Active galactic nuclei (AGNs) are a key component of galaxy evolution owing to feedback on the host from its supermassive black hole. The morphology of warm inflowing and outflowing dusty material can reveal the nature of the onset of feedback, AGN feeding and the unified model of AGN. Here we use the Large Binocular Telescope Interferometer (LBTI) to image the dense, obscuring disk and extended dusty outflow region of NGC 1068. In Fizeau imaging mode, the LBTI synthesizes the equivalent resolution of a 22.8 m telescope. The 8.7 μm Fizeau images of NGC 1068 have an effective resolution of 47 × 90 mas (3.3 × 6.2 pc) in a 5″ field of view after performing point spread function deconvolution techniques described here. This is the only extragalactic source to be Fizeau imaged using the LBTI, and the images bridge the scales measured with the Very Large Telescope Interferometer (0.5–5 pc) and those of single telescopes such as James Webb Space Telescope and Keck (>15 pc). The images detect and spatially resolve the low surface brightness mid-infrared features in the AGN disk/wind region that are overresolved by the Very Large Telescope Interferometer. The images show strong correlation between mid-infrared dust emission and near-infrared emission of highly excited atomic lines observed by SINFONI. Such LBTI imaging is a precursor to infrared imaging using the upcoming generation of extremely large telescopes, with angular resolutions up to six times better than James Webb Space Telescope, the largest space telescope in orbit. Detailed infrared images of the region around the supermassive black hole of NGC 1068 from the Large Binocular Telescope Interferometer reveal a dense disk, dusty outflow and emissions linked to radio jets, suggesting that active galactic nucleus torus models should include jet interactions.

Active galactic nuclei (AGNs) are a key component of galaxy evolution due to feedback on the host from its supermassive black hole. The morphology of warm, in- and outflowing dusty material can reveal the nature of the onset of feedback, AGN feeding, and the unified model of AGN. Here we use the Large Binocular Telescope Interferometer (LBTI) to image the dense, obscuring disk and extended dusty outflow region of NGC 1068. In Fizeau imaging mode the LBTI synthesizes the equivalent resolution of a 22.8 m telescope. The 8.7 μm Fizeau images of NGC 1068 have an effective resolution of 47×90 mas (3.3×6.2 pc) in a 5" field of view after performing PSF deconvolution techniques described here. This is the only extragalactic source to be Fizeau imaged using the LBTI, and the images bridge the scales measured with the Very Large Telescope Interferometer (VLTI; 0.5-5 pc) and those of single telescopes such as JWST and Keck (>15 pc). The images detect and spatially resolve the low surface brightness mid-infrared (MIR) features in the AGN disk/wind region that are over-resolved by the VLTI. The images show strong correlation between MIR dust emission and near-infrared (NIR) emission of highly excited atomic lines observed by SINFONI. Such LBTI imaging is a precursor to infrared imaging using the upcoming generation of extremely large telescopes, with angular resolutions up to 6x better than JWST, the largest space telescope in orbit.

The Large Binocular Telescope Interferometer (LBTI) is a strategic instrument which combines the two 8.4m apertures of the LBT for sensitive, high-angular-resolution imaging and interferometric observations in the thermal infrared. Through its observing modes utilizing adaptive optics, Fizeau imaging, and nulling interferometry, the LBTI is in many respects the first ELT; it serves as a pioneer for upcoming ELTs in terms of both science and instrumentation. LBTI has completed a large survey for habitable-zone dust around main sequence stars, exploiting its angular resolution to obtain 100x better sensitivity than space-based photometric observations. Recently we have emphasized Fizeau imaging, supporting high-contrast and precision-astrometric observations. We obtained the first extragalactic and N band observations in this mode, demonstrating high-fidelity, high-sensitivity imaging on a 23 m baseline. We are now pushing to image the first rocky planet in the habitable zone around a nearby Sun-like star. In this paper we present an overview of the LBTI's design and capabilities as a 23 m telescope. In particular, we focus on open loop Fizeau imaging, presenting the state of the art. We measure the stability of the Fizeau PSF, test frame selection criteria, and demonstrate PSF deconvolution. Finally, we outline future developments and synergies with current and upcoming facilities.

New mid-infrared HgCdTe (MCT) detector arrays developed in collaboration with Teledyne Imaging Sensors (TIS) have paved the way for improved 10-$μ$m sensors for space- and ground-based observatories. Building on the successful development of longwave HAWAII-2RGs for space missions such as NEO Surveyor, we characterize the first 13-$μ$m GeoSnap detector manufactured to overcome the challenges of high background rates inherent in ground-based mid-IR astronomy. This test device merges the longwave HgCdTe photosensitive material with Teledyne's 2048x2048 GeoSnap-18 (18-$μ$m pixel) focal plane module, which is equipped with a capacitive transimpedance amplifier (CTIA) readout circuit paired with an onboard 14-bit analog-to-digital converter (ADC). The final assembly yields a mid-IR detector with high QE, fast readout (>85 Hz), large well depth (>1.2 million electrons), and linear readout. Longwave GeoSnap arrays would ideally be deployed on existing ground-based telescopes as well as the next generation of extremely large telescopes. While employing advanced adaptive optics (AO) along with state-of-the-art diffraction suppression techniques, instruments utilizing these detectors could attain background- and diffraction-limited imaging at inner working angles <10 $λ/D$, providing improved contrast-limited performance compared to JWST MIRI while operating at comparable wavelengths. We describe the performance characteristics of the 13-$μ$m GeoSnap array operating between 38 and 45K, including quantum efficiency, well depth, linearity, gain, dark current, and frequency-dependent (1/f) noise profile.

We present the fifth incarnation of the Mid-Infrared Array Camera (MIRAC-5) instrument which will use a new GeoSnap (3 – 13 microns) detector. Advances in adaptive optics (AO) systems and detectors are enabling ground based mid-infrared systems capable of high spatial resolution and deep contrast. As one of the only 3 – 13 micron cameras used in tandem with AO, MIRAC-5 will be complementary to the James Webb Space Telescope (JWST) and capable of characterizing gas giant exoplanets and imaging forming protoplanets (helping to characterize their circumplanetary disks). We describe key features of the MIRAC-5 GeoSnap detector, a long-wave Mercury-Cadmium-Telluride (MCT) array produced by Teledyne Imaging Sensors (TIS), including its high quantum efficiency (> 65%), large well-depth, and low noise. We summarize MIRAC-5’s important capabilities, including prospects for obtaining the first continuum mid-infrared measurements for several gas giants and the first 10.2-10.8 micron NH3 detection in the atmosphere of the warm companion GJ 504b (Teff ~ 550 K) within 8 hours of observing time. Finally, we describe plans for future upgrades to MIRAC-5 such as adding a coronagraph. MIRAC5 will be commissioned on the MMT utilizing the new MAPS AO system in late 2022 with plans to move to Magellan with the MagAO system in the future.

One of the main design considerations of the Large Binocular Telescope (LBT) was the goal to resolve the habitable zones (HZs) of the nearest stars at mid-infrared wavelengths around 10 μm. The LBT Interferometer (LBTI) makes use of the telescope’s two 8.4m mirrors on a common mount and their 22.7m edge-to-edge separation for sensitive, high-angular resolution observations at thermal-infrared wavelengths. In addition to adaptive optics imaging using the two mirrors separately, the instrument enables nulling and Fizeau imaging interferometry exploiting the full resolving power of the LBT. The LBTI team has successfully completed the Hunt for Observable Signatures of Terrestrial planetary Systems (HOSTS), for which we used nulling-interferometry to search for exozodiacal dust, and we are continuing the characterization of the detected systems. Here, we describe a new program to exploit the LBTI’s Fizeau imaging interferometric capabilities for a deep imaging search for low-mass, HZ planets around a small sample of particularly suitable, nearby stars. We also review the LBTI’s current status relevant to the proposed project to demonstrate the instrument is ready for such a large project.

The young (50–400 Myr) A3V star β Leo is a primary target to study the formation history and evolution of extrasolar planetary systems as one of the few stars with known hot (∼1600 K), warm (∼600 K), and cold (∼120 K) dust belt components. In this paper, we present deep mid-infrared measurements of the warm dust brightness obtained with the Large Binocular Telescope Interferometer (LBTI) as part of its exozodiacal dust survey (HOSTS). The measured excess is 0.47% ± 0.050% within the central 1.5 au, rising to 0.81% ± 0.026% within 4.5 au, outside the habitable zone of β Leo. This dust level is 50 ± 10 times greater than in the solar system’s zodiacal cloud. Poynting–Robertson drag on the cold dust detected by Spitzer, and Herschel underpredicts the dust present in the habitable zone of β Leo, suggesting an additional delivery mechanism (e.g., comets) or an additional belt at ∼5.5 au. A model of these dust components is provided that implies the absence of planets more than a few Saturn masses between ∼5 au and the outer belt at ∼40 au. We also observationally constrain giant planets with the LBTI imaging channel at 3.8 μm wavelength. Assuming an age of 50 Myr, any planet in the system between approximately 5–50 au must be less than a few Jupiter masses, consistent with our dust model. Taken together, these observations showcase the deep contrasts and detection capabilities attainable by the LBTI for both warm exozodiacal dust and giant exoplanets in or near the habitable zone of nearby stars.

We introduce the Michigan Infrared Test Thermal ELT N-band (MITTEN) Cryostat, a new facility for testing infrared detectors with a focus on mid-infrared (MIR) wavelengths (8-13 microns). New generations of large format, deep well, fast readout MIR detectors are now becoming available to the astronomical community. As one example, Teledyne Imaging Sensors (TIS) has introduced a long-wave Mercury-Cadmium-Telluride (MCT) array, GeoSnap, with high quantum efficiency (> 65 %) and improved noise properties compared to previous generation Si:As blocked impurity band (BIB) detectors. GeoSnap promises improved sensitivities, and efficiencies, for future background-limited MIR instruments, in particular with future extremely large telescopes (ELTs). We describe our new test facility suitable for measuring characteristics of these detectors, such as read noise, dark current, linearity, gain, pixel operability, quantum efficiency, and point source imaging performance relative to a background scene, as well as multiple point sources of differing contrast. MITTEN has an internal light source, and soon an accompanying filter wheel and aperture plate, reimaged onto the detector using an Offner relay. The baseline temperature of the cryostat interior is maintained < 40 K and the optical bench maintains a temperature of 16 K using a two-stage pulse-tube cryocooler package from Cryomech. No measurable background radiation from the cryostat interior has yet been detected.

The Large Binocular Telescope Interferometer (LBTI) enables nulling interferometric observations across the N band (8 to 13 μm) to suppress a star’s bright light and probe for faint circumstellar emission. We present and statistically analyze the results from the LBTI/Hunt for Observable Signatures of Terrestrial Systems survey for exozodiacal dust. By comparing our measurements to model predictions based on the solar zodiacal dust in the N band, we estimate a 1σ median sensitivity of 23 zodis times the solar system dust surface density in its habitable zone (HZ; 23 zodis) for early-type stars and 48 zodis for Sun-like stars, where 1 zodi is the surface density of HZ dust in the solar system. Of the 38 stars observed, 10 show significant excess. A clear correlation of our detections with the presence of cold dust in the systems was found, but none with the stellar spectral type or age. The majority of Sun-like stars have relatively low HZ dust levels (best-fit median: 3 zodis, 1σ upper limit: 9 zodis, 95% confidence: 27 zodis based on our N band measurements), while ∼20% are significantly more dusty. The solar system’s HZ dust content is consistent with being typical. Our median HZ dust level would not be a major limitation to the direct imaging search for Earth-like exoplanets, but more precise constraints are still required, in particular to evaluate the impact of exozodiacal dust for the spectroscopic characterization of imaged exo-Earth candidates.

The Large Binocular Telescope Interferometer (LBTI) combines the light from the two 8.4 m primary mirrors of the LBT for interferometry and adaptive optics (AO) imaging. With two high performance, state-of-the-art AO systems and adaptive secondary mirrors, a cryogenic instrument, and an edge-to-edge baseline of 23 m, the LBTI is a unique instrument for sensitive, high-angular resolution and high-contrast thermal infrared observations. After the successful completion of the NASA-funded HOSTS nulling interferometry survey for exozodiacal dust, our team is now completing the commissioning and extending the capabilities of other observing modes, namely Fizeau imaging interferometry, spectro-interferometry, integral field spectroscopy, non-redundant aperture masking, and coronagraphy for general astronomical observations. In this paper we briefly review the design of the LBTI, summarize the results and performance of HOSTS, and describe the LBTI’s wider current and future capabilities.

We present high spatial resolution LBTI/NOMIC 9-12 mu m images of VY CMa and its massive outflow feature, the Southwest (SW) Clump. Combined with high-resolution imaging from the Hubble Space Telescope (0.4-1 mu m) and LBT/LMIRCam (1-5 mu m), we isolate the spectral energy distribution (SED) of the clump from the star itself. Using radiative-transfer code DUSTY, we model both the scattered light from VY CMa and the thermal emission from the dust in the clump to estimate the optical depth, mass, and temperature of the SW Clump. The SW Clump is optically thick at 8.9 mu m with a brightness temperature of similar to 200 K. With a dust chemistry of equal parts silicates and metallic iron, as well as assumptions on grain size distribution, we estimate a dust mass of 5.4 x 10(-5) M-circle dot. For a gas-to-dust ratio of 100, this implies a total mass of 5.4 x 10(-3) M-circle dot. Compared to the typical mass-loss rate of VY CMa, the SW Clump represents an extreme, localized mass-loss event from less than or similar to 300 yr ago.

[abridged] The presence of large amounts of dust in the habitable zones of nearby stars is a significant obstacle for future exo-Earth imaging missions. We executed an N band nulling interferometric survey to determine the typical amount of such exozodiacal dust around a sample of nearby main sequence stars. The majority of our data have been analyzed and we present here an update of our ongoing work. We find seven new N band excesses in addition to the high confidence confirmation of three that were previously known. We find the first detections around Sun-like stars and around stars without previously known circumstellar dust. Our overall detection rate is 23%. The inferred occurrence rate is comparable for early type and Sun-like stars, but decreases from 71% [+11%/-20%] for stars with previously detected mid- to far-infrared excess to 11% [+9%/-4%] for stars without such excess, confirming earlier results at high confidence. For completed observations on individual stars, our sensitivity is five to ten times better than previous results. Assuming a lognormal luminosity function of the dust, we find upper limits on the median dust level around all stars without previously known mid to far infrared excess of 11.5 zodis at 95% confidence level. The corresponding upper limit for Sun-like stars is 16 zodis. An LBTI vetted target list of Sun-like stars for exo-Earth imaging would have a corresponding limit of 7.5 zodis. We provide important new insights into the occurrence rate and typical levels of habitable zone dust around main sequence stars. Exploiting the full range of capabilities of the LBTI provides a critical opportunity for the detailed characterization of a sample of exozodiacal dust disks to understand the origin, distribution, and properties of the dust.

The Hunt for Observable Signatures of Terrestrial Systems survey searches for dust near the habitable zones (HZs) around nearby, bright main-sequence stars. We use nulling interferometry in the N band to suppress the bright stellar light and to probe for low levels of HZ dust around the 30 stars observed so far. Our overall detection rate is 18%, including four new detections, among which are the first three around Sun-like stars and the first two around stars without any previously known circumstellar dust. The inferred occurrence rates are comparable for early-type and Sun-like stars, but decrease from % for stars with previously detected cold dust to % for stars without such excess, confirming earlier results at higher sensitivity. For completed observations on individual stars, our sensitivity is five to ten times better than previous results. Assuming a lognormal excess luminosity function, we put upper limits on the median HZ dust level of 13 zodis (95% confidence) for a sample of stars without cold dust and of 26 zodis when focusing on Sun-like stars without cold dust. However, our data suggest that a more complex luminosity function may be more appropriate. For stars without detectable Large Binocular Telescope Interferometer (LBTI) excess, our upper limits are almost reduced by a factor of two, demonstrating the strength of LBTI target vetting for future exo-Earth imaging missions. Our statistics are limited so far, and extending the survey is critical to informing the design of future exo-Earth imaging surveys.

ABSTRACT We present mid- and far-IR imaging of four famous hypergiant stars: the red supergiants μ Cep and VY CMa, and the warm hypergiants IRC +10420 and ρ Cas. Our 11–37 μm SOFIA/FORCAST imaging probes cool dust not detected in visual and near-IR imaging studies. Adaptive optics 8–12 μm imaging of μ Cep and IRC +10420 with MMT/MIRAC reveals extended envelopes that are the likely sources of these stars’ strong silicate emission features. We find μ Cep’s mass-loss rate to have declined by about a factor of five over a 13,000 year history, ranging from 5 × 10−6 down to ∼1× 10−6 M ⊙ yr−1. The morphology of VY CMa indicates a cooler dust component coincident with the highly asymmetric reflection nebulae seen in the visual and near-IR. The lack of cold dust at greater distances around VY CMa indicates that its mass-loss history is limited to the last ∼1200 years, with an average rate of 6 × 10−4 M ⊙ yr−1. We find two distinct periods in the mass-loss history of IRC +10420 with a high rate of 2 × 10−3 M ⊙ yr−1 until approximately 2000 years ago, followed by an order of magnitude decrease in the recent past. We interpret this change as evidence of its evolution beyond the RSG stage. Our new infrared photometry of ρ Cas is consistent with emission from the expanding dust shell ejected in its 1946 eruption, with no evidence of newer dust formation from its more recent events.

The Large Binocular Telescope Interferometer uses a near-infrared camera to measure the optical path length variations between the two AO-corrected apertures and provide high-angular resolution observations for all its science channels (1.5-13 microns). There is however a wavelength dependent component to the atmospheric turbulence, which can introduce optical path length errors when observing at a wavelength different from that of the fringe sensing camera. Water vapor in particular is highly dispersive and its effect must be taken into account for high-precision infrared interferometric observations as described previously for VLTI/MIDI or the Keck Interferometer Nuller. In this paper, we describe the new sensing approach that has been developed at the LBT to measure and monitor the optical path length fluctuations due to dry air and water vapor separately. After reviewing the current performance of the system for dry air seeing compensation, we present simultaneous H-, K-, and N-band observations that illustrate the feasibility of our feedforward approach to stabilize the path length fluctuations seen by the LBTI nuller.

The Large Binocular Telescope Interferometer (LBTI) is a high spatial resolution instrument developed for coherent imaging and nulling interferometry using the 14.4 m baseline of the 2×8.4 m LBT. The unique telescope design, comprising of the dual apertures on a common elevation-azimuth mount, enables a broad use of observing modes. The full system is comprised of dual adaptive optics systems, a near-infrared phasing camera, a 1-5 μm camera (called LMIRCam), and an 8-13 μm camera (called NOMIC). The key program for LBTI is the Hunt for Observable Signatures of Terrestrial planetary Systems (HOSTS), a survey using nulling interferometry to constrain the typical brightness from exozodiacal dust around nearby stars. Additional observations focus on the detection and characterization of giant planets in the thermal infrared, high spatial resolution imaging of complex scenes such as Jupiter's moon, Io, planets forming in transition disks, and the structure of active Galactic Nuclei (AGN). Several instrumental upgrades are currently underway to improve and expand the capabilities of LBTI. These include: Improving the performance and limiting magnitude of the parallel adaptive optics systems; quadrupling the field of view of LMIRcam (increasing to 20"x20"); adding an integral field spectrometry mode; and implementing a new algorithm for path length correction that accounts for dispersion due to atmospheric water vapor. We present the current architecture and performance of LBTI, as well as an overview of the upgrades.

The Large Binocular Telescope Interferometer (LBTI) is a versatile instrument designed for high angular resolution and high-contrast infrared imaging (1.5-13 mu m). In this paper, we focus on the mid-infrared (8-13 mu m) nulling mode and present its theory of operation, data reduction, and on-sky performance as of the end of the commissioning phase in 2015 March. With an interferometric baseline of 14.4 m, the LBTI nuller is specifically tuned to resolve the habitable zone of nearby main-sequence stars, where warm exozodiacal dust emission peaks. Measuring the exozodi luminosity function of nearby main-sequence stars is a key milestone to prepare for future exo-Earth direct imaging instruments. Thanks to recent progress in wavefront control and phase stabilization, as well as in data reduction techniques, the LBTI demonstrated in 2015 February a calibrated null accuracy of 0.05% over a 3 hr long observing sequence on the bright nearby A3V star beta Leo. This is equivalent to an exozodiacal disk density of 15-30. zodi for a Sun-like star located at 10 pc, depending on the adopted disk model. This result sets a new record for high-contrast mid-infrared interferometric imaging and opens a new window on the study of planetary systems.

We report on the first nulling interferometric observations with the Large Binocular Telescope Interferometer (LBTI), resolving the N′ band (9.81–12.41 μm) emission around the nearby main-sequence star η Crv (F2V, 1–2 Gyr). The measured source null depth amounts to 4.40% ± 0.35% over a field-of-view of 140 mas in radius (∼2.6 AU for the distance of η Crv) and shows no significant variation over 35° of sky rotation. This relatively low null is unexpected given the total disk to star flux ratio measured by the Spitzer Infrared Spectrograph (IRS; ∼23% across the N′ band), suggesting that a significant fraction of the dust lies within the central nulled response of the LBTI (79 mas or 1.4 AU). Modeling of the warm disk shows that it cannot resemble a scaled version of the solar zodiacal cloud unless it is almost perpendicular to the outer disk imaged by Herschel. It is more likely that the inner and outer disks are coplanar and the warm dust is located at a distance of 0.5–1.0 AU, significantly closer than previously predicted by models of the IRS spectrum (∼3 AU). The predicted disk sizes can be reconciled if the warm disk is not centrosymmetric, or if the dust particles are dominated by very small grains. Both possibilities hint that a recent collision has produced much of the dust. Finally, we discuss the implications for the presence of dust for the distance where the insolation is the same as Earth's (2.3 AU).

The Large Binocular Telescope Interferometer (LBTI) is a strategic instrument of the LBT designed for high-sensitivity, high-contrast, and high-resolution infrared (1.5-13 μm) imaging of nearby planetary systems. To carry out a wide range of high-spatial resolution observations, it can combine the two AO-corrected 8.4-m apertures of the LBT in various ways including direct (non-interferometric) imaging, coronagraphy (APP and AGPM), Fizeau imaging, non-redundant aperture masking, and nulling interferometry. It also has broadband, narrowband, and spectrally dispersed capabilities. In this paper, we review the performance of these modes in terms of exoplanet science capabilities and describe recent instrumental milestones such as first-light Fizeau images (with the angular resolution of an equivalent 22.8-m telescope) and deep interferometric nulling observations.

The Large Binocular Telescope Interferometer is a NASA-funded nulling and imaging instrument designed to coherently combine the two 8.4-m primary mirrors of the LBT for high-sensitivity, high-contrast, and highresolution infrared imaging (1.5-13 μm). PHASECam is LBTI's near-infrared camera used to measure tip-tilt and phase variations between the two AO-corrected apertures and provide high-angular resolution observations. We report on the status of the system and describe its on-sky performance measured during the first semester of 2014. With a spatial resolution equivalent to that of a 22.8-meter telescope and the light-gathering power of single 11.8-meter mirror, the co-phased LBT can be considered to be a forerunner of the next-generation extremely large telescopes (ELT).