Reinhard Genzel

We present a spatially resolved study of cold molecular gas and dust in ten main-sequence galaxies at z = 1.1−1.6, using observations of CO(4−3), CO(3−2), [C I ](1−0), and dust continuum from the NOEMA ^3D survey. We find widespread spatially extended molecular gas and dust, with sizes comparable to those of the stellar disk, in contrast to those of centrally dominated starburst galaxies at similar redshifts. Among the targeted molecular gas tracers, the CO line ( J = 3 − 2 or J = 4 − 3) remains the most effective for mapping molecular gas distribution and kinematics. The spatially resolved correlations between different molecular gas tracers exhibit about twice the scatter as their galactic-integrated correlations, indicating that interstellar medium (ISM) conditions already deviate from global averages on scales of 3−6 kpc. This likely reflects the clumpy or inhomogeneous ISM in cosmic noon star-forming galaxies. Within our sample, both the molecular gas fraction and its depletion time are nearly constant across the galactic disks out to 2 × R _e , supporting a global linear Kennicutt-Schmidt law. These galaxies also have relatively small bulges, with bulge-to-total ratios between 6–24%, and are actively forming stars. These results provide a resolved view of how galaxies can remain on the star-forming main sequence during their secular evolution at late cosmic noon, an evolutionary stage supported by quasi-steady gas accretion and efficient gas transport via prominent spiral arms and/or bars.

Detections of protoplanets are rare and protoplanetary disk features mischaracterized as planets are common. PDS 70 is one of only two stars known to host multiple confirmed protoplanets, PDS 70 b and c, and repeat detections of a third point-like source in the system suggest the presence of third inner planet. However, previous observations of this third source are insufficient to distinguish whether it is a planet or a concentrated dust clump in Keplerian motion. Our observations with VLTI/GRAVITY+ did not re-detect this point-like source, suggesting that it is, in fact, a dust clump and not a planet. These observations demonstrate how the angular resolving power of VLTI/GRAVITY+ can be used to distinguish between protoplanets and protoplanetary disk features.

Context. High-precision astrometric observations at the microarcsecond level require a consistent relativistic framework for modelling both the dynamics of test particles and the propagation of light in gravitational fields. Aims. We aim to formulate the post-Newtonian (PN) expansion in the test body limit in a manner that yields simple and broadly applicable expressions for the motion of massive and massless particles in generic, spherically symmetric spacetimes. In particular, we intend to formulate it such that the formalism suits the modelling of observations of stars orbiting the Galactic centre (GC). Methods. We employed the PN expansion scheme to derive equations of motion for test particles and applied a perturbative solution method to solve the boundary value problem of identifying the geodesic connecting a given emitter–observer pair. Results are validated against numerical integration of the photon geodesic equation. Results. We derive the PN equations of motion for test particles in a generic, spherically symmetric spacetime. We derive analytical expressions for the apparent position of stars as measured by an observer on Earth and show the importance of this formalism for the GC science case. We compare our results with other approaches taken in the literature and discuss its implications for the modelling of orbital motion around Sgr A*. Conclusions. The proposed framework is well suited for the analysis of astrometric observations of stars orbiting the GC with microarcsecond accuracy. In this context, measurements performed with the GRAVITY+ instrument at the Very Large Telescope Interferometer can be used to place constraints on metric theories of gravity through the combined modelling of stellar dynamics and relativistic light propagation near Sgr A*.

We present NOEMA ^3D , a unique high-resolution study of purely molecular gas kinematics at z ~ 1.1 to 1.6, providing a dedicated view of cold gas dynamics at the late stages of the peak epoch of cosmic star formation. Using deep (≳20 h on source per target) IRAM–NOEMA CO observations of ten massive (10.45 ≤ log(M _⋆ /M _⊙ ) ≤ 11.43) main-sequence galaxies, complemented by high-resolution JWST imaging, we resolved the molecular gas kinematics and morphology on kiloparsec scales. We find that all galaxies exhibit ordered rotation with moderate intrinsic turbulence (median σ ₀ ~ 32 ± 10 km s ⁻¹ , median V _c / σ ₀ ~ 8.6 ± 2.9), consistent with dynamically turbulent disks at late cosmic noon. Modeling the axisymmetric rotation with the forward-modeling code DysmalPy , we find spatially coherent velocity residuals in all but one edge-on system. The inferred in-plane noncircular motions reach amplitudes of ~50–100 km s ⁻¹ , which are significantly larger than typically observed in local disk galaxies. Interpreting these noncircular motions as radial flows, we find that the velocity residuals spatially coincide with non-axisymmetric structures - spiral arms and bars – demonstrating a direct link between galaxy morphology and gas transport at z ~ 1–2. In spiral galaxies, the residual velocity patterns are typically dominated by inflows, while barred systems display an apparent inflow-outflow pattern, characteristic of in-plane bar-driven gas motions. We further find that the inferred molecular gas inflow rates are substantial, with a typical net inflow rate on the order of the star formation rate ( M ^˙¯ ~ −46M _⊙ /yr). This implies that spiral arms and bars at cosmic noon are highly efficient at funneling cold gas toward galaxy centers, perhaps driving the buildup of bulges and feeding central star forming regions and supermassive black holes.

Dense gas is the direct fuel for star formation, but measuring it has long been difficult at z ≥ 2, especially in unlensed star-forming main-sequence galaxies. In this work, we report the first detection of HNC (J = 5–4) and CN (N = 4–3) emission in a massive unlensed main-sequence galaxy, BX610, at z = 2.21. The velocity integrated emission of HNC(5–4)+CN(4–3) is concentrated in the galactic centre, coincident with the region of ongoing intense star formation. Based on line decomposition, we measure a line flux ratio HNC(5-4)∕CN(4-3) of 1.05 ± 0.23, similar to that of lensed starburst galaxies at comparable redshifts but lower than that of quasar host galaxies. The low HNC/CN ratio disfavours the presence of a strongly buried AGN in BX610, consistent with optical line diagnostics. The radiative transfer analysis favours the presence of dense gas with a density of (2-4) × 10 ⁶ cm ⁻³ and a kinetic temperature of 50–80 K. The derived abundance ratio between N (HNC) and N (CN) favours dense gas clouds near photodissociation regions, as commonly seen in typical starburst environments. The inferred dense-gas line luminosity closely follows the scaling relation between far-IR and dense-gas line luminosities established for local luminous infrared galaxies (LIRGs). Our observations support the view that star formation in cosmic noon galaxies is primarily controlled by the availability of dense gas, which could be enhanced in central galactic regions with efficient cold gas inflows as observed in BX610 along the inner spiral arms and a possible stellar bar.

We report the direct imaging discovery of a third exoplanet in the β Pictoris ( β Pic) system. We detect β Pictoris d ( β Pic d) in noncoronagraphic observations obtained with the Very Large Telescope (VLT) Enhanced Resolution Imager and Spectrograph (ERIS), as well as multi-epoch archival datasets from the JWST Near Infrared Camera (NIRCam) and VLT/SPHERE. Astrometric measurements over an 11 yr baseline demonstrate that it is consistent with a gravitationally bound source with orbital motion. Joint multi-planet orbit fits of all three planets in the system yield a semimajor axis of 26 . 0 − 6.1 + 2.2 au and inclination 89 . 0 − 0.6 + 0.7 deg for planet d. β Pic d has a larger orbital semimajor axis than the other known planets in the system, but is coplanar with the inner two planets, and its orbit is consistent with sculpting the inner edge of the debris disk. β Pic d has a contrast of Δ L ′ = 12.11 ± 0.15 mag, with colors and luminosity that closely match those of 51 Eri b, another exoplanet in the β Pic moving group. Its VLT/ERIS and JWST/NIRCam colors are distinct from those of free-floating planetary-mass objects of a similar age and temperature. Its red F410M − F444W color indicates strong CO ₂ absorption in its atmosphere and suggests significant enhancement in metals compared to free-floating objects. From the ATMO hot-start evolutionary models, we estimate an effective temperature of 60 0 − 60 + 45 K and mass of 2.4 ± 0.6 M _Jup , which also closely matches similar estimates for 51 Eri b. β Pic d is among the lowest-mass exoplanets imaged from the ground. This discovery highlights the deep sensitivity achievable with ground-based imaging in the mid-infrared and the discovery potential of future high-contrast observations with the Extremely Large Telescope.

We present gas-phase radial metallicity profiles for 20 main-sequence galaxies at 4 < z < 6 primarily based on JWST NIRSpec IFU observations obtained as part of the JWST-ALPINE-CRISTAL programme. Our study aims to connect the metallicity gradients of these galaxies with their kinematic properties from [C II ] 158 μm ALMA observations. We mapped the radial profiles of oxygen abundance using the strong-line method, leveraging the rich set of rest-frame optical emission lines. Linear fits to the annular-binned radial profiles show that, on average, the metallicity gradients are slightly positive with a median of +0.039 ± 0.010 dex kpc ⁻¹ . However, only three galaxies show a gradient > 0.05 dex kpc ⁻¹ at 1 σ , and none have a significant negative gradient. There are no substantial systematic offsets in gradients when using different line diagnostics. We investigated the correlation between the metallicity gradients and the intrinsic gas velocity dispersion σ ₀ as well as the V _rot / σ ₀ ratio of the disks. Combining our sample with mass-matched literature samples at 3 ≲ z ≲ 7, we found a negative shallow correlation between V _rot / σ ₀ and the metallicity gradients, but no strong relationships with σ ₀ . As V _rot / σ ₀ increases towards later cosmic times, the observed negative trend with V _rot / σ ₀ is consistent with the overall cosmic evolution of metallicity gradients from high to low redshifts. This suggests that disk maturity plays a crucial role in shaping the radial metallicity gradients. We do not find the metallicity gradients of disk galaxies to be significantly different from non-disk galaxies, which could be attributed to the frequent accretion events that took place in these gas-rich systems. Additionally, we find no strong dependence of metallicity gradients on stellar mass and only a marginal positive dependence on specific star-formation rate. Our study extends the efforts to connect the internal kinematics of galaxies with their gas-phase chemical enrichment at kiloparsec scales from cosmic noon to z > 4.

We present Northern Extended Millimeter Array observations of the CO (2–1) molecular gas kinematics in the nearby Compton-thick Seyfert 2 galaxy NGC 3079, with an angular resolution of 0 . ″ 5 (∼40 pc). To interpret the observed CO (2–1) kinematics, we model the rotating disk using two software tools, 3D-Barolo and DysmalPy, to generate mock 3D data cubes. Both models indicate, in addition to the rotating disk, the presence of a spatially unresolved nuclear component characterized by high velocity dispersion. Analysis of the visibility data reveals that the blueshifted, high-velocity component is spatially offset from the continuum peak by 0 . ″ 17 (∼14 pc) and exhibits line-of-sight velocities of v − v _sys = −350 to −450 km s ⁻¹ , which we interpret as a nuclear molecular outflow. We calculate a molecular gas mass outflow rate of 8.82 M _⊙ yr ⁻¹ , with a kinetic power ( E ̇ out ) of 3.8 ×10 ⁴¹ erg s ⁻¹ and a momentum rate ( p ̇ out ) of 2.05 × 10 ³⁴ Dyne. The momentum rate exceeds the AGN radiation momentum rate by a factor of ∼15, suggesting an energy-driven outflow. Furthermore, we argue that the derived kinetic power of the nuclear molecular outflow favors a jet-powered scenario that explains the slowdown and brightening of the parsec-scale radio source observed with the Very Long Baseline Array.

Cosmic noon represents the prime epoch where today's massive galaxies assembled most of their stellar masses, and it is an ideal period for observations with both the space-based (JWST) and ground-based near-IR integral-field unit (IFU) spectrographs. This work analyzes JWST NIRSpec Micro Shutter Array (MSA) and NIRCam Wide Field Slitless Spectroscopy (WFSS) observations of $), and ionization parameter (log(U)≃-3.0). The central bulge is modestly massive (M_⋆=(7±3)times10^9 M_⊙), heavily obscured (A_V=6.43±0.55), and likely formed most of its stellar mass in the past (SFR=82±42 James Webb Telescope a large spiral, star-forming (SF) galaxy at z=2.224 with evidence of radial gas inflows. Leveraging ground-based IFU ERIS observations, we conducted a comprehensive and resolved study of the interstellar medium and stellar properties of this galaxy, covering the rest-frame optical to near-IR. Our analysis -- using several emission-line diagnostics, resolved spectral energy distribution (SED) fitting of high-resolution imaging, and line detection in NIRCam WFSS data -- reveals massive SF clumps (M_⋆≃(0.67-3.5)times10^9 M_⊙) with star formation rates (SFRs) of 3-24 low dust attenuation (A_V≃0.4), electron densities (n_̊m ełesssim300 cm -3 over the last ∼100 Myr). Yet, it continues to form stars at a lower rate (SFR$=12 over the last ∼10 Myr). We infer a relatively low sulfur abundance of log(S/O)≃-1.9, which may have implications for sulfur production via type I supernova explosions. Moreover, all distinct galaxy regions feature a metallicity of 12+log(O/H)≈8.54, likely due -- along with the enhanced N/O abundance (i.e., log(N/O)≃$-1.0) -- to dilution effects from radial inflows of metal-poor gas. Lastly, we find tentative evidence of a negative gradient in stellar age, suggesting possible inside-out growth for

Context . Constraining the link between the atmospheric composition of giant exoplanets and their formation history is a key goal of exoplanet studies. In particular, the atmospheric carbon-to-oxygen (C/O) ratio and metallicity – which are readily measurable with direct spectroscopic observations – are believed to be chemical tracers of the birth location of substellar and planetary companions. Aims . We aim to collect observational constraints for planet formation theories by performing a large and systematic survey of the atmospheric C/O ratio and metallicity. Methods . We collected new K -band moderate-resolution ( R ~ 11 000) spectroscopic observations of 13 directly imaged planetary-mass companions spanning the molecular snowlines of CO ₂ , CO, and CH ₄ and with masses 4–30 M _J with VLT/ERIS/SPIFFIER. Additionally, we gathered a large portion of the available archival observations for these targets, amounting to 40 spectra and 140 photometric fluxes. We performed spectral fits using self-consistent grid models and freely parametrisable models. We obtained robust estimates of the key atmospheric parameters by aggregating the results from the different models, thereby reducing modelling systematics. Results . Using molecular mapping, we detected H ₂ O and CO in 12 of our targets as well as ¹³ CO in HR 2562 B. With our multimodel spectral fitting strategy, we obtained stellar to superstellar C/O ratios – ranging between 0.3 and 0.8 – and predominantly superstellar metallicities – between −1 and 1 dex – across all targets. We measured a substantial enrichment of ¹³ CO for HR 2562 B with ¹² CO/ ¹³ CO= 12.0 _−3.3 ^+4.5 . If corroborated by independent observations, it could indicate that the companion might have formed beyond the CO snowline and later migrated inwards to its current location. We find an anti-correlation ( R = −0.64) between the C/O ratio and the companion mass, consolidating a previous result. Conclusions . Our work demonstrates the scientific potential of the ERIS/SPIFFIER instrument for the orbital and atmospheric characterisation of close-in substellar and exoplanet companions.