Context. Obscured AGN are fundamental to understand the history of supermassive black hole growth and their influence on galaxy formation. However, the Compton-thick AGN (NH > 10^24 cm-2) population is basically unconstrained, with less than a few dozen confirmed Compton-thick AGN found and studied so far. A way to select heavily obscured AGN is to compare the X-ray emission below 10 keV (which is strongly depressed) with the emission from other bands that are less affected by the absorption, like the IR band. To this end, we have cross-correlated the 2XMM catalogue with the IRAS Point Source catalogue and, by using the X-ray to infrared flux ratio and X-ray colours, we selected a well defined sample of Compton-thick AGN candidates at z < 0.1. Aims: The aim of this work is to confirm the nature and to study one of these local Compton-thick AGN candidates, the nearby (z = 0.029) Seyfert 2 galaxy IRAS 04507+0358, by constraining the amount of intrinsic absorption (NH) and thus the intrinsic luminosity. Methods: To this end we obtained deep (100 ks) Suzaku observations (AO4 call) and performed a joint fit with SWIFT-BAT data. We analysed XMM-Newton, Suzaku and SWIFT-BAT data and present here the results of this broad-band (0.4-100 keV) spectral analysis. Results: We found that the broad-band X-ray emission of IRAS 04507+0358 requires a large amount of absorption (higher than 10^24 cm-2) to be well reproduced, thus confirming the Compton-thick nature of this source. In particular, the most probable scenario is that of a mildly (NH ~ 1.3-1.5 × 1024 cm-2, L(2-10 keV) ~ 5-7 × 10^43 erg s-1) Compton-thick AGN.
Severgnini P., Caccianiga A., Della Ceca A., Braito V., Vignali C., La Parola V., et al. (2011). Suzaku and Swift-BAT observations of a newly discovered Compton-thick AGN. ASTRONOMY & ASTROPHYSICS, 525, 1-8 [10.1051/0004-6361/201015575].
Suzaku and Swift-BAT observations of a newly discovered Compton-thick AGN
VIGNALI, CRISTIAN;
2011
Abstract
Context. Obscured AGN are fundamental to understand the history of supermassive black hole growth and their influence on galaxy formation. However, the Compton-thick AGN (NH > 10^24 cm-2) population is basically unconstrained, with less than a few dozen confirmed Compton-thick AGN found and studied so far. A way to select heavily obscured AGN is to compare the X-ray emission below 10 keV (which is strongly depressed) with the emission from other bands that are less affected by the absorption, like the IR band. To this end, we have cross-correlated the 2XMM catalogue with the IRAS Point Source catalogue and, by using the X-ray to infrared flux ratio and X-ray colours, we selected a well defined sample of Compton-thick AGN candidates at z < 0.1. Aims: The aim of this work is to confirm the nature and to study one of these local Compton-thick AGN candidates, the nearby (z = 0.029) Seyfert 2 galaxy IRAS 04507+0358, by constraining the amount of intrinsic absorption (NH) and thus the intrinsic luminosity. Methods: To this end we obtained deep (100 ks) Suzaku observations (AO4 call) and performed a joint fit with SWIFT-BAT data. We analysed XMM-Newton, Suzaku and SWIFT-BAT data and present here the results of this broad-band (0.4-100 keV) spectral analysis. Results: We found that the broad-band X-ray emission of IRAS 04507+0358 requires a large amount of absorption (higher than 10^24 cm-2) to be well reproduced, thus confirming the Compton-thick nature of this source. In particular, the most probable scenario is that of a mildly (NH ~ 1.3-1.5 × 1024 cm-2, L(2-10 keV) ~ 5-7 × 10^43 erg s-1) Compton-thick AGN.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
