Structure of the Circumnuclear Region of Seyfert 2 Galaxies Revealed by RXTE Hard X-ray Observations of NGC 4945

G. M. Madejski; P. T. Zycki; C. Done; A. Valinia; P. Blanco; R. Rothschild; B. Turek

doi:10.1086/312703

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Structure of the Circumnuclear Region of Seyfert 2 Galaxies Revealed by RXTE Hard X-ray Observations of NGC 4945

G. M. Madejski·P. T. Zycki·C. Done·A. Valinia·P. Blanco·R. Rothschild·B. Turek

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Abstract

We report the Rossi X-ray Timing Explorer observations of the heavily absorbed Seyfert 2 galaxy NGC 4945, which confirm the large column density of the absorber, corresponding to the optical depth to Thomson scattering of about 2.4. The hard X-ray flux (8-30 keV) measured by us is rapidly variable with a large amplitude, on time scales of a day or less. This implies that the bulk of the extreme absorption does not originate in a parsec-size, geometrically thick molecular torus: limits on the amount of scattered flux require that the optically thick material on parsec scales must be rather geometrically thin, subtending a half-angle of less than 10 degrees as seen from the nucleus. This presents a problem in accounting for the Cosmic X-ray Background primarily with AGN possessing such geometry.

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G. M. Madejski, P. T. Zycki, C. Done, A. Valinia, P. Blanco, R. Rothschild, B. Turek. 2000-02-02. Structure of the Circumnuclear Region of Seyfert 2 Galaxies Revealed by RXTE Hard X-ray Observations of NGC 4945. https://doi.org/10.1086/312703

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