منابع مشابه
Millimeter VLBI and Variability in AGN Jets
Millimeter-VLBI images probe as deep as never before the nuclei of AGN. VLBI at 147GHz yields transatlantic fringes for the first time. Now we can begin to study the relation between jet kinematics and spectral activity with a few ten micro-arcsecond resolution. 1. Present Status of 3mm-VLBI The main advantage of VLBI observations at short millimeter wavelengths (mmVLBI) is the very high angula...
متن کاملAGN variability: from Seyfert nuclei to QSOs
The continuum variability of optically selected Active Galactic Nuclei (AGN) is found to be consistent with that expected from a simple Poissonian process, in which the total luminosity of an object is produced by the multiple superposition of identical pulses. The energies, time-scales and rates of the pulses are found to be in the range of those expected from supernovae which generate fast ev...
متن کاملCan star collisions explain the AGN variability ?
Star collisions may easily occur in a cluster of stars orbiting around a massive black hole. Such collisions can transform part of the star kinetic energy in observable radiating energy. In this paper we derive the star collision rate and the resulting highly variable luminosity for the case of a cluster containing stars of different masses. The variability of the derived light curves is comput...
متن کاملHard X-ray Variability of AGN
Aims. Active Galactic Nuclei are known to be variable throughout the electromagnetic spectrum. An energy domain poorly studied in this respect is the hard X-ray range above 20 keV. Methods. The first 9 months of the Swift/BAT all-sky survey are used to study the 14 – 195 keV variability of the 44 brightest AGN. The sources have been selected due to their detection significance of > 10σ. We test...
متن کاملIntranight polarization variability in radio-loud and radio-quiet AGN
Intranight polarization variability in AGN has not been studied extensively so far. Studying the variability in polarization makes it possibly to distinguish between different emission mechanisms. Thus it can help answering the question if intranight variability in radio-loud and radio-quiet AGN is of the same or of fundamentally different origin. In this paper we investigate intranight polariz...
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ژورنال
عنوان ژورنال: Symposium - International Astronomical Union
سال: 1999
ISSN: 0074-1809
DOI: 10.1017/s0074180900162291