Abstract. We present an X-ray spectral analysis of 21 low redshift quasars observed with XMM-Newton EPIC. All the sources are Palomar Green quasars with redshifts between 0.05 and 0.4 and have low Galactic absorption along the line-of-sight. A large majority of quasars in the sample (19/21) exhibit a significant soft excess below ∼1-1.5 keV, whilst two objects (PG 1114+445 and I Zw1) show a deficit of soft X-ray flux due to the presence of a strong warm absorber. Indeed, contrary to previous studies with ASCA and ROSAT, we find that the presence of absorption features near 0.6-1.0 keV is common in our sample. At least half of the objects appear to harbor a warm absorber, as found previously in Seyfert 1 galaxies. We find significant detections of Fe Kα emission lines in at least twelve objects, whilst there is evidence for some broadening of the line profile, compared to the EPIC-pn resolution, in five of these quasars. The determination of the nature of this broadening (e.g., Keplerian motion, a blend of lines, relativistic effects) is not possible with the present data and requires either higher S/N or higher resolution spectra. In seven objects the line is located between 6.7-7 keV, corresponding to highly ionized iron, whereas in the other five objects the line energy is consistent with 6.4 keV, i.e. corresponding to near neutral iron. The ionized lines tend to be found in the quasars with the steepest X-ray spectra. We also find a correlation between the continuum power law index Γ and the optical Hβ width, in both the soft and hard X-ray bands, whereby the steepest X-ray spectra are found in objects with narrow Hβ widths, which confirms previous ROSAT and ASCA results. The soft and hard band X-ray photon indices are also strongly correlated, i.e. the steepest soft X-ray spectra correspond the steepest hard X-ray spectra. We propose that a high accretion rate and a smaller black hole mass is likely to be the physical driver responsible for these trends, with the steep spectrum objects likely to have smaller black hole masses accreting near the Eddington rate.

Combining newly identiÐed and previously known BL Lacertae objects from the ROSAT All-Sky SurveyÈGreen Bank (RGB) catalog, we present a sample of 127 BL Lacertae objects, the largest ever derived from a single uniform survey. A complete sample of 33 objects brighter than O \ 18.0 mag is also presented. These samples are compared to other known BL Lac samples and are generally found to exhibit properties intermediate between those of the previously disparate classes of high-and lowenergyÈpeaked BL Lacertae objects (HBLs and LBLs, respectively). This result is most dramatic in the distribution of the X-ray to radio logarithmic Ñux ratios, where the RGB BL Lacertae objects are shown to peak precisely where the sharp dichotomy between the two subclasses was previously seen. The a ro versus diagram also shows the RGB sample smoothly bridges the gap between the previously distinct a ox subclasses of LBLs and HBLs. The range of broadband spectral energy distributions (SEDs) exhibited by the RGB objects also shows that, contrary to prior claims, searches based on relatively deep surveys cannot limit follow-up spectroscopy to targets with a narrow range of SEDs since BL Lacertae objects clearly constitute a homogeneous population with a wide range of SEDs. As in results based on the Einstein Extended Medium Sensitivity Survey (EMSS) and 1 Jy BL Lac samples, we Ðnd a weak but statistically signiÐcant correlation between the composite X-ray spectral index and the radio-optical a xox spectral index This implies that the more LBL-like RGB BL Lacertae objects have secondary a ro . sources of X-ray emission, possibly from inverse Compton components. This result, in addition to other characteristics of the RGB sample, indicates that the simple uniÐed scheme, which postulates that HBLs and LBLs di †er solely by orientation, may be in need of revision. We also present both the X-ray and radio log N-log S distributions for which the competing HBL/LBL uniÐcation scenarios have di †ering predictions. The unknown e †ects of the triple Ñux limit inherent in the RGB Complete sample makes quantitative analysis uncertain, but the characteristics of the RGB sample compare well both with results obtained from previous samples and with general theoretical predictions based on a simple Monte Carlo simulation. Our analysis indicates that the unimodal distribution of BL Lac properties found in the RGB sample likely reliably reÑects the underlying population, while the bimodal distribution found in earlier studies arose primarily from observational selection e †ects. The presence of not only intermediate but also extreme HBL and LBL objects is the RGB surveyÏs unique strength and o †ers clear avenues for future studies that can undoubtedly address the question of how HBLs and LBLs are related.

The X-ray spectra of SS 433 were measured with ASCA at a precession phase 0.48 when the Doppler-shifted iron lines from both the receding and approaching jets were clearly separated. The X-ray emission lines of SS 433 were analyzed on the basis of a numerical model of the radiatively cooling jets. The measured intensities of the iron-emission lines were compared with the results from numerical calculations in order to constrain the physical parameters of the jets, such as the temperature, mass outflow rate, density, and length. We also studied the emission lines from elements with smaller atomic number, and found that these lines were heavily absorbed only in the receding jet. This implies the existence of absorbing gas in a precessing plane perpendicular to the jets.

Results are presented on the X-ray properties of 9 high-redshift (1.2 < z < 3.4) radio-loud quasars (RLQs) observed by ASCA (10 observations) and ROSAT (11 observations, for a subset of 6 quasars). New ASCA observations of S5 0014+81 (z = 3.38) and S5 0836+71 (z = 2.17) and ROSAT observations of PKS 2126-158 for which results were never presented elsewhere, are included.A simple model consisting of a power law plus cold, uniform absorption gives acceptable fits to the spectra of all sources. The ASCA spectra of the 6 brightest objects show evidence for absorption in excess of the Galactic value at a ≫ 99% confidence level. Comparison with the ROSAT data suggests that absorption has significantly varied (∆N H ∼ 8 × 10 20 cm −2 ) in the case of S5 0836+71, on a time-scale of ∼ 0.8 yr in the quasar frame. For the remaining 5 sources for which ROSAT spectra were available, the two instruments gave consistent results and the data were combined yielding unprecedent spectral coverage (typically ∼ 0.4-40 keV in the quasar frame) for high-z quasars. This allows to put severe limits on several different descriptions of the continuum (e.g. broken power law, bremsstrahlung, reflection component). No Fe Kα emission line is detected in any of the ASCA spectra. An absorption edge consistent with Fe Kα at the quasar redshift is marginally detected in S5 0014+81. Possible origins for the observed low energy absorption are discussed. In particular, contributions from the molecular clouds and dust present in our Galaxy (usually disregarded) are carefully considered. In the light of the new results for S5 0836+71 and S5 0014+81, absorption intrinsic to the quasars is considered and discussed.The average slope obtained from the 8 ASCA spectra in the observed ∼ 0.5-10 keV energy band is < Γ 0.5−10keV > ≃ 1.61 ± 0.04, with a dispersion σ 0.5−10keV ≃ 0.10 ± 0.03. The average photon index in the observed 2-10 keV band, where the effect of absorption is negligible, is < Γ 2−10keV > ≃ 1.53 ± 0.05, with a dispersion σ 2−10keV < ∼ 0.12. Furthermore, the implications of the present results on the calculations of the contribution of quasars to the cosmic X-and γ-ray backgrounds (XRB and GRB) are briefly discussed.