Violent intra-night optical variability of the blazar S4 0954+65 during its unprecedented 2015 February outburst

Abstract

In this letter we present results from intra-night monitoring in three colors (BRI) of the blazar S4 0954+65 during its recent (2015 February) unprecedented high state. We find violent variations on very short time scales, reaching magnitude change levels of 0.1-0.2 mag/h. On some occasions, changes of ~0.1 mag are observed even within ~10 min. During the night of 14.02.2015 an exponential drop of ~0.7 magnitudes is detected for about 5 hours. Cross-correlation between the light curves does not reveal any detectable wavelength-dependent time delays, larger than ~5 min. Color changes "bluer-when-brighter" are observed on longer time scales. Possible variability mechanisms to explain the observations are discussed and a preference to the geometrical one is given.

MNRAS, accepted

References in corpus (1)

• The Outburst of the Blazar S40954+658 in March-April 2011

Cited by in corpus (11)

• The complex variability of blazars: Time-scales and periodicity analysis in S4 0954+65
• Multi-wavelength Intra-day Variability and Quasi-periodic Oscillation in Blazars
• Optical Variability of TeV Blazars on long time-scales
• Intra-night optical flux and polarization variability of BL~Lacertae during its 2020 $-$ 2021 high state
• Intra-night variability of the blazar CTA 102 during its 2012 and 2016 giant outbursts
• Multiband optical flux density and polarization microvariability study of optically bright blazars
• Detection of Quasi-Periodic Oscillations in the Blazar S4 0954+658 with TESS
• Optical variability power spectrum analysis of blazar sources on intranight timescales
• IXPE Observation of the Low-Synchrotron Peaked Blazar S4 0954+65 During An Optical-X-ray Flare
• Investigating the origin of optical flares from the TeV blazar S4 0954+65
• The Extremes in Intra-Night Blazar Variability: The S4 0954+65 Case