We report the discovery of a luminosity distance estimator using Active Galactic Nuclei (AGN). We combine the correlation between the X-ray variability amplitude and the Black Hole (BH) mass with the single epoch spectra BH mass estimates which depen
d on the AGN luminosity and the line width emitted by the broad line region. We demonstrate that significant correlations do exist which allows one to predict the AGN (optical or X-ray) luminosity as a function of the AGN X-ray variability and either the HBeta or the PaBeta line widths. In the best case, when the PaBeta is used, the relationship has an intrinsic dispersion of ~0.6 dex. Although intrinsically more disperse than Supernovae Ia, this relation constitutes an alternative distance indicator potentially able to probe, in an independent way, the expansion history of the Universe. With this respect, we show that the new mission concept Athena should be able to measure the X-ray variability of hundreds of AGN and then constrain the distance modulus with uncertainties of 0.1 mag up to z~0.6. We also discuss how, using a new dedicated wide field X-ray telescope able to measure the variability of thousands of AGNs, our estimator has the prospect to become a cosmological probe even more sensitive than current Supernovae Ia samples.
In about half of Seyfert galaxies, the X-ray emission is absorbed by an optically thin, ionized medium, the so-called Warm Absorber, whose origin and location is still a matter of debate. The aims of this paper is to put more constraints on the warm
absorber by studying its variability. We analyzed the X-ray spectra of a Seyfert 1 galaxy, Mrk 704, which was observed twice, three years apart, by XMM-Newton. The spectra were well fitted with a two zones absorber, possibly covering only partially the source. The parameters of the absorbing matter - column density, ionization state, covering factor - changed significantly between the two observations. Possible explanations for the more ionized absorber are a torus wind (the source is a polar scattering one) or, in the partial covering scenario, an accretion disk wind. The less ionized absorber may be composed of orbiting clouds in the surroundings of the nucleus, similarly to what already found in other sources, most notably NGC 1365.
We are carrying out a search for all radio loud Active Galactic Nuclei observed with XMM-Newton, including targeted and field sources to perform a multi-wavelength study of these objects. We have cross-correlated the Veron-Cetty & Veron (2010) catalo
gue with the XMM-Newton Serendipitous Source Catalogue (2XMMi) and found about 4000 matched sources. A literature search provided radio, optical, and X-ray data for 403 sources. Here we summarize the first results of our study.
We present a detailed analysis of the XMM-Newton RGS high resolution X-ray spectra of the Seyfert 2 galaxy, Mrk573. This analysis is complemented by the study of the Chandra image, and its comparison to optical (HST) and radio (VLA) data. The soft X-
ray emission is mainly due to gas photoionised by the central AGN, as indicated by the detection of radiative recombination continua from OVII and OVIII, as well as by the prominence of the OVII forbidden line. This result is confirmed by the best fit obtained with a self-consistent CLOUDY photoionisation model. However, a collisionally excited component is also required, in order to reproduce the FeXVII lines, accounting for about 1/3 of the total luminosity in the 15-26 A band. Once adopted the same model in the Chandra ACIS data, another photoionised component, with higher ionisation parameter, is needed to take into account emission from higher Z metals. The broadband ACIS spectrum also confirms the Compton-thick nature of the source. The imaging analysis shows the close morphological correspondence between the soft X-ray and the [OIII] emission. The radio emission appears much more compact, although clearly aligned with the narrow line region. The collisional phase of the soft X-ray emission may be due to starburst, requiring a star formation rate of $simeq5-9$ M$_odot$ yr$^{-1}$, but there is no clear evidence of this kind of activity from other wavelengths. On the other hand, it may be related to the radio ejecta, responsible for the heating of the plasma interacting with the outflow, but the estimated pressure of the hot gas is much larger than the pressure of the radio jets, assuming equipartition and under reasonable physical parameters.
