We describe the analysis of the seven broad-band X-ray continuum observations of the archetypal Seyfert 1 galaxy NGC 5548 that were obtained with XMM-Newton or Chandra, simultaneously with high-energy (> 10 keV) observations with NuSTAR and INTEGRAL.
These data were obtained as part of a multiwavelength campaign undertaken from the summer of 2013 till early 2014. We find evidence of a high-energy cut-off in at least one observation, which we attribute to thermal Comptonization, and a constant reflected component that is likely due to neutral material at least a few light months away from the continuum source. We confirm the presence of strong, partial covering X-ray absorption as the explanation for the sharp decrease in flux through the soft X-ray band. The obscurers appear to be variable in column density and covering fraction on time scales as short as weeks. A fit of the average spectrum over the range 0.3-400 keV with a realistic Comptonization model indicates the presence of a hot corona with a temperature of 40(+40,-10) keV and an optical depth of 2.7(+0.7,-1.2) if a spherical geometry is assumed.
The microquasar GX 339-4 was observed by Suzaku five times, spaced by a few days, during its transition back to the hard state at the end of its 2010-2011 outburst. The 2-10 keV source flux decreases by a factor ~10 between the beginning and the end
of the monitoring. Simultaneous radio and OIR observations highlighted the re-ignition of the radio emission just before the beginning of the campaign, the maximum radio emission being reached between the two first Suzaku pointings, while the IR peaked a few weeks latter. A fluorescent iron line is always significantly detected. Fits with a gaussian or Laor profiles give statistically equivalent results. In the case of a Laor profile, fits of the five data sets simultaneously agree with a disk inclination angle of ~20 degrees. The disk inner radius is <10-30 R_g in the first two observations but almost unconstrained in the last three. A soft X-ray excess is also present in these two first observations. Fits with a multicolor disk component give disk inner radii in agreement with those obtained with the iron line fits. The use of a physically more realistic model, including a blurred reflection component and a comptonization continuum, give some hints of the increase of the disk inner radius but the significances are always weak. Interestingly, the addition of warm absorption significantly improves the fit of OBS1 while it is not needed in the other observations. The radio-jet re-ignition occurring between OBS1 and OBS2, these absorption features may indicate the natural evolution from a disk wind and a jet. The comparison with a long 2008 Suzaku observation of GX 339-4 in a persistent faint hard state where a narrow iron line clearly indicates a disk recession, is discussed.
(Abridged) The simultaneous UV to X-rays/gamma rays data obtained during the multi-wavelength XMM/INTEGRAL campaign on the Seyfert 1 Mrk 509 are used in this paper and tested against physically motivated broad band models. Each observation has been f
itted with a realistic thermal comptonisation model for the continuum emission. Prompted by the correlation between the UV and soft X-ray flux, we use a thermal comptonisation component for the soft X-ray excess. The UV to X-rays/gamma-rays emission of Mrk 509 can be well fitted by these components. The presence of a relatively hard high-energy spectrum points to the existence of a hot (kT~100 keV), optically-thin (tau~0.5) corona producing the primary continuum. On the contrary, the soft X-ray component requires a warm (kT~1 keV), optically-thick (tau~15) plasma. Estimates of the amplification ratio for this warm plasma support a configuration close to the theoretical configuration of a slab corona above a passive disk. An interesting consequence is the weak luminosity-dependence of its emission, a possible explanation of the roughly constant spectral shape of the soft X-ray excess seen in AGNs. The temperature (~ 3 eV) and flux of the soft-photon field entering and cooling the warm plasma suggests that it covers the accretion disk down to a transition radius $R_{tr}$ of 10-20 $R_g$. This plasma could be the warm upper layer of the accretion disk. On the contrary the hot corona has a more photon-starved geometry. The high temperature ($sim$ 100 eV) of the soft-photon field entering and cooling it favors a localization of the hot corona in the inner flow. This soft-photon field could be part of the comptonised emission produced by the warm plasma. In this framework, the change in the geometry (i.e. $R_{tr}$) could explain most of the observed flux and spectral variability.
We reinvestigate the problem of the appearance of relativistic jets when geometrical opening is taken into account. We propose a new criterion to define apparent velocities and Doppler factors, which we think being determined by the brightest zone of
the jet. We numerically compute the apparent velocity and the Doppler factor of a non homokinetic jet using different velocity profiles. We argue that if the motion is relativistic, the high superluminal velocities beta_{app} ~ gamma, expected in the case of an homokinetic jet, are only possible for geometrical collimation smaller than the relativistic beaming angle 1/gamma. This is relatively independent of the jet velocity profile. For jet collimation angles larger than 1/gamma, the apparent image of the jet will always be dominated by parts of the jet traveling directly towards the observer at lorentz factors < gamma resulting in maximal apparent velocities smaller than gamma}. Furthermore, getting rid of the homokinetic hypothesis yields a complex relation between the observing angle and the Doppler factor, resulting in important consequences for the numerical computation of AGN population and unification scheme model.
Based on a dynamical model describing how stationary, powerful and self-collimated jets are being launched from a magnetized disk, we build a consistent disk+jet microquasar picture. Our disk is a new type of disk solution called the Jet Emitting Dis
k (JED), and whose characteristics are directly constrained by the presence of a jet. We assume a one-temperature plasma with thermal particles only. By solving the radiative equilibrium of the disk, we obtain three branches of solutions, a hot and a cold ones (both thermally stable), and an intermediate one, thermally unstable. The hot solution possess the global observed characteristics of what has been often called a corona located above the inner disk region. We present this new disk solution, and how the radiative equilibrium is computed. We discuss the richness of the solution, and show the ability of the model to reproduce an observed spectral energy distribution of XTE J1118+480 with reasonable parameters. We finally outline some perspectives of the model.
We present preliminary results and observables from a model of microquasar based on a theoretical framework where stationary, powerful, compact jets are launched and then accelerated from an inner magnetized disk. This model aim at providing a consis
tent picture of microquasars in all their spectral states. It is composed of an outer standard accretion disk down to a variable transition radius where it changes to a magnetized disk, called the Jet Emitting Disk (JED). The theoretical framework providing the heating, we solve the radiative equilibrium and obtain the JED structure. Our JED solutions are rich, and reproduce the already known scheme where a cold optically-thick and a hot optically-thin solutions bracket a thermally unstable one. We present the model and preliminary results, whith a first attempt at reproducing the observed SED of XTE J1118+480.
