Related papers: Correlated X-ray and Optical Variability in X-ray …

We use both time-domain and Fourier techniques to study the correlated optical and X-rays variability in the black hole X-ray nova XTE J1118+480. Its X-ray timing properties, such as the shape of the X-ray power spectrum and…

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…

Marked correlations are reported between the ionization of the X-ray line spectra of normal OB stars, as observed by the Chandra X-Ray Observatory, and their optical spectral types. These correlations include the progressive weakening of…

The main goal of this work is to investigate the fast photometric variability of the optical counterparts to supergiant X-ray binaries and to compare the general patterns of such variability with the Galactic population of other early-type…

We investigate the relationship between the quasi-thermal baryon-related photosphere in relativistic outflows, and the internal shocks arising outside them, which out to a limiting radius may be able to create enough pairs to extend the…

The observed relation between the X-ray radiation from AGNs, originating in the corona, and the optical/UV radiation from the disk is usually described by the anticorrelation between the UV to X-ray slope alpha_ox and the UV luminosity.…

We test the "reprocessing paradigm" of the optical -- UV AGN variability by detailed modeling of the correlated X-ray -- optical (3590 and 5510 Angstrem) variability of the recent multiwavelength campaign of NGC 3516. We produce model…

We report simultaneous X-ray and optical observations of V404 Cyg in quiescence. The X-ray flux varied dramatically by a factor of >20 during a 60ks observation. X-ray variations were well correlated with those in Halpha, although the…

Active galactic nuclei (AGNs) are known to be variable across all wavelengths. Significant observational efforts have been invested in the last decade in studying their ultraviolet (UV) and optical variability. Long and densely sampled,…

Strongly magnetized, accreting neutron stars show periodic and aperiodic variability over a wide range of time scales. By obtaining spectral and timing information on these different time scales, we can have a closer look into the physics…

The reflection of X-ray radiation produced near a compact object from its stellar companion contributes to the orbital variability of polarization in X-ray binaries. The X-rays are reflected mainly via Thomson scattering resulting in a high…

Sco X-1 is the brightest extra-solar point source of X-rays, and may serve as a prototype for low mass X-ray binaries as a class. It has been suggested that the UV and optical emission arise as a result of reprocessing of X-rays, and that a…

Currently available information on fast variability of the X-ray emission from accreting collapsed objects constitutes a complex phenomenology which is difficult to interpret. We review the current observational standpoint for black-hole…

Swift monitoring of NGC 4151 with ~6 hr sampling over a total of 69 days in early 2016 is used to construct light curves covering five bands in the X-rays (0.3-50 keV) and six in the ultraviolet (UV)/optical (1900-5500 A). The three hardest…

We present the results from a monitoring campaign of the Narrow-Line Seyfert~1 galaxy PG 1211+143. The object was monitored with ground-based facilities (UBVRI photometry; from February to July, 2007) and with Swift (X-ray…

The new multi-wavelength monitoring campaign on NGC 5548 shows clearly that the variability of the UV/optical lightcurves lags by progressively longer times at longer wavelengths, as expected from reprocessing of an optically thick disk,…

A comprehensive review of aperiodic rapid X-ray variability (QPO and noise) in X-ray binaries with neutron stars and black holes.

X-ray binaries provide exceptional laboratories for understanding the physics of matter under the most extreme conditions. Until recently, there were few, if any, observational constraints on the circumbinary environments of X-ray binaries…

The hot inner flow in black-hole X-ray binaries is not just a static corona rotating around the black hole, but it must be partially outflowing. We have developed a model, in which Comptonization takes place in this outflowing corona. We…

We study the relationship between the UV and X-ray variability of the narrow-line Seyfert 1 galaxy 1H~0707-495. Using a year long {\it Swift} monitoring and four long {\it XMM-Newton} observations, we perform cross-correlation analyses of…