Time lag in transient cosmic accreting sources

Abstract

Context. We develop models for time lag between the maxima of the source brightness in different wavelengths during a transient flash of luminosity that is connected with a short-period increase of the mass flux onto the central compact object. Aims. We derive a simple formula for finding the time delay among events in different wavelengths which is valid in general for all disk-accreting cosmic sources. We quantitatively also discuss a model for time-lag formation in active galactic nuclei (AGNs). Methods. In close binaries with accretion disks, the time lag is connected with effects of viscosity that define a radial motion of matter in the accretion disk. In AGN flashes, the infalling matter has a low angular momentum, and the time lag is defined by the free-fall time to the gravitating center. Results. We show the validity of these models by means of several examples of galactic and extragalactic accreting sources.

X-Ray Binary Systems – A Cauldron of Physical Processes

“…Such a signature would provide direct evidence for the presence of a warped disk and, potentially, even a measure of the warp radius, which, in turn, could be used to infer the viscosity parameter of the disk. This is very important PoS(HEASA 2016)031 since the knowledge of the viscosity in accretion disks is a critical point, as discussed for instance by Giovannelli, Bisnovatyi-Kogan & Klepnev (2013), and Bisnovatyi-Kogan & Giovannelli (2016).…”

“…Time delays have been detected also in several other X-ray transient binaries. This is the reason that urged Bisnovatyi-Kogan & Giovannelli (2016) to generalize the aforementioned model, developed for the particular case of A 0535+26/HDE 245770 (Flavia' star). This general model provides the formula (6.1) of the time delay in transient cosmic accreting sources:…”

“…In the same paper, Bisnovatyi-Kogan & Giovannelli (2016) developed also a general model for explaining the X-ray/optical delay in Active Galactic Nuclei (AGN), such as Mrk 509, NGC 7469, 3C 120, NGC 3516, and NGC 4051. Briefly, the flashes in AGN occur when a disruption of a star on evolution phase of a giant enters the radius of strong tidal forces.…”

Time lag in transient cosmic accreting sources

“…The accretion disks around SMBH have much wider regions, with P = P rad , so the formula for the time lag is written as [4] τ r = 4.9 × 10 7 m 2/3…”

“…A simple formula is derived for the time delay among events in different wavelengths, valid in general for all disk accreting cosmic sources. A model for time lag formation in AGNs is discussed quantitatively in [4].…”