The broad-band X-ray spectrum of Mrk 3

We use non-simultaneous Ginga ASCA ROSAT observations to investigate the complex X-ray spectrum of the Seyfert 2 galaxy Mrk 3. We find that the composite spectrum can be well described in terms of a heavily cut-off hard X-ray continuum, iron Kα emission and a soft X-ray excess, with spectral variability confined to changes in the continuum normalization and the flux in the iron line. Previous studies have suggested that the power-law continuum in Mrk 3 is unusually hard. We obtain a canonical value for the energy index of the continuum (i.e., α ≈ 0.7) when a warm absorber (responsible for an absorption edge observed near 8 keV) is included in the spectral model. Alternatively, the inclusion of a reflection component yields a comparable power-law index. The soft-excess flux cannot be modelled solely in terms of pure electron scattering of the underlying power-law continuum. However, a better fit to the spectral data is obtained if we include the effects of both emission and absorption in a partially photoionized scattering medium. In particular, the spectral feature prominent at ∼ 0.9 keV could represent O VIII recombination radiation produced in a hot photoionized medium. We discuss our results in the context of other recent studies of the soft X-ray spectra of Seyfert 2 galaxies.     

XMM–Newton and Suzaku analysis of the Fe K complex in the type 1 Seyfert galaxy Mrk 509

We report on partially overlapping XMM–Newton (∼260 ks) and Suzaku (∼100 ks) observations of the iron K band in the nearby, bright type 1 Seyfert galaxy Mrk 509. The source shows a resolved neutral Fe K line, most probably produced in the outer part of the accretion disc. Moreover, the source shows further emission bluewards of the 6.4 keV line due to ionized material. This emission is well reproduced by a broad line produced in the accretion disc, while it cannot be easily described by scattering or emission from photoionized gas at rest. The summed spectrum of all XMM–Newton observations shows the presence of a narrow absorption line at 7.3 keV produced by highly ionized outflowing material. A spectral variability study of the XMM–Newton data shows an indication for an excess of variability at 6.6–6.7 keV. These variations may be produced in the red wing of the broad ionized line or by variation of a further absorption structure. The Suzaku data indicate that the neutral Fe K α line intensity is consistent with being constant on long time-scales (of a few years), and they also confirm as most likely the interpretation of the excess blueshifted emission in terms of a broad ionized Fe line. The average Suzaku spectrum differs from the XMM–Newton one in the disappearance of the 7.3 keV absorption line and around 6.7 keV, where the XMM–Newton data alone suggested variability.     

Chandra HRC and HST observations of NGC 6240: resolving the active galactic nucleus and starburst

We present high spatial resolution X-ray Chandra HRC and HST WFPC2 H α observations of the prototypical infrared-luminous galaxy NGC 6240. The central region of this system shows a remarkably complex morphology, with filaments and loops observed in the optical and X-rays. The total X-ray luminosity is dominated by the extended emission. Both nuclei are clearly detected in the HRC image and both appear to be extended. The energetics of the nuclei imply that the southern nucleus is the more plausible counterpart to the obscured active galactic nucleus. The overall spectral energy distribution of the galaxy is in good agreement with a blend of starburst and AGN components that have similar bolometric luminosities,   L _bol∼5×10⁴⁵ erg s^-1  , with the starburst dominating the observed continuum in the near-infrared ( K band), optical and soft X-ray bands.     

Optical continuum variability of the active galaxy Mrk 279 – implications for different accretion regimes

We present results from a recent broad‐band monitoring in optics of the Seyfert 1 type galaxy Mrk 279. We build and analyse the BV RI light curve covering a period of seven years (1995–2002). We also show some evidence for the existence of two different states in brightness and suggest, based on a modelling of the optical continuum, that these states may result from transition between a thin disk and an ADAF accretion modes. We assume that the short‐term variability is due to a reprocessing of a variable X‐ray emission from an inner ADAF part of the flow, while the long‐term one may be a result from a change of the transition radius. Our tests show a good match with the observations for a reasonable set of accretion parameters, close to the expected ones for Mrk 279. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

The gas kinematics in the Mrk 533 nucleus and circumnuclear region: a gaseous outflow

We present an analysis of 3D spectra of Mrk 533, observed with the integral-field spectrograph MultiPupil Fiber Spectrograph (MPFS) and using the Fabry-Perot Interferometer (FPI) of the Special Astrophysical Observatory of the Russian Academy of Sciences (SAO RAS) 6-m telescope. We found emissions of gas from the active type 2 Seyfert nucleus in the centre and also from the H  ii regions in a spiral structure and a circumnuclear region. The gas kinematics shows regular non-circular motions in the wide range of galactocentric distances from 500 pc up to 15 kpc. The maps of inward and outward radial motions of the ionized gas were constructed. We found that the narrow-line region (NLR) is composed of at least two (probably three) kinematically separated regions. We detect a stratification in the NLR of Mrk 533 with the outflow velocity ranging from 20–50 km s⁻¹ to 600–700 km s⁻¹, respectively, on the radial distances of ∼2.5 and ∼1.5 kpc. The maximal outflow velocity comes from the nucleus and corresponds to the position of the observed radio structure, which is assumed to be created in an approaching jet. We suggest that these ionized gas outflows are triggered by the radio jet intrusion in an ambient medium.     

XMM‐Newton monitoring observations of Mrk 3

We present monitoring analysis of 8 XMM‐Newton observations of the Seyfert 2 galaxy Mrk 3, spanning a period of ∼19 months. The continuum flux in the 3–12 keV band remains constant during this observing period. The X‐ray spectrum is well described, in agreement with previous works, by a highly absorbed (N _H > 10²⁴ cm^–2) power law model, with a photon index Γ = 1.9 and a strong reflection component. A strong Fe Kα line at 6.4 keV with an equivalent width of ∼500 eV is detected in the X‐ray spectrum. When we consider the co‐added spectrum we also detect a weaker emission line at 7.4 keV corresponding to neutral Ni Kα emission and weak evidence for the presence of an ionized Fe Kα line at 6.7 keV. Direct comparison with the results obtained from an earlier XMM‐Newton observation of Mrk 3, shows a decrease in the continuum flux of ∼30 per cent followed by a similar decrease in the reflected component. Both emission line components at 6.4 and 6.7 keV do not vary. However we find that an alternative model where the N _H varies by 20 per cent is also plausible. In this case both the continuum and the reflected emission do not change. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

The 0.1–100 keV spectrum and variability of Mrk 421 in a high state

The results of a BeppoSAX target of opportunity (TOO) observation of the BL Lac object Mrk 421 during a high-intensity state are reported and compared with monitoring X-ray data collected with the BeppoSAX Wide Field Cameras (WFC) and the RXTE All Sky Monitor (ASM). The 0.1–100 keV spectrum of Mrk 421 shows continuous convex curvature that can be interpreted as the high-energy end of the synchrotron emission. The source shows significant short-term temporal and spectral variability, which can be interpreted in terms of synchrotron cooling. The comparison of our results with those of previous observations when the source was a factor 3–5 fainter shows evidence for strong spectral variability, with the maximum of the synchrotron power shifting to higher energy during high states. This behaviour suggests an increase in the number of energetic electrons during high states.     

Suzaku observations of Markarian 335: evidence for a distributed reflector

We report on a 151-ks net exposure Suzaku observation of the narrow-line Seyfert 1 galaxy Mrk 335. The 0.5–40 keV spectrum contains a broad Fe line, a strong soft excess below about 2 keV and a Compton hump around 20–30 keV. We find that a model consisting of a power law and two reflectors provides the best fit to the time-averaged spectrum. In this model, an ionized, heavily blurred, inner reflector produces most of the soft excess, while an almost neutral outer reflector (outside ∼ 40 r _g) produces most of the Fe line emission. The spectral variability of the observation is characterized by spectral hardening at very low count rates. In terms of our power-law + two-reflector model it seems like this hardening is mainly caused by pivoting of the power law. The rms spectrum of the entire observation has the curved shape commonly observed in active galactic nuclei, although the shape is significantly flatter when an interval which does not contain any deep dip in the light curve is considered. We also examine a previous 133-ks XMM–Newton observation of Mrk 335. We find that the XMM–Newton spectrum can be fitted with a similar two-reflector model as the Suzaku data and we confirm that the rms spectrum of the observation is flat. The flat rms spectra, as well as the high-energy data from the Suzaku PIN detector, disfavour an absorption origin for the soft excess in Mrk 335.