Journal
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
Volume 453, Issue 4, Pages 3461-3473Publisher
OXFORD UNIV PRESS
DOI: 10.1093/mnras/stv1686
Keywords
binaries: close; stars: fundamental parameters; stars: individual: PSR J1023+0038; stars: neutron; X-rays: binaries
Categories
Funding
- Spanish Ministry of Economy and Competitiveness (MINECO) [AYA2010-18080, AYA2012-38700, AYA2013-42627]
- Ramon y Cajal fellowship [RYC-2010-05762]
- STFC [ST/J001589/1]
- Science and Technology Facilities Council [ST/M001350/1, ST/L000733/1] Funding Source: researchfish
- STFC [ST/L000733/1, ST/M001350/1, ST/M002012/1] Funding Source: UKRI
Ask authors/readers for more resources
We present time-resolved optical photometry of the binary millisecond 'redback' pulsar PSR J1023+0038 (=AY Sex) during its low-mass X-ray binary phase. The light curves taken between 2014 January and April show an underlying sinusoidal modulation due to the irradiated secondary star and accretion disc. We also observe superimposed rapid flaring on time-scales as short as similar to 20 s with amplitudes of similar to 0.1-0.5 mag and additional large flare events on time-scales of similar to 5-60 min with amplitudes of similar to 0.5-1.0 mag. The power density spectrum of the optical flare light curves is dominated by a red-noise component, typical of aperiodic activity in X-ray binaries. Simultaneous X-ray and UV observations by the Swift satellite reveal strong correlations that are consistent with X-ray reprocessing of the UV light, most likely in the outer regions of the accretion disc. On some nights we also observe sharp-edged, rectangular, flat-bottomed dips randomly distributed in orbital phase, with a median duration of similar to 250 s and a median ingress/egress time of similar to 20 s. These rectangular dips are similar to the mode-switching behaviour between disc 'active' and 'passive' luminosity states, observed in the X-ray light curves of other redback millisecond pulsars. This is the first time that the optical analogue of the X-ray mode-switching has been observed. The properties of the passive-and active-state light curves can be explained in terms of clumpy accretion from a trapped inner accretion disc near the corotation radius, resulting in rectangular, flat-bottomed optical and X-ray light curves.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available