Abstract. We present results of a systematic analysis of the XMM-Newton spectra of 40 quasars (QSOs) (z ≤ 1.72) from the Palomar-Green (PG) Bright Quasar Survey sample (M B < −23). The sample includes 35 radio-quiet quasars (RQQs) and 5 radio-loud quasars (RLQs). The analysis of the spectra above 2 keV reveals that the hard X-ray continuum emission can be modeled with a power law component with Γ 2−12 keV = 1.89 ± 0.11 and Γ 2−12 keV = 1.63−0.01 for the RQQs and RLQs, respectively. Below 2 keV, a strong, broad excess is present in most QSO spectra. This feature has been fitted with four different models assuming several physical scenarios. All tested models (blackbody, multicolor blackbody, bremsstrahlung and power law) satisfactorily fitted the majority of the spectra. However, none of them is able to provide an adequate parameterization for the soft excess emission in all QSOs, indicating the absence of a universal shape for this spectral feature. An additional cold absorption component was required only in three sources. On the other hand, as recently pointed out by Porquet et al. (2004) for a smaller sample of PG QSOs, warm absorber features are present in 50% of the QSO spectra in contrast with their rare occurrence (∼5−10%) in previous studies. The XMM-Newton view of optically selected bright QSOs therefore suggests that there are no significant differences in the X-ray spectral properties compared with those of the low-luminosity Seyfert 1 galaxies. Properties of the Fe Kα emission lines are presented in a companion paper.

Using a 100 ks XMM-Newton exposure of NGC 4051, we show that the time evolution of the ionization state of the X-ray absorbers in response to the rapid and highly variable X-ray continuum constrains all the main physical and geometrical properties of an AGN ''warm absorber'' wind. The absorber consists of two different ionization components, with a difference of %100 in ionization parameter and %5 in column density. By tracking the response in the opacity of the gas to changes in the ionizing continuum, we were able to constrain the electron density of the system. We find n e ¼ (5:8Y21:0) ; 10 6 cm À3 for the high-ionization absorber and n e > 8:1 ; 10 7 cm À3 for the low-ionization absorber. These densities require that the high-and low-ionization absorbing components of NGC 4051 must be compact, at distances 0.5Y1.0 lt-days (2200R S Y4400R S ) and <3.5 lt-days (<15;800R S ) from the continuum source, respectively. This rules out an origin in the dusty obscuring torus, as the dust sublimation radius is at least an order of magnitude larger ($12 lt-days). An accretion-disk origin for the warm absorber wind is strongly suggested, and an association with the high-ionization, He ii emitting, broad emission line region (radius <2 lt-days) is possible. The two detected phases are consistent with pressure equilibrium, which suggests that the absorber consists of a two-phase medium. A radial flow in a spherical geometry is unlikely, and a conical wind geometry is preferred. The implied mass outflow rate from this wind can be well constrained and is 2%Y5% of the mass accretion rate. If the mass outflow rate scaling with accretion rate is representative of all quasars, our results imply that warm absorbers in powerful quasars are unlikely to produce important evolutionary effects on their larger environment, unless we are observing the winds before they get fully accelerated. Only in such a scenario can AGN winds be important for cosmic feedback.

We present the results of a homogeneous X-ray analysis for 82 nearby low-ionisation, narrow emission-line regions (LINERs) selected from the catalogue of Carrillo et al. (1999, Rev. Mex. Astron. Astrofis., 35, 187). All sources have available Chandra (68 sources) and/or XMM-Newton (55 sources) observations. This is the largest sample of LINERs with X-ray spectral data (60 out of the 82 objects), and it significantly improves our previous analysis based on Chandra data for 51 LINERs (Gonzalez-Martin et al. 2006b, A&A, 460, 45). It both increases the sample size and adds XMM-Newton data. New models permit the inclusion of double absorbers in the spectral fits. Nuclear X-ray morphology is inferred from the compactness of detected nuclear sources in the hard band (4.5-8.0 keV). Sixty per cent of the sample shows a compact nuclear source and are classified as active galactic nucleus (AGN) candidates. The spectral analysis indicates that best fits involve a composite model: 1) absorbed primary continuum and 2) soft spectrum below 2 keV described by an absorbed scatterer and/or a thermal component. The resulting median spectral parameters and their standard deviations are Γ = 2.11 ± 0.52, kT = 0.54 ± 0.30 keV, log(NH1) = 21.32 ± 0.71 and log(NH2) = 21.93 ± 1.36. We complement our X-ray results with an analysis of HST optical images and literature data on emission lines, radio compactness, and stellar population. After adding all these multiwavelength data, we conclude that evidence supports the AGN nature of their nuclear engine for 80% of the sample (66 out of 82 objects).

Lyman-alpha (Lyα) is one of the dominant tools used to probe the star-forming galaxy population at high-redshift (z). However, astrophysical interpretations of data drawn from Lyα alone hinge on the Lyα escape fraction which, due to the complex radiative transport, may vary greatly. Here we map the Lyα emission from the local luminous blue compact galaxy Haro 11, a known emitter of Lyα and the only known candidate for low-z Lyman continuum emission (LyC). To aid in the interpretation we perform a detailed UV and optical multi-wavelength analysis and model the stellar population, dust distribution, ionising photon budget, and star-cluster population. We use archival X-ray observations to further constrain properties of the starburst and estimate the neutral hydrogen column density.The Lyα morphology is found to be largely symmetric around a single young star forming knot and is strongly decoupled from other wavelengths. From general surface photometry, only very slight correlation is found between Lyα and Hα, E(B − V ), and the age of the stellar population. Only around the central Lyα-bright cluster do we find the Lyα/Hα ratio at values predicted by recombination theory. The total Lyα escape fraction is found to be just 3%. We compute that ∼ 90% of the Lyα photons that escape do so after undergoing multiple resonance scattering events, masking their point of origin. This leads to a largely symmetric distribution and, by increasing the distance that photons must travel to escape, decreases the escape probability significantly. While dust must ultimately be responsible for the destruction of Lyα, it plays little role in governing the observed morphology, which is regulated more by ISM kinematics and geometry. We find tentative evidence for local Lyα equivalent width in the immediate vicinity of star-clusters being a function of cluster age, consistent with hydrodynamic studies. We estimate the intrinsic production of ionising photons and put further constraints of ∼ 9% on the escaping fraction of photons at 900Å.

We present a XMM-Newton observation of Markarian 304, a Seyfert 1 galaxy at z = 0.066. The EPIC data show that MKN 304 is affected by heavy (N H ≈ 10 23 cm −2 ) obscuration arising from ionized gas. A two-phase warm absorber provides an adequate parametrization of this gas. The ionization parameter of the two components is ξ ≈ 6 erg cm −2 s −1 and ξ ≈ 90 erg cm −2 s −1 , respectively. The observed continuum photon index ( ≈ 1.9) is typical for Seyfert 1 galaxies. Two significant emission lines are detected at 0.57 keV and 6.4 keV, respectively. The former is mostly likely due to He-like oxygen triplet emission arising from an ionized plasma (maybe the warm absorber itself). The latter is due to fluorescent emission of K-shell iron in a low-ionization state (Fe I-XV). The upper limit for the line width of σ K α < 0.18 keV most likely rules out an origin in the inner parts of the accretion disc. Interestingly, the strength of such line is consistent with the possibility that the emission is produced in the warm absorber itself. However, a substantial contribution from the torus is plausible too. We have also found a weak (4 per cent of the primary continuum) soft excess emission component. The presence of this excess could be explained by either emission/scattering from a warm gas or partial covering, or a combination of them.