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The upcoming extremely large telescopes will have to deal with the so-called ''pupil fragmentation'' effect: for what concerns the Extremely Large Telescope (ELT), the presence of thick spider legs supporting the secondary mirror may induce unseen phase discontinuities across the pupil sectors that could limit the performance of the adaptive optics correction. In this context, we propose a wavefront sensor (WFS), the CiaoCiao WFS, consisting in a rotational shearing interferometer to sense phase differences between the pupil sectors. In this work, we present the CiaoCiao WFS concept and the first analyses carried out through numerical simulations. In particular, we analyze the performance of such a wavefront sensor in case the phase discontinuities are induced by low-wind effect during observations with the Multiconjugate adaptive Optics Relay For ELT Observations (MORFEO).

Methods: Broad- and narrow-band imaging of AFGL 5180 was made in the NIR with the LBT, in both seeing-limited ($\sim0.5\arcsec$) and high angular resolution ($\sim0.09\arcsec$) Adaptive Optics (AO) modes, as well as with HST. Archival ALMA continuum data was also utilized. Results: At least 40 jet knots were identified via NIR emission from H$_2$ and [FeII] tracing shocked gas. Bright jet knots outflowing from the central most massive protostar, S4, are detected towards the east of the source and are resolved in fine detail with the AO imaging. Additional knots are distributed throughout the field, likely indicating the presence of multiple driving sources. Sub-millimeter sources detected by ALMA are shown to be grouped in two main complexes, AFGL 5180 M and a small cluster $\sim15\arcsec$ to the south, AFGL 5180 S. From our NIR continuum images we identify YSO candidates down to masses of $\sim 0.1\:M_\odot$. Combined with the sub-mm sources, this yields a surface number density of such YSOs of $N_* \sim 10^3 {\rm pc}^{-2}$ within a projected radius of about 0.1 pc. Such a value is similar to those predicted by models of both Core Accretion from a turbulent clump environment and Competitive Accretion. The radial profile of $N_*$ is relatively flat on scales out to 0.2~pc, with only modest enhancement around the massive protostar inside 0.05~pc. Conclusions: This study demonstrates the utility of high-resolution NIR imaging, in particular with AO, for detecting outflow activity and YSOs in distant regions. The presented images reveal the complex morphology of outflow-shocked gas within the large-scale bipolar flow of a massive protostar, as well as clear evidence for several other outflow driving sources in the region. Finally, this work presents a novel approach to compare the observed YSO surface number density from our study against different models of massive star formation., Comment: Accepted to Astronomy & Astrophysics (A&A)

The Gaia-Multi-Peak (GMP) technique can be used to identify large numbers of dual or lensed AGN candidates at sub-arcsec separation, allowing us to study both multiple SMBHs in the same galaxy and rare, compact lensed systems. The observed samples can be used to test the predictions of the models of SMBH merging once 1) the selection function of the GMP technique is known, and 2) each system has been classified as dual AGN, lensed AGN, or AGN/star alignment. Here we show that the GMP selection is very efficient for separations above 0.15'' when the secondary (fainter) object has magnitude G<20.5. We present the spectroscopic classification of five GMP candidates using VLT/ERIS and Keck/OSIRIS, and compare them with the classifications obtained from: a) the near-IR colors of 7 systems obtained with LBT/LUCI, and b) the analysis of the total, spatially-unresolved spectra. We conclude that colors and integrated spectra can already provide reliable classifications of many systems. Finally, we summarize the confirmed dual AGNs at z>0.5 selected by the GMP technique, and compare this sample with other such systems from the literature, concluding that GMP can provide a large number of confirmed dual AGNs at separations below 7 kpc., Comment: 14 pages,A&A, in press

ERIS, the Enhanced Resolution Imager and Spectrograph, is an instrument that both extends and enhances the fundamental diffraction limited imaging and spectroscopy capability for the VLT. It replaces two instruments that were being maintained beyond their operational lifetimes, combines their functionality on a single focus, provides a new wavefront sensing module for natural and laser guide stars that makes use of the Adaptive Optics Facility, and considerably improves on their performance. The observational modes ERIS provides are integral field spectroscopy at 1-2.5 {\mu}m, imaging at 1-5 {\mu}m with several options for high contrast imaging, and longslit spectroscopy at 3-4 {\mu}m, The instrument is installed at the Cassegrain focus of UT4 at the VLT and, following its commissioning during 2022, has been made available to the community., Comment: 20 pages with 29 figures; accepted for A&A (minor changes)

We exploit the increased sensitivity of the recently installed AO SOUL at the LBT to obtain new high-spatial-resolution NIR images of the massive young stellar object IRAS20126+4104 and its outflow. We aim to derive the jet proper motions and kinematics, as well as to study its photometric variability by combining the novel performances of SOUL together with previous NIR images. We used both broad-band ($K_{s}$, $K'$) and narrow-band (Br$\gamma$, H2) observations from a number of NIR cameras (UKIRT/UFTI,SUBARU/CIAO,TNG/NICS,LBT/PISCES,and LBT/LUCI1) to derive maps of the continuum and the H$_2$ emission in the 2.12 $\mu$m line. Three sets of images, obtained with AO systems (CIAO,2003; FLAO,2012; SOUL,2020), allowed us to derive the proper motions of a large number of H$_2$ knots along the jet. Photometry from all images was used to study the jet variability. We derived knot proper motions in the range of 1.7-20.3 mas yr$^{-1}$ (i.e. 13-158 km s$^{-1}$ at 1.64 kpc, avg. outflow tangential velocity $\sim$ 80 km s$^{-1}$). The derived knot dynamical age spans a $\sim$ 200-4000 yr interval. A ring-like H$_2$ feature near the protostar location exhibits peculiar kinematics and may represent the outcome of a wide-angle wind impinging on the outflow cavity. Both H$_2$ geometry and velocities agree with those inferred from proper motions of the H$_2$O masers, located at a smaller distance from the protostar. Although the total H$_2$ line emission from the knots does not exhibit time variations at a $\widetilde{>}$ 0.3 mag level, we have found a clear continuum flux variation (radiation scattered by the dust in the cavity opened by the jet) which is anti-correlated between the blue-shifted and red-shifted lobes and may be periodic (with a period of $\sim$ 12-18 yr). We suggest that the continuum variability might be related to inner-disc oscillations which have also caused the jet precession., Comment: 26 pages, 22 figures, 2 mpeg files, accepted by Astronomy & Astrophysics

In this paper we will discuss the application of optimal filtering techniques for the adaptive optics system of the LBT telescope. We have studied the application of both Kalman and H$_\infty$ filters to estimate the temporal evolution of the phase perturbations due to the atmospheric turbulence and the telescope vibrations on tip/tilt modes. We will focus on the H$_\infty$ filter and on its advantages and disadvantages over the Kalman filter., Comment: 6 pages, 6 figures, 3 tables, European Control Conference (ECC) 2009, Budapest, Hungary, August 23-26, 2009

Characterizing the PSF of adaptive optics instruments is of paramount importance both for instrument design and observation planning/optimization. Simulation software, such as PASSATA, have been successfully utilized for PSF characterization in instrument design, which make use of standardized atmospheric turbulence profiles to produce PSFs that represent the typical instrument performance. In this contribution we study the feasibility of using such tool for nowcast application (present-time forecast), such as the characterization of an on-sky measured PSF in real observations. Specifically we will analyze the performance of the simulation software in characterizing the real-time PSF of two different state-of-the-art SCAO adaptive optics instruments: SOUL at the LBT, and SAXO at the VLT. The study will make use of on-sky measurements of the atmospheric turbulence and compare the results of the simulations to the measured PSF figures of merit (namely the FHWM and the Strehl Ratio) retrieved from the instrument telemetry in real observations. Our main goal in this phase is to quantify the level of uncertainly of the AO simulations in reproducing real on-sky observed PSFs with an end-to-end code (PASSATA). In a successive phase we intend to use a faster analytical code (TIPTOP). This work is part of a wider study which aims to use simulation tools joint to atmospheric turbulence forecasts performed nightly to forecast in advance the PSF and support science operations of ground-based telescopes facilities. The 'PSF forecast' option might therefore be added to ALTA Center or the operational forecast system that will be implemented soon at ESO., Comment: 10 pages, 6 figures

Gamma-ray bursts (GRBs) are classified as long and short events. Long GRBs (LGRBs) are associated with the end states of very massive stars, while short GRBs (SGRBs) are linked to the merger of compact objects. GRB 200826A was a peculiar event, because by definition it was a SGRB, with a rest-frame duration of ~ 0.5 s. However, this event was energetic and soft, which is consistent with LGRBs. The relatively low redshift (z = 0.7486) motivated a comprehensive, multi-wavelength follow-up campaign to characterize its host, search for a possible associated supernova (SN), and thus understand the origin of this burst. To this aim we obtained a combination of deep near-infrared (NIR) and optical imaging together with spectroscopy. Our analysis reveals an optical and NIR bump in the light curve whose luminosity and evolution is in agreement with several LGRB-SNe. Analysis of the prompt GRB shows that this event follows the $E_{\rm p,i}-E_{\rm iso}$ relation found for LGRBs. The host galaxy is a low-mass star-forming galaxy, typical for LGRBs, but with one of the highest star-formation rates (SFR), especially with respect to its mass ($\log M_\ast/M_\odot = 8.6$, SFR $\sim 4.0 \,M_\odot$/yr). We conclude that GRB 200826A is a typical collapsar event in the low tail of the duration distribution of LGRBs. These findings support theoretical predictions that events produced by collapsars can be as short as 0.5 s in the host frame and further confirm that duration alone is not an efficient discriminator for the progenitor class of a GRB., Comment: 19 pages, 11 figures, 2 tables. Accepted for publication in ApJ

The optimization and scheduling of scientific observations done with instrumentation supported by adaptive optics could greatly benefit from the forecast of PSF figures of merit (FWHM, Strehl Ratio, Encircle Energy and contrast), that depend on the AO instrument, the scientific target and turbulence conditions during the observing night. In this contribution we explore the the possibility to forecast a few among the most useful PSF figures of merit (SR and FWHM). To achieve this goal, we use the optical turbulence forecasted by the mesoscale atmospheric model Astro-Meso-NH on a short timescale as an input for PSF simulation software developed and tailored for specific AO instruments. A preliminary validation will be performed by comparing the results with on-sky measured PSF figures of merit obtained on specific targets using the SCAO systems SOUL (FLAO upgrade) feeding the camera LUCI at LBT and SAXO, the extreme SCAO system feeding the high resolution SPHERE instrument at VLT. This study will pave the way to the implementation of an operational forecasts of such a figure of merits on the base of existing operational forecast system of the atmosphere (turbulence and atmospheric parameters). In this contribution we focus our attention on the forecast of the PSF on-axis., Comment: 9 pages, 3 figures, 2 tables

Context. High redshift radio galaxies are among the most massive galaxies at their redshift, are often found at the center of protoclusters of galaxies, and are expected to evolve into the present day massive central cluster galaxies. Thus they are a useful tool to explore structure formation in the young Universe. Aims. 3C~294 is a powerful FR II type radio galaxy at z = 1.786. Past studies have identified a clumpy structure, possibly indicative of a merging system, as well as tentative evidence that 3C~294 hosts a dual active galactic nucleus (AGN). Due to its proximity to a bright star, it has been subject to various adaptive optics imaging studies. Method. In order to distinguish between the various scenarios for 3C~294 we performed deep, high-resolution adaptive optics near-infrared imaging and optical spectroscopy of 3C~294 with the Large Binocular Telescope. Results. We resolve the 3C~294 system into three distinct components separated by a few tenths of an arcsecond on our images. One is compact, the other two are extended, and all appear to be non-stellar. The nature of each component is unclear. The two extended components could be a galaxy with an internal absorption feature, a galaxy merger, or two galaxies at different redshifts. We can now uniquely associate the radio source of 3C~294 with one of the extended components. Based on our spectroscopy, we determined a redshift of z = 1.784+-0.001, which is similar to the one previously cited. In addition we found a previously unreported emission line at $\lambda$6749.4 \AA\ in our spectra. It is not clear that it originates from 3C~294. It could be the Ne [IV] doublet lambda 2424/2426 AA at z = 1.783, or belong to the compact component at a redshift of z ~ 4.56. We thus cannot unambiguously determine whether 3C~294 hosts a dual AGN or a projected pair of AGNs., Comment: 9 pages, 4 figures, accepted for publication in A&A

Several telescopes include large Deformable Mirrors (DM) located directly inside the telescope. These adaptive telescopes trigger new constraints for the calibration of the Adaptive Optics (AO) systems as they usually offer no access to an artificial calibration source for the interaction matrix measurement. Moreover, the optical propagation between the DM and the Wave-Front Sensor (WFS) may evolve during the operation, resulting in mis-registrations that highly affect the AO performance and thus the scientific observation. They have to be measured and compensated, for instance by updating the calibration. A new strategy consists of estimating the mis-registrations and injecting them into synthetic models to generate noise-free interaction matrices. This pseudo-synthetic approach is the baseline for the Adaptive Optics Facility working with a Shack-Hartmann WFS and seems particularly suited for the future Extremely Large Telescope as the calibration will have to be regularly updated, for a large numbers of actuators. In this paper, the feasibility of a pseudo synthetic calibration with Pyramid WFS at the Large Binocular Telescope (LBT) is investigated. A synthetic model of the LBT AO systems is developed, and the procedure to adjust the mis-registrations parameters is introduced, extracting them from an experimental interaction matrix. We successfully tested an interaction matrix generated from the model on the real system in high-order AO mode. We recorded a slightly better performance with respect to the experimental one. This work demonstrates that a high accuracy calibration can be obtained using the pseudo synthetic approach with pyramid WFS.

A robust post processing technique is mandatory to analyse the coronagraphic high contrast imaging data. Angular Differential Imaging (ADI) and Principal Component Analysis (PCA) are the most used approaches to suppress the quasi-static structure in the Point Spread Function (PSF) in order to revealing planets at different separations from the host star. The focus of this work is to apply these two data reduction techniques to obtain the best limit detection for each coronagraphic setting that has been simulated for the SHARK-NIR, a coronagraphic camera that will be implemented at the Large Binocular Telescope (LBT). We investigated different seeing conditions ($0.4"-1"$) for stellar magnitude ranging from R=6 to R=14, with particular care in finding the best compromise between quasi-static speckle subtraction and planet detection., Comment: 9 pages, 8 figures, proceeding for the fifth Adaptive Optics for Extremely Large Telescopes (AO4ELT5) meeting in 2017

In this article, we present a simulator conceived for the conceptual study of an AO-fed high-contrast coronagraphic imager. The simulator implements physical optics: a complex disturbance (the electric field) is Fresnel-propagated through any user-defined optical train, in an end-to-end fashion. The effect of atmospheric residual aberrations and their evolution with time can be reproduced by introducing in input a temporal sequence of phase screens: synthetic images are then generated by co-adding instantaneous PSFs. This allows studying with high accuracy the impact of AO correction on image quality for different integration times and observing conditions. In addition, by conveniently detailing the optical model, the user can easily implement any coronagraphic set-up and introduce optical aberrations at any position. Furthermore, generating multiple images can allow exploring detection limits after a differential post-processing algorithm is applied (e.g. Angular Differential Imaging). The simulator has been developed in the framework of the design of SHARK-NIR, the second-generation high contrast imager selected for the Large Binocular Telescope., Comment: 10 pages, 5 figures, Adaptive Optics for Extremely Large Telescopes V (AO4ELT5)

We present the last version of the PyrAmid Simulator Software for Adaptive opTics Arcetri (PASSATA), an IDL and CUDA based object oriented software developed in the Adaptive Optics group of the Arcetri observatory for Monte-Carlo end-to-end adaptive optics simulations. The original aim of this software was to evaluate the performance of a single conjugate adaptive optics system for ground based telescope with a pyramid wavefront sensor. After some years of development, the current version of PASSATA is able to simulate several adaptive optics systems: single conjugate, multi conjugate and ground layer, with Shack Hartmann and Pyramid wavefront sensors. It can simulate from 8m to 40m class telescopes, with diffraction limited and resolved sources at finite or infinite distance from the pupil. The main advantages of this software are the versatility given by the object oriented approach and the speed given by the CUDA implementation of the most computational demanding routines. We describe the software with its last developments and present some examples of application., Comment: 9 pages, 2 figures, 3 tables. SPIE conference Astronomical Telescopes and Instrumentation, 26 June - 01 July 2016, Edinburgh, Scotland, United Kingdom

ERIS is the new AO instrument for VLT-UT4 led by a Consortium of Max-Planck Institut fuer Extraterrestrische Physik, UK-ATC, ETH-Zurich, ESO and INAF. The ERIS AO system provides NGS mode to deliver high contrast correction and LGS mode to extend high Strehl performance to large sky coverage. The AO module includes NGS and LGS wavefront sensors and, with VLT-AOF Deformable Secondary Mirror and Laser Facility, will provide AO correction to the high resolution imager NIX (1-5um) and the IFU spectrograph SPIFFIER (1-2.5um). In this paper we present the preliminary design of the ERIS AO system and the estimated correction performance., Comment: 11 pages, 11 figures, 1 table. SPIE conference Astronomical Telescopes and Instrumentation, 26 June - 01 July 2016, Edinburgh, Scotland, United Kingdom

Diffraction limited resolution adaptive optics (AO) correction in visible wavelengths requires a high performance control. In this paper we investigate infinite impulse response filters that optimize the wavefront correction: we tested these algorithms through full numerical simulations of a single-conjugate AO system comprising an adaptive secondary mirror with 1127 actuators and a pyramid wavefront sensor (WFS). The actual practicability of the algorithms depends on both robustness and knowledge of the real system: errors in the system model may even worsen the performance. In particular we checked the robustness of the algorithms in different conditions, proving that the proposed method can reject both disturbance and calibration errors.

We have performed H and Ks band observations of the planetary system around HR 8799 using the new AO system at the Large Binocular Telescope and the PISCES Camera. The excellent instrument performance (Strehl ratios up to 80% in H band) enabled detection the inner planet HR8799e in the H band for the first time. The H and Ks magnitudes of HR8799e are similar to those of planets c and d, with planet e slightly brighter. Therefore, HR8799e is likely slightly more massive than c and d. We also explored possible orbital configurations and their orbital stability. We confirm that the orbits of planets b, c and e are consistent with being circular and coplanar; planet d should have either an orbital eccentricity of about 0.1 or be non-coplanar with respect to b and c. Planet e can not be in circular and coplanar orbit in a 4:2:1 mean motion resonances with c and d, while coplanar and circular orbits are allowed for a 5:2 resonance. The analysis of dynamical stability shows that the system is highly unstable or chaotic when planetary masses of about 5 MJup for b and 7 MJup for the other planets are adopted. Significant regions of dynamical stability for timescales of tens of Myr are found when adopting planetary masses of about 3.5, 5, 5, and 5 Mjup for HR 8799 b, c, d, and e respectively. These masses are below the current estimates based on the stellar age (30 Myr) and theoretical models of substellar objects., Comment: 13 pages, 10 figures, A&A, accepted

The new 8.4m LBT adaptive secondary AO system, with its novel pyramid wavefront sensor, was used to produce very high Strehl (75% at 2.16 microns) near infrared narrowband (Br gamma: 2.16 microns and [FeII]: 1.64 microns) images of 47 young (~1 Myr) Orion Trapezium theta1 Ori cluster members. The inner ~41x53" of the cluster was imaged at spatial resolutions of ~0.050" (at 1.64 microns). A combination of high spatial resolution and high S/N yielded relative binary positions to ~0.5 mas accuracies. Including previous speckle data, we analyse a 15 year baseline of high-resolution observations of this cluster. We are now sensitive to relative proper motions of just ~0.3 mas/yr (0.6 km/s at 450 pc) this is a ~7x improvement in orbital velocity accuracy compared to previous efforts. We now detect clear orbital motions in the theta1 Ori B2/B3 system of 4.9+/-0.3 km/s and 7.2+/-0.8 km/s in the theta1 Ori A1/A2 system (with correlations of PA vs. time at >99% confidence). All five members of the theta1 Ori B system appear likely as a gravitationally bound "mini-cluster". The very lowest mass member of the theta1 Ori B system (B4; mass ~0.2 Msun) has, for the first time, a clearly detected motion (at 4.3+/-2.0 km/s; correlation=99.7%) w.r.t B1. However, B4 is most likely in an long-term unstable (non-hierarchical) orbit and may "soon" be ejected from this "mini-cluster". This "ejection" process could play a major role in the formation of low mass stars and brown dwarfs., Comment: 27 pages, 14 figures, accepted for publication by the Astrophysical Journal