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The mid-infrared (IR) regime is well suited to directly detect the thermal signatures of exoplanets in our solar neighborhood. The NEAR experiment: demonstration of high-contrast imaging (HCI) capability at ten microns, can reach sub-mJy detection sensitivity in a few hours of observation time, which is sufficient to detect a few Jupiter mass planets in nearby systems. One of the big limitations for HCI in the mid-IR is thermal sky-background. In this work, we show that precipitate water vapor (PWV) is the principal contributor to thermal sky background and science PSF quality. In the presence of high PWV, the HCI performance is significantly degraded in the background limited regime., Comment: 8 pages, 4 figures, conference proceedings (SPIE Astronomical telescopes and instrumentation 2022)

Instrumental aberrations strongly limit high-contrast imaging of exoplanets, especially when they produce quasistatic speckles in the science images. With the help of recent advances in deep learning, we have developed in previous works an approach that applies convolutional neural networks (CNN) to estimate pupil-plane phase aberrations from point spread functions (PSF). In this work we take a step further by incorporating into the deep learning architecture the physical simulation of the optical propagation occurring inside the instrument. This is achieved with an autoencoder architecture, which uses a differentiable optical simulator as the decoder. Because this unsupervised learning approach reconstructs the PSFs, knowing the true phase is not needed to train the models, making it particularly promising for on-sky applications. We show that the performance of our method is almost identical to a standard CNN approach, and that the models are sufficiently stable in terms of training and robustness. We notably illustrate how we can benefit from the simulator-based autoencoder architecture by quickly fine-tuning the models on a single test image, achieving much better performance when the PSFs contain more noise and aberrations. These early results are very promising and future steps have been identified to apply the method on real data., SPIE Astronomical Telescopes + Instrumentation 2022

Vortex phase masks have been shown to be an efficient means to reduce the blinding stellar light in high-contrast imaging instruments. Once placed at the focal plane of the telescope, the helical phase ramp of a vortex phase mask diffracts the light of a bright on-axis source outside the re-imaged telescope pupil, while transmitting the light of a faint off-axis companion nearly unaffected. The Annular Groove Phase Mask (AGPM) is a broadband metasurface implementation of a vector vortex phase mask using the artificial birefringence of a circular subwavelength grating etched onto a diamond substrate. To date, the AGPM design has been optimized using rigorous coupled-wave analysis (RCWA), which is a valid tool to simulate periodic straight gratings. However, we have now reached a performance level where the curvature of the grating lines at the center becomes a limiting factor. Here, we use a finite-difference time-domain (FDTD) method to correctly describe the AGPM performance, including the effect of the curved grating close to its center. We confirm the validity of this simulation framework by comparing its predictions with experimental results obtained on our infrared coronagraphic test bench, and we show that RCWA fails at reproducing correctly the central AGPM performance, confirming the need for a full 3d simulation tool such as FDTD. Finally, we use FDTD to optimize the grating parameters at the AGPM center, and conclude with a new optimal design.

Direct imaging is a powerful exoplanet discovery technique that is complimentary to other techniques with great promise in the era of 30-meter class telescopes. Space-based transit surveys have revolutionized our understanding of the frequency of planets at small orbital radii around sun-like stars. The next generation of extremely large ground-based telescopes will have the angular resolution and sensitivity to directly image planets with R < 4 Earth radii around the very nearest stars. Here we predict yields from a direct imaging survey of a volume-limited sample of sun-like stars with the Mid-Infrared ELT Imager and Spectrograph (METIS) instrument, planned for the 39-m European Southern Observatory (ESO) Extremely Large Telescope (ELT) that is expected to be operational towards the end of the decade. Using Kepler occurrence rates, a sample of stars with spectral types A-K within 6.5 pc, and simulated contrast curves based on an advanced model of what is achievable from coronagraphic imaging with adaptive optics, we estimate the expected yield from METIS using Monte Carlo simulations. We find the METIS expected yield of small planets in the N2 band (10.10 - 12.40 μm) is 1.15 planets which is greater than similar observations in the L (3.70 - 3.95 μm) and M (4.70 - 4.90 μm) bands. We also determine a 42% chance of detecting at least one Jovian planet in the background limited regime assuming a 1-hour integration. We calculate the yield per star and estimate optimal observing revisit times to increase the yield. We also analyze this survey if performed in the northern hemisphere and find there are additional targets worth considering. Finally, we present an observing strategy in order to maximize the possible yield for limited telescope time, resulting in 1.52 expected planets in the N2 band.

The planet detection thresholds of space-based coronagraphs are predicted to lie within an order of magnitude from their theoretical (shot-noise) limits. Ground-based telescopes, on the other hand, are limited by larger systematic uncertainties in the point spread function (PSF) of the residual light which rapidly fluctuates due to atmospheric turbulence. The PSF is affected by Adaptive Optics (AO) which reduce the intensity of the speckles but also make them less predictable. Although not a common practice, it is possible to take millisecond exposures of the so-called “frozen” speckles and record the history of AO controls, in which case the collected data resembles that of simulated space coronagraphs. In this work we use the HEEPS simulation of the EELT/METIS to assess the applicability of this newly-developed space-oriented approach to ground-based postprocessing. Unlike intensity-based algorithms, this method formulates the estimation problem in terms of the electric field of the speckles and therefore can incorporate controls history and various temporal models of the electric field variations. In our simulations, we artificially introduced small deformable mirror (DM) probes on top of AO controls, and achieved a post-processing error lower by a factor of 2 than that of Angular Differential Imaging (ADI). However, our attempt at incorporating the AO history without DM probes, has so far resulted in higher errors than ADI.

Context.TheMBH–σ⋆relation is considered a result of coevolution between the host galaxies and their supermassive black holes. For elliptical bulge hosting inactive galaxies, this relation is well established, but there is still discussion concerning whether active galaxies follow the same relation.Aims.In this paper, we estimate black hole masses for a sample of 19 local luminous active galactic nuclei (AGNs; LLAMA) to test their location on theMBH–σ⋆relation. In addition, we test how robustly we can determine the stellar velocity dispersion in the presence of an AGN continuum and AGN emission lines, and as a function of signal-to-noise ratio.Methods.Supermassive black hole masses (MBH) were derived from the broad-line-based relations for Hα, Hβ, and Paβemission line profiles for Type 1 AGNs. We compared the bulge stellar velocity dispersion (σ⋆) as determined from the Ca II triplet (CaT) with the dispersion measured from the near-infrared CO (2-0) absorption features for each AGN and find them to be consistent with each other. We applied an extinction correction to the observed broad-line fluxes and we corrected the stellar velocity dispersion by an average rotation contribution as determined from spatially resolved stellar kinematic maps.Results.The Hα-based black hole masses of our sample of AGNs were estimated in the range 6.34 ≤ logMBH ≤ 7.75M⊙and theσ⋆CaTestimates range between 73 ≤ σ⋆CaT ≤ 227 km s−1. From the so-constructedMBH − σ⋆relation for our Type 1 AGNs, we estimate the black hole masses for the Type 2 AGNs and the inactive galaxies in our sample.Conclusions.We find that our sample of local luminous AGNs is consistent with theMBH–σ⋆relation of lower luminosity AGNs and inactive galaxies, after correcting for dust extinction and the rotational contribution to the stellar velocity dispersion.

We present $L$'-band imaging of the PDS 70 planetary system with Keck/NIRC2 using the new infrared pyramid wavefront sensor. We detected both PDS 70 b and c in our images, as well as the front rim of the circumstellar disk. After subtracting off a model of the disk, we measured the astrometry and photometry of both planets. Placing priors based on the dynamics of the system, we estimated PDS 70 b to have a semi-major axis of $20^{+3}_{-4}$~au and PDS 70 c to have a semi-major axis of $34^{+12}_{-6}$~au (95\% credible interval). We fit the spectral energy distribution (SED) of both planets. For PDS 70 b, we were able to place better constraints on the red half of its SED than previous studies and inferred the radius of the photosphere to be 2-3~$R_{Jup}$. The SED of PDS 70 c is less well constrained, with a range of total luminosities spanning an order of magnitude. With our inferred radii and luminosities, we used evolutionary models of accreting protoplanets to derive a mass of PDS 70 b between 2 and 4 $M_{\textrm{Jup}}$ and a mean mass accretion rate between $3 \times 10^{-7}$ and $8 \times 10^{-7}~M_{\textrm{Jup}}/\textrm{yr}$. For PDS 70 c, we computed a mass between 1 and 3 $M_{\textrm{Jup}}$ and mean mass accretion rate between $1 \times 10^{-7}$ and $5 \times~10^{-7} M_{\textrm{Jup}}/\textrm{yr}$. The mass accretion rates imply dust accretion timescales short enough to hide strong molecular absorption features in both planets' SEDs., Comment: 20 pages, 5 figures, Accepted to AJ. Updated author list from original version. Fixed equation typo

Coronagraphy is a high-contrast imaging technique that aims to reduce the blinding glare of a star to detect a potential companion in its close environment. Vortex phase mask coronagraphy is widely recognized as one of the most promising approaches. The vortex optical demonstrator for coronagraphic application (VODCA) is a test bench currently developed at the University of Liege. Its main goal is to optically characterize infrared phase masks, in particular vortex masks. We detail the layout and salient features of VODCA and present the performance of the latest L-band (3575 to 4125 nm) and M-band (4600 to 5000 nm) annular groove phase masks (AGPMs) manufactured by our team. We obtain the highest rejection ratio ever measured for an AGPM at L-band: 3.2 × 103 in a narrowband filter (3425 to 3525 nm) and 2.4 × 103 in a broad L-band filter. By providing measurements close to the intrinsic limit of science-grade AGPMs, VODCA proves to be a step forward in terms of the evaluation of vortex phase masks performance.

We analyse high spatial resolution near infra-red (NIR) imaging of NGC6384, a Milky Way like galaxy, using ARGOS commissioning data at the Large Binocular Telescope (LBT). ARGOS provides a stable PSF$_{\rm FWHM}\!=\!0.2"\!-\!0.3"$ AO correction of the ground layer across the LUCI2 NIR camera $4'\!\times4'$ field by using six laser guide stars (three per telescope) and a natural guide star for tip-tilt sensing and guiding. Enabled by this high spatial resolution we analyse the structure of the nuclear star cluster (NSC) and the central kiloparsec of NGC6384. We find via 2D modelling that the NSC ($r_{\rm eff}\!\simeq\!10$pc) is surrounded by a small ($r_{\rm eff}\!\simeq\!100$pc) and a larger Sersi\'c ($r_{\rm eff}\!\simeq\!400$pc), all embedded within the NGC\,6384 large-scale boxy/X-shaped bulge and disk. This proof-of-concept study shows that with the high spatial resolution achieved by ground-layer AO we can push such analysis to distances previously only accessible from space. SED-fitting to the NIR and optical HST photometry allowed to leverage the age-metallicity-extinction degeneracies and derive the effective NSC properties of an young to old population mass ratio of $8\%$ with ${\cal M}_{\rm\star,old}\!\simeq\!3.5\times10^7M_\odot$, Age$_{\rm old,\ young}\!=\!10.9\pm1.3$Gyr and 226\,Myr $\pm62\%$, metallicity [M/H]$=\!-0.11\pm0.16$ and $0.33\pm39\%$dex, and $E(B\!-\!V)\!=\!0.63$ and 1.44mag., Comment: 12 pages (+9 appendix), 11 figures, Accepted in MNRAS

Since its first light at the VLT in 2012, the Annular Groove Phase Mask (AGPM) has been used to implement vortex coronagraphy into AO-assisted infrared cameras at two additional world-leading observatories: the Keck Observatory and the LBT. In this paper, we review the status of these endeavors, and briefly highlight the main scientific results obtained so far. We explore the performance of the AGPM vortex coronagraph as a function of instrumental constraints, and identify the main limitations to the sensitivity to faint, off-axis companions in high-contrast imaging. These limitations include the AGPM itself, non-common path aberrations, as well as the data processing pipeline; we briefly describe our on-going efforts to further improve these various aspects. Based on the lessons learned from the first five years of on-sky exploitation of the AGPM, we are now preparing its implementation in a new generation of high-contrast imaging instruments. We detail the specificities of these instruments, and how they will enable the full potential of vortex coronagraphy to be unleashed in the future. In particular, we explain how the AGPM will be used to hunt for planets in the habitable zone of alpha Centauri A and B with a refurbished, AO-assisted version of the VISIR mid-infrared camera at the VLT (aka the NEAR project), and how this project paves the way towards mid-infrared coronagraphy on the ELT with the METIS instrument. We also discuss future LM-band applications of the AGPM with VLT/ERIS, ELT/METIS, and with a proposed upgrade of Keck/NIRC2, as well as future applications at shorter wavelengths, such as a possible upgrade of VLT/SPHERE with a K-band AGPM.

For several years, we have been developing vortex phase masks based on sub-wavelength gratings, known as Annular Groove Phase Masks. Etched onto diamond substrates, these AGPMs are currently designed to be used in the thermal infrared (ranging from 3 to 13 {\mu}m). Our AGPMs were first installed on VLT/NACO and VLT/VISIR in 2012, followed by LBT/LMIRCam in 2013 and Keck/NIRC2 in 2015. In this paper, we review the development, commissioning, on-sky performance, and early scientific results of these new coronagraphic modes and report on the lessons learned. We conclude with perspectives for future developments and applications., Comment: To appear in SPIE proceedings vol. 9908

We present the results of the laboratory characterization of the ARGOS LGS wavefront sensor (LGSW) and dichroic units. ARGOS is the laser guide star adaptive optics system of the Large Binocular Telescope (LBT). It implements a Ground Layer Adaptive Optics (GLAO) correction for LUCI, an infrared imager and multi-object spectrograph (MOS), using 3 pulsed Rayleigh beacons focused at 12km altitude. The LGSW is a Shack-Hartman sensor having 15 × 15 subaspertures over the telescope pupil. Each LGS is independently stabilized for on-sky jitter and gated to reduce spot elongation. The 3 LGS pupils are stabilized to compensate mechanical flexure and are arranged on a single detector. Two units of LGSW have been produced and tested at Arcetri Observatory. We report on the results obtained in the pre-shipment laboratory test: internal active flexure compensation loop performance, optomechanical stability under different gravity conditions, thermal cycling, Pockels cells performance. We also update on the upcoming installation and commissioning campaign at LBT.

Argos is the ground-layer adaptive optics system for the Large Binocular Telescope. In order to perform its wide-field correction, Argos uses three laser guide stars which sample the atmospheric turbulence. To perform the correction, Argos has at disposal three different wavefront sensing measurements : its three laser guide stars, a NGS tip-tilt, and a third wavefront sensor. We present the wavefront sensing architecture and its individual components, in particular: the finalized Argos pnCCD camera detecting the 3 laser guide stars at 1kHz, high quantum efficiency and 4e - noise; the Argos tip-tilt sensor based on a quad-cell avalanche photo-diodes; and the Argos wavefront computer. Being in the middle of the commissioning, we present the first wavefront sensing configurations and operations performed at LBT, and discuss further improvements in the measurements of the 3 laser guide star slopes as detected by the pnCCD.

ARGOS is the Laser Guide Star and Wavefront sensing facility for the Large Binocular Telescope. With first laser light on sky in 2013, the system is currently undergoing commissioning at the telescope. We present the overall status and design, as well as first results on sky. Aiming for a wide field ground layer correction, ARGOS is designed as a multi- Rayleigh beacon adaptive optics system. A total of six powerful pulsed lasers are creating the laser guide stars in constellations above each of the LBTs primary mirrors. With a range gated detection in the wavefront sensors, and the adaptive correction by the deformable secondary’s, we expect ARGOS to enhance the image quality over a large range of seeing conditions. With the two wide field imaging and spectroscopic instruments LUCI1 and LUCI2 as receivers, a wide range of scientific programs will benefit from ARGOS. With an increased resolution, higher encircled energy, both imaging and MOS spectroscopy will be boosted in signal to noise by a large amount. Apart from the wide field correction ARGOS delivers in its ground layer mode, we already foresee the implementation of a hybrid Sodium with Rayleigh beacon combination for a diffraction limited AO performance.

Commissioning time for an instrument at an observatory is precious, especially the night time. Whenever astronomers come up with a software feature request or point out a software defect, the software engineers have the task to find a solution and implement it as fast as possible. In this project phase, the software engineers work under time pressure and stress to deliver a functional instrument control software (ICS). The shortness of development time during commissioning is a constraint for software engineering teams and applies to the ARGOS project as well. The goal of the ARGOS (Advanced Rayleigh guided Ground layer adaptive Optics System) project is the upgrade of the Large Binocular Telescope (LBT) with an adaptive optics (AO) system consisting of six Rayleigh laser guide stars and wavefront sensors. For developing the ICS, we used the technique Test- Driven Development (TDD) whose main rule demands that the programmer writes test code before production code. Thereby, TDD can yield a software system, that grows without defects and eases maintenance. Having applied TDD in a calm and relaxed environment like office and laboratory, the ARGOS team has profited from the benefits of TDD. Before the commissioning, we were worried that the time pressure in that tough project phase would force us to drop TDD because we would spend more time writing test code than it would be worth. Despite this concern at the beginning, we could keep TDD most of the time also in this project phase This report describes the practical application and performance of TDD including its benefits, limitations and problems during the ARGOS commissioning. Furthermore, it covers our experience with pair programming and continuous integration at the telescope.

Argos, the wide eld Laser Guide Stars adaptive optics system for the Large Binocular Telescope, is now entering its installation phase. In the meanwhile, we have started a test bench in order to integrate various Argos sub-systems and demonstrate its wavefront measurements. To this objective, we rst validate three key components of the Argos wavefront sensor which we then integrate together. The test bench therefore comprises the Argos wavefront camera system - including a large frame, fast framerate, high quantum eciency and low readout noise pnCCD -, the slope computer, and a optical gating unit.While we present here the demonstration of those three key components, it is also a step to their system level integration that enables us to validate the wavefront measurements in term of noises, timing and computation. In the near future, those system will be integrated to the wavefront sensor system of Argos.

In this paper we present the integration status of the ARGOS wavefront sensor and the results of the closed loop tests performed in laboratory. ARGOS is the laser guide star adaptive optics system of the Large Binocular Telescope. It is designed to implement a Ground Layer Adaptive Optics correction for LUCI, an infrared imaging camera and multi-object spectrograph, using 3 pulsed Rayleigh beacons focused at 12km altitude. The WFS is configured as a Shack-Hartman sensor having a 15 x 15 subaspertures over the telescope pupil. In the WFS each LGS is independently stabilized for on-sky jitter and range-gated to reduce spot elongation. The 3 LGS are arranged on a single lenslet array and detector by the use of off-axis optics in the final part of the WFS. The units of WFS are in the integration and testing phase at Arcetri Observatory premises. We describe here the test aimed to demonstrate the functionality of the WFS in an adaptive optics closed loop performed using the internal light sources of the WFS and a MEMS deformable mirror.

ARGOS the Advanced Rayleigh guided Ground layer adaptive Optics System for the LBT (Large Binocular Telescope) is built by a German-Italian-American consortium. It will be a seeing reducer correcting the turbulence in the lower atmosphere over a field of 2' radius. In such way we expect to improve the spatial resolution over the seeing of about a factor of two and more and to increase the throughput for spectroscopy accordingly. In its initial implementation, ARGOS will feed the two near-infrared spectrograph and imager - LUCI I and LUCI II. The system consist of six Rayleigh lasers - three per eye of the LBT. The lasers are launched from the back of the adaptive secondary mirror of the LBT. ARGOS has one wavefront sensor unit per primary mirror of the LBT, each of the units with three Shack-Hartmann sensors, which are imaged on one detector. In 2010 and 2011, we already mounted parts of the instrument at the telescope to provide an environment for the main sub-systems. The commissioning of the instrument will start in 2012 in a staged approach. We will give an overview of ARGOS and its goals and report about the status and new challenges we encountered during the building phase. Finally we will give an outlook of the upcoming work, how we will operate it and further possibilities the system enables by design.

ARGOS is the Laser Guide Star adaptive optics system for the Large Binocular Telescope. Aiming for a wide field adaptive optics correction, ARGOS will equip both sides of LBT with a multi laser beacon system and corresponding wavefront sensors, driving LBT's adaptive secondary mirrors. Utilizing high power pulsed green lasers the artificial beacons are generated via Rayleigh scattering in earth's atmosphere. ARGOS will project a set of three guide stars above each of LBT's mirrors in a wide constellation. The returning scattered light, sensitive particular to the turbulence close to ground, is detected in a gated wavefront sensor system. Measuring and correcting the ground layers of the optical distortions enables ARGOS to achieve a correction over a very wide field of view. Taking advantage of this wide field correction, the science that can be done with the multi object spectrographs LUCIFER will be boosted by higher spatial resolution and strongly enhanced flux for spectroscopy. Apart from the wide field correction ARGOS delivers in its ground layer mode, we foresee a diffraction limited operation with a hybrid Sodium laser Rayleigh beacon combination.

Wide field correction allowing large field to benefit from adaptive optics (AO) is challenging in more than one aspect. We address here the wavefront sensor (WFS) detector side where, in addition to high sensitivity and low noise, the simultaneous detection of multiple laser beacons and the large number of sub-apertures in a Shack-Hartmann WFS require a detector to have a large imaging area while preserving a very high readout frame rate. The detector considered has a frame area of 264×264 pixels with a pixel size of 48 microns. By splitting the image into two framestore areas during readout, repetition rates of more than 1000 frames per second can be achieved. The electronic noise contribution is approximately 3 electrons at the operating temperature. We therefore analyze its performances, showing it fulfills the requirements, in a wavefront sensing application: the measurement of centroids in the case of a Shack-Hartmann WFS for the Argos AO project.

Wide-field optical imaging surveys will contain tens of thousands of new strong gravitational lenses. Some of these will have new and unusual image configurations, and so will enable new applications: for example, systems with high image multiplicity will allow more detailed study of galaxy and group mass distributions, while high magnification is needed to super-resolve the faintest objects in the high redshift universe. Inspired by a set of six unusual lens systems [including five selected from the Sloan Lens ACS (SLACS) and Strong Lensing Legacy (SL2S) surveys, plus the cluster Abell 1703], we consider several types of multi-component, physically-motivated lens potentials, and use the ray-tracing code "glamroc" to predict exotic image configurations. We also investigate the effects of galaxy source profile and size, and use realistic sources to predict observable magnifications and estimate very approximate relative cross-sections. We find that lens galaxies with misaligned disks and bulges produce swallowtail and butterfly catastrophes, observable as "broken" Einstein rings. Binary or merging galaxies show elliptic umbilic catastrophes, leading to an unusual Y-shaped configuration of 4 merging images. While not the maximum magnification configuration possible, it offers the possibility of mapping the local small-scale mass distribution. We estimate the approximate abundance of each of these exotic galaxy-scale lenses to be ~1 per all-sky survey. In higher mass systems, a wide range of caustic structures are expected, as already seen in many cluster lens systems. We interpret the central ring and its counter-image in Abell 1703 as a "hyperbolic umbilic" configuration, with total magnification ~100 (depending on source size). The abundance of such configurations is also estimated to be ~1 per all-sky survey., 21 pages, 30 figures, accepted by MNRAS, copyright material cleared for re-printing. High-resolution version available from http://www.slac.stanford.edu/~pjm/atlas

This erratum corrects the omission of authors and references from the paper as it was originally published.