Key Projects

Newly discovered gravitational waves can alert us to cataclysmic events in the Universe, such as the merging of two neutron stars, or a neutron star merging with a black hole. In such events, the heaviest elements in the Universe are created, producing a quick flash of light. When gravitational-wave detectors alert us to such an event, we will immediately point the Las Cumbres Observatory network of telescopes at the source in an attempt to catch its fleeting light signature, and use it to learn something new about the laws of nature.

The discovery of the first gravitational-wave signal from a neutron-star merger together with the first kilonova in 2017, initiated the era of gravitational-wave - electromagnetic-wave multi-messenger astronomy. Using LCO, we obtained some of the earliest and best-sampled optical to near-infrared observations of the rapidly-evolving kilonova (not possible with almost any other facility). This discovery provided a wealth of insights into many open issues in astrophysics, including the neutron-star equation of state, the source of heavy elements in the Universe, and the first "standard-siren" constraints on the Hubble constant. Yet many open questions remain, most of which can be tied to the nature of the early optical emission. Competing models can be distinguished only with very early observations for a sample of events. We propose a key project to obtain such observations for ~15 new kilonovae to be discovered during the next gravitational-wave observing run (O4), and perhaps also the first observations of an optical counterpart to a neutron-star - black-hole merger. Our proposal for automatic ultra-rapid triggering of a galaxy-targeted search in the localization region following gravitational-wave events, and high-cadence follow-up of counterpart candidates, is based on a strategy that was highly successful for the 2017 event. While the ongoing observing run (O3) is solidifying the rate of NS mergers, O4, with its increased sensitivity and four detectors, will present us with the first opportunity to go from a single source to a sample of joint gravitational - electromagnetic wave events. LCO's unique robotic, global, and rapid-response capabilities are ideal for significantly advancing this exciting new field.

The "Hidden Populations" Key Project is focused on the detection of isolated stellar-mass black holes and planetary and stellar binaries using the gravitational microlensing method. Several ongoing and future public surveys allow the detection of microlensing events in the entire sky, but additional observations are necessary to characterize the lens system in great detail. This key project conducts such follow-up automatically using the LCO network of telescopes to reveal the population of the faintest objects of the Milky Way.

The mass distribution of stellar remnants in the Milky Way holds the key to some of the most impactful open questions in astrophysics. Massive stars undergoing core collapse supernovae can result in the formation of black holes and neutron stars, either as isolated objects or in binaries with other stellar or compact objects, and the rate of such events is an essential parameter in models of stellar evolution. However, primordial black holes may also have formed in regions of high density at the early stages of expansion, and those with masses in the range 10-1000 M☉ may still remain. The two scenarios may be distinguished by measuring masses of the galactic population of stellar remnants, and the binarity fraction. But whereas stellar remnants in binary systems can be detected through several methods, such as accretion signatures and gravitational wave events, isolated stellar remnants can be all but invisible. Microlensing provides the means to study these elusive isolated objects. Wide-area surveys such as Gaia and ZTF, as well as Galactic Bulge surveys OGLE and MOA, are routinely discovering candidates, but over large regions of their survey footprints, they cannot monitor with high enough cadence to measure the properties of the lensing object. The same surveys also discover planetary and stellar binaries that expand our sample of known exoplanets beyond the Solar neighborhood, enabling us to explore planet formation in different stellar environments. This project uses the Las Cumbres Observatory (LCO) Network to deliver the high-cadence photometry and time series spectroscopy necessary to characterize these transient targets. LCO's geographically distributed telescope network, combined with its dynamical scheduler is ideal to enable observations to be made in response to survey discovery alerts at short notice, and to adapt quickly to targets that can evolve in brightness and priority as quickly as microlensing events. Our team has built a Target and Observation Manager system customized for microlensing science that has proven its ability to conduct this sophisticated and responsive observing strategy in a fully automated manner. This proposal will determine masses for ~35 stellar remnant events across the Milky Way as well as~46 binary events with planetary, brown dwarf and stellar companions. This is a unique opportunity to study events discovered by the Gaia Mission in its last 2 years of operation. Gaia's exquisitely precise time series astrometry will enable us to verify the stellar remnants discovered.

While it is believed that all galaxies harbor supermassive black holes in their centers, only a small fraction are currently actively accreting matter, causing them to glow brightly at optical, UV and X-ray wavelengths. We have developed a new observational technique that measures "light echoes" between these wavebands by combining high-rate monitoring by the LCO network in optical light and the orbiting Swift UV/X-ray satellite. These light echoes allow astronomers to systematically study the size and structure of these black hole accretion disks, which are so distant that they cannot otherwise be directly imaged with conventional optical telescopes.

We propose to build on the success of our LCO AGN Intensive Broadband Reverberation Mapping (IBRM) program and take it in exciting new directions. These are based on the important advances our previous LCO Key Projects have made in changing our picture of AGN central engines. This includes establishing for the first time that AGN inter-band continuum lags increase smoothly with wavelength throughout the optical/UV, consistent with the 𝛕 ∝ λ^4/3 prediction of standard thin accretion disk theory, and discovery of excess lags especially around the Balmer jump, apparently due to diffuse continuum emission from the broad-line region (BR). However, the disk sizes appear too large, and there is no simple relation between optical and X-ray variations, causing severe problems for the standard reprocessing model and forcing development of new models of AGN central engines. We propose to address these issues using LCO's unique capabilities for intensive multi-band and spectroscopic monitoring in conjunction with X-ray, UV, and IR monitoring by space-based observatories. Among our science goals are: i) investigate the (lack of) connection between X-rays and optical variability, by combining high-throughput X-ray observations with high-cadence C O monitoring; ii) determine if the disks appear larger than expected due to BLR contributions to AGN variability; iii) test scaling laws by extending our sample to higher and lower black hole masses; iv) measure dust reverberation lags to constrain the composition and temperature structure of AGN dust tori; v) identify state changes in AGN through low-cadence multi-year photometric monitoring of a large sample of bright AGN.

The Global Supernova Project is a worldwide collaboration of more than 200 scientists studying stellar explosions using more than 40 telescopes around the world and in space.  We are studying 500 supernovae over 3 years to add to the 800+ we have already studied.  The primary goal is to use LCO's "always on" network to study supernovae within hours of explosion, which can help reveal the nature of the elusive final stages of stellar evolution.  Another goal is to use supernovae as standard candles to reveal the expansion rate of the universe, and to support future efforts to measure Dark Energy.

The Global Supernova Project is a worldwide collaboration of more than 200 astronomers who have studied approximately 1000 supernovae and published 168 papers over the last 8+ years. During the 2023B-2026A semesters, the Project will observe 500 supernovae with LCO resources, and a subset with 36+ facilities and instruments, spanning X-ray to radio wavelengths. The Project will prioritize preparing for the LSST era, creating a baseline of comparison data to be used for Al training, and by continuously improving our filters for Alert Brokers that enable us to pick particularly interesting, early, or fast-evolving targets from the ZTF and other data streams. This will help us pick out and study emerging mysterious new supernova subtypes, including fast transients, SNe Icn, and electron capture supernovae, and expand on the Project's pioneering work revealing the progenitors of SNe la, SNe I, and stripped envelope supernovae from observations taken just after explosion. We will also work to improve the use of supernovae in cosmology, improving the comparison sample for missions such as the Nancy Grace Roman Space Telescope, understanding the systematic errors in supernovae, and improving the tools used to standardize them. With large samples of both common and exotic SNe, we will break new ground studying luminosity functions, splitting SNe into subsamples by metallicity and other properties, simulating them, and finding outliers that reveal new physics.

The field of extrasolar planets (exoplanets) - the discovery and study of planets orbiting other stars, other than the Sun - is one of the most exciting and fast developing fields in astronomy. This LCO Key Project is focused on observations of exoplanet candidates identified by the NASA TESS Mission, and will lead to a census of exoplanets orbiting bright and nearby stars throughout the entire sky. That new knowledge will revolutionize our understanding of exoplanet structure and composition, in turn shedding light on planetary system formation and evolution processes.

Accomplishing the exoplanet science enabled by Transiting Exoplanet Survey Satellite (TESS) requires follow-up observations of many transiting planet candidates throughout the entire sky, to identify which of the candidates are real planets and which false positives (FPs). An efficient follow-up program requires a global facility and a large amount of telescope time. This Las Cumbres Observatory (LCO) Key Project is designed to do just that. We will use all LCO telescopes, all equipped with imagers, and we will use also the high resolution NRES spectrographs, installed in 4 sites on 1m telescopes. We will use imagers to observe the TESS candidates during transit and check if the transit signal seen in TESS data originates from the target or from a nearby star blended with the target in the TESS wide pixels and wide point spread function. We will use the NRES spectrograph for measuring the stellar parameters of bright TESS candidate host stars down to 10th magnitude, identifying obvious FPs (SB1, SB2), and when possible measuring the orbits of massive planets. This Key Project will be part of most TESS planet discoveries.

This project aims to build a statistical sample of at least 50 planets using the gravitational microlensing method. High-magnification microlensing events are sensitive to planets orbiting far from their host stars but need high-cadence data to detect planetary signals. This project will conduct high-cadence follow-up observations for high-magnification microlensing events discovered by the KMTNet microlensing survey.

The gravitational microlensing technique is most sensitive to cold planets and is currently the only method that can probe low mass-ratio (q ≲ 10^-4) cold planets. However, the mass-ratio function and multiplicity distribution for microlensing planets are still uncertain due to small-number statistics. Follow-up observations of high-magnification (HM) microlensing events can efficiently form a statistical sample, and the LCO network is the only system that can form a large statistical sample from follow-up of HM events. Therefore, we propose a new three-year LCO key project for follow-up of HM microlensing events.The key project will detect about 50 planets, including about ten low mass-ratio planets and six multiple-planet systems. Combined with our discoveries in 2020B-2023A, our statistical sample will become at least three times larger than any existing sample for cold planets and thus reveal the mass-ratio function and multiplicity distribution for cold planets, including the first robust measurement for the occurrence rate of low mass-ratio cold planets. The key project will provide a sound basis for optimizing the Roman microlensing strategy before its launch. The KMTNet and μFUN will provide strong support for the key project, including about 200 hr/yr observing time from each network.

This project seeks to elucidate the late stages of evolution of massive stars by studying their pulsations. This method of understanding stellar structure, processing, and motion is called asteroseismology and is analogous to how geologists can infer the internal structure of the earth by studying the waves emanating from earthquakes.

We propose to implement a novel method for performing asteroseismology of massive stars by utilizing the Las Cumbres Observatory network's unique capabilities. In particular, we intend to obtain long-duration, multi-site, multi-band observations of 20 Beta Cep stars, tripling the sample of such stars for which full asteroseismic studies have been performed. Our observations will allow us to constrain the mixing, metallicity, and internal rotation for a large sample of massive stars. These parameters are key for solving long-standing questions in massive-star structure and evolution, supernova physics and compact remnant properties. We will select targets already observed by TESS, allowing us to tune our observations to the known oscillation modes of these stars. Our multi-band data will allow us to identify the different modes (not possible with the single-band TESS data alone) - a crucial component for accurate and valuable asteroseismic modeling. This key project will thus combine existing TESS data with the unique capabilities of the Las Cumbres network to make significant progress in our understanding of massive stars, their explosive deaths, and the remnants they leave behind.