arXiv subjects

Marcel Neeleman

Publications and source records attributed to Marcel Neeleman.

At least 19 recordsLinked to original sources

arXiv2026

A VLA Study of the Disturbed Massive Cluster PLCK G165.7 + 67.0 and Its Two Narrow Angle Tail Galaxies

Since spectroscopic measurements provide only the line-of-sight velocity, transverse motions are difficult to constrain. In the vast majority of cases, transverse velocities have been measured only for local galaxies. Radio galaxies whose jets are bent back by ram pressure into nearly parallel Narrow-Angle Tails (NATs) offer a way to extend such measurements to higher redshifts. Here, we present proprietary 15~GHz (Ku-band) and archival 6~GHz (C-band) continuum observations from the Very Large Array (VLA) of six radio galaxies in the galaxy cluster field PLCK G165.7+67.0 (G165). VLA imaging resolves two of the cluster galaxies into NATs whose tails both extend toward the Southwest, away from the cluster center of mass. Spectral index maps made at matched angular resolution resolve a steepening gradient consistent with radiative aging along the length of the tails. Physical properties of the NATs are measured and used to constrain two independent models: a Mach cone model and a nonrelativistic hydrodynamic flow model based on Euler's equation. The models returned transverse velocities of $\sim 2000 ~\rm km~ \rm s^{-1}$ for both galaxies. One NAT is the brightest cluster galaxy (BCG) and has a measured radial velocity of $-3300 ~\rm km ~\rm s^{-1}$, resulting in an even higher space velocity. The high inferred 3D velocity of the BCG may be explained if it is intercepted close to core passage.

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arXiv2026

Resolving the Assembly of Disk Galaxies from the Epoch of Reionisation to Cosmic Noon

Most of the mass and angular momentum of today's disk galaxies assembled at $z>1$. Yet, it remains unclear how these galaxies acquired their gas, how their baryons and dark matter coevolved, and how feedback and radial gas transport shaped their disks. Addressing these gaps requires resolved observations of cold gas, which carries most of the mass and angular momentum involved in galaxy assembly. By resolving CO and [C II] at kpc scales, ALMA revealed a surprising population of rotation-dominated disks, even at $z>2$, exhibiting kinematic signatures consistent with spiral arms, bars, and tidal tails. Yet, these studies are limited to massive ($M_\star>10^{10.5}$ M$_\odot$) and highly star-forming (SFRs$\gtrsim 100$ M$_\odot$yr$^{-1}$) galaxies, the progenitors of today's most massive elliptical and disk galaxies. To understand how most present-day spirals (like the Milky Way) assembled, it is crucial to resolve their low-mass progenitors, which dominate the star-forming galaxy population by number at $z>1$. Achieving this goal demands a tenfold increase in line sensitivity and hence a next-generation sub-/millimetre facility: ALMA2040. This leap in sensitivity will enable routine resolved studies of hundreds of $M_\star>10^9$ M$_\odot$ galaxies, including those on and below the main sequence of star-forming galaxies, providing representative, statistical galaxy samples with sub-kpc constraints on the cold gas kinematics and morphology. By uniquely providing resolved CO, [C I], and [C II] observations across $z=1-6$, ALMA2040 will trace a much larger fraction of the cold-gas reservoir than is accessible today, extending resolved studies from rare massive and/or lensed systems to representative galaxy populations. In this way, ALMA2040 will transform our understanding of how galaxy disks formed and evolved.

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arXiv2026

Direct measures of black hole masses through cosmic time

Supermassive black holes (BHs) are thought to reside in all massive galaxies. They play a fundamental role in shaping galaxy evolution by suppressing star formation and halting the stellar growth of the most massive galaxies via feedback mechanisms. However, to date, measuring even their most basic property, their mass, is still challenging. The mass of BHs carries information on the growth history and the mutual interplay with the host galaxy. Uncertain BH masses leave many key questions on galaxy evolution wide open. Here we show that a transformational facility such as ALMA2040 would open a new window to measure BH mass by directly observing the kinematics of cold gas in galaxy cores from the local Universe up to very high redshift, irrespective of BH activity. This would revolutionise our understanding of BH formation, growth, and their role within galaxy evolution.

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arXiv2026

A dense, metal-rich absorber driven by a heavily dust-obscured galaxy: The direct evidence of CGM enrichment at $z\sim7$

We report the serendipitous discovery of a dense, metal-enriched circumgalactic medium (CGM) absorber at z=7.03, together with its host galaxy, identified along the sightline toward a red quasar. The absorber exhibits the largest rest-frame equivalent widths and column densities observed to date at z>5, tracing a metal-enriched gaseous halo. Using deep JWST/NIRSpec and NOEMA observations, we characterize the absorber's physical properties and identify its host, ND1, as a vigorously star-forming galaxy at an exceptionally close impact parameter of ~16kpc, so heavily dust-obscured that it is detected only in the longest-wavelength NIRCam bands. Detections of [OIII]$λ$5007, H$α$, and [CII]$λ158\,μ$m emission anchor the systemic redshift to z~7.0321, revealing a coherent ~50km/s blueshift of the absorbing gas relative to the host, suggesting outflow-driven metal transport into the halo. The outflow velocity, combined with the measured column density, implies an outflow rate of $\dot{M}_{\rm out}=64 M_\odot\,yr^{-1}$ and a mass loading factor $η=3$, indicating an energetic, chemically-enriched wind launched from a dust-obscured starburst. While the overall ionization state and [Mg/Fe] ratio align with empirical cosmic evolutionary trends, the absorber displays an enhanced carbon-to-oxygen ([C/O]) ratio. This abundance pattern suggests the nucleosynthetic yields of Population~III stellar explosions, and aligns with the host's star-formation history extending to $z \gtrsim 8$, potentially offering a rare fossil record of primordial metal enrichment. Our findings demonstrate that intense star-formation feedback can rapidly and efficiently pollute the CGM/IGM well into the Epoch of Reionization. The NIR-dark nature of the host further implies that rest-UV surveys may systematically miss the dusty sources that drive CGM- and IGM-scale metal enrichment in the early Universe.

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arXiv2026

The KAGG survey: KCWI Analysis of Gas around Galaxies at z~3-5

We present the KCWI Analysis of Gas around Galaxies (KAGG) survey of Ly$α$ emission around Damped Ly$α$ Absorbers (DLAs) at z~3-5 with the Keck Cosmic Web Imager (KCWI) integral-field spectrograph. The KAGG survey is characterized by the sample of 36 DLAs spanning a wide metallicity range, the wide search area for associated Ly$α$ emission (impact parameter b$~\lesssim 120~$kpc), and the high emission sensitivity, reaching Ly$α$ luminosities $\lesssim10^{42}$ erg s$^{-1}$. We identify 7 DLA Ly$α$ emitters that are likely DLA galaxy candidates due to the good match between the Ly$α$ emission and DLA redshifts. Based on a composite sample of 11 DLA Ly$α$ emitters from KAGG and MAGG (MUSE Analysis of Gas around Galaxies), we find that the impact parameters of DLA Ly$α$ emitters decrease with DLA metallicity, from b$~>50~$kpc at [M/H]~-2 to b$~<50~$kpc at [M/H]~-1. Including Ly$α$ emitters at larger velocity offsets and at larger impact parameters from the DLAs, we construct samples of 35 "Group" Ly$α$ emitters and 17 "Large-scale" Ly$α$ emitters. We find that their impact parameters and incidence rates also depend on DLA metallicity. Based on simulations of our survey and comparisons with models of galaxy formation, we conclude that higher DLA metallicities are associated with higher halo masses. The low Ly$α$ emission detection rate at low impact parameters suggests that most DLA galaxies either have low stellar masses (M$~\lesssim10^{8}M_{\odot}$) or have their Ly$α$ emission suppressed due to HI resonant scattering and/or dust absorption.

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arXiv2026

The Qz5 Survey (II): Metallicity Evolution of Damped Lyα Systems Out to z$\sim$5

Damped Ly$α$ absorbers (DLAs) are the highest \HI\ column density (\NHI) absorption line systems detected in the spectra of background quasars. DLAs dominate the neutral gas content of the Universe ($Ω_{\rm HI}$) and are used to measure the metallicity evolution of \HI\ gas. In this work, we introduce a sample of five recently detected DLAs at $z > 4.7$, found in mid to high-resolution spectroscopy from VLT/X-shooter and Keck/HIRES. These DLAs were not pre-selected based on metallicity, enabling an unbiased study of the metallicity of HI gas at $z \sim 5$. We also search for DLAs unbiased in metallicity at $0<z<5.5$ from the literature, we apply a combined correction for dust depletion and $α$-enhancement (assuming no depletion of S, Si, and Zn) to Fe abundances, and we measure the cosmic metallicity evolution of $α$-elements using a linear fit with a slope of$-0.22 \pm 0.05$ dex per unit redshift. For the highest redshift bin, we find an \NHI weighted average of $\langle Z \rangle = -2.00$. This value is $4.4σ$ deviant from the trend recovered at $z < 4.7$ and a K-S test comparison gives a $2.4 σ$ difference. We conclude that the metallicity of HI gas sharply decreases at $z \sim 5$, in agreement with previous tentative evidence. This sharp decrease may be connected with the onset of the enrichment of galaxies' circumgalactic media or with the end of cosmic reionization, though we cannot exclude that it is driven by small sample statistics.

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arXiv2025

ALMA and JWST Imaging of $z\ >\ 6$ Quasars: No Spatial Position Offset Observed Between Quasars and Their Host Galaxies

We present a study determining the spatial offset between the position of the supermassive black hole (as traced through their broad line regions) and the host galaxy in six $z > 6$ quasars. We determined the host galaxy's position from $\lesssim$$0.1^{\prime\prime}$ ($\lesssim$ 600 pc) resolution Atacama Large Millimeter/sub-millimeter Array (ALMA) [CII] 158 $μm$ and corresponding dust continuum imaging. We determined the quasar's position from $\lesssim$ 400 pc resolution James Webb Space Telescope Near-Infrared Camera (JWST NIRCam) imaging. We estimated the observational uncertainties on the quasar's position using astrometric data from the Global Astrometric Interferometer for Astrophysics (GAIA) of field stars within the NIRCam images. We find that all six quasars are found within the central $\sim 400$ pc of their host galaxy dust continuum and [CII] emission. Apparent offsets seen in rest-frame optical JWST observations are not detected in our ALMA data, suggesting they likely result from dust obscuration rather than a true physical separation between the SMBH and its host galaxy. Kinematic modeling of these data further reveals that none of the galaxies show evidence for recent merger activity, and most of the galaxies can be accurately modeled using a simple disk model. The lack of an offset supports theoretical models that predict that positional offset within these galaxies are either short-lived or intrinsically rare.

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arXiv2025

A [CII]-158-micron Survey of DLA galaxies at z~4: Observations of Dense and Metal-Enriched Neutral Gas within the Circumgalactic Medium of Star-Forming Galaxies

We present a survey undertaken with the Atacama Large Millimeter/submillimeter Array (ALMA) to study the galaxies associated with a representative sample of 16 damped Ly-alpha absorbers (DLAs) at z~4.1-4.5, using the [CII]-158-micron ([CII]) line. We detect seven [CII]-emitting galaxies in the fields of 5 DLAs, all of which have absorption metallicity [M/H] > -1.5. We find that the detectability of these HI-selected galaxies with ALMA is a strong function of DLA metallicity, with a detection rate of 71^{+11}_{-20}% for DLAs with [M/H] > -1.5 and 0^{+18}% for DLAs with [M/H] <-1.5. The identified DLA galaxies have far-infrared properties similar to those of typical star-forming galaxies at z ~ 4, with estimated obscured star-formation rates ranging from ~6 Msun/yr to 110 Msun/yr. High-metallicity DLAs therefore provide an efficient way to identify and study samples of high-redshift, star-forming galaxies without preselecting the galaxies by their emission properties. The agreement between the velocities of the metal absorption lines of the DLA and the [CII] emission line of the DLA galaxy indicates that the metals within the DLA originated in the galaxy. With observed impact parameters between 14 and 59 kpc, this indicates that star-forming galaxies at z ~ 4 have a substantial reservoir of dense, cold neutral gas within their circumgalactic medium that has been enriched with metals from the galaxy.

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arXiv2025

Kiloparsec-Scale Alignment of a Radio Jet with Cool Gas and Dust in a z~6 Quasar

We present high-angular resolution (0.068", ~400pc) ALMA imaging of the [CII] line and dust continuum emission of PSO J352.4034-15.3373, a radio-loud quasar at z=5.83. The observations reveal a remarkably close match between the orientation of the [CII] and thermal dust emission mapped by ALMA, and radio synchrotron emission of a radio jet previously mapped by the VLBA. This narrow alignment extends over ~4kpc, reminiscent of the well-studied 'alignment effect' in lower-redshift radio galaxies. The [CII] kinematics show a linear increase in velocity with galactocentric radii up to ~200 km/s at r=2kpc, consistent with bulk motions within the galaxy potential, and not relativistic jet motions. The kinematics and respective morphologies are consistent with a picture in which the relativistic jet injects energy into the interstellar medium (potentially leading to subsequent star formation), giving rise to the observed alignment and significant (> 100 km/s) [CII] velocity dispersion within the host galaxy on kiloparsec scales. Indeed, the astonishingly close alignment and narrow linearity of the radio jet with the [CII] and dust emission are hard to conceive without some fundamental relationship between the two.

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arXiv2025

The Qz5 Survey (I): How the HI Mass Density of the Universe Evolves With Cosmic Time

We report that the neutral hydrogen (HI) mass density of the Universe ($ρ_{HI}$) increases with cosmic time since $z \sim 5$, peaks at $z \sim 3$, and then decreases toward $z \sim 0$. This is the first result of Qz5, our spectroscopic survey of 63 quasars at $z \gtrsim 5$ with VLT/X-SHOOTER and Keck/ESI aimed at characterizing intervening HI gas absorbers at $z \sim 5$. The main feature of Qz5 is the high resolution ($R \sim 7000 - 9000$) of the spectra, which allows us to (1) accurately detect high column density HI gas absorbers in an increasingly neutral intergalactic medium at $z \sim 5$ and (2) determine the reliability of previous $ρ_{HI}$ measurements derived with lower resolution spectroscopy. We find 5 intervening Damped Ly$α$ absorbers (DLAs) at $z > 4.5$, which corresponds to the lowest DLA incidence rate ($0.034^{0.05}_{0.02}$) at $z \gtrsim 2$. We also measure the lowest $ρ_{HI}$ at $z \gtrsim 2$ from our sample of DLAs and subDLAs, corresponding to $ρ_{HI} = 0.56^{0.82}_{0.31} \times 10^8~$M$_{\odot}~$Mpc$^{-3}$ at $z \sim 5$. Taking into account our measurements at $z \sim 5$ and systematic biases in the DLA detection rate at lower spectral resolutions, we conclude that $ρ_{HI}$ doubles from $z \sim 5$ to $z \sim 3$. From these results emerges a qualitative agreement between how the cosmic densities of HI gas mass, molecular gas mass, and star-formation rate build up with cosmic time.

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arXiv2025

A massive HI-absorption-selected galaxy at $z\approx2.356$

We use the Karl G. Jansky Very Large Array (VLA) and the Atacama Large Millimeter/submillimeter Array (ALMA) to detect $\rm CO(1-0)$, $\rm CO(3-2)$, and rest-frame 349-GHz continuum emission from an HI-selected galaxy, DLA1020+2733g, at $z\approx2.3568$ in the field of the $z=2.3553$ damped Lyman-$α$ absorber (DLA) towards QSO J1020+2733. The VLA $\rm CO(1-0)$ detection yields a molecular gas mass of $(2.84\pm0.42)\times10^{11}\times(α_{\rm CO}/4.36)\,\rm{M_\odot}$, the largest ever measured in an HI-selected galaxy. The DLA metallicity is $+0.28 \pm 0.16$, from the ZnII$\, \lambda2026$Å absorption line detected in a Keck Echellette Spectrograph and Imager spectrum. This continues the trend of high-metallicity DLAs being frequently associated with massive galaxies. We obtain a star-formation rate (SFR) of $\lesssim400~$M$_\odot~$yr$^{-1}$ from the rest-frame 349-GHz continuum emission, and a relatively long molecular gas depletion timescale of $\gtrsim0.6~$Gyr. The excitation of the J=3 rotational level is sub-thermal, with $r_{31}\equiv{L'_{\rm{CO(3-2)}}/L'_{\rm{CO(1-0)}}}=0.513\pm0.081$, suggesting that DLA1020+2733g has a low SFR surface density. The large velocity spread of the CO lines, $\approx500~\rm km~s^{-1}$, and the long molecular gas depletion timescale suggest that DLA1020+2733g is likely to be a cold rotating-disk galaxy.

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arXiv2025

ALMA 360 pc high-frequency observations reveal warm dust in the center of a $z=6.9$ quasar

The temperature of the cold dust in z>6 galaxies is a potential tracer of Active Galactic Nucleus (AGN) and stellar feedback, and is the dominant source of uncertainty in inferring properties from the far-infrared (FIR) emission of these galaxies. We present the first resolved dust temperature map in a $z>6$ quasar host galaxy. We combine new 360 pc resolution ALMA Band 9 continuum observations with literature 190 pc Band 6 observations to derive the dust temperature and opacity at 0.1<r<0.5 kpc scales in a $z=6.9$ luminous quasar host galaxy (J2348-3054). We find that the dust temperature (and opacity) increases at the center (r<216 pc) of the galaxy up to $T_d=73-88$ K, and potentially up to $T_d<149$ K at r<110 pc. The combination of the resolved and integrated FIR Spectral Energy Distribution (SED) further reveal a dust temperature gradient and a significant contribution of the AGN hot dust torus at $ν_{\rm{obs}}\gtrsim 700$ GHz. By taking into account the torus contribution and resolved optically-thick emission, we derive a total infrared luminosity ($L_{TIR}=8.78\pm0.10)\times 10^{12}L_\odot$) and corresponding star-formation rate (SFR$=1307\pm15\ M_\odot\ \rm{yr}^{-1}$), that are at least a factor $\sim 3.6$ ($\sim0.56$ dex) lower than previous measurements assuming optically-thin emission. We compare the resolved dust temperature, mass and IR luminosity profiles to simulations where they are only reproduced by models in which the AGN radiation heats the dust in the center of the galaxy. Our observations provide evidence that dust in J2348--3054 cannot be assumed to be uniformly cold and optically thin. Whether J2348-3054 is representative of the larger population of high-redshift quasars and galaxies remains to be determined with dedicated high-resolution and high-frequency ALMA observations.

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arXiv2024

Pushing ALMA to the limit: 140 pc resolution observations of a z=6.6 quasar-galaxy merger resolve strikingly different morphologies of dust continuum and [CII] 158 um emission

We present $0."026$ $(140\ \rm{pc})$ resolution ALMA observations of [C II] $158\ μ\rm{m}$ and dust continuum emission of the $z=6.6$ quasar J0305--3150, resolved over $\sim 300-400$ independent resolution elements. The dust continuum emission is compact with $\sim 80\%$ recovered within $r<0."3$ $(1.6\ \rm{kpc})$, whereas the [C II] emission profile is composed of a central Gaussian ($r<0."4$, i.e. $<2.2\ \rm{kpc}$) and an extended component (detected up to $\sim 10\ \rm{kpc}$ at $>3σ$). We infer a direct contribution of the quasar to the observed 260\ \rm{GHz} continuum $S_{ν,\rm{QSO}} / S_{ν,\rm{QSO+Host}} \lesssim 1\%$. We report the detection of FIR-detected star-forming clumps with $r<200 \ \rm{pc}$ and properties similar to that of rest-frame UV-optical clumps reported in the literature. The $200\ \rm{pc}$ resolved [C II]/FIR ratio follows the global relation with the FIR surface brightness established in low- and high-redshift galaxies, even at the quasar location. We find that dust continuum is emitted in regions of $\sim0."02-0."04$ consistent with the size of photo-dissociation regions (PDR), whereas $50\%$ of the [C II] originates from larger physical scales ($θ\gtrsim 2"$). The large-scale [C II] emission presents a velocity gradient aligned with a nearby companion with perturbed kinematics, and misaligned with the kinematics of the small-scale emission. The absence of significant [C II] emission by structures with physical scale $\lesssim 1\ \rm{kpc}$ implies that [C II] emission is not produced in dense PDR located at the boundary of Giant Molecular Clouds. We argue instead that [C II] is produced in low-density PDRs in the interstellar medium and diffuse HI gas tidally-stripped during the ongoing merger.

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arXiv2024

A quasar-galaxy merger at $z\sim 6.2$: rapid host growth via accretion of two massive satellite galaxies

We present JWST/NIRSpec Integral Field Spectroscopy in the rest-frame optical bands of the system PJ308-21, a quasar at $z=6.2342$ caught as its host galaxy interacts with companion galaxies. We detect spatially extended emission of several emission lines (H$α$, H$β$, [OIII], [NII], [SII], HeII), which we use to study the properties of the ionized phase of the interstellar medium: the source and hardness of the photoionizing radiation field, metallicity, dust reddening, electron density and temperature, and star formation. We also marginally detect continuum starlight emission associated with the companion sources. We find that at least two independent satellite galaxies are part of the system. While the quasar host appears highly enriched and obscured, with AGN-like photoionization conditions, the western companion shows minimal dust extinction, low metallicity ($Z\sim0.4$ Z$_\odot$), and star-formation driven photoionization. The eastern companion shows higher extinction and metallicity ($Z\sim0.8$ Z$_\odot$) compared to the western companion, and it is at least partially photoionized by the nearby quasar. We do not find any indication of AGN in the companion sources. Our study shows that while the quasar host galaxy is already very massive ($M_{\rm dyn}>10^{11}$ M$_\odot$), it is still rapidly building up by accreting two relatively massive ($M_{\rm star}\sim 10^{10}$ M$_\odot$) companion sources. This dataset showcases the power of JWST in exposing the build-up of massive galaxies in the first Gyr of the Universe.

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arXiv2024

The cold molecular gas in z$\gtrsim$6 quasar host galaxies

Probing the molecular gas reservoirs of z>~6 quasar (QSO) host galaxies is fundamental to understanding the coevolution of star formation and black hole growth in these extreme systems. Yet, there is still an inhomogeneous coverage of molecular gas tracers. To measure the average excitation and mass of the molecular gas reservoirs in the brightest z>6.5 QSO hosts, we combined new observations of CO(2-1) emission with existing observations of CO(6-5), CO(7-6), [C I], [C II], and dust-continuum emission. We reduced and analysed the VLA observations of CO(2-1) in three z=6.5-6.9 QSO hosts -- the highest redshift observations of CO(2-1) to date. By combining these with the nine z=5.7-6.4 QSO hosts for which CO(2-1) has already been observed, we studied the spread in molecular gas masses and CO excitation. Two of our three QSOs, were undetected in CO(2-1), implying more highly excited CO than in the z=6.4 QSO J1148+5251. We detected CO(2-1) at $5.1σ$ for our highest-redshift target, J2348-3054, yielding a molecular gas mass of $(1.2\pm0.2)\times 10^{10}\, \mathrm{M}_\odot$. This molecular gas mass is equivalent to the lower limit on the dynamical mass measured from resolved [C II] observations, implying little mass in stars or neutral gas within the [C II]-emitting region. On average, these QSO hosts have far higher CO(6-5)-, CO(7-6)-, and [C II] vs CO(2-1) line ratios than local AGN hosts; with a mean CO(6-5)-to-CO(1-0) line luminosity ratio of $r_{6,1}=0.9\pm0.2$. Our new CO(2-1) observations show that even at 780 Myr after the Big Bang, QSO host galaxies can already have molecular gas masses of $10^{10}$ M$_\odot$, consistent with a picture in which these z>6 QSOs reside in massive starbursts that are coevolving with the supermassive black holes. Our results imply the presence of extremely dense and warm molecular gas reservoirs illuminated by strong interstellar radiation fields.

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arXiv2024

A quasar-galaxy merger at $z\sim6.2$: black hole mass and quasar properties from the NIRSpec spectrum

We present JWST/NIRSpec integral field data of the quasar PJ308-21 at $z=6.2342$. As shown by previous ALMA and HST imaging, the quasar has two companion sources, interacting with the quasar host galaxy. The high-resolution G395H/290LP NIRSpec spectrum covers the $2.87-5.27\ \rm μm$ wavelength range and shows the rest-frame optical emission of the quasar with exquisite quality ($S/N\sim 100-400$ per spectral element). Based on the H$β$ line from the broad line region, we obtain an estimate of the black hole mass $M_{\rm BH,Hβ}\sim 2.7\times 10^{9}\ \rm M_{\odot}$. This value is within a factor $\lesssim 1.5$ of the H$α$-based black hole mass from the same spectrum ($M_{\rm BH, Hα}\sim 1.93\times 10^{9}\ \rm M_{\odot}$) and is consistent with a previous estimate relying on the MgII $λ2799$ ($M_{\rm BH, MgII}\sim 2.65\times 10^{9}\ \rm M_{\odot}$). All these $M_{\rm BH}$ are within the $\sim 0.5$ dex intrinsic scatter of the adopted mass calibrations. The high Eddington ratio of PJ308-21 $λ_{\rm Edd,Hβ}\sim 0.67$ ($λ_{\rm Edd,Hα}\sim 0.96$) is in line with the overall quasar population at $z \gtrsim 6$. The relative strengths of the [OIII], FeII and H$β$ lines are consistent with the empirical "Eigenvector 1" correlations as observed for low redshift quasars. We find evidence for blueshifted [OIII] $λ5007$ emission with a velocity offset $Δv_{\rm [OIII]}=-1922\pm 39$ km s$^{-1}$ from the systemic velocity and a $\rm FWHM([OIII])=2776^{+75}_{-74}$ km s$^{-1}$. This may be the signature of an outflow from the nuclear region, despite the true values of $Δv_{\rm [OIII]}$ and $\rm FWHM([OIII])$ are likely more uncertain due to the blending with H$β$ and FeII lines. Our study demonstrates the unique capabilities of NIRSpec in capturing quasar spectra at cosmic dawn and studying their properties in unprecedented detail.

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arXiv2024

A survey of Ly$α$ emission around Damped Ly$α$ absorbers at $z \approx 2$ with the Keck Cosmic Web Imager

We present Keck Cosmic Web Imager (KCWI) Ly$α$ integral field spectroscopy of the fields surrounding 14 Damped Ly$α$ absorbers (DLAs) at $z \approx 2$. Of these 14 DLAs, 9 have high metallicities ([M/H]$~> -0.3$), and 4 of those 9 feature a CO-emitting galaxy at an impact parameter $\lesssim 30$ kpc. Our search reaches median Ly$α$ line flux sensitivities of $\sim 2 \times 10^{-17}$ erg s$^{-1}$ cm$^{-2}$ over apertures of $\sim6$ kpc and out to impact parameters of $\sim50$ kpc. We recover the Ly$α$ flux of three known Ly$α$-emitting H I-selected galaxies in our sample. In addition, we find two Ly$α$ emitters at impact parameters of $\approx 50-70$ kpc from the high metallicity DLA at $z \approx 1.96$ toward QSO B0551-366. This field also contains a massive CO-emitting galaxy at an impact parameter of $\approx 15$ kpc. Apart from the field with QSO B0551-366, we do not detect significant Ly$α$ emission in any of the remaining 8 high-metallicity DLA fields. Considering the depth of our observations and our ability to recover previously known Ly$α$ emitters, we conclude that H I-selected galaxies associated with high-metallicity DLAs at $z \approx 2$ are dusty, and therefore might feature low Ly$α$ escape fractions. Our results indicate that complementary approaches -- using Ly$α$, CO, H$α$, and [C II] 158$μ$m emission -- are necessary to identify the wide range of galaxy types associated with $z \approx 2$ DLAs.

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arXiv2024

ALMA 300 pc resolution imaging of a z=6.79 quasar: no evidence for supermassive black hole influence on the [C II] kinematics

We present Atacama Large Millimeter/submillimeter Array (ALMA) [C II] 158 $μ\rm{m}$ and dust continuum observations of the $z=6.79$ quasar J0109--3047 at a resolution of $0."045$ ($\sim$300 pc). The dust and [C II] emission are enclosed within a $\sim 500\, \rm{pc}$ radius, with the central beam ($r<144\ \rm{pc}$) accounting for $\sim$25\% (8\%) of the total continuum ([C II]) emission. The far--infrared luminosity density increases radially from $\sim$5 $\times 10^{11} L_\odot\ \rm{kpc}^{-2}$ to a central value of $\sim$70 $\times 10^{11} L_\odot\ \rm{kpc}^{-2}$ (SFRD $\sim$50-700 $M_\odot\ \rm{yr}^{-1}\ \rm{kpc}^{-2}$). The [C II] kinematics are dispersion-dominated with a constant velocity dispersion of $137 \pm 6 \,\rm{km\ s}^{-1}$. The constant dispersion implies that the underlying mass distribution is not centrally peaked, consistent with the expectations of a flat gas mass profile. The lack of an upturn in velocity dispersion within the central beam is inconsistent with a black hole mass greater than $M_{\rm{BH}}<6.5\times 10^{8}\ M_\odot\ (2σ$ level), unless highly fine-tuned changes in the ISM properties conspire to produce a decrease of the gas mass in the central beam comparable to the black hole mass. Our observations therefore imply either that a) the black hole is less massive than previously measured or b) the central peak of the far-infrared and [C II] emission are not tracing the location of the black hole, as suggested by the tentative offset between the near-infrared position of the quasar and the ALMA continuum emission.

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