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See detailPolarimetric view of the changing type Seyfert galaxy ESO 362-G018.
Agis-Gonzalez, Beatriz ULiege; Bagnulo, S.; Hutsemekers, Damien ULiege et al

in Highlights on Spanish Astrophysics IX (2017, March 01)

ESO362-G018 is an active galactic nucleus (AGN) which is classified as a Seyfert 1.5 galaxy e.g. by Bennert et al. (2006), (black data set on figure 1). However, Parisi et. al (2009) found an optical ... [more ▼]

ESO362-G018 is an active galactic nucleus (AGN) which is classified as a Seyfert 1.5 galaxy e.g. by Bennert et al. (2006), (black data set on figure 1). However, Parisi et. al (2009) found an optical spectrum of this source which was taken during the 6dF Galaxy Survey, but it does not show the broad Balmer lines required to classify it as Seyfert 1 galaxy (red data set on figure 1). On the other hand, the results obtained by Agis-Gonzalez et al. (2014❩ in a X-ray analysis of this same source reveal that the inclination of ESO362- G018 i = 53° ± 5° is consistent with the picture of an AGN looked through the upper layers of a clumpy, dusty torus. Thus, according to the Unification Models of AGN and the clumpy nature of the torus, our interpretation of the different spectra is the following one. On 30th of January of 2003 (when the spectrum belonging to the 6dF survey was obtained), our line of sight intercepted a (or several aligned) torus clump(s) with much greater column density than its environment. Accordingly, the nucleus and the broad line region (❨BLR)❩ would be obscured. This allowed only the narrow emission lines to emerge from the narrow line region (NRL). Otherwise, on 18th of September of 2004 (when the spectrum by Bennert et al. 2006 was obtained) there is no clump to intercept and the BLR is not obscured so that the broad Balmer emission lines could be detected. [less ▲]

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See detailEclipsing the innermost accretion disc regions in AGN
Sanfrutos, M.; Miniutti, G.; Dovčiak, M. et al

in Astronomische Nachrichten (2016), 337

Variable X-ray absorption has been observed in active galactic nuclei (AGN) on several time scales. Observations allow us to identify the absorber with clouds associated either with the clumpy torus ... [more ▼]

Variable X-ray absorption has been observed in active galactic nuclei (AGN) on several time scales. Observations allow us to identify the absorber with clouds associated either with the clumpy torus (parsec scales, long timescales) or with the broad line region (BLR) (short timescales). In the latter, the cloud size has been estimated to be of the order of few gravitational radii from the observed absorption variability. Such small cloud sizes are comparable to the X-ray emitting regions so that a detailed modeling of occultation events in AGN has the potential of enabling us to infer accurately the geometry of the system. We have developed a relativistic X-ray spectral model for occultation events and we present here theoretical predictions on the different observables that can be inferred by studying X-ray eclipses in simulated XMM-Newton data. These include the size of the X-ray emitting regions as well as more fundamental parameters such as the black hole spin and the system inclination. We find that absorption varies as a function of the energy range and that its maximum takes place when the approaching part of the accretion disc is covered. Therefore we study the hard-to-soft (H / S) ratio light curves produced during an eclipse and use them to characterise the properties of the inner accretion disc in a new model-independent way. [less ▲]

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See detailThe ionized X-ray outflowing torus in ESO 323-G77: low-ionization clumps confined by homogeneous warm absorbers
Sanfrutos, M.; Miniutti, G.; Krongold, Y. et al

in Monthly Notices of the Royal Astronomical Society (2016), 457

We report on the long- and short-term X-ray spectral analysis of the polar-scattered Seyfert 1.2 galaxy ESO 323-G77, observed in three epochs between 2006 and 2013 with Chandra and XMM-Newton. Four high ... [more ▼]

We report on the long- and short-term X-ray spectral analysis of the polar-scattered Seyfert 1.2 galaxy ESO 323-G77, observed in three epochs between 2006 and 2013 with Chandra and XMM-Newton. Four high-resolution Chandra observations give us a unique opportunity to study the properties of the absorbers in detail, as well as their short time-scale (days) variability. From the rich set of absorption features seen in the Chandra data, we identify two warm absorbers with column densities and ionizations that are consistent with being constant on both short and long time-scales, suggesting that those are the signatures of a rather homogeneous and extended outflow. A third absorber, ionized to a lesser degree, is also present and it replaces the strictly neutral absorber that is ubiquitously inferred from the X-ray analysis of obscured Compton-thin sources. This colder absorber appears to vary in column density on long time-scales, suggesting a non-homogeneous absorber. Moreover, its ionization responds to the nuclear luminosity variations on time-scales as short as a few days, indicating that the absorber is in photoionization equilibrium with the nuclear source on these time-scales. All components are consistent with being co-spatial and located between the inner and outer edges of the so-called dusty, clumpy torus. Assuming co-spatiality, the three phases also share the same pressure, suggesting that the warm / hot phases confine the colder, most likely clumpy, medium. We discuss further the properties of the outflow in comparison with the lower resolution XMM-Newton data. [less ▲]

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See detailBlack hole spin and size of the X-ray-emitting region(s) in the Seyfert 1.5 galaxy ESO 362-G18
Agis-Gonzalez, Beatriz ULiege; Miniutti, G.; Kara, E. et al

in Monthly Notices of the Royal Astronomical Society (2014), 443

We report results from multi-epoch X-ray observations of the Seyfert 1.5 galaxy ESO 362-G18 performed between 2005 November and 2010 June. ESO 362-G18 generally exhibits the typical X-ray spectrum of type ... [more ▼]

We report results from multi-epoch X-ray observations of the Seyfert 1.5 galaxy ESO 362-G18 performed between 2005 November and 2010 June. ESO 362-G18 generally exhibits the typical X-ray spectrum of type 1 active galactic nuclei. A disc-reflection component accounts for broad residuals in the iron K band and above 10 keV, as well as for a significant soft excess. From our best-fitting reflection model, we measure a black hole spin a ≥ 0.92 at the 99.99 per cent confidence level. ESO 362-G18 is also (typically) mildly absorbed by a column of neutral gas. The absorber is variable and one observation, performed ˜2 months after a typical mildly absorbed one, is heavily absorbed by a cold column density of ˜ 3-4 × 10[SUP]23[/SUP] cm[SUP]-2[/SUP], nearly two orders of magnitude higher than that during any other observation. UV variability between the heavily absorbed observation and the others suggests that the absorber can be identified with a dusty, clumpy torus. The absorption variability time-scale enables us to locate the X-ray-emitting region within the innermost ˜50 gravitational radii. Such result holds not only for the X-ray continuum, but also for the soft excess. [less ▲]

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See detailThe properties of the clumpy torus and BLR in the polar-scattered Seyfert 1 galaxy ESO 323-G77 through X-ray absorption variability
Miniutti, G.; Sanfrutos, M.; Beuchert, T. et al

in Monthly Notices of the Royal Astronomical Society (2014), 437

We report results from multi-epoch (2006-2013) X-ray observations of the polar-scattered Seyfert 1 galaxy ESO 323-G77. The source exhibits remarkable spectral variability from months to years timescales ... [more ▼]

We report results from multi-epoch (2006-2013) X-ray observations of the polar-scattered Seyfert 1 galaxy ESO 323-G77. The source exhibits remarkable spectral variability from months to years timescales. The observed spectral variability is entirely due to variations of the column density of a neutral absorber towards the intrinsic nuclear continuum. The column density is generally Compton-thin ranging from a few times 10[SUP]22[/SUP] cm[SUP]-2[/SUP] to a few times 10[SUP]23[/SUP] cm[SUP]-2[/SUP]. However, one observation reveals a Compton-thick state with column density of the order of 1.5 × 10[SUP]24[/SUP] cm[SUP]-2[/SUP]. The observed variability offers a rare opportunity to study the properties of the X-ray absorber(s) in an active galaxy. We identify variable X-ray absorption from two different components, namely (i) a clumpy torus whose individual clumps have a density of ≤1.7 × 10[SUP]8[/SUP] cm[SUP]-3[/SUP] and an average column density of ˜4 × 10[SUP]22[/SUP] cm[SUP]-2[/SUP], and (ii) the broad-line region (BLR), comprising individual clouds with density of 0.1-8 × 10[SUP]9[/SUP] cm[SUP]-3[/SUP] and column density of 10[SUP]23[/SUP]-10[SUP]24[/SUP] cm[SUP]-2[/SUP]. The derived properties of the clumpy torus can also be used to estimate the torus half-opening angle, which is of the order of 47°. We also confirm the previously reported detection of two highly ionized warm absorbers with outflow velocities of 1000-4000 km s[SUP]-1[/SUP]. The observed outflow velocities are consistent with the Keplerian/escape velocity at the BLR. Hence, the warm absorbers may be tentatively identified with the warm/hot intercloud medium which ensures that the BLR clouds are in pressure equilibrium with their surroundings. The BLR line-emitting clouds may well be the cold, dense clumps of this outflow, whose warm/hot phase is likely more homogeneous, as suggested by the lack of strong variability of the warm absorber(s) properties during our monitoring. [less ▲]

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See detailThe size of the X-ray emitting region in SWIFT J2127.4+5654 via a broad line region cloud X-ray eclipse
Sanfrutos, M.; Miniutti, G.; Agis-Gonzalez, Beatriz ULiege et al

in Monthly Notices of the Royal Astronomical Society (2013), 436

We present results obtained from the time-resolved X-ray spectral analysis of the Narrow-Line-Seyfert 1 galaxy SWIFT J2127.4+5654 during a ˜130 ks XMM-Newton observation. We reveal large spectral ... [more ▼]

We present results obtained from the time-resolved X-ray spectral analysis of the Narrow-Line-Seyfert 1 galaxy SWIFT J2127.4+5654 during a ˜130 ks XMM-Newton observation. We reveal large spectral variations, especially during the first ˜90 ks of the XMM-Newton exposure. The spectral variability can be attributed to a partial eclipse of the X-ray source by an intervening low-ionization/cold absorbing structure (cloud) with column density N[SUB]H[/SUB] = 2.0^{+0.2}_{-0.3}× 10^{22} cm[SUP]-2[/SUP] which gradually covers and then uncovers the X-ray emitting region with covering fraction ranging from zero to ˜43 per cent. Our analysis enables us to constrain the size, number density and location of the absorbing cloud with good accuracy. We infer a cloud size (diameter) of D[SUB]c[/SUB] ≤ 1.5 × 10[SUP]13[/SUP] cm, corresponding to a density of n[SUB]c[/SUB] ≥ 1.5 × 10[SUP]9[/SUP] cm[SUP]-3[/SUP] at a distance of R[SUB]c[/SUB] ≥ 4.3 × 10[SUP]16[/SUP] cm from the central black hole. All of the inferred quantities concur to identify the absorbing structure with one single cloud associated with the broad line region of SWIFT J2127.4+5654. We are also able to constrain the X-ray emitting region size (diameter) to be D[SUB]s[/SUB] ≤ 2.3 × 10[SUP]13[/SUP] cm which, assuming the black hole mass estimated from single-epoch optical spectroscopy (1.5 × 10[SUP]7[/SUP] M[SUB]⊙[/SUB]), translates into D[SUB]s[/SUB] ≤ 10.5 gravitational radii (r[SUB]g[/SUB]) with larger sizes (in r[SUB]g[/SUB]) being associated with smaller black hole masses, and vice versa. We also confirm the presence of a relativistically distorted reflection component off the inner accretion disc giving rise to a broad relativistic Fe K emission line and small soft excess (small because of the high Galactic column density), supporting the measurement of an intermediate black hole spin in SWIFT J2127.4+5654 that was obtained from a previous Suzaku observation. [less ▲]

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