Persistent and occasional: searching for the variable population of the ZTF/4MOST sky using ZTF data release 11

Abstract

We present a variability, color and morphology based classifier, designed to identify transients, persistently variable, and non-variable sources, from the Zwicky Transient Facility (ZTF) Data Release 11 (DR11) light curves of extended and point sources. The main motivation to develop this model was to identify active galactic nuclei (AGN) at different redshift ranges to be observed by the 4MOST ChANGES project. Still, it serves as a more general time-domain astronomy study. The model uses nine colors computed from CatWISE and PS1, a morphology score from PS1, and 61 single-band variability features computed from the ZTF DR11 g and r light curves. We trained two versions of the model, one for each ZTF band. We used a hierarchical local classifier per parent node approach, where each node was composed of a balanced random forest model. We adopted a 17-class taxonomy, including non-variable stars and galaxies, three transient classes, five classes of stochastic variables, and seven classes of periodic variables. The macro averaged precision, recall and F1-score are 0.61, 0.75, and 0.62 for the g-band model, and 0.60, 0.74, and 0.61, for the r-band model. When grouping the four AGN classes into one single class, its precision, recall, and F1-score are 1.00, 0.95, and 0.97, respectively, for both the g and r bands. We applied the model to all the sources in the ZTF/4MOST overlapping sky, avoiding ZTF fields covering the Galactic bulge, including 86,576,577 light curves in the g-band and 140,409,824 in the r-band. Only 0.73\% of the g-band light curves and 2.62\% of the r-band light curves were classified as stochastic, periodic, or transient with high probability ($P_{init}\ge 0.9$). We found that, in general, more reliable results are obtained when using the g-band model. Using the latter, we identified 384,242 AGN candidates, 287,156 of which have $P_{init}\ge 0.9$.

arXiv commentAccepted for publication in Astronomy & Astrophysics. Abstract shortened for arXiv. Tables containing the classifications and features for the ZTF g and r bands, and the labeled sets will be available at CDS. Individual catalogs per class and band, as well as the labeled set catalogs, can be downloaded at Zenodo DOI:10.5281/zenodo.7826045

References in corpus (64)

• The Sloan Digital Sky Survey: Technical Summary
• The Gaia mission
• Gaia Data Release 3: Summary of the content and survey properties
• LSST: from Science Drivers to Reference Design and Anticipated Data Products
• The SIMBAD astronomical database
• The Zwicky Transient Facility: System Overview, Performance, and First Results
• The Zwicky Transient Facility: Data Processing, Products, and Archive
• Gaia Early Data Release 3: Photometric content and validation
• Catalogue of cataclysmic binaries, low-mass X-ray binaries and related objects (Seventh edition)
• The Catalina Surveys Periodic Variable Star Catalog
• The ASAS-SN Catalog of Variable Stars I: The Serendipitous Survey
• Seventeen Tidal Disruption Events from the First Half of ZTF Survey Observations: Entering a New Era of Population Studies
• The 5th edition of the Roma-BZCAT. A short presentation
• SDSS Standard Star Catalog for Stripe 82: the Dawn of Industrial 1% Optical Photometry
• The CatWISE2020 Catalog
• The Zwicky Transient Facility Catalog of Periodic Variable Stars
• Stellar velocity dispersions and emission line properties of SDSS-III/BOSS galaxies
• The Final Season Reimagined: 30 Tidal Disruption Events from the ZTF-I Survey
• The Automatic Learning for the Rapid Classification of Events (ALeRCE) Alert Broker
• The ASAS-SN Catalog of Variable Stars III: Variables in the Southern TESS Continuous Viewing Zone
• Rotation of Low-Mass Stars in Upper Scorpius and Rho Ophiuchus with K2
• Alert Classification for the ALeRCE Broker System: The Light Curve Classifier
• The CatWISE Preliminary Catalog: Motions from $WISE$ and $NEOWISE$ Data
• Exploring the Variable Sky with LINEAR. III. Classification of Periodic Light Curves
• A New Catalogue of Type 1 AGN and its Implication on the AGN Unified Model
• Fink, a new generation of broker for the LSST community
• SPICY: The Spitzer/IRAC Candidate YSO Catalog for the Inner Galactic Midplane
• A Morphological Classification Model to Identify Unresolved PanSTARRS1 Sources: Application in the ZTF Real-Time Pipeline
• Transient processing and analysis using $\text{AMPEL}$: Alert Management, Photometry and Evaluation of Lightcurves
• Rotation of Late-Type Stars in Praesepe with K2
• Machine Learning-based Brokers for Real-time Classification of the LSST Alert Stream
• Rotation of Low-Mass Stars in Taurus with K2
• Gaia Data Release 2: The first Gaia catalogue of long-period variable candidates
• The ASAS-SN Catalog of Variable Stars V: Variables in the Southern Hemisphere
• Catalogue of new Herbig Ae/Be and classical Be stars. A machine learning approach to Gaia DR2
• Supernova Photometric Classification Pipelines Trained on Spectroscopically Classified Supernovae from the Pan-STARRS1 Medium-Deep Survey
• Anomaly detection in the Zwicky Transient Facility DR3
• The Hydrogen-Poor Superluminous Supernovae from the Zwicky Transient Facility Phase-I Survey: I. Light Curves and Measurements
• Deep-Learnt Classification of Light Curves
• Search for associations containing young stars (SACY) VII. New stellar and substellar candidate members in the young associations
• Scalable End-to-end Recurrent Neural Network for Variable star classification
• Large-amplitude variables in Gaia Data Release 2. Multi-band variability characterization
• Searching for changing-state AGNs in massive datasets -- I: applying deep learning and anomaly detection techniques to find AGNs with anomalous variability behaviours
• YSOVAR: Mid-IR variability in the star forming region Lynds 1688
• Search for associations containing young stars (SACY) VIII. An updated census of spectroscopic binary systems showing hints of non-universal multiplicity among these associations
• Gaia Data Release 2: All-sky classification of high-amplitude pulsating stars
• Identification of Young Stellar Variables with KELT for K2 I: Campaign 13 Taurus Dippers and Rotators
• Confirming new changing--look AGNs discovered through optical variability using a random-forest based light curve classifier
• ASTROMER: A transformer-based embedding for the representation of light curves
• Robust period estimation using mutual information for multi-band light curves in the synoptic survey era
• The ZTF Source Classification Project: I. Methods and Infrastructure
• Fink: early supernovae Ia classification using active learning
• YSOVAR: mid-infrared variability of young stellar objects and their disks in the cluster IRAS 20050+2720
• Photometric Cross-Calibration of the SDSS Stripe 82 Standard Stars catalogue with Gaia EDR3, and Comparison with Pan-STARRS1, DES, CFIS and GALEX catalogues
• Characterising the i-band variability of YSOs over six orders of magnitude in timescale
• Deep Attention-Based Supernovae Classification of Multi-Band Light-Curves
• YSOVAR: Mid-infrared Variability Among YSOs in the Star Formation Region GGD 12-15
• The Type 1 and Type 2 AGN dichotomy according to their ZTF optical variability
• Identification of Young Stellar Variables with KELT for K2 II: The Upper Scorpius Association
• Variability of young stellar objects in the star-forming region Pelican Nebula
• Towards an understanding of YSO variability: A multi-wavelength analysis of bursting, dipping, and symmetrically varying light curves of disc-bearing YSOs
• SNAD Transient Miner: Finding Missed Transient Events in ZTF DR4 using k-D trees
• SNGuess: A method for the selection of young extragalactic transients
• Near-infrared time-series photometry in the field of Cygnus OB2 association II. Mapping the variability of candidate members

Cited by in corpus (10)

• ATAT: Astronomical Transformer for time series And Tabular data
• Identifying Light-curve Signals with a Deep Learning Based Object Detection Algorithm. II. A General Light Curve Classification Framework
• Selection of optically variable active galactic nuclei via a random forest algorithm
• The Success of Optical Variability in Uncovering AGNs in Low-stellar Mass Galaxies
• FALCO: a Foundation model of Astronomical Light Curves for time dOmain astronomy
• Detailed Investigation of a W UMa Contact Binary with an Ultralow Mass Ratio and a Third-Body as a Potential Merger Candidate
• Scalable and Robust Multiband Modeling of AGN Light Curves in Rubin-LSST
• High-cadence stellar variability studies of RR Lyrae stars with DECam: New multi-band templates
• Unlocking AGN Variability with Custom ZTF Photometry for High-Fidelity Light Curves and Robust Selection
• Identification of quasars variable over long time scales from infrared surveys. Ensemble variability and structure function properties