[en] 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.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Miniutti, G.; Centro de Astrobiología (CSIC-INTA), Dep. de Astrofísica ; ESAC, PO Box 78, Villanueva de la Cañada, E-28691 Madrid, Spain
Sanfrutos, M.; Centro de Astrobiología (CSIC-INTA), Dep. de Astrofísica ; ESAC, PO Box 78, Villanueva de la Cañada, E-28691 Madrid, Spain
Beuchert, T.; Dr Remeis Sternwarte & ECAP, Universität Erlangen-Nürberg, Sternwartstr. 7, D-96049 Bamberg, Germany
Agis-Gonzalez, Beatriz ; Centro de Astrobiología (CSIC-INTA), Dep. de Astrofíica, Villanueva de la Cañada, E-28692, Madrid, Spain
Longinotti, A. L.; European Space Astronomy Centre of ESA PO Box 78, Villanueva de la Cañada, E-28691 Madrid, Spain
Piconcelli, E.; Osservatorio Astronomico di Roma (INAF), Via Frascati 33, I-00040 Monteporzio Catone, Roma, Italy
Krongold, Y.; Instituto de Astronomía, Universidad Nacional Autónoma de México, Apdo. 70-264, Cd. Universitaria, México DF 04510, Mexico
Guainazzi, M.; European Space Astronomy Centre of ESA PO Box 78, Villanueva de la Cañada, E-28691 Madrid, Spain
Bianchi, S.; Dipartimento di Matematica e Fisica, Università degli Studi Roma Tre, Via della Vasca Navale 84, I-00146 Roma, Italy
Matt, G.; Dipartimento di Matematica e Fisica, Università degli Studi Roma Tre, Via della Vasca Navale 84, I-00146 Roma, Italy
Jiménez-Bailón, E.; Instituto de Astronomía, Universidad Nacional Autónoma de México, Apdo. 70-264, Cd. Universitaria, México DF 04510, Mexico)
Language :
English
Title :
The properties of the clumpy torus and BLR in the polar-scattered Seyfert 1 galaxy ESO 323-G77 through X-ray absorption variability
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