Gaia method paper: an algorithm to detect flare events in Gaia time-series

Abstract

The third Gaia data release (GDR3) includes the gdr3_rotmod catalogue of 474026 stars with variability that is attributed to magnetic activity analogous to that observed in the Sun, arising from rotational modulation induced by spots and faculae. These stars are therefore expected to exhibit flaring activity driven by magnetic reconnection processes. We aim to demonstrate that stellar flares can be reliably identified and characterised in the sparsely sampled \gaia\ photometric time series. We developed and validated a dedicated flare-detection pipeline that exploits the simultaneous multi-band photometry in the G, G_BP, and G_RP bands. The algorithm identifies outliers associated with a concurrent increase in brightness and blueing of the stellar colour, and applies consistency criteria to distinguish genuine flare events from instrumental or calibration artefacts. Applying this method to the gdr3_rotmod catalogue, we detect 3217 flares occurring on 2818 stars out of 474026 analysed sources. All events are provided in a dedicated catalogue together with their photometric amplitudes. For a subset of 348 flares, we estimate an effective temperature using a black-body approximation, and we identify 29 hyper-flares with amplitudes A(G)≥0.75 mag, which occur preferentially in M dwarfs. Despite the sparse temporal sampling of Gaia, our results demonstrate that its multi-band photometry and spectrophotometric information enable the robust detection of flares and the basic characterisation of their properties across an all-sky stellar sample. This work establishes the methodological foundation for future Gaia flare catalogues and provides a homogeneous, complementary view of stellar flaring activity alongside high-cadence missions such as Kepler and TESS.

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BibTeX RIS

BibTeX

@misc{distefano2026gaia,
  title = {{Gaia method paper: an algorithm to detect flare events in Gaia time-series}},
  author = {E. Distefano and A. C. Lanzafame and A. F. Lanza and S. Messina and I. Pagano and M. Audard and G. Jevardat de Fombelle and B. Holl and I. Lecoeur-Taibi and N. Mowlavi and K. Nienartowicz and L. Rimoldini and D. W. Evans and M. Riello and P. García-Lario and P. Gavra and L. Eyer},
  howpublished = {arXiv},
  year = {2026},
  month = sep,
  doi = {10.48550/arxiv.2609.20417},
  eprint = {2609.20417},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2609.20417},
  note = {CC BY 4.0},
}

RIS

TY  - UNPB
TI  - Gaia method paper: an algorithm to detect flare events in Gaia time-series
AU  - E. Distefano
AU  - A. C. Lanzafame
AU  - A. F. Lanza
AU  - S. Messina
AU  - I. Pagano
AU  - M. Audard
AU  - G. Jevardat de Fombelle
AU  - B. Holl
AU  - I. Lecoeur-Taibi
AU  - N. Mowlavi
AU  - K. Nienartowicz
AU  - L. Rimoldini
AU  - D. W. Evans
AU  - M. Riello
AU  - P. García-Lario
AU  - P. Gavra
AU  - L. Eyer
PY  - 2026
DA  - 2026/09/17
PB  - arXiv
DO  - 10.48550/arxiv.2609.20417
UR  - https://arxiv.org/abs/2609.20417
AB  - The third Gaia data release (GDR3) includes the gdr3_rotmod catalogue of 474026 stars with variability that is attributed to magnetic activity analogous to that observed in the Sun, arising from rotational modulation induced by spots and faculae. These stars are therefore expected to exhibit flaring activity driven by magnetic reconnection processes. We aim to demonstrate that stellar flares can be reliably identified and characterised in the sparsely sampled \gaia\ photometric time series. We developed and validated a dedicated flare-detection pipeline that exploits the simultaneous multi-band photometry in the G, G_BP, and G_RP bands. The algorithm identifies outliers associated with a concurrent increase in brightness and blueing of the stellar colour, and applies consistency criteria to distinguish genuine flare events from instrumental or calibration artefacts. Applying this method to the gdr3_rotmod catalogue, we detect 3217 flares occurring on 2818 stars out of 474026 analysed sources. All events are provided in a dedicated catalogue together with their photometric amplitudes. For a subset of 348 flares, we estimate an effective temperature using a black-body approximation, and we identify 29 hyper-flares with amplitudes A(G)≥0.75 mag, which occur preferentially in M dwarfs. Despite the sparse temporal sampling of Gaia, our results demonstrate that its multi-band photometry and spectrophotometric information enable the robust detection of flares and the basic characterisation of their properties across an all-sky stellar sample. This work establishes the methodological foundation for future Gaia flare catalogues and provides a homogeneous, complementary view of stellar flaring activity alongside high-cadence missions such as Kepler and TESS.
ER  -

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