Exploring X-ray emission and absorption in AGN with XMM-Newton EPIC

Exploring X-ray emission and absorption in AGN with XMM-Newton EPI

Is the X-ray spectrum of the narrow emission line QSO PG1211+143 defined by its energetic outflow?

An XMM–Newton observation of the bright QSO PG1211+143 in 2001 revealed a blueshifted absorption line spectrum indicative of a high-velocity radial outflow of highly ionized gas. Unless highly collimated, the outflow mass rate was shown to be comparable to the accretion rate, with mechanical energy a significant fraction of the bolometric luminosity. Analysis of the full XMM–Newton data set now allows the wider effects of that energetic outflow to be explored.We find that absorption and re-emission of the primary continuum flux in the ionized outflow, together with a second, less strongly absorbed, continuum component can explain the strong ‘soft excess’ in PG1211+143 without the extreme velocity ‘smearing’ in conflict with observed absorption line widths. Previously unpublished data from a second XMM–Newton observation of PG1211+143 is shown to be consistent with the new spectral model, finding that the additional continuum component dominates the spectral variability.We speculate that this variable continuum component is powered by the high-velocity outflow

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

The Variable Fast Soft X-Ray Wind in PG 1211+143

The analysis of a series of seven observations of the nearby (z = 0.0809) QSO PG 1211+143, taken with the Reflection Grating Spectrometer (RGS) onboard XMM-Newton in 2014, are presented. The high-resolution soft X-ray spectrum, with a total exposure exceeding 600 ks, shows a series of blueshifted absorption lines from the He and H-like transitions of N, O, and Ne, as well as from L-shell Fe. The strongest absorption lines are all systematically blueshifted by −0.06c, originating in two absorption zones from low- and high-ionization gas. Both zones are variable on timescales of days, with the variations in absorber opacity effectively explained by either column density changes or the absorber ionization responding directly to the continuum flux. We find that the soft X-ray absorbers probably exist in a two-phase wind at a radial distance of ∼1017–1018 cm from the black hole with the lower-ionization gas as denser clumps embedded within a higher-ionization outflow. The overall mass outflow rate of the soft X-ray wind may be as high as 2M yr−1 , close to the Eddington rate for PG 1211+143 and similar to that previously deduced from the Fe K absorption

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

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

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 signature of supernova ejecta in the X-ray afterglow of the gamma-ray burst 011211

Now that γ-ray bursts (GRBs) have been determined to lie at cosmological distances, their isotropic burst energies are estimated to be as high as 10[superscript 54] erg (ref. 2), making them the most energetic phenomena in the Universe. The nature of the progenitors responsible for the bursts remains, however, elusive. The favoured models range from the merger of two neutron stars in a binary system[superscript 3-5] to the collapse of a massive star[superscript 6-8]. Spectroscopic studies of the afterglow emission could reveal details of the environment of the burst, by indicating the elements present, the speed of the outflow and an estimate of the temperature. Here we report an X-ray spectrum of the afterglow of GRB011211, which shows emission lines of magnesium, silicon, sulphur, argon, calcium and possibly nickel, arising in metal-enriched material with an outflow velocity of the order of one-tenth the speed of light. These observations strongly favour models[superscript 30] where a supernova explosion from a massive stellar progenitor precedes the burst event and is responsible for the outflowing matter