure, influencing star formation efficiency, and dust distribution.

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arXiv2025

Cloud Properties and Star Formation in M31

We present a catalogue of 453 molecular clouds in M31 extracted from CO J=1-0 data observed with CARMA using a dendrogram. Our clouds have the mean values of 2.8 km s$^{-1}$, 22.1 pc and 10$^{5.2}$ M$_\odot$ for the velocity dispersion, radius and mass, respectively. The velocity dispersion shows a weak anti-correlation with the galactocentric radius. The clouds in M31 show mean and median values of 2.0 and 1.4, respectively, for their virial parameters, indicating that most of them are gravitationally bound. Our dendrogram analysis identifies 35 sources with multiple velocity components, which we classify as molecular cloud complexes. We study the size-velocity dispersion and size-mass relationships for the clouds in M31, finding the slopes of 0.43$\pm$0.05 and 1.36$\pm$0.06 for the former and the latter, respectively. Our size-velocity dispersion relationship agrees with those of Milky Way (MW) and M31 clouds. The slope of our size-mass relationship is shallower than those in clouds and cloud complexes of the MW. We find offsets between the isosurfaces of the clouds and star formation rate (SFR) peaks in M31, supporting the scenario where the evolutionary state of individual sources plays a role in the Kennicutt-Schmidt (KS) law at parsec scales. We find a slope of 0.66$\pm$0.07 for the KS law, which is slightly lower than the values of $\sim$0.8 for MW clouds.

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arXiv2025

The dust emissivity index beta in infrared-bright galaxies at 1.5 < z < 4.2

We have measured the dust emissivity index beta for 21 infrared-bright sources (including several gravitationally lensed galaxies) at 1.5 < z < 4.2 using Atacama Large Millimeter/submillimeter Array (ALMA) 101-199 GHz data sampling the Rayleigh-Jeans side of the SED. These data are largely insensitive to temperature variations and therefore should provide robust measurements of beta. We obtain a mean beta of 2.2 with a standard deviation of 0.6 that is at the high end of the range of values that had previously been measured in many galactic and extragalactic sources. We find no systematic variation in beta versus redshift. We also demonstrate with a subset of our sources that these higher beta values have significant implications for modelling dust emission and in particular for calculating dust masses or the wavelength at which dust becomes optically thick.

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arXiv2025

Cloud populations versus galactic environment in NGC4689, NGC628, NGC1566, and NGC4321

The study of molecular clouds in galaxies beyond the Local Group is limited by the need to efficiently sample diverse galactic environments across galactic discs, typically resulting in a loss of resolution. Using a high-resolution dust extinction technique, we image the dust (and gas) of 4 nearby galaxies (<18 Mpc; NGC 4689, NGC 628, NGC 1566, and NGC 4321) with resolutions between 5-9 pc. We present catalogues of spatially-resolved clouds for these galaxies, with which we investigate whether different galactic environments and morphologies have a significant impact on observed cloud properties. We find no systematic differences in cloud size, aspect ratio, or morphology with galactic environment or radius. We do find changes in cloud masses/surface densities between the centres and discs of galaxies, with clouds in centres typically displaying higher values of mass/surface density. Furthermore, we find distinct distributions of cloud surface densities across the bars of NGC 1566 and NGC 4321. Differences between the arm and inter-arm populations are more subtle, with some galaxies in the sample having much higher cloud masses/surface densities in their spiral arms, and other galaxies showing fairly similar arm/inter-arm distributions. These results suggest that, even within this small sample of galaxies, not all spiral arms and bars seem to behave and affect the interstellar medium equally. Therefore, performing a qualitative environment analysis, where clouds of different galaxies are all binned together under the same visual environmental classification, leads to the loss of information on interesting property variations which in turn demonstrate the impact of the underlying dynamics.

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arXiv2024

Interpreting Millimeter Emission from IMEGIN galaxies NGC 2146 and NGC 2976

The millimeter continuum emission from galaxies provides important information about cold dust, its distribution, heating, and role in their InterStellar Medium (ISM). This emission also carries an unknown portion of the free-free and synchrotron radiation. The IRAM 30m Guaranteed Time Large Project, Interpreting Millimeter Emission of Galaxies with IRAM and NIKA2 (IMEGIN) provides a unique opportunity to study the origin of the millimeter emission on angular resolutions of <18" in a sample of nearby galaxies. As a pilot study, we present millimeter observations of two IMEGIN galaxies, NGC 2146 (starburst) and NGC 2976 (peculiar dwarf) at 1.15 mm and 2 mm. Combined with the data taken with Spitzer, Herschel, Plank, WSRT, and the 100m Effelsberg telescopes, we model the infrared-to-radio Spectral Energy Distribution (SED) of these galaxies, both globally and at resolved scales, using a Bayesian approach to 1) dissect different components of the millimeter emission, 2) investigate the physical properties of dust, and 3) explore correlations between millimeter emission, gas, and Star Formation Rate (SFR). We find that cold dust is responsible for most of the 1.15 mm emission in both galaxies and at 2 mm in NGC 2976. The free-free emission emits more importantly in NGC 2146 at 2 mm. The cold dust emissivity index is flatter in the dwarf galaxy ($β= 1.3\pm 0.1$) compared to the starburst galaxy ($β= 1.7\pm 0.1$). Mapping the dust-to-gas ratio, we find that it changes between 0.004 and 0.01 with a mean of $0.006\pm0.001$ in the dwarf galaxy. In addition, no global balance holds between the formation and dissociation of H$_2$ in this galaxy. We find tight correlations between the millimeter emission and both the SFR and molecular gas mass in both galaxies.

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arXiv2024

The UK Submillimetre and Millimetre Astronomy Roadmap 2024

In this Roadmap, we present a vision for the future of submillimetre and millimetre astronomy in the United Kingdom over the next decade and beyond. This Roadmap has been developed in response to the recommendation of the Astronomy Advisory Panel (AAP) of the STFC in the AAP Astronomy Roadmap 2022. In order to develop our stragetic priorities and recommendations, we surveyed the UK submillimetre and millimetre community to determine their key priorities for both the near-term and long-term future of the field. We further performed detailed reviews of UK leadership in submillimetre/millimetre science and instrumentation. Our key strategic priorities are as follows: 1. The UK must be a key partner in the forthcoming AtLAST telescope, for which it is essential that the UK remains a key partner in the JCMT in the intermediate term. 2. The UK must maintain, and if possible enhance, access to ALMA and aim to lead parts of instrument development for ALMA2040. Our strategic priorities complement one another: AtLAST (a 50m single-dish telescope) and an upgraded ALMA (a large configurable interferometric array) would be in synergy, not competition, with one another. Both have identified and are working towards the same overarching science goals, and both are required in order to fully address these goals.

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arXiv2024

The MeerKAT Fornax Survey. III. Ram-pressure stripping of the tidally interacting galaxy NGC 1427A in the Fornax cluster

We present MeerKAT Fornax Survey HI observations of NGC 1427A, a blue irregular galaxy with a stellar mass of 2e+9 Msun located near the centre of the Fornax galaxy cluster. Thanks to the excellent resolution (1 to 6 kpc spatially, 1.4 km/s in velocity) and HI column density sensitivity (4e+19/cm^2 to 1e+18/cm^2 depending on resolution), our data deliver new insights on the long-debated interaction of this galaxy with the cluster environment. We confirm the presence of a broad, one-sided, starless HI tail stretching from the outer regions of the stellar body and pointing away from the cluster centre. We find the tail to have 50% more HI (4e+8 Msun) and to be 3 times longer (70 kpc) than in previous observations. In fact, we detect scattered HI clouds out to 300 kpc from the galaxy in the direction of the tail -- possibly the most ancient remnant of the passage of NGC 1427A through the intracluster medium of Fornax. Both the velocity gradient along the HI tail and the peculiar kinematics of HI in the outer region of the stellar body are consistent with the effect of ram pressure given the line-of-sight motion of the galaxy within the cluster. However, several properties cannot be explained solely by ram pressure and suggest an ongoing tidal interaction. This includes: the close match between dense HI and stars within the disturbed stellar body; the abundant kinematically-anomalous HI; and the inversion of the HI velocity gradient near the base of the HI tail. We rule out an interaction with the cluster tidal field, and conclude that NGC 1427A is the result of a high-speed galaxy encounter or of a merger started at least 300 Myr ago, where ram pressure shapes the distribution and kinematics of the HI in the perturbed outer stellar body and in the tidal tails.

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arXiv2024

MHONGOOSE -- A MeerKAT Nearby Galaxy HI Survey

The MHONGOOSE (MeerKAT HI Observations of Nearby Galactic Objects: Observing Southern Emitters) survey maps the distribution and kinematics of the neutral atomic hydrogen (HI) gas in and around 30 nearby star-forming spiral and dwarf galaxies to extremely low HI column densities. The HI column density sensitivity (3 sigma over 16 km/s) ranges from ~ 5 x 10^{17} cm^{-2} at 90'' resolution to ~4 x 10^{19} cm^{-2} at the highest resolution of 7''. The HI mass sensitivity (3 sigma over 50 km/s) is ~5.5 X 10^5 M_sun at a distance of 10 Mpc (the median distance of the sample galaxies). The velocity resolution of the data is 1.4 km/s. One of the main science goals of the survey is the detection of cold, accreting gas in the outskirts of the sample galaxies. The sample was selected to cover a range in HI masses, from 10^7 M_sun to almost 10^{11} M_sun, to optimally sample possible accretion scenarios and environments. The distance to the sample galaxies ranges from 3 to 23 Mpc. In this paper, we present the sample selection, survey design, and observation and reduction procedures. We compare the integrated HI fluxes based on the MeerKAT data with those derived from single-dish measurement and find good agreement, indicating that our MeerKAT observations are recovering all flux. We present HI moment maps of the entire sample based on the first ten percent of the survey data, and find that a comparison of the zeroth- and second-moment values shows a clear separation between the physical properties of the HI in areas with star formation and areas without, related to the formation of a cold neutral medium. Finally, we give an overview of the HI-detected companion and satellite galaxies in the 30 fields, five of which have not previously been catalogued. We find a clear relation between the number of companion galaxies and the mass of the main target galaxy.

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arXiv2023

Exploring the interstellar medium of NGC 891 at millimeter wavelengths using the NIKA2 camera

In the framework of the IMEGIN Large Program, we used the NIKA2 camera on the IRAM 30-m telescope to observe the edge-on galaxy NGC 891 at 1.15 mm and 2 mm and at a FWHM of 11.1" and 17.6", respectively. Multiwavelength data enriched with the new NIKA2 observations fitted by the HerBIE SED code (coupled with the THEMIS dust model) were used to constrain the physical properties of the ISM. Emission originating from the diffuse dust disk is detected at all wavelengths from mid-IR to mm, while mid-IR observations reveal warm dust emission from compact HII regions. Indications of mm excess emission have also been found in the outer parts of the galactic disk. Furthermore, our SED fitting analysis constrained the mass fraction of the small (< 15 Angstrom) dust grains. We found that small grains constitute 9.5% of the total dust mass in the galactic plane, but this fraction increases up to ~ 20% at large distances (|z| > 3 kpc) from the galactic plane.

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arXiv2023

The stratification of ISM properties in the edge-on galaxy NGC 891 revealed by NIKA2

As the millimeter wavelength range remains a largely unexplored spectral region for galaxies, the IMEGIN large program aims to map the millimeter continuum emission of 22 nearby galaxies at 1.15 and 2 mm. Using the high-resolution maps produced by the NIKA2 camera, we explore the existence of very cold dust and take possible contamination by free-free and synchrotron emission into account. We study the IR-to-radio emission coming from different regions along the galactic plane and at large vertical distances. New observations of NGC 891, using the NIKA2 camera on the IRAM 30m telescope, along with a suite of observations at other wavelengths were used to perform a multiwavelength study of the spectral energy distribution in the interstellar medium in this galaxy. This analysis was performed globally and locally, using the advanced hierarchical Bayesian fitting code, HerBIE, coupled with the THEMIS dust model. Our dust modeling is able to reproduce the near-IR to millimeter emission of NGC 891, with the exception of an excess at a level of 25% obtained by the NIKA2 observations in the outermost parts of the disk. The radio continuum and thermal dust emission are distributed differently in the disk and galaxy halo. Different dusty environments are also revealed by a multiwavelength investigation of the emission features. Our detailed decomposition at millimeter and centimeter wavelengths shows that emission at 1 mm is purely originated by dust. Radio components become progressively important with increasing wavelengths. Finally, we find that emission arising from small dust grains accounts for ~ 9.5% of the total dust mass, reaching up to 20% at large galactic latitudes. Shock waves in the outflows that shatter the dust grains might explain this higher fraction of small grains in the halo.

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arXiv2023

Bright Extragalactic ALMA Redshift Survey (BEARS) III: Detailed study of emission lines from 71 Herschel targets

We analyse the molecular and atomic emission lines of 71 bright Herschel-selected galaxies between redshifts 1.4 to 4.6 detected by the Atacama Large Millimetre/submillimetre Array. These lines include a total of 156 CO, [C I], and H2O emission lines. For 46 galaxies, we detect two transitions of CO lines, and for these galaxies we find gas properties similar to those of other dusty star-forming galaxy (DSFG) samples. A comparison to photo-dissociation models suggests that most of Herschel-selected galaxies have similar interstellar medium conditions as local infrared-luminous galaxies and high-redshift DSFGs, although with denser gas and more intense far-ultraviolet radiation fields than normal star-forming galaxies. The line luminosities agree with the luminosity scaling relations across five orders of magnitude, although the star-formation and gas surface density distributions (i.e., Schmidt-Kennicutt relation) suggest a different star-formation phase in our galaxies (and other DSFGs) compared to local and low-redshift gas-rich, normal star-forming systems. The gas-to-dust ratios of these galaxies are similar to Milky Way values, with no apparent redshift evolution. Four of 46 sources appear to have CO line ratios in excess of the expected maximum (thermalized) profile, suggesting a rare phase in the evolution of DSFGs. Finally, we create a deep stacked spectrum over a wide rest-frame frequency (220-890 GHz) that reveals faint transitions from HCN and CH, in line with previous stacking experiments.

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arXiv2023

The MeerKAT Fornax Survey -- I. Survey description and first evidence of ram pressure in the Fornax galaxy cluster

The MeerKAT Fornax Survey maps the distribution and kinematics of atomic neutral hydrogen gas (HI) in the nearby Fornax galaxy cluster using the MeerKAT telescope. The 12 deg^2 survey footprint covers the central region of the cluster out to ~ Rvir and stretches out to ~ 2 Rvir towards south west to include the NGC 1316 galaxy group. The HI column density sensitivity (3 sigma over 25 km/s) ranges from 5e+19/cm^2 at a resolution of ~ 10" (~ 1 kpc at the 20 Mpc distance of Fornax) down to ~ 1e+18/cm^2 at ~ 1' (~ 6 kpc), and slightly below this level at the lowest resolution of ~ 100" (~ 10 kpc). The HI mass sensitivity (3 sigma over 50 km/s) is 6e+5 Msun. The HI velocity resolution is 1.4 km/s. In this paper we describe the survey design and HI data processing, and we present a sample of six galaxies with long, one-sided, star-less HI tails (of which only one was previously known) radially oriented within the cluster and with measurable internal velocity gradients. We argue that the joint properties of the HI tails represent the first unambiguous evidence of ram pressure shaping the distribution of HI in the Fornax cluster. The disturbed optical morphology of all host galaxies supports the idea that the tails consist of HI initially pulled out of the galaxies' stellar body by tidal forces. Ram pressure was then able to further displace the weakly bound HI and give the tails their present direction, length and velocity gradient.

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arXiv2023

The Bright Extragalactic ALMA Redshift Survey (BEARS) II: Millimetre photometry of gravitational lens candidates

We present 101 and 151 GHz ALMA continuum images for 85 fields selected from Herschel observations that have 500 micron flux densities >80 mJy and 250-500 micron colours consistent with z > 2, most of which are expected to be gravitationally lensed or hyperluminous infrared galaxies. Approximately half of the Herschel 500 micron sources were resolved into multiple ALMA sources, but 11 of the 15 brightest 500 micron Herschel sources correspond to individual ALMA sources. For the 37 fields containing either a single source with a spectroscopic redshift or two sources with the same spectroscopic redshift, we examined the colour temperatures and dust emissivity indices. The colour temperatures only vary weakly with redshift and are statistically consistent with no redshift-dependent temperature variations, which generally corresponds to results from other samples selected in far-infrared, submillimetre, or millimetre bands but not to results from samples selected in optical or near-infrared bands. The dust emissivity indices, with very few exceptions, are largely consistent with a value of 2. We also compared spectroscopic redshifts to photometric redshifts based on spectral energy distribution templates designed for infrared-bright high-redshift galaxies. While the templates systematically underestimate the redshifts by ~15%, the inclusion of ALMA data decreases the scatter in the predicted redshifts by a factor of ~2, illustrating the potential usefulness of these millimetre data for estimating photometric redshifts.

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arXiv2022

The star-formation rates of QSOs

We examine the far-IR properties of a sample of 5391 optically selected QSOs in the 0.5 44.7, using SPIRE data from Herschel-ATLAS. We split the sample in a grid of 74 luminosity-redshift bins and compute the average optical-infrared spectral energy distribution (SED) in each bin. By normalising an intrinsic AGN template to the AGN optical power (at 5100A) we decompose the total infrared emission (L_IR; 8-1000um) into an AGN (L_IR,AGN) and star-forming component (L_IR,SF). We find that the AGN contribution to L_IR increases as a function of AGN power which manifests as a reduction of the `far-IR bump' in the average QSO SEDs. We note that L_IR,SF does not correlate with AGN power; the mean star formation rates (SFRs) of AGN host galaxies are a function of redshift only and they range from ~6 Msun/yr at z~0 to a plateau of <200 Msun/yr at z~2.6. Our results indicate that the accuracy of far-IR emission as a proxy for SFR decreases with increasing AGN luminosity. We show that, at any given redshift, observed trends between infrared luminosity (whether monochromatic or total) and AGN power (in the optical or X-rays) can be explained by a simple model which is the sum of two components: (A) the infrared emission from star-formation, uncorrelated with AGN power and (B) the infrared emission from AGN, directly proportional to AGN power in the optical or X-rays.

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arXiv2022

Herschel-ATLAS Data Release III: Near-infrared counterparts in the South Galactic Pole field -- Another 100,000 submillimetre galaxies

In this paper we present the third data release (DR3) of the Herschel Astrophysical Terahertz Large Area Survey (H-ATLAS). We identify likely near-infrared counterparts to submillimetre sources in the South Galactic Pole (SGP) field using the VISTA VIKING survey. We search for the most probable counterparts within 15 arcsec of each Herschel source using a probability measure based on the ratio between the likelihood the true counterpart is found close to the submillimetre source and the likelihood that an unrelated object is found in the same location. For 110 374 (57.0$\%$) sources we find galaxies on the near-infrared images where the probability that the galaxy is associated to the source is greater than 0.8. We estimate the false identification rate to be 4.8$\%$, with a probability that the source has an associated counterpart on the VIKING images of 0.835$\pm$0.009. We investigate the effects of gravitational lensing and present 41 (0.14 deg$^{-2}$) candidate lensed systems with observed flux densities > 100 mJy at 500 $μ$m. We include in the data release a probability that each source is gravitationally lensed and discover an additional 5 923 sources below 100 mJy that have a probability greater than 0.94 of being gravitationally lensed. We estimate that $\sim$ 400 - 1 000 sources have multiple true identifications in VIKING based on the similarity of redshift estimates for multiple counterparts close to a Herschel source. The data described in this paper can be found at the H-ATLAS website.

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arXiv2022

The Bright Extragalactic ALMA Redshift Survey (BEARS) I: redshifts of bright gravitationally-lensed galaxies from the Herschel ATLAS

We present spectroscopic measurements for 71 galaxies associated with 62 of the brightest high-redshift submillimeter sources from the Southern fields of the Herschel Astrophysical Terahertz Large Area Survey (H-ATLAS), while targeting 85 sources which resolved into 142. We have obtained robust redshift measurements for all sources using the 12-m Array and an efficient tuning of ALMA to optimise its use as a redshift hunter, with 73 per cent of the sources having a robust redshift identification. Nine of these redshift identifications also rely on observations from the Atacama Compact Array. The spectroscopic redshifts span a range $1.41<z<4.53$ with a mean value of 2.75, and the CO emission line full-width at half-maxima range between $\rm 110\,km\,s^{-1} < FWHM < 1290\,km\,s^{-1}$ with a mean value of $\sim$ 500kms$^{-1}$, in line with other high-$z$ samples. The derived CO(1-0) luminosity is significantly elevated relative to line-width to CO(1-0) luminosity scaling relation, which is suggestive of lensing magnification across our sources. In fact, the distribution of magnification factors inferred from the CO equivalent widths is consistent with expectations from galaxy-galaxy lensing models, though there is a hint of an excess at large magnifications that may be attributable to the additional lensing optical depth from galaxy groups or clusters.

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