Six New Circumbinary Disk Occultation (CBO) Candidates from the Zwicky Transient Facility

TL;DR

This paper reports the discovery of six new circumbinary disk occultation candidates from ZTF data, nearly doubling the known sample, and provides insights into their properties and potential disk structures.

Contribution

The study introduces six new CBO candidates identified through a systematic ZTF photometry search, expanding the sample for population studies.

Findings

Six new CBO candidates identified with periods 30-530 days.

Deep dimming events with large duty cycles observed.

Infrared excess suggests dust component presence.

Abstract

Circumbinary disk occultation (CBO) systems, in which a misaligned circumbinary disk periodically obscures the central binary, provide unique probes of disk structure and dynamics. However, fewer than ten candidates with measured orbital periods were previously known. In this work, we identify six new CBO candidates, designated ZTF-CBO-1 through ZTF-CBO-6, through a systematic search of Zwicky Transient Facility (ZTF) photometry. These systems exhibit deep ($\gtrsim$1 mag) periodic dimming events with orbital periods ranging from $\sim$30 to $\sim$530 days and occultation durations spanning 32%-77% of their orbital periods. Such large duty cycles rule out the interpretation of circum-companion material occultation. Spectral energy distributions of ZTF-CBO-1 and ZTF-CBO-2 reveal infrared excess indicative of a dust component. TESS observations of ZTF-CBO-1 show no hours- to days-timescale variability during ingress and egress, indicating a smooth disk edge. These discoveries nearly double the known CBO sample, enabling meaningful population-level studies.