TESS Captures Full Optical Rise of AT 2019wey BH Binary
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- TESS recorded AT 2019wey’s outburst from two days before to 25 days after the event, providing uninterrupted 27‑day, 30‑minute cadence photometry in Sector 19.
- TESS measured the outburst onset on 26 Nov 2019 with a power‑law rise index of ~0.74, predating the first detections by ZTF and ATLAS.
- MAXI X‑ray data showed brightening began before ZTF detection, supporting an inside‑out outburst scenario where thermal instability starts in the inner accretion disk.
- ZTF had previously reported a 1.3‑hour periodic modulation in AT 2019wey, but TESS found no significant periodic signals above 0.48 mJy for periods from one hour to 14 days.
- Alyana Jusino and her team at City College of New York posted the findings on arXiv (Mar 25 2026), highlighting TESS’s capability to monitor transient astrophysical phenomena beyond exoplanets.
Why it matters: Astrophysicists gain the first continuous, high‑precision optical light curve of a black‑hole X‑ray binary outburst, captured before any ZTF detection, enabling direct testing of inside‑out instability models and refuting earlier claims of a 1.3‑hour modulation; the result also validates TESS’s extended‑mission value for transient astronomy beyond exoplanet hunting.
