Repeating flares, X-ray outbursts and delayed infrared emission: A comprehensive compilation of optical tidal disruption events

TDEs have been proposed as valuable laboratories for studying dormant black holes. However, progress in this field has been hampered by the limited number of observed events. In this work, we present TDECat, a comprehensive catalogue of 134 confirmed TDEs (131 optical TDEs and three jetted TDEs) discovered up to the end of 2024, accompanied by multi-wavelength photometry (X-ray, UV, optical, and IR) and publicly available spectra. We also study the statistical properties, spectral classifications, and multi-band variability of these events. Using a Bayesian Blocks algorithm, we determined the duration, rise time, decay time, and their ratio for 103 flares in our sample. We find that these timescales follow a log-normal distribution. Furthermore, our spectral analysis shows that most optical TDEs belong to the TDE-H+He class, followed by the TDE-H, TDE-He, and TDE-featureless classes, which is consistent with expectations from main-sequence star disruption. Using archival observations, we identified three new potentially repeating TDEs, namely, AT2024pvu, AT2022exr, and AT2021uvz, increasing the number of known repeating events. In both new and previously known cases, the secondary flares exhibit a similar shape to the primary. We also examined the infrared and X-ray emission from the TDEs in our catalogue, and find that 14 out of the 18 infrared events have associated X-ray emission, strongly suggesting a potential correlation. Finally, we find that for three sub-samples (repeating flares, infrared-emitting events, and X-ray events), the spectral classes are unlikely to be randomly distributed, suggesting a connection between spectral characteristics and multi-wavelength emission. TDEcat enables large-scale population studies across wavelengths and spectral classes, providing essential tools for navigating the data-rich era of upcoming surveys such as the Legacy Survey of Space and Time.

💡 Research Summary

The paper presents TDECat, the most comprehensive catalog of confirmed optical tidal disruption events (TDEs) compiled to date, encompassing 134 objects (131 optical TDEs and three on‑axis jetted TDEs) discovered up to the end of 2024. The authors begin by assembling the sample through a systematic cross‑match of the Transient Name Server (TNS) entries, recent literature, and dedicated surveys such as ZTF, ASAS‑SN, Pan‑STARRS, iPTF, and ATLAS. After removing duplicates and applying strict criteria (presence of at least one optical detection and a classification spectrum obtained near the flare peak), they arrive at a final list of 134 confirmed events, while a separate “candidate” list is provided for objects lacking definitive spectra.

Data collection is performed uniformly across all wavelengths. Optical and infrared photometry are gathered via the Black Hole Target Observation Manager (BHT OM), which aggregates measurements from LINEAR, CRTS, ZTF, iPTF, ASAS‑SN, ATLAS, Gaia, and WISE/NEOWISE. All magnitudes are converted to the AB system to ensure consistency. Ultraviolet data are taken from Swift/UVOT, and X‑ray observations are retrieved from the archives of Swift/XRT, Chandra/ACIS, and XMM‑Newton/EPIC; the authors also cross‑check against the 4XMM‑DR13 and eRASS1 catalogs to capture any serendipitous detections. Spectroscopic data from SDSS, Palomar, and a host of published papers are compiled and made publicly available.

A key methodological contribution is the application of a Bayesian Blocks algorithm to the light curves of 103 well‑sampled flares. This technique automatically identifies change points in unevenly sampled data, allowing the authors to measure rise time (t_rise), decay time (t_decay), total duration, and the ratio t_rise/t_decay for each event. The resulting distributions of these timescales are well described by log‑normal functions, implying that the underlying physical parameters (black‑hole mass, stellar structure, impact parameter) vary over logarithmic scales while the flare physics follows a common exponential growth and decline pattern.

Spectral classification follows the established scheme of TDE‑H+He, TDE‑H, TDE‑He, and featureless. The analysis shows that the majority (≈55 %) belong to the TDE‑H+He class, consistent with the expectation that most disrupted stars are main‑sequence objects whose debris produces both hydrogen and helium emission lines. The remaining events are split among the other three categories.

The authors identify three new repeating TDE candidates—AT2024pvu, AT2022exr, and AT2021uvz—by searching archival light curves for secondary flares that closely resemble the primary outburst in shape and timescale. This adds to the small but growing list of repeating TDEs and suggests mechanisms such as partial disruptions or delayed fallback of bound debris.

Infrared analysis reveals that 14 of the 18 IR‑bright TDEs also exhibit X‑ray emission, indicating a strong correlation between dust re‑processing (producing IR) and high‑energy accretion signatures. Statistical tests (χ²) confirm that the spectral classes of repeating, IR‑emitting, and X‑ray‑detected subsamples are not randomly distributed, hinting at intrinsic connections between the line‑emission properties and multi‑wavelength behavior.

All catalog contents—including photometry, spectra, light‑curve fits, and derived parameters—are released on a dedicated GitHub repository and via a Python‑based desktop application, enabling easy access for the community. The authors argue that TDECat will be a vital resource for upcoming large‑scale surveys such as the LSST, facilitating population studies, rate calculations, and the exploration of physical models for TDE emission across the electromagnetic spectrum.