Super-Orbital Variability in Hard X-rays

Abstract

We present the results of a study with the \emph{Swift} Burst Alert Telescope in the 14 -- 195 keV range of the long-term variability of 5 low mass X-ray binaries with reported or suspected super-orbital periods -- 4U 1636-536, 4U 1820-303, 4U 1916-053, Cyg X-2 and Sco X-1. No significant persistent periodic modulation was detected around the previously reported periods in the 4U 1916-053, Cyg X-2 or Sco X-1 light curves. The $\sim$170 d period of 4U 1820-303 was detected up to 24 keV, consistent with variable accretion due to the previously proposed triple system model. The $\sim$46 d period in 4U 1636-536 was detected up to 100 keV, with the modulation in the low and high energy bands found to be phase shifted by $\sim 180^{\circ }$ with respect to each other. This phase shift, when taken together with the near-coincident onset of the $\sim$46 d modulation and the low/hard X-ray state, leads us to speculate that the modulation could herald transient jet formation.

19 pages, 16 figures, 3 tables, accepted for publication in MNRAS

References in corpus (12)

• A Systematic Search for Periodicities in RXTE/ASM Data
• Detection of the Irradiated Donor in the LMXBs 4U 1636-536 (=V801 Ara) and 4U 1735-444 (=V926 Sco)
• The superorbital variability and triple nature of the X-ray source 4U 1820-303
• Linking Jet Emission, X-ray States and Hard X-ray Tails in the Neutron Star X-ray Binary GX 17+2
• Swift/BAT and RXTE Observations of the Peculiar X-ray Binary 4U 2206+54 - Disappearance of the 9.6 Day Modulation
• A Detailed Study of 2S 0114+650 with the RXTE
• A Hard X-ray View on Scorpius X-1 with INTEGRAL: non-Thermal Emission ?
• Dependence of the orbital modulation of X-rays from 4U 1820-303 on the accretion rate
• INTEGRAL spectral variability study of the atoll 4U 1820-30: first detection of hard X-ray emission
• Disc-Jet coupling in the LMXB 4U1636-53 from INTEGRAL
• Jet disc coupling in black hole binaries
• Evolution of the periodicities in 2S 0114+650

Cited by in corpus (14)

• The Swift/BAT Hard X-ray Transient Monitor
• Characterizing X-ray binary long-term variability
• Superexpansion as a possible probe of accretion in 4U 1820-30
• SWIFT Detection of a 65-Day X-ray Period from the Ultraluminous Pulsar NGC 7793 P13
• The doubling of the superorbital period of Cyg X-1
• Outbursts of the intermediate-mass black hole HLX-1: a wind instability scenario
• Long-term monitoring of LS I+61303 with INTEGRAL
• A Comprehensive Study of Thermonuclear X-ray Bursts from 4U 1820-30 with NICER: Accretion Disk Interactions and a Candidate Burst Oscillation
• Long-term X-ray Variability of Ultraluminous X-ray Sources
• Decade time-scale modulation of low mass X-ray binaries
• Correlated Optical/X-ray Long-term Variability in LMXB 4U1636-536
• INTEGRAL and Swift observations of the Be X-ray binary 4U 1036-56 (RX J1037.5-5647) and its possible relation with gamma-ray transients
• The Orbital Period of Scorpius X-1
• Recurrent outbursts revealed in 3XMM J031820.8-663034