Transient obscuration event captured in NGC 3227
Astronomy and Astrophysics, vol. 673, pp. A26
Abstract
Context. Obscuration events in type I active galactic nuclei (AGN) have been detected more frequently in recent years. The strong flux decrease in the soft X-ray band between observations has been caused by clouds with large column densities transiting our line of sight (LOS) and covering the central AGN. Another event has been captured in NGC 3227 at the end of 2019, which was observed with XMM-Newton, NuSTAR, and the Hubble Space Telescope. Aims. We aim to determine the nature and origin of the observed spectral variability in the 2019 obscuration event. Methods. We study the evolution of the obscurer by splitting the two XMM-Newton observations from 2019 into timing bins of length ∼10 ks. We used the SPEX code to analyse the 0.35–10 keV EPIC-PN spectra of each timing bin. Results. In the first observation (Obs 1), there is a strong anti-correlation between the column density (NH) of the obscurer and the continuum normalisations of the X-ray power law and soft Comptonisation components (Npow and Ncomt, respectively). The power-law continuum models the hard X-rays produced by the corona, and the Comptonisation component models the soft X-ray excess and emission from the accretion disk. Through further testing, we conclude that the continuum is likely to drive the observed variability, but we cannot rule out a possible contribution from NH of the obscurer if it fully transverses across the ionising source within our LOS during the observation. The ionisation parameter (ξ) of the obscurer is not easily constrained, and therefore it is not clear whether it varies in response to changes in the ionising continuum. The second observation (Obs 2) displays a significantly lower count rate due to the combination of a high NH and covering fraction of the obscurer, and a lower continuum flux. Conclusions. The observed variability seen during the obscuration event of NGC 3227 in 2019 is likely driven by the continuum, but the obscurer varies at the same time, making it difficult to distinguish between the two possibilities with full certainty.
Authors 16
-
Affiliation as printed
Mullard Space Science Laboratory , University College London , Holmbury St. Mary , Dorking , Surrey RH5 6NT , UK
Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Dorking, Surrey RH5 6NT, UK
-
Hiroshima University · University of Strathclyde · Space Research Organisation Netherlands
Affiliation as printed
Department of Physics, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
Department of Physics, University of Strathclyde, Glasgow G4 0NG, UK
SRON Netherlands Institute for Space Research, Niels Bohrweg 4, 2333 CA Leiden, The Netherlands
-
Space Telescope Science Institute · Space Research Organisation Netherlands
Affiliation as printed
SRON Netherlands Institute for Space Research , Niels Bohrweg 4 , 2333 CA Leiden , The Netherlands
Space Telescope Science Institute , 3700 San Martin Drive , Baltimore , MD 21218 , USA
SRON Netherlands Institute for Space Research, Niels Bohrweg 4, 2333 CA Leiden, The Netherlands
Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
-
Affiliation as printed
Mullard Space Science Laboratory , University College London , Holmbury St. Mary , Dorking , Surrey RH5 6NT , UK
Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Dorking, Surrey RH5 6NT, UK
-
Affiliation as printed
Mullard Space Science Laboratory , University College London , Holmbury St. Mary , Dorking , Surrey RH5 6NT , UK
Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Dorking, Surrey RH5 6NT, UK
-
Leiden University · Leiden Observatory · Space Research Organisation Netherlands
Affiliation as printed
Leiden Observatory , Leiden University , PO Box 9513 , 2300 RA Leiden , The Netherlands
SRON Netherlands Institute for Space Research , Niels Bohrweg 4 , 2333 CA Leiden , The Netherlands
Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands
SRON Netherlands Institute for Space Research, Niels Bohrweg 4, 2333 CA Leiden, The Netherlands
-
Leiden University · University of Science and Technology of China · Chinese Academy of Sciences · Leiden Observatory · Space Research Organisation Netherlands
Affiliation as printed
CAS Key Laboratory for Research in Galaxies and Cosmology, Department of Astronomy, University of Science and Technology of China, Hefei 230026, PR China
Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands
SRON Netherlands Institute for Space Research, Niels Bohrweg 4, 2333 CA Leiden, The Netherlands
School of Astronomy and Space Science, University of Science and Technology of China, Hefei 230026, PR China
-
National Institute for Astrophysics
Affiliation as printed
INAF-IASF Palermo , Via U. La Malfa 153 , 90146 Palermo , Italy
INAF-IASF Palermo, Via U. La Malfa 153, 90146 Palermo, Italy
-
Space Telescope Science Institute
Affiliation as printed
Space Telescope Science Institute , 3700 San Martin Drive , Baltimore , MD 21218 , USA
Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
-
Affiliation as printed
Institute of Astronomy , University of Cambridge , Madingley Road , Cambridge CB3 0HA , UK
Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK
-
Centre National de la Recherche Scientifique · Institut de Planétologie et d'Astrophysique de Grenoble
Affiliation as printed
Univ. Grenoble Alpes , CNRS , IPAG , 38000 Grenoble , France
IPAG - Institut de Planétologie et d'Astrophysique de Grenoble (414, Rue de la Piscine BP 53 38041 Grenoble Cedex 9 - France)
-
Brera Astronomical Observatory · Max Planck Institute for Extraterrestrial Physics · National Institute for Astrophysics
Affiliation as printed
INAF -Osservatorio Astronomico di Brera , Via E. Bianchi 46 , 23807 Merate (LC) , Italy
Max Planck Institute fur Extraterrestriche Physik , 85748 Garching , Germany
INAF -Osservatorio Astronomico di Brera, Via E. Bianchi 46, 23807 Merate (LC), Italy
Max Planck Institute fur Extraterrestriche Physik, 85748 Garching, Germany
-
Universitat Politècnica de Catalunya
Affiliation as printed
Departament de Física , EEBE , Universitat Politècnica de Catalunya , Av. Eduard Maristany , 16 , Barcelona 08019 , Spain
Departament de Física, EEBE, Universitat Politècnica de Catalunya, Av. Eduard Maristany, 16, Barcelona 08019, Spain
-
Affiliation as printed
Dipartimento di Matematica e Fisica , Università degli Studi Roma Tre , via della Vasca Navale 84 , 00146 Roma , Italy
Dipartimento di Matematica e Fisica, Università degli Studi Roma Tre, via della Vasca Navale 84, 00146 Roma, Italy
-
Technion – Israel Institute of Technology
Affiliation as printed
Department of Physics , Technion-Israel Institute of Technology , 32000 Haifa , Israel
Department of Physics, Technion-Israel Institute of Technology, 32000 Haifa, Israel
-
European Space Agency · European Space Astronomy Centre
Affiliation as printed
Telespazio UK for the European Space Agency (ESA) , European Space Astronomy Centre (ESAC) , Camino Bajo del Castillo , s/n , 28692 Villanueva de la Cañada , Madrid , Spain
ESA - Agence Spatiale Européenne = European Space Agency (Agence spatiale européenne (ESA) 8-10, rue Mario Nikis F-75015 Paris - France)
Cited by 7 stored of 7
7 results
No patents citing this paper on Lens.org (checked 2026-10-11).