Armando Riccardi

Large optics have become mandatory with the new generation of large telescopes. In this work, we aim to refine the optical surface estimation of a mirror. By using partial surface measurements, as in a standard sub-aperture sampling approach, we populate our surface using a continuously refined reconstructor that is optimal in a least-squares sense, converging to a stable solution that ensures surface continuity. Simultaneously, we estimate both the cavity and alignment errors for each individual measurement of the partial optical surface. The basis chosen for the estimation consists of the Zernike modes by Noll. Optical surfaces are estimated together with cavity and alignment parameters in a single, unified minimization process.

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.

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.

The black hole in the Galactic center, Sgr A*, is prototypical of ultra-low-fed galactic nuclei. The discovery of a handful of gas clumps with masses on the order of a few Earth masses in its immediate vicinity provides a gas reservoir sufficient to power Sgr A*. In particular, the gas cloud G2 is of interest due to its extreme orbit, on which it passed at a pericenter distance of around 100 AU and notably lost kinetic energy during the fly-by due to interaction with the black hole accretion flow. Thirteen years prior to G2, a similar gas cloud called G1, passed Sgr A* on a similar orbit. The origin of G2 remained a topic of discussion, with models including a central (stellar) source still proposed as alternatives to pure gas clouds. Here, we report the orbit of a third gas clump moving along (nearly) the same orbital trace. Since the probability of finding three stars on such similar orbits is very low, this strongly argues against stellar-based source models. Instead, we show that the gas streamer G1–2–3 plausibly originates from the stellar wind of the massive binary star IRS 16SW. This claim is substantiated by the fact that the small differences between the three orbits – the orientations of the orbital ellipses in their common plane as a function of time – are consistent with the orbital motion of IRS 16SW.

Context. The Enhanced Resolution Imager and Spectrograph (ERIS) is the new adaptive optics (AO) assisted infrared instrument at the Very Large Telescope (VLT). Its refurbished integral field spectrograph (IFS) SPIFFIER leverages a new AO module, enabling high-contrast imaging applications and giving access to the orbital and atmospheric characterisation of super-Jovian exoplanets. Aims. We tested the detection limits of ERIS, and demonstrate its scientific potential by exploring the atmospheric composition of the young super-Jovian AF Lep b. Additionally, we improved its orbital solution by measuring its radial velocity relative to its host star. Methods. We present new spectroscopic observations of AF Lep b in K-band at R ∼ 11 000 obtained with ERIS/SPIFFIER at the VLT. We reduced the data using the standard pipeline together with a custom wavelength calibration routine, and removed the stellar point spread function using principal component analysis along the spectral axis. We computed molecular maps by cross-correlating the residuals with molecular spectral templates and measured the radial velocity of the planet relative to the star. Furthermore, we computed contrast grids for molecular mapping by injecting fake planets. Results. We detect a strong signal from H₂O and CO but not from CH₄ or CO₂. This result corroborates the hypothesis of chemical disequilibrium in the atmosphere of AF Lep b. Our measurement of the RV of the planet yields Δ v_{R, P ⋆} = 7.8 ± 1.7 km s⁻¹. This enables us to disentangle the degeneracy of the orbital solution; specifically, the correct longitude of the ascending node is Ω = 248_−0.7^+0.4 deg and the argument of periapsis is ω = 109₋₂₁⁺¹³ deg. Our detection limits reach a contrast of ΔK = 11.5 mag at 0′′.12 for the spectral templates of H₂O and CO, significantly extending the parameter space available to moderately high spectral resolution towards small angular separation. Conclusions. Our results demonstrate the competitiveness of the new ERIS/SPIFFIER instrument for the orbital and atmospheric characterisation of exoplanets at high contrast and small angular separation.

The Large Binocular Telescope (LBT) Observatory pioneered Adaptive Optics (AO) technologies such as Adaptive Secondary Mirror (ASM), Pyramid wavefront sensor, and Ground-layer AO using Rayleigh lasers at 8 to 10m class telescopes. We have initiated an effort to turn LBT AO into a facility-class capability. The effort involves (1) building an AO team with AO development capability, (2) improving the robustness of the AO, (3) developing in-house AO expertise to maintain and troubleshoot the AO systems, (4) automating processes for efficient on-sky operation, (5) tracking performance metrics and cultivating accountability for on-sky AO performance, and (6) minimizing the operational risks for the ASMs. We present the status of these developments. LBTO continues its efforts to develop innovative technology. We explore the next phase of AO developments, including Agile Extreme Adaptive Optics (AgXAO) on the DX side of the LINC-NIRVANA optical bench to overcome the limitation imposed by varying and large atmospheric seeing at Mount Graham. AgXAO implementation includes the development of (1) a high-order, high-sensitivity wavefront sensor, (2) a high-density deformable mirror with 3000 actuators and next-generation ASM with about 950 actuators, (3) active optics integration, (4) vibration and wavefront piston control, (5) atmospheric turbulence measurements and weather forecast integration, and (6) a visible camera and an AO-corrected narrow-field fiber-coupled IFU spectrograph using one of the existing workhorse visible spectrographs. Developing AgXAO on the SX side, too, would enable Fizeau imaging in the visible wavelengths. AgXAO will also serve as a general-purpose high-contrast (and subsequently a Fizeau imaging) Testbed on LBT to test advanced wavefront control algorithms, including astrophotonics experiments, and machine learning algorithms with minimal impact on routine science operations. We propose developing AgXAO through student projects to train the next-generation scientists and engineers for the extremely large telescope (ELT) era. The ultimate goal is to push large aperture ground-based telescopes to their performance limits and make them competitive with space telescopes in terms of PSF stability and performance to enable breakthrough science.

Hyperluminous infrared galaxies (HyLIRGs) are the rarest and most extreme starbursts and found only in the distant Universe (z ≳ 1). They have intrinsic infrared (IR) luminositiesL_IR ≥ 10¹³ L_⊙and are commonly found to be major mergers. Recently, the Planck All-Sky Survey to Analyze Gravitationally-lensed Extreme Starbursts project (PASSAGES) searched ~10⁴deg²of the sky and found ~20 HyLIRGs. We describe a detailed study of PJ0116-24, the brightest (μL_IR ≈ 2.6 × 10¹⁴ L_⊙, magnified withμ ≈ 17) Einstein-ring HyLIRG in the southern sky, atz = 2.125, with observations from the near-IR integral-field spectrograph VLT/ERIS and the submillimetre interferometer ALMA. We detected Hα, Hβ, [Nii] and [Sii] lines and obtained an extreme Balmer decrement (Hα/Hβ ≈ 8.73 ± 1.14). We modelled the molecular-gas and ionized-gas kinematics with CO(3–2) and Hα data at ~100–300 pc and (sub)kiloparsec delensed scales, respectively, finding consistent regular rotation. We found PJ0116-24 to be highly rotationally supported (v_rot/σ_{0, mol. gas} ≈ 9.4) with a richer gaseous substructure than other known HyLIRGs. Our results imply that PJ0116-24 is an intrinsically massive (M_baryon ≈ 10^11.3 M_⊙) and rare starbursty disk (star-formation rate, SFR = 1,490 M_⊙ yr⁻¹) probably undergoing secular evolution. This indicates that the maximal SFR (≳1,000 M_⊙ yr⁻¹) predicted by simulations could occur during a galaxy’s secular evolution, away from major mergers.

The interferometric calibration and measurement of deformable mirrors for adaptive optics are often performed on complex optical system with spider arms. The spider shadows may divide the mirror surface into separate islands on the detector, so the interferometer fails in reconnecting them to a common phase value. The calibration measurements then suffer from such artificial differential pistons across islands, which is converted into a wrong actuator command and in general into a poor calibration. We review the effects of spider arms shadowing as experienced during the optical calibration of large format adaptive mirrors, such as the Large Binocular Telescope and Very Large Telescope ones; we describe the procedures that we tested to cope with these issues and their effectiveness; and we present a laboratory assessment of the effect of such a shadowing with a dedicated test setup. Our work is part of a preparatory activity for the optical test of the European Extremely Large Telescope adaptive mirror M4.

Enhanced Resolution Imager and Spectrograph is an instrument currently under commissioning at the Cassegrain focus of the Very Large Telescope UT4. Its mission is to replace the suite of instruments NAOS-CONICA and SINFONI and push to the edge the capabilities of this 8-meter class telescope, by leveraging the adaptive optics module. The instrument has been designed for maximum lifetime and reliability and minimum downtime. We will present the instrument constraints and our approach to the reliability, availability, and maintainability (RAM) analysis. We identified the main actors in the system, then for each of them, we compiled a database of reliability parameters in order to build-up the reliability diagram, describing the failure sources. Starting from this information, we computed the system-wide reliability parameters and compared them with the requirements by the customer. Such a scheme is very general and may be taken as an example of RAM analysis for astronomical instrumentation; it may be also customized for the needs of other projects. In the end, we summarize the lessons learned.