A dataset provided by the European Space Agency

Proposal ID 0220033
Obs ID 02200330001, 02200330004
Title INTEGRAL Studies of borderline Compton thick Seyfert 2 Galaxies
Download Data Associated to the proposal https://isla.esac.esa.int/tap/download/bundle?format=ascii_curl&product_id=prop_id:0220033
DOI https://doi.org/10.57780/esa-k4pg8io
Author Dean
Abstract A basic idea of the unified model is that all Seyfert 2 galaxies harbour a bright Seyfert 1 nucleus, which is hidden from our view by an optically and geometrically thick obscuring torus. The difference between type 1 and 2 objects should only be due to the viewing angle that determines whetehr the galaxy nucleus is seen directly, or through a torus of molecular gas and dust grains. X-ray (2-10 keV) observations have provided strong support for the obscuring torus hypothesis by measuring large (up to 1E22-23 cm-2) column densities of neutral material in Seyfert 2 galaxies. For the case of cosmic abundances, the Thompson cross-section is equal to the photoelectric cross-section at around 10 keV, so that this energy may be assumed to be the boundary between photoelectric and Compton dominated regimes. This energy turns out to be the practical limit of X-ray satellites, which can observe Compton thick sources in the photoelectric regime where the emission is dominated by reflection/scattering components. These borderline objects turn out to be particularly bright in hard (>10 keV) X-rays as at these energies the transparency effect is coupled to a strong reflection component and are therefore interesting targets for INTEGRAL observations. INTEGRAL allows us to observe these objects well into the Compton dominated regime where the nuclear emission component can be studied and clearly separated from the reflection and absorption effects that dominate the X-ray emissions. The three Compton-obscured source targets have been selected for studies with INTEGRAL for the basic pragmatic reasons that they are nearby and very bright (~ 1E-10 ergs cm-2 s-1) in hard X-ray emission above 10 keV. Good spectral measurements will be possible with INTEGRAL, enabling us to study the nuclear emission spectrum and the nature of the absorbing material for the interesting case of these borderline Compton thick objects, as well as assess their contributions to the CDB.
Publications
Temporal Coverage 2004-11-17T23:25:21Z / 2005-02-05T17:58:03Z
Version 1.0
Mission Description The INTEGRAL (International Gamma-Ray Astrophysics Laboratory) mission, launched by the European Space Agency (ESA) on October 17, 2002, was designed to study high-energy phenomena in the universe. INTEGRAL was operating until february 2025 and it was equipped with three high-energy instruments: the Imager on Board the INTEGRAL Satellite (IBIS), the Spectrometer on INTEGRAL (SPI), and the JEM-X (Joint European Monitor for X-rays). Its Optical Monitoring Camera (OMC) provided optical V-band magnitude measurements, complementing the high-energy observations.
Creator Contact https://www.cosmos.esa.int/web/integral/helpdesk
Date Published 2025-03-25T09:54:30Z
Publisher And Registrant European Space Agency
Credit Guidelines European Space Agency, Dean, 2025, 'INTEGRAL Studies of borderline Compton thick Seyfert 2 Galaxies', 1.0, European Space Agency, https://doi.org/10.57780/esa-k4pg8io