XMM-Newton RGS observations of active galaxies. G Branduardi-Raymont 1* , J Blustin 1 , J Kaastra 2 , A Brinkman 2 , E Behar 3 , S Kahn 3 & M Sako 4. 1 MSSL, Holmbury St. Mary, Dorking, Surrey RH5 6NT, UK 2 SRON, Sorbonnelaan 2, 3584 CA Utrecht, Netherlands
G Branduardi-Raymont1*, J Blustin1, J Kaastra2, A Brinkman2, E Behar3,
S Kahn3 & M Sako4
1 MSSL, Holmbury St. Mary, Dorking, Surrey RH5 6NT, UK
2 SRON, Sorbonnelaan 2, 3584 CA Utrecht, Netherlands
3 Columbia University, New York, NY 10027, USA
4 Caltech, Pasadena, CA 91125, USA
We present and compare the XMM-Newton RGS spectra of four active galaxies (ranging from a Narrow Line Seyfert 1 to a Seyfert 1.9) which vividly illustrate the variety of characteristics revealed for the first time by high resolution grating spectroscopy coupled with a large collecting area.
High resolution soft X-ray spectra of Seyfert galaxies are generally found to display much weaker absorption edges than expected on the basis of the 'classical' warm absorber interpretation; the broad-band features which were thought to be edges are now resolved into a multitude of narrow absorption lines, which offer a powerful diagnostic tool of the physical properties of the gas surrounding the nucleus. Emission features are also observed, some narrow, most probably associated with the warm absorber, and some broad, which have been explained, with some controversy, in terms of emission from a relativistic disk around a spinning black hole (the alternative, that of a 'dusty warm absorber', does not provide an adequate representation of the RGS data).
Markarian 766 is one of only two Narrow Line Seyfert 1 galaxies (the other being MCG -6-30-15) which have shown evidence for relativistic line emission in their RGS spectra (the broad 'humps' peaking at ~ 18, 24 and 33 angstroms, corresponding to OVIII, NVII and CVI Lya emission respectively). We also see clear signatures of warm absorption in this spectrum: in particular, we distinguish two gas phases, with the cooler of the two giving rise to an Unresolved Transition Array (UTA) of Fe M-shell ions (Mason et al., and poster by Ogle et al., this conference).
The RGS spectrum of the Seyfert 1.2 galaxy NGC 7469 displays a very different kind of warm absorber to that found in NGC 3783: the hot phase is hotter (x ~ 3, compared with x = 2.4 in NGC 3783), and the weaker UTA may indicate that Fe, in this case, is not overabundant as in NGC 3783. We also see narrow absorption lines in the RGS spectrum from ions which absorb in both the UV and the X-ray regimes: they allow unambiguous connections to be made between X-ray and UV warm absorbers. This object will be a prime target for future studies of how the absorption seen in UV spectra of AGN is related to that in soft X-rays.
The RGS spectrum of this Seyfert 1 galaxy is discussed in detail in the poster by Blustin et al., this conference. This galaxy is seen to possess the strongest warm absorber and UTA yet, but no, or only very weak, edges are observed. The RGS spectrum of the nucleus shows strong signatures of absorption by a two-phase ionised gas flowing out of the centre of the galaxy at ~1000 km s-1. The high resolution of the RGS enables us to examine the temperature structure, elemental composition and density of this gas at an unprecedented level of spectroscopic detail.
NGC 7314 has a Seyfert 1.9 nucleus at its centre. RGS spectroscopy shows a heavily absorbed continuum (represented by the absorbed power-law model, in red) with some evidence of line emission (e.g. the OVII forbidden line at ~ 22 angstroms, suggesting an origin in a warm photoionised region). Detailed spectroscopic comparison of this and similar galaxies with other Seyferts will be a powerful test of unification scenarios.