An XMM-Newton observation of Mkn 3 - a Seyfert galaxy just over the edge

A 100-ks XMM–Newton observation of the nearby Seyfert 2 galaxy Mkn 3 offers a unique opportunity to explore the complexity of its X-ray spectrum. We find the ∼3–8 keV continuum to be dominated by reflection from cold matter, with fluorescent K-shell lines detected from Ni, Fe, Ca, Ar, S, Si and Mg. At higher energies an intrinsic power-law continuum, with canonical Seyfert 1 photon index, is seen through a near-Compton-thick cold absorber. A soft excess below ∼3 keV is found to be dominated by line emission from an outflow of ‘warm’ gas, photoionized and photoexcited by the intrinsically strong X-ray continuum. Measured blueshifts in the strong Fe Kα and OVII and OVIII emission lines are discussed in terms of the properties of the putative molecular torus and ionized outflow

X-ray absorption and re-emission from an ionized outflow in the Type I quasi-stellar object 2MASS 234449+1221 observed by XMM-Newton

We report on the analysis of a short XMM–Newton observation of the reddened Type 1 quasistellar object (QSO) 2MASS 234449+1221 first identified in the Two-Micron All-Sky Survey (2MASS). The underlying X-ray continuum is found to be typical of a broad-line active galaxy, with photon index Γ ∼ 1.9. Low-energy absorption can be modelled by a column NH ∼ 10²² cm−² of moderately ionized gas or a smaller column of cold gas. Addition of a soft X-ray emission component significantly improves the fit in both cases. With the assumption that the soft X-ray flux represents emission from gas photoionized by the incident X-ray continuum, a comparison of the absorbed and emitted luminosities indicates a covering factor of ∼8–17 per cent. The unusual opportunity simultaneously to observe and quantify ionized absorption and emission in 2MASS 234449+1221 is due to the relatively large opacity – for a Type 1 active galactic nucleus (AGN) – of the absorbing gas, which depresses the normally strong continuum below ∼1 keV. A comparison of the soft X-ray emission of 2MASS 234449+1221 with that of other Type 1 and Type 2AGNs suggests the existence of an inner turbulent extension to ionized outflows, not detected in current high-resolution X-ray spectra

XMM–Newton observations of seven soft X-ray excess quasi-stellar objects

XMM–Newton observations of seven quasi-stellar objects (QSOs) are presented and the EPIC spectra analysed. Five of the active galactic nuclei (AGN) show evidence for Fe Kα emission, with three being slightly better fitted by lines of finite width; at the 99 per cent level they are consistent with being intrinsically narrow, though. The broad-band spectra can be well modelled by a combination of different temperature blackbodies (BBs) with a power law, with temperatures between kT ∼ 100 and 300 eV. On the whole, these temperatures are too high to be direct thermal emission from the accretion disc, so a Comptonization model was used as a more physical parametrization. The Comptonizing electron population forms the soft excess emission, with an electron temperature of ∼120–680 eV. Power-law, thermal plasma and disc BB models were also fitted to the soft X-ray excess. Of the sample, four of the active galactic nuclei are radio quiet and three radio loud. The radio-quiet QSOs may have slightly stronger soft excesses, although the electron temperatures cover the same range for both groups

An X-ray Baldwin effect for the narrow Fe Kα lines observed in active galactic nuclei

The majority of active galactic nuclei (AGN) observed by XMM–Newton reveal narrow Fe Kα lines at ∼6.4 keV, due to emission from cold (neutral) material. There is an X-ray Baldwin effect in type I AGN, in that the equivalent width (EW) of the line decreases with increasing luminosity, with weighted linear regression giving EW∝ L[superscript −0.17±0.08] (Spearman Rank probability of >99.9 per cent).With current instrumental capabilities it is not possible to determine the precise origin for the narrow line, with both the broad-line region and putative molecular torus being possibilities. A possible explanation for the X-ray Baldwin effect is a decrease in the covering factor of the material forming the fluorescence line

Evidence of a high-velocity ionized outflow in a second narrow-line quasar PG 0844+349

Following the discovery of X-ray absorption in a high-velocity outflow from the bright quasar PG 1211 + 143 we have searched for similar features in XMM–Newton archival data of a second (high accretion rate) quasar PG 0844+349. Evidence is found for several faint absorption lines in both the EPIC and RGS spectra, whose most likely identification with resonance transitions in H-like Fe, S and Ne implies an origin in highly ionized matter with an outflow velocity of order ~0.2c. The line equivalent widths require a line-of-sight column density of NH ~4 × 10²³ cm², at an ionization parameter of log ξ ~3.7. Assuming a radial outflow being driven by radiation pressure from the inner accretion disc, as suggested previously for PG 1211 + 143, the flow in PG 0844+349 is also likely to be optically thick, in this case within ~25 Schwarzschild radii. Our analysis suggests that a high-velocity, highly ionized outflow is likely to be a significant component in the mass and energy budgets of active galactic nuclei accreting at or above the Eddington rate

XMM-Newton spectroscopy of high-redshift quasars

XMM–Newton observations of 29 high-redshift (z > 2) quasars, including seven radio-quiet, 16 radio-loud and six broad absorption line (BAL) objects, are presented; due to the high redshifts, the rest-frame energy bands extend up to ∼30–70 keV. Over 2–10 keV, the quasars can be well fitted in each case by a simple power law, with no strong evidence for iron emission lines. The lack of iron lines is in agreement both with dilution by the radio jet emission (for the radio-loud quasars) and the X-ray Baldwin effect. No Compton reflection humps at higher energies (i.e. above 10 keV in the rest frame) are detected either. Over the broad-band (0.3–10 keV), approximately half (nine out of 16) of the radio-loud quasars are intrinsically absorbed, with the values of N[subscript H] generally being 1 × 10²² to 2 × 10²² cm[superscript -]² in the rest frames of the objects. None of the seven radio-quiet objects shows excess absorption, while four of the six BAL quasars are absorbed. The radio-loud quasars have flatter continuum slopes than their radio-quiet counterparts (Γ[subscript RL] ∼ 1.55; Γ[subscript RQ] ∼ 1.98 over 2–10 keV), while, after modelling the absorption, the underlying photon index for the six BAL quasars is formally consistent with the non-BAL radio-quiet objects

Serendipitous active galactic nuclei in the XMM–Newton fields of Markarian 205 and QSO 0130−403

The X-ray spectra of serendipitously observed active galactic nuclei (AGN) in the XMM–Newton fields of Mrk 205 and QSO 0130−403 are analysed. The sample consists of 23 objects, none of which is detected at radio frequencies, with a median X-ray luminosity of ∼4 × 10[superscript 44] erg s[superscript −1] and redshifts ranging from ∼0.1 to just over 3. The mean photon index was found to be 1.89 ± 0.04. In contrast with past ASCA and ROSAT observations of high-redshift radio-loud quasars, we find little evidence for excess intrinsic absorption in these radio-quiet objects, with only three sources requiring a column density in excess of the Galactic value. Comparing the measured spectral indices over the redshift range, we also find there is no X-ray spectral evolution of quasi-stellar objects (QSOs) with time, up to redshift of 3. Within the sample there is no evidence for evolution of the optical to X-ray spectral index, α[subscript ox], with redshift, the mean value being −1.66 ± 0.04. However, upon comparing the values from the Bright Quasar Survey at low redshift (z 4), a slight steepening of αox is noted for the more distant objects. In most of the sources there is no significant requirement for a soft excess, although a weak thermal component (⩽ 10 per cent of L[subscript X]) cannot be excluded. There is an indication of spectral flattening (by ΔΓ = 0.2) at higher energies (>3 keV, QSO rest frame) for the sample as a whole. This is consistent with the presence of a Compton reflection component in these radio-quiet AGN, with the scattering medium (such as an accretion disc or molecular torus) occupying a solid angle of 2π sr to the X-ray source

Fe K emission and absorption features in XMM-Newton spectra of Markarian 766: evidence for reprocessing in flare ejecta

We report on the analysis of a long XMM–Newton European Photon Imaging Camera (EPIC) observation in 2001 May of the narrow-line Seyfert 1 galaxy Markarian 766 (Mrk 766). The 3–11 keV spectrum exhibits a moderately steep power-law continuum, with a broad emission line at 6.7 keV, probably blended with a narrow line at 6.4 keV, and a broad absorption trough above 8.7 keV. We identify both broad spectral features with reprocessing in He-like Fe. An earlier XMM–Newton observation of Mrk 766 in 2000 May, when the source was a factor 2 fainter, shows a similar broad emission line, but with a slightly flatter power law and absorption at a lower energy. In neither observation do we find a requirement for the previously reported broad 'red wing' to the line and hence of reflection from the innermost accretion disc. More detailed examination of the longer XMM–Newton observation reveals evidence for rapid spectral variability in the Fe K band, apparently linked with the occurrence of X-ray 'flares'. A reduction in the emission line strength and increased high-energy absorption during the X-ray flaring suggests that these transient effects are due to highly ionized ejecta associated with the flares. Simple scaling from the flare avalanche model proposed for the luminous quasi-stellar object PDS 456 confirms the feasibility of coherent flaring being the cause of the strong peaks seen in the X-ray light curve of Mrk 766

A high-velocity ionized outflow and XUV photosphere in the narrow emission line quasar PG1211+143

We report on the analysis of a 60-ks XMM–Newton observation of the bright, narrow emission line quasar PG1211+143. Absorption lines are seen in both European Photon Imaging Camera and Reflection Grating Spectrometer spectra corresponding to H- and He-like ions of Fe, S, Mg, Ne, O, N and C. The observed line energies indicate an ionized outflow velocity of 24 000 km s1. The highest energy lines require a column density of NH 5 × 1023 cm2, at an ionization parameter of log ξ 3.4. If the origin of this high-velocity outflow lies in matter being driven from the inner disc, then the flow is likely to be optically thick within a radius of 130 Schwarzschild radii, providing a natural explanation for the big blue bump (and strong soft X-ray) emission in PG1211+143

THE 7.1 HR X-RAY-ULTRAVIOLET-NEAR-INFRARED PERIOD OF THE gamma-RAY CLASSICAL NOVA MONOCEROTIS 2012

Nova Monocerotis 2012 is the third γ-ray transient identified with a thermonuclear runaway on a white dwarf, that is, a nova event. Swift monitoring has revealed the distinct evolution of the harder and super-soft X-ray spectral components, while Swift-UV and V- and I-band photometry show a gradual decline with subtle changes of slope. During the super-soft emission phase, a coherent 7.1 hr modulation was found in the soft X-ray, UV, optical, and near-IR data, varying in phase across all wavebands. Assuming this period to be orbital, the system has a near-main-sequence secondary, with little appreciable stellar wind. This distinguishes it from the first GeV nova, V407 Cyg, where the γ-rays were proposed to form through shock-accelerated particles as the ejecta interacted with the red giant wind. We favor a model in which the γ-rays arise from the shock of the ejecta with material close to the white dwarf in the orbital plane. This suggests that classical novae may commonly be GeV sources. We ascribe the orbital modulation to a raised section of an accretion disk passing through the line of sight, periodically blocking and reflecting much of the emission. The disk must therefore have reformed by day 150 after outburst