arXiv subjects

Frank Eisenhauer

Publications and source records attributed to Frank Eisenhauer.

At least 19 recordsLinked to original sources

arXiv2026

MATISSE in the era of GRAVITY+

MATISSE, the mid-infrared spectro-interferometric imager of the Very Large Telescope Interferometer (VLTI), has been feeding on the light corrected by the GRAVITY+ Adaptive Optics (GPAO) systems since the retirement of MACAO on the four Unit Telescopes in 2024. We report the assessment of the new MATISSE performance with GPAO, based on commissioning observations obtained in 2024 and 2025 and compared with archival MACAO observations of the same stellar sources. The instrumental visibility transfer function is more stable in the L band, while its typical value in the L and N bands is unchanged; the visibility signal-to-noise ratio is consistent with, or better than, the values reported at the initial MATISSE commissioning. The correlated flux increases by 20--30\% in GRA4MAT mode thanks to a better fringe tracking performance, and the total flux injected into the instrument increases by a factor of 1.3 to 1.4 (up to 1.7) in the L band at low spectral resolution, with no measurable loss in the N band. Combined with the new K-band fringe-tracking limits enabled by GPAO, this translates into a sensitivity gain of a factor 2 to 6 in the L and M bands, a confirmation of the N-band limits similar to the MACAO era. We then report the performances of MATISSE with the GPAO's laser guide stars in November and December 2025. The updated noise figures follow the exposure time calculator predictions in LM LOW and MED and come out better than them in N LOW, the L-band transfer function is stable at the few percent level between observing blocks an hour apart, and correlated fluxes, differential phases and closure phases are recovered down to a 10\,mJy target. Embedded young stellar objects and AGN are now within reach, thanks to the better performances on red targets brought by the lasers. We finally discuss the science cases opened by this gain and the case for a future upgrade of the instrument.

astro-ph.CO↗

arXiv2026

NOEMA3D: Extended CO, [C I] and dust in massive star-forming main-sequence galaxies at cosmic noon

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), [CI](1-0), and dust continuum from the NOEMA3D 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 2xRe, 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.

astro-ph.GA↗

arXiv2026

GRAVITY+: reducing non-common-path aberrations for sub-10 μas astrometric accuracy

GRAVITY is a state-of-the-art instrument for near-infrared astrometric interferometry that routinely achieves astrometric accuracy of 30-100 microarcsecond in its phase-referenced dual-field mode. However, its fundamental limit is not yet reached, and can still be improved by several factors. In this paper, we focus on the effect of systematics, and in particular the effect of non-common path aberrations between the science channel and the metrology signal in the GRAVITY Fiber Coupler. Through comprehensive laboratory measurements using a dedicated fiber coupler replica and phase-shifting interferometry at 1908 nm, we have characterized these high-order wavefront errors with nanometer precision in the laboratory. We characterized on-sky the effect of these high-order wavefront imperfections on narrow-angle astrometry, using observations of the binary system GJ65. As part of the GRAVITY+ project, high-precision mirrors designed for nanometer-level surface quality, bringing an order of magnitude improvement over existing GRAVITY injection optics, are currently in production and will be installed in the fiber coupler units by the end of 2027. This upgrade is expected to enable astrometric accuracy at the sub-10 microarcsecond level in dual-field mode with integration times of just a few minutes.

astro-ph.IM↗

arXiv2026

Resolving stellar populations, star formation, and interstellar medium conditions with JWST in a large spiral galaxy at $z\approx2$

Cosmic noon represents the prime epoch of galaxy assembly, and a sweet spot for observations with the James Webb Telescope (JWST) and ground-based near-IR integral-field unit (IFU) spectrographs. This work analyses JWST NIRSpec Micro Shutter Array (MSA), NIRCam Wide Field Slitless Spectroscopy (WFSS) of K20-ID7, a large spiral, star-forming (SF) galaxy at z=2.2, with evidence for radial gas inflows. By exploiting the synergy with ground-based IFU ERIS observations, we conduct a comprehensive and resolved study of the interstellar medium (ISM) and stellar properties, from rest optical to near-IR, via emission-line diagnostics, resolved spectral energy distribution (SED) fitting of high-resolution imaging, and Pa$β$ line detection in NIRCam WFSS data. Our analysis reveals massive ($M_{\star}\simeq$(0.67-3.5)$\times$10$^{9}$ $M_{\odot}$) SF clumps with star formation rates (SFRs) ~3-24 $M_{\odot}$/yr, and quite low dust attenuation ($A_V\simeq$0.4), electron density ($n_{e}$<300 cm$^{-3}$), and ionisation (log(U)$\simeq -3.0$). The central bulge turns out to be modestly massive ($M_{\star}$=(7$\pm$3)$\times$10$^{9}$ M$_{\odot}$), heavily obscured ($A_V$=6.43$\pm$0.55), and likely to have formed most of its stellar mass in the past (SFR=82$\pm$42 $M_{\odot}$/yr over the last 100 Myr), yet still forming stars at a lower rate (SFR=12$\pm$8 M$_{\odot}$/yr over the last 10 Myr). We infer a metallicity 12+log(O/H)~8.54 and an apparent enhancement of the N/O abundance (log(N/O)$\simeq -1.0$) in all distinct galaxy regions, a likely consequence of dilution effects due to radial inflows of metal-poor gas. We measure a sub-solar sulfur abundance (log(S/O)$\simeq$-1.9). Finally, the radial stellar age profile reveals older stellar populations in the inner galaxy regions compared to the outskirts, pointing to an inside-out growth of K20-ID7.

astro-ph.GA↗

arXiv2026

Superdiffusion at the Galactic Centre

Tracking S-star cluster orbits around Sgr A* calibrates orbital transport models for space-borne gravitational wave detectors. Standard kinetic theories model this cluster via local Fokker-Planck equations, which predict that general relativistic precession halts angular momentum diffusion at the Schwarzschild barrier. Because inverse-square gravitational encounters generate a Holtsmark torque distribution with infinite variance, resonant relaxation operates as a space-fractional process governed by non-local Lévy flights. We simulate this superdiffusive continuous-time random walk using a Markov chain initialized with empirical S-star orbits, including the recently observd S301. Integro-differential fractional operators allow trajectories to cross regions of quenched local diffusion without density buildup at the barrier. Non-equilibrium regimes yield immediate linear flux growth, while secular tidal heating at periastron inflates stellar radii to shift disruption boundaries. Regularized backward integration of the fractional transport equation traces current phase space configurations back to initial deposition states, matching the energy requirements of the \emph{Fermi} bubbles. Relativistic precession does not suppress mass-ratio inspiral rates, which provides a model for event topologies in target galactic nuclei.

astro-ph.GA↗

arXiv2026

Stellar rotation of S301 as a macroscopic gyroscope to test general relativity

Stellar trajectories around the Galactic Center provide a testing environment for general relativity. The intrinsic rotation of these stars evolves under covariant transport in curved spacetime and classical Newtonian quadrupole torques. We analyze the recently observed S301 S-star to quantify the relativistic precession of its rotational axis. Its 8.7-year period and eccentricity of $e = 0.982$ localize geodetic precession and Newtonian quadrupole torques to a step function at periapsis. We incorporate first-order post-Newtonian corrections into the orbital kinematics to calculate the spatial trajectory. Sampling an isotropic distribution of initial orientations and viewing geometries over a 40-year period across a grid of equatorial velocities and rotational ellipticities, we calculate the statistical likelihood of an absolute shift in the projected rotational line broadening, $|Δv \sin i|$. The relativistic geodetic shift scales linearly with $v_{\rm rot}$ and the classical quadrupole shift is independent of rotation speed, scaling with $q$. The absolute maximum velocity shift saturates at $46.1\,\kms$ for oblate stars. The absolute median shifts, driven by geodetic precession, range from $3\,\kms$ to $6.3\,\kms$. We calculate the time-domain observable $|Δv \sin i|$ to provide a target for infrared spectrographs testing the Schwarzschild metric around Sgr~A$^\ast$. The spin of S301 acts as a flying gyroscope whose drift, if measured, can test Einstein's theory in a regime that has not previously been accessible.

astro-ph.GA↗

arXiv2026

Direct Imaging Discovery of Giant Exoplanet $β$ Pictoris d: A Decade-Long Game of Hide-and-Seek

We report the direct imaging discovery of a third exoplanet in the $β$ Pictoris system. We detect $β$ Pictoris d ($β$ Pic d) in non-coronagraphic observations obtained with VLT/ERIS as well as multi-epoch archival datasets from JWST/NIRCam and VLT/SPHERE. Astrometric measurements over an 11-year 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 semi-major axis of $26.0^{+2.2}_{-6.1}$ au and inclination $89.0^{+0.7}_{-0.6}$ deg for planet d. $β$ Pic d has a larger orbital semi-major 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 $ΔL^{\prime}=12.11\pm0.15$ mag, with colors and luminosity that closely match those of 51 Eri b, another exoplanet in the $β$ Pictoris 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 $600^{+45}_{-60}$ K and mass of $2.4\pm0.6$ $M_{\rm Jup}$, 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.

astro-ph.EP↗

arXiv2026

BlackTHUNDER Reveals a Massive Filament around a Compact AGN at $z\simeq5.23$

Despite the growing number of compact active galactic nuclei (AGN) at $z>4$ discovered by JWST, their formation and evolution remain poorly understood. This paper investigates the large-scale environment of GN-77652, a compact AGN at $z=5.229$ observed as part of the JWST NIRSpec IFU Large Program BlackTHUNDER and complemented by deep multi-band NIRCam imaging. GN-77652 lies in close proximity to a 12 kpc-long filament composed of multiple sources at $z\simeq5.23$, spanning a remarkable range in stellar masses ($M_{\star}=0.7-13 \times 10^8$ ${M_\odot}$), gas phase metallicities (12$+$log(O/H) $=$ 7.6-8.5) and star formation rates (SFR $=0.4-6$ ${M_\odot}$ yr$^{-1}$). The [OIII]$λ$5007 kinematics reveals a smooth large-scale velocity gradient centred on the central, massive ($M_{\star}\simeq1.1\times10^9$ ${M_\odot}$) and metal rich ($Z\sim0.6$ $Z_{\odot}$) system of the group. In this source, only 2.4 kpc (projected) from GN-77652, [OIII]$λ$4363 line diagnostics provide possible evidence for a second AGN. GN-77652 exhibits a shallow ($-30$ to $+20$ km s$^{-1}$) velocity gradient that is consistent with disk rotation according to dynamical modelling. The Lyman-Werner radiation field produced by the filament is too weak for the black hole (BH) in GN-77652 to have formed recently via direct collapse. However, the required conditions may have existed at earlier epochs, or alternative scenarios (e.g. a recoiling BH ejected from the filament) could also be plausible. The whole system is expected to coalesce in $150-440$ Myr, also motivating an exploration of its future evolution through toy-model extrapolations and numerical simulations. Our analysis suggests that the compact AGN appearance of GN-77652 represents a transient evolutionary phase, consistent with the apparent decline with redshift in number density of compact AGN identified with JWST.

astro-ph.GA↗

arXiv2026

Using VLTI/GRAVITY+ to determine the identity of a third planet candidate in the PDS 70 system

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.

astro-ph.EP↗

arXiv2026

The first detection of dense gas in a massive main-sequence galaxy at cosmic noon

Dense gas is the direct fuel for star formation, but measuring it has long been difficult at z>2, especially in typical 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 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 $1.05\pm0.23$, similar to that of starburst galaxies at comparable redshifts but lower than that of quasar/AGN host galaxies. The comparatively fainter HNC(5--4) 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 $(2-4)\times10^{6}\,\text{cm}^{-3}$ 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.

astro-ph.GA↗

arXiv2026

$^{13}$CO and potential variability in $β$ Pictoris b with GRAVITY+

The $^{12}$CO/$^{13}$CO ratio was introduced as an indicator for where in the disk a planet has formed. Previously a lower value compared to the host star's was suggested to show that a planet accreted CO ice beyond the disk's CO ice line. In this letter we aim to determine the $^{12}$CO/$^{13}$CO value of the directly imaged planet $β$ Pictoris b, and whether we can link it to its formation. Its apparent brightness results in an exceptional S/N of up to ~60 per wavelength point. We present the first science observations with the upgraded GRAVITY+ instrument at a spectral resolution of R ~ 4000, which we analyse with petitRADTRANS. Our retrievals robustly indicate the presence of $^{13}$CO with a $^{12}$CO/$^{13}$CO ratio of 91$^{+24}_{-17}$, consistent with both a solar to ISM-like value. Our $^{12}$CO/$^{13}$CO value corroborates recent interpretations that $^{13}$CO may be a less useful tracer of formation location in the disk than previously thought; nonetheless, we discuss theories with which this value is consistent. As our observations span ~7 hours, this enabled us to search for atmospheric variability in $β$ Pictoris b; we report a tentative constraint on the variability amplitude of about 1.4$^{+0.6}_{-0.7}$%.

astro-ph.EP↗

arXiv2026

NOEMA$^\rm{3D}$: A deep view of cold gas flows in a barred spiral galaxy at $z\sim1$

We present a deep, high-resolution CO(4-3) IRAM-NOEMA observation of a main sequence, barred, spiral galaxy at $z\approx1.12$, with an on-source integration time of $\approx37$ hours and a beam FWHM of $\approx0.\!\!^{\prime\prime}3$. We use the molecular gas data in conjunction with the available deep multi-band JWST and HST imaging, covering restframe UV to near-IR wavelengths, to quantitatively study the gas flows in the disk plane of this cosmic noon barred spiral. We find that this target is a massive ($\log(M_{\rm{baryons}}/M_\odot)\approx10.96$), baryon-dominated ($f_{\rm{dm}}(<R_e)=u^2_{\rm{circ,dm}}(R_e)/u^2_{\rm{circ}}(R_e)\sim4\%$), gas-rich ($f_{\rm{gas}}=M_{\rm{gas}}/(M_{\rm{\star}}+M_{\rm{gas}})\approx40\%$) disk, hosting a long ($a_{\rm{bar}}\approx4.2$ kpc), strong ($Q_{\rm{b}}\approx0.37$), and fast ($\mathcal{R}=R_{\rm{CR}}/a_{\rm{bar}}\approx1.05$) bar, which rotates at an angular speed of $Ω_{\rm{pattern}}\approx$ 50 km/s/kpc. This bar is driving molecular gas inflows with a net inflow rate of $\dot{M}\sim30$ $M_\odot$/yr, based on three estimates, which is of the same order as the galaxy-integrated star formation rate ($\rm{SFR}\approx36$ $M_\odot$/yr). We additionally identify evidence of a well-defined dust lane shock at the northwestern side of the bar, with gas motions parallel to this feature, in agreement with expectations for an established bar-driven flow. Our study highlights the possible role of bars as key drivers of galaxy evolution for a significant fraction of cosmic noon galaxies, offering a detailed picture of well-defined, bar-driven inflows in a high-$z$ barred spiral.

astro-ph.GA↗

arXiv2026

BlackTHUNDER: Evidence of three massive black holes in a z~5 galaxy

We present observational evidence of three massive, accreting black holes (BHs) in the z=5.0167 galaxy J0148-4214 from JWST/NIRSpec-IFU spectroscopy. The BHs are revealed through broad H$α$ emission (FWHM=430-2920 km/s) without a forbidden-line counterpart in the bright [OIII] doublet. Channel maps of the asymmetric central H$α$ profile isolate two spatially distinct broad-line regions (BLRs), separated by $190\pm40$ pc, while a third BLR is found in the galaxy outskirts with a projected separation of 1.7 kpc. We discuss whether this emission could be due to supernovae, shocks, winds, or massive stars, but find the BLR origin most likely. Using single-epoch virial relations, we estimated BH masses of $\log(M_\bullet/M_\odot)=7.9\pm0.4$ (primary), $5.8\pm0.5$ (secondary), and $6.3\pm0.5$ (third off-nuclear). We argue that the two central BHs will likely rapidly merge, with a simple dynamical friction time estimate of the order of $\lesssim700$ Myr. Assuming that the third off-nuclear BH is also in the process of sinking towards the centre, it will likely lead to a second merger, and we investigated the detection probability of such mergers with LISA. Alternatively, the third BH may be the result of a previous central three-body interaction or a gravitational recoil, where our observations would provide evidence that such BHs may retain their accretion discs and BLRs even in the aftermath of such extreme dynamical interactions. The possible discovery of a BH triplet at high z, together with other recent results on distant BH pairs, indicates that multiple massive BH systems were likely common in the early Universe. Our results highlight the importance of IFU observations for the detection of massive BH multiplets in distant galaxies, the progenitors of massive BH mergers that may be detected with next-generation gravitational wave observatories.

astro-ph.GA↗

arXiv2026

NOEMA3D: Resolving radial gas flows in disk galaxies at z~1.1-1.6 with high-resolution CO observations

We present NOEMA3D, a unique high-resolution study of purely molecular gas kinematics at $z \sim 1.1$ 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 ($> 20$ hr on source per target) IRAM-NOEMA CO observations of 10 massive ($10.45 < \log(M^*/M_\odot) < 11.43$)) main-sequence galaxies, complemented by high-resolution JWST imaging, we resolve the molecular gas kinematics and morphology on kiloparsec scales. We find that all galaxies exhibit ordered rotation with moderate intrinsic turbulence (median $σ_0 \sim 32 \pm 10$ km/s, median $V_c/σ_0 \sim 8.6 \pm 2.9$), consistent with dynamically turbulent disks at late cosmic noon. After modeling the axisymmetric rotation with the forward-modeling code DysmalPy, we reveal spatially coherent velocity residuals in all but one more inclined system. The inferred in-plane non circular motions reach amplitudes of $\sim 50$-100 km/s, significantly larger than typically observed in local disk galaxies. Interpreting these non-circular 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 $z \sim 1$-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 of the order of the star formation rate ($\dot M \sim -50 M_\odot$/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.

astro-ph.GA↗

arXiv2026

The S stars' zone of avoidance in the Galactic center

This paper investigates the origin and orbital evolution of S stars in the Galactic center using models of binary disruption and relaxation processes. We focus on explaining the recently discovered ``zone of avoidance'' in S-star orbital parameters, defined as a region where no S stars are observed with pericenters of $\log(r_p / {\rm AU}) \leq 1.57 + 2.6(1 - e)$ pc. We demonstrate that the observed S-star orbital distributions, including this zone of avoidance and their thermal eccentricity distribution, can be largely explained by the continuous disruption of binaries near the central supermassive black hole, followed by orbital relaxation. Our models consider binaries originating from large scales ($5$--$100$ pc) and incorporate empirical distributions of binary properties. We simulate close encounters between binaries and the black hole, tracking the remnant stars' orbits. The initially highly eccentric orbits of disrupted binary remnants evolve due to nonresonant and resonant relaxation in the Galactic center potential. While our results provide insights into the formation mechanism of S stars, there are limitations, such as uncertainties in the initial binary population and mass function and simplifications in our relaxation models. Despite these caveats, our study demonstrates the power of using S-star distributions to probe the dynamical history and environment of the central parsec of our Galaxy.

astro-ph.GA↗

arXiv2026

Constraints on the host galaxy and AGN properties of three z > 6 JWST AGN from NOEMA observations

We targeted with deep NOEMA observations the [CII]158$μ$m emission of three JWST-discovered AGN at z>6. Two of them have the typical features of Little Red Dots (LRDs), while the third one is a blue, extended, Type I AGN. We do not significantly detect [CII] emission or dust continuum in any of the targets, even after stacking. The resulting [CII] luminosity upper limits, $\log (L_{[CII]}/L_{\odot})<7.77-8.1$, lie $\sim2σ$ below the values expected from the [CII]-SFR relation, and we explore different scenarios to explain the lack of [CII]. We obtained upper limits on the gas masses of $\log (M_{gas}/M_{\odot})<9.26-9.59$ corresponding to $\log( M_{dust}/M_{\odot})<5.68-6.55$ assuming a metallicity dependent dust to gas ratio. Using the continuum non-detections (rms $\sim 16-25 ~μJy$) together with JWST/MIRI constraints, we performed a revised SED-fitting decomposition, resulting in stellar masses up to $\sim 2$ dex lower than previously reported, and implying $0.03\lesssim M_{BH}/M_{*}\lesssim0.7$. For the two LRDs, the SED is well reproduced by stellar emission in the rest-frame UV, while the rising rest-frame optical slope, flattening toward the near-infrared, is consistent with emission from a Type I AGN partially obscured along the polar direction with $E(B-V)_{\rm polar}\simeq 1$, in agreement with attenuation derived from the broad lines Balmer decrement. This decomposition demonstrates that a relatively standard AGN configuration can reproduce the SEDs of the two LRDs, without invoking more exotic scenarios. Finally, we investigate the positions of the three sources in the $IRX-β_{UV}$ plane, finding that they lie in a parameter space where galaxies are typically characterized by patchy dust distributions. Our analysis highlights the importance of millimeter constraints to characterize the different physical properties of high-z AGN.

astro-ph.GA↗

arXiv2026

Direct spectroscopic confirmation of the young embedded proto-planet WISPIT 2c

WISPIT 2 is a nearby young star with a multi-ringed disk which was recently confirmed to host a ~4.9 MJup gas giant planet embedded in a large (60 au) gap at a radial separation of 57 au from the host star. We confirm and characterise a second, close-in planet in the WISPIT 2 system using a combination of new VLT/SPHERE H-band dual-polarisation imaging and VLTI/GRAVITY K-band interferometric observations of the WISPIT 2 system. The GRAVITY detection is consistent with a point-like source while its extracted K-band spectrum shows CO band-head absorption at 2.3 microns and a continuum shape consistent with a young giant planet. From the GRAVITY data we extract a medium resolution K-band spectrum of the companion and fit atmospheric model grids using the species tool with nested sampling to constrain its effective temperature, radius, and luminosity. We infer Teff of 1500-2600 K, a radius of 0.91-2.2 RJup, and a luminosity of (-3.47)-(-3.63). Comparison with evolutionary tracks implies a mass range of 8-12 MJup, approximately twice as massive as the previously confirmed WISPIT 2b. The astrometry rules out a background source and marginally detects orbital motion of WISPIT 2c, which needs further follow-up observations for confirmation. WISPIT 2 now becomes an analogue to PDS 70, offering a second laboratory for studying the formation and early evolution of a multi-planet system within its natal disk.

astro-ph.EP↗

arXiv2025

Hunting exomoons with a kilometric baseline interferometer

Despite numerous search campaigns based on a diverse set of observational techniques, exomoons - prospective satellites of extrasolar planets - remain an elusive and hard-to-pin-down class of objects. Yet, the case for intensifying this search is compelling: as in the Solar System, moons can act as proxies for studying planet formation and evolution, provide direct clues as to the migration history of the planetary hosts and, in favourable cases, offer potentially habitable environments. Here, we present an investigation into how the search for exomoons would benefit from a new interferometric facility operating in the optical wavelength domain and leveraging baselines substantially longer than the ones the VLTI is currently equipped with. We find that an interferometer providing an astrometric precision of 1$\,μ$as would be able to robustly detect Earth-mass and sub-Earth-mass exomoons on dynamically stable orbits around Jupiter-like planets at distances between 50 and 200 pc.

astro-ph.IM↗