Related papers: The optical long `period' of LMC X-3
The X-ray persistence and characteristically soft spectrum of the black hole X-ray binary LMC X-3 make this source a touchstone for penetrating studies of accretion physics. We analyze a rich, 10-year collection of optical/infrared (OIR)…
We have studied the long-term (~ years) temporal variability of the prototype supersoft X-ray source (SSS) CAL 83 in the LMC, using data from the MACHO and OGLE projects. The CAL 83 light curve exhibits dramatic brightness changes of ~1 mag…
We present the results of concurrent X-ray and optical monitoring of the Seyfert 1 galaxy Mrk 79 over a period of more than five years. We find that on short to medium time-scales (days to a few tens of days) the 2-10 keV X-ray and optical…
We present simultaneous X-ray and optical B and V band light curves of the Seyfert Galaxy NGC3783 spanning 2 years. The flux in all bands is highly variable and the fluctuations are significantly correlated. As shown before by Stirpe et al.…
Explaining variability observed in the accretion flows of black hole X-ray binary systems remains challenging, especially concerning timescales less than, or comparable to, the viscous timescale but much larger than the inner orbital period…
Long-term X-ray modulations on timescales from tens to hundreds of days have been widely studied for X-ray binaries located in the Milky Way and the Magellanic Clouds. For other nearby galaxies, only the most luminous X-ray sources can be…
A linear relation between absolute rms variability and flux in X-ray observations of compact accreting sources has recently been identified. Such a relation suggests that X-ray lightcurves are non-linear and composed of a lognormal…
Eight years of optical photometry from OGLE-III are presented of the optical counterpart to the High Mass X-ray Binary system, SMC X-1. The optical data provide the best view to date of the modulation of the light from the system at the…
We analysed the light curves of a large sample of long period variables in the LMC from the AGAPEROS catalogue. The (non)regularity of the light change is discussed in detail showing that the majority of the light curves cannot be described…
The black-hole binary LMC X-3 is known to be variable on time scales of days to years. We investigate X-ray and ultraviolet variability in the system as a function of the 1.7 day binary phase using a 6.4 day observation with the Rossi X-ray…
We have obtained high time resolution (seconds) photometry of LMC X-2 in December 1997, simultaneously with the Rossi X-ray Timing Explorer (RXTE), in order to search for correlated X-ray and optical variability on timescales from seconds…
Long term X-ray monitoring data from the RXTE ASM and CGRO BATSE reveal that the third (superorbital) period in SMC X-1 is not constant, but varies between 40-60 days. A dynamic power spectrum analysis indicates that the third period has…
We searched for long period variation in V-band, Ic-band and RXTE X-ray light curves of the High Mass X-ray Binaries (HMXBs) LS 1698 / RX J1037.5-5647, HD 110432 / 1H 1249-637 and HD 161103 / RX J1744.7-2713 in an attempt to discover…
The supersoft X-ray binary RX J0513.9-6951 shows cyclic changes between optical-low / X-ray-on states and optical-high / X-ray-off states. It is supposed to be accreting close to the Eddington-critical limit and driven by "accretion wind…
We combine the long-term optical light curve of the Seyfert 1 galaxy NGC5548 with the X-ray light curve measured by the Rossi X-ray Timing Explorer over 6 years, to determine the relationship between the optical and X-ray continua. The…
We present a multi-wavelength timing study of the eclipsing low mass X-ray binary EXO 0748-676 (UY Vol) using XMM-Newton when the source was in a hard spectral state. The orbital optical and X-ray light curves show a fairly large amount of…
The high-mass X-ray binary LS I +61$^\circ$303 is detected across the electromagnetic spectrum from radio until the very high energy gamma-ray regime. The emission is not only highly variable on many time scales, but is also periodic at all…
Cen X-3 is a compact high mass X-ray binary likely powered by Roche lobe overflow. We present a phase-resolved X-ray spectral and timing analysis of two pointed XMM-Newton observations. The first one took place during a normal state of the…
We have investigated the long term flux variation in Cen X-3 using orbital modulation and pulsed fraction in different flux states using observations made with the All Sky Monitor and the Proportional Counter Array on board the Rossi X-ray…
Long-term ("superorbital") periods or modulations have been detected in a wide variety of both low and high-mass X-ray binaries at X-ray and optical wavelengths. A variety of mechanisms have been proposed to account for the variability…