Consider the plane as a checkerboard, with each unit square colored black or white in an arbitrary manner. We show that for any such coloring there are straight line segments, of arbitrarily large length, such that the difference of their white length minus their black length, in absolute value, is at least the square root of their length, up to a multiplicative constant. For the corresponding ...

We update our previous work on the description of twisted configurations for complex massless scalar field on the Kerr black holes as the sections of complex line bundles over the Kerr black hole topology R × S . From physical point of view the appearance of twisted configurations is linked with the natural presence of Dirac monopoles that arise as connections in the above line bundles. We cons...

ASCA observations of Narrow-Line Seyfert 1 galaxies (NLS1s) are presented. We focus on the black hole size of the NLS1 sources by employing two independent methods for the mass estimation; one is using X-ray variability, the other is using a blackbody fit to the soft component. Although the coincidence is not good for some sources, the mass estimated by these methods ranges from 10 to 10 M⊙, sy...

A new technique is presented for determining the black-hole masses of high-redshift quasars from optical spectroscopy. The new method utilizes the full-width half maximum (FWHM) of the low-ionization Mgii emission line and the correlation between broad-line region (BLR) radius and continuum luminosity at 3000Å. Using archival UV spectra it is found that the correlation between BLR radius and 30...

We assembled a sample of broad line and narrow lines AGNs observed by ASCA, whose excess variances have been determined. The central black hole masses in this sample can be obtained from the reverberation mapping method and the width of Hβ emission line. Using the black hole masses and the bolometric luminosity, the Eddington ratio can also be obtained. We confirmed the strong anti-correlation ...

malian animals, i.e. that of a cat. It was also influenced by the spring-mass model representation [2]. Compliant prismatic legs show an intrinsic robustness for their angle of attack [2], they have a stability region. If the leg design is changed into a two segmented leg with a specific linear torsional spring, the leg stiffness kleg becomes nonlinear (Fig. 2(b) blue line), similar to that of ...

I report the discovery of a prominent broad and asymmetrical feature near 6.4 keV in the Seyfert 1 MCG-02-14-009 (z=0.028) with XMM-Newton/EPIC. The present short X-ray observation (PN net exposure time ∼5 ks) is the first one above 2 keV for MCG-02-14-009. The feature can be explained by either a relativistic iron line around either a Schwarzschild (non-rotating) or a Kerr (rotating) black hol...

We have investigated the influence of nuclear parameters such as black hole mass and photoionizing luminosity on the FRI/FRII transition in a sample of nearby (z < 0.2) radio galaxies from the 3CR catalogue. The sample was observed with medium-resolution, optical spectroscopy and contains some galaxies with unpublished velocity dispersion measurements and emission-line fluxes. The measured velo...

Iron line emission is common in the X-ray spectra of accreting black holes. When the line emission is broad or variable then it is likely to originate from close to the black hole. X-ray irradiation of the accretion flow by the power-law X-ray continuum produces the X-ray ’reflection’ spectrum which includes the iron line. The shape and variability of the iron lines and reflection can be used a...

We show that the X-ray power density spectra do not simply scale linearly with the mass of the black hole over many decades. Nevertheless, the high frequency tail of the power density spectrum can be successfully used for determination of the black hole mass in an AGN if another AGN is used as a reference. We determine the masses of the black holes in 6 Broad Line Seyfert 1 galaxies, 5 Narrow L...