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Machine Learning for the Zwicky Transient Facility
Duev, Dmitry A.; Riddle, Reed; Saunders, Nicholas +47 more
The Zwicky Transient Facility is a large optical survey in multiple filters producing hundreds of thousands of transient alerts per night. We describe here various machine learning (ML) implementations and plans to make the maximal use of the large data set by taking advantage of the temporal nature of the data, and further combining it with other…
The Nucleus of comet 67P/Churyumov-Gerasimenko - Part I: The global view - nucleus mass, mass-loss, porosity, and implications
Tellmann, Silvia; Pätzold, Martin; Häusler, Bernd +7 more
The radio science experiment RSI on-board Rosetta determined the mass of the nucleus of comet 67P/Churyumov-Gerasimenko at the start of the prime mission from 2014 August to November (GM = 666.2 ± 0.2 m3 s-2 or 9982 ± 3 × 1012 kg) and shortly before the end of the mission from 2016 July to September (GM …
Resolving the Metallicity Distribution of the Stellar Halo with the H3 Survey
Conroy, Charlie; Johnson, Benjamin D.; Caldwell, Nelson +4 more
The Galactic stellar halo is predicted to have formed at least partially from the tidal disruption of accreted dwarf galaxies. This assembly history should be detectable in the orbital and chemical properties of stars. The H3 Survey is obtaining spectra for 200,000 stars and, when combined with Gaia data, is providing detailed orbital and chemical…
The Brightest z ≳ 8 Galaxies over the COSMOS UltraVISTA Field
Franx, Marijn; Illingworth, Garth D.; Muzzin, Adam +12 more
We present 16 new ultrabright H AB ≲ 25 galaxy candidates at z ∼ 8 identified over the COSMOS/UltraVISTA field. The new search takes advantage of the deepest-available ground-based optical and near-infrared observations, including the DR3 release of UltraVISTA and full-depth Spitzer/IRAC observations from the SMUVS and SPLASH programs…
Low-mass halo perturbations in strong gravitational lenses at redshift z ∼ 0.5 are consistent with CDM
Vegetti, S.; McKean, J. P.; Auger, M. W. +3 more
We use a sample of 17 strong gravitational lens systems from the BELLS GALLERY survey to quantify the amount of low-mass dark matter haloes within the lensing galaxies and along their lines of sight, and to constrain the properties of dark matter. Based on a detection criterion of 10σ, we report no significant detection in any of the lenses. Using…
Architectures of exoplanetary systems - I. A clustered forward model for exoplanetary systems around Kepler's FGK stars
Ford, Eric B.; Ragozzine, Darin; He, Matthias Y.
Observations of exoplanetary systems provide clues about the intrinsic distribution of planetary systems, their architectures, and how they formed. We develop a forward modelling framework for generating populations of planetary systems and `observed' catalogues by simulating the Kepler detection pipeline (SysSim). We compare our simulated catalog…
A giant exoplanet orbiting a very-low-mass star challenges planet formation models
Schmitt, J. H. M. M.; Rebolo, R.; del Burgo, C. +179 more
Surveys have shown that super-Earth and Neptune-mass exoplanets are more frequent than gas giants around low-mass stars, as predicted by the core accretion theory of planet formation. We report the discovery of a giant planet around the very-low-mass star GJ 3512, as determined by optical and near-infrared radial-velocity observations. The planet …
Discovery of an equal-mass `twin' binary population reaching 1000 + au separations
Tian, Haijun; Duchêne, Gaspard; Rix, Hans-Walter +2 more
We use a homogeneous catalogue of 42 000 main-sequence wide binaries identified by Gaia to measure the mass ratio distribution, p(q), of binaries with primary masses 0.1 < M1/M⊙ < 2.5, mass ratios 0.1 ≲ q < 1, and separations 50 < s/au < 50 000. A well-understood selection function allows us to constrain p(q) i…
Spatially Resolved Stellar Kinematics of the Ultra-diffuse Galaxy Dragonfly 44. I. Observations, Kinematics, and Cold Dark Matter Halo Fits
van Dokkum, Pieter; Forbes, Duncan A.; Romanowsky, Aaron J. +8 more
We present spatially resolved stellar kinematics of the well-studied ultra-diffuse galaxy (UDG) Dragonfly 44, as determined from 25.3 hr of observations with the Keck Cosmic Web Imager. The luminosity-weighted dispersion within the half-light radius is {σ }1/2={33}-3+3 km s-1, lower than what we had infe…
The southern stellar stream spectroscopic survey (S5): Overview, target selection, data reduction, validation, and early science
Geha, M.; Bechtol, K.; Allam, S. +30 more
We introduce the southern stellar stream spectroscopy survey (S5), an on-going program to map the kinematics and chemistry of stellar streams in the southern hemisphere. The initial focus of S5 has been spectroscopic observations of recently identified streams within the footprint of the dark energy survey (DES), with the eve…