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How relevant is the torus activity/geometry for the TeV gamma-rays emitted in the jet of M87 ? Abstract. Motivated by unification schemes of active galactic nuclei, we review evidence for the existence of a small-scale dust torus in M87, a Fanaroff-Riley Class I radio galaxy. Since there is no direct evidence of any thermal emission from its torus we(More)
The 2-10 keV continuum of AGN is well represented by a single power law, generally attributed to a hot comptonizing medium, such as a corona above the accretion disk. At smaller energies the continuum displays an excess with respect to the extrapolation of this power law, called the " soft X-ray excess ". Until now it was attributed, either to reflection of(More)
In the era of XMM-Newton and Chandra missions, it is crucial to use codes able to compute correctly the line spectrum of X-ray irradiated thick media (Thomson thickness of the order of unity), in order to build models for the structure and the emission of the central regions of Active Galactic Nuclei (AGN), or of X-ray binaries. In all photoionized codes(More)
We develop an exploratory model for the outer, grav-itationally unstable regions of accretion disks around massive black holes. We consider black holes of mass 10 6 to 10 10 M , and primeval or solar abundances. In a first step we study star formation and evolution in a purely gaseous marginally unstable disk, and we show that unstable fragments should(More)
Context. Scatter around the relationship between central black hole masses in active galactic nuclei (AGNs) obtained by reverberation-mapping methods and host-galaxy bulge velocity dispersion indicates that the masses are uncertain typically by a factor of about three. Aims. In this paper, we try to identify the sources and systematics of this uncertainty.(More)
In a previous paper, Collin & Huré (2001), using a sample of Active Galactic Nuclei (AGN) where the mass has been determined by reverberation studies (the Kaspi et al. 2000 sample), have shown that if the optical luminosity is emitted by a steady accretion disc, it implies that about half of the objects of the sample are accreting close to the Eddington(More)
Context. Many active galactic nuclei exhibit X-ray features typical of the highly ionized gas called " Warm Absorber " (WA). Such a material appears to be stratified, displaying zones of different density, temperature, and ionization. In this paper, we investigate the possibility of modelling the WA gas in NGC 3783 as a single medium in total pressure(More)
  • A I Shapovalova, C Popovi´c, +6 authors A Kovačevi´c
  • 2009
Results of a long-term monitoring (10 years) of the broad line and continuum fluxes of three Active Galactic Nuclei (AGN), 3C 390.3, NGC 4151, and NGC 5548, are presented. We analyze the Hα and Hβ profile variations during the monitoring period and study different details (as bumps, absorption bands) which can indicate structural changes in the Broad Line(More)
We have monitored the AGN 3C 390.3 between 1995 and 2000. A historical B-Band light curve dating back to 1966, shows a large increase in brightness during 1970 – 1971, followed by a gradual decrease down to a minimum in 1982. During the 1995–2000 lapse the broad Hβ emission and the continuum flux varied by a factor of ≈ 3. Two large amplitude outbursts, of(More)