Short timescale variables in the Gaia era: detection and characterization by structure function analysis

TL;DR

This paper evaluates Gaia's ability to detect and analyze short timescale variability in stars using variogram analysis, demonstrating its effectiveness for identifying fast periodic and transient events with minimal contamination.

Contribution

It introduces a variogram-based method for detecting and characterizing short timescale variability in Gaia data, validated through extensive simulations.

Findings

Detects fast periodic variability down to millimagnitude amplitudes

Identifies short timescale transients like M dwarf flares and supernovae

Provides valuable timescale estimates complementing other methods

Abstract

We investigate the capabilities of the ESA Gaia mission for detecting and character- izing short timescale variability, from tens of seconds to a dozen hours. We assess the efficiency of the variogram analysis, for both detecting short timescale variability and estimating the underlying characteristic timescales from Gaia photometry, through extensive light-curve simulations for various periodic and transient short timescale variable types. We show that, with this approach, we can detect fast periodic variabil- ity, with amplitudes down to a few millimagnitudes, as well as some M dwarf flares and supernovae explosions, with limited contamination from longer timescale variables or constant sources. Timescale estimates from the variogram give valuable informa- tion on the rapidity of the underlying variation, which could complement timescale estimates from other methods, like Fourier-based periodograms, and be reinvested in preparation of ground-based photometric follow-up of short timescale candidates evi- denced by Gaia. The next step will be to find new short timescale variable candidates from real Gaia data, and to further characterize them using all the Gaia information, including color and spectrum.