IRAS 13197-1627 has them all: Compton-thin absorption, photo-ionized gas, thermal plasmas, and a broad Fe line

We report results from the XMM-Newton observation of IRAS 13197-1627, a luminous IR galaxy with a Seyfert 1.8 nucleus. The hard X-ray spectrum is steep and is absorbed by Compton-thin neutral gas. We detect an Fe emission line at 6.4 keV, consistent with transmission through the absorber. The most striking result of our spectral analysis is the detection of a dominant X-ray reflection component and broad Fe line from the inner accretion disc. The reflection-dominated hard X-ray spectrum is confirmed by the strong Compton hump seen in a previous BeppoSAX observation and could be the sign that most of the primary X-rays are radiated from a compact corona (or e.g. base of the jet) within a few gravitational radii from the black hole. We also detect a relatively strong absorption line at 6.81 keV which, if interpreted as Fe xxv resonant absorption intrinsic to the source, implies an outflow with velocity of about 5000 km/s. In the soft energy band, the high-resolution RGS and the CCD-resolution data show the presence of both photo-ionized gas and thermal plasma emission, the latter being most likely associated with a recent starburst of 15-20 solar masses per year.Comment: accepted for publication in MNRA

XMM-Newton unveils the type 2 nature of the BLRG 3C 445

We present an observation of XMM-Newton that unambiguously reveals the ``Seyfert 2'' nature of the Broad Line Radio Galaxy 3C 445. For the first time the soft excess of this source has been resolved. It consists of unobscured scattered continuum flux and emission lines, likely produced in a warm photoionized gas near the pole of an obscuring torus. The presence of circumnuclear (likely stratified) matter is supported by the complex obscuration of the nuclear region. Seventy percent of the nuclear radiation (first component) is indeed obscured by a column density ~4*10^{23} cm^{-2}, and 30 % (second component) is filtered by ~7* 10^{22} cm^{-2}. The first component is nuclear radiation directly observed by transmission through the thicker regions. The second one is of more uncertain nature. If the observer has a deep view into the nucleus but near the edge of the torus, it could be light scattered by the inner wall of the torus and/or by photoionized gas within the Broad Line Region observed through the thinner rim of the circumnuclear matter.Comment: MNRAS Letters, in pres

A connection between accretion state and Fe K absorption\textit{Fe K absorption} in an accreting neutron star: black hole-like soft state winds?

High resolution X-ray spectra of accreting stellar mass Black Holes reveal the presence of accretion disc winds, traced by high ionisation Fe K lines. These winds appear to have an equatorial geometry and to be observed only during disc dominated states in which the radio jet is absent. Accreting neutron star systems also show equatorial high ionisation absorbers. However, the presence of any correlation with the accretion state has not been previously tested. We have studied EXO 0748-676, a transient neutron star system, for which we can reliably determine the accretion state, in order to investigate the Fe K absorption/accretion state/jet connection. Not one of twenty X-ray spectra obtained in the hard state revealed any significant Fe K absorption line. However, intense Fe ${\scriptsize{\rm XXV}}$ and Fe ${\scriptsize{\rm XXVI}}$ (as well as a rarely observed Fe ${\scriptsize{\rm XXIII}}$ line plus S ${\scriptsize{\rm XVI}}$; a blend of S ${\scriptsize{\rm XVI}}$ and Ar ${\scriptsize{\rm XVII}}$; Ca ${\scriptsize{\rm XX}}$ and Ca ${\scriptsize{\rm XIX}}$, possibly produced by the same high ionisation material) absorption lines ($EW_{\rm Fe~{XXIII-XXV}}=31\pm3$ eV, $EW_{\rm Fe~XXVI}=8\pm3$ eV) are clearly detected during the only soft state observation. This suggests that the connection between Fe K absorption and states (and anticorrelation between the presence of Fe K absorption and jets) is also valid for EXO 0748-676 and therefore it is not a unique property of black hole systems but a more general characteristic of accreting sources.Comment: Accepted for publication in MNRAS Letter

Constraints on a strong X-ray flare in the Seyfert galaxy MCG-6-30-15

We discuss implications of a strong flare event observed in the Seyfert galaxy MCG-6-30-15 assuming that the emission is due to localized magnetic reconnection. We conduct detailed radiative transfer modeling of the reprocessed radiation for a primary source that is elevated above the disk. The model includes relativistic effects and Keplerian motion around the black hole. We show that for such a model setup the observed time-modulation must be intrinsic to the primary source. Using a simple analytical model we then investigate time delays between hard and soft X-rays during the flare. The model considers an intrinsic delay between primary and reprocessed radiation, which measures the geometrical distance of the flare source to the reprocessing sites. The observed time delays are well reproduced if one assumes that the reprocessing happens in magnetically confined, cold clouds.Comment: 4 pages, 2 figures, proceedings of a talk given at the symposium 238 at the IAU General Assembly 200

Polarization and long-term variability of Sgr A* X-ray echo

We use a model of the molecular gas distribution within ~100 pc from the center of the Milky Way (Kruijssen, Dale & Longmore) to simulate time evolution and polarization properties of the reflected X-ray emission, associated with the past outbursts from Sgr A*. While this model is too simple to describe the complexity of the true gas distribution, it illustrates the importance and power of long-term observations of the reflected emission. We show that the variable part of X-ray emission observed by Chandra and XMM from prominent molecular clouds is well described by a pure reflection model, providing strong support of the reflection scenario. While the identification of Sgr A* as a primary source for this reflected emission is already a very appealing hypothesis, a decisive test of this model can be provided by future X-ray polarimetric observations, that will allow placing constraints on the location of the primary source. In addition, X-ray polarimeters (like, e.g., XIPE) have sufficient sensitivity to constrain the line-of-sight positions of molecular complexes, removing major uncertainty in the model.Comment: 17 pages, 10 figures, accepted for publication in MNRA

Can Sgr A* flares reveal the molecular gas density PDF?

Illumination of dense gas in the Central Molecular Zone (CMZ) by powerful X-ray flares from Sgr A* leads to prominent structures in the reflected emission that can be observed long after the end of the flare. By studying this emission we learn about past activity of the supermassive black hole in our Galactic Center and, at the same time, we obtain unique information on the structure of molecular clouds that is essentially impossible to get by other means. Here we discuss how X-ray data can improve our knowledge of both sides of the problem. Existing data already provide: i) an estimate of the flare age, ii) a model-independent lower limit on the luminosity of Sgr A* during the flare and iii) an estimate of the total emitted energy during Sgr A* flare. On the molecular clouds side, the data clearly show a voids-and-walls structure of the clouds and can provide an almost unbiased probe of the mass/density distribution of the molecular gas with the hydrogen column densities lower than few $10^{23}\;{\rm cm^{-2}}$. For instance, the probability distribution function of the gas density $PDF(\rho)$ can be measured this way. Future high energy resolution X-ray missions will provide the information on the gas velocities, allowing, for example a reconstruction of the velocity field structure functions and cross-matching the X-ray and molecular data based on positions and velocities.Comment: 13 pages, 7 figures; Accepted for publication in MNRA

Not that long time ago in the nearest galaxy: 3D slice of molecular gas revealed by a 110 years old flare of Sgr A*

A powerful outburst of X-ray radiation from the supermassive black hole Sgr A* at the center of the Milky Way is believed to be responsible for the illumination of molecular clouds in the central ~100 pc of the Galaxy (Sunyaev et al., 1993, Koyama et al., 1996). The reflected/reprocessed radiation comes to us with a delay corresponding to the light propagation time that depends on the 3D position of molecular clouds with respect to Sgr A*. We suggest a novel way of determining the age of the outburst and positions of the clouds by studying characteristic imprints left by the outburst in the spatial and time variations of the reflected emission. We estimated the age of the outburst that illuminates the Sgr A molecular complex to be ~110 yr. This estimate implies that we see the gas located ~10 pc further away from us than Sgr A*. If the Sgr B2 complex is also illuminated by the same outburst, then it is located ~130 pc closer than our Galactic Center. The outburst was short (less than a few years) and the total amount of emitted energy in X-rays is $\displaystyle \sim 10^{48}\rho_3^{-1}$ erg, where $\rho_3$ is the mean hydrogen density of the cloud complex in units of $10^3 {\rm cm^{-3}}$. Energetically, such fluence can be provided by a partial tidal disruption event or even by a capture of a planet. Further progress in more accurate positioning and timing of the outburst should be possible with future X-ray polarimetric observations and long-term systematic observations with Chandra and XMM-Newton. A few hundred-years long X-ray observations would provide a detailed 3D map of the gas density distribution in the central $\sim 100$ pc region.Comment: 10 pages, 7 figures, accepted for publication in MNRA