Theoretical implications of the recent simultaneous ROSAT/OSSE observation of the Seyfert 1 IC 4329A are discussed. We find that either thermal or non-thermal Comptonization models can fit the data. Thermal models require optically thin plasma and mildly relativistic electrons. Non-thermal models require most of the injected power to be at low values of the electron Lorentz factor. Both models predict a spectral cut-off at energies below ~1 MeV, which agrees with broad-band data including non- simultaneous Ginga spectra that match the ROSAT 2-keV flux. Also, Compton reflection corresponding to cold matter covering a solid angle of 2π is required, and partial covering is ruled out. Since the spectrum of IC 4329A is typical of Seyfert 1s, their contribution to the cosmic hard X-ray background can be estimated: without cosmological evolution, it is 30 per cent at 3 keV. As the peak of the vF_v_ spectrum of IC 4329A is much broader than that of the hard X-ray background, however, Seyfert 1s cannot account for the X-ray background spectrum without spectral evolution.

Physical processes in the X-ray/gamma-ray source of IC 4329A / Zdziarski, A. A.; Fabian, A. C.; Nandra, K.; Celotti, Anna Lisa; Rees, M. J.; Done, C.; Coppi, P. S.; Madejski, G. M.. - In: MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY. - ISSN 0035-8711. - 269:4(1994), pp. L55-L60. [10.1093/mnras/269.1.L55]

Physical processes in the X-ray/gamma-ray source of IC 4329A

Celotti, Anna Lisa;
1994-01-01

Abstract

Theoretical implications of the recent simultaneous ROSAT/OSSE observation of the Seyfert 1 IC 4329A are discussed. We find that either thermal or non-thermal Comptonization models can fit the data. Thermal models require optically thin plasma and mildly relativistic electrons. Non-thermal models require most of the injected power to be at low values of the electron Lorentz factor. Both models predict a spectral cut-off at energies below ~1 MeV, which agrees with broad-band data including non- simultaneous Ginga spectra that match the ROSAT 2-keV flux. Also, Compton reflection corresponding to cold matter covering a solid angle of 2π is required, and partial covering is ruled out. Since the spectrum of IC 4329A is typical of Seyfert 1s, their contribution to the cosmic hard X-ray background can be estimated: without cosmological evolution, it is 30 per cent at 3 keV. As the peak of the vF_v_ spectrum of IC 4329A is much broader than that of the hard X-ray background, however, Seyfert 1s cannot account for the X-ray background spectrum without spectral evolution.
1994
269
4
L55
L60
https://ui.adsabs.harvard.edu/abs/1994MNRAS.269L..55Z/abstract
Zdziarski, A. A.; Fabian, A. C.; Nandra, K.; Celotti, Anna Lisa; Rees, M. J.; Done, C.; Coppi, P. S.; Madejski, G. M.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.11767/17277
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