TY - JOUR
T1 - EUV emission from a sample of Active Galactic Nuclei
AU - Lieu, R.
AU - Mittaz, J.
AU - Bowyer, S.
AU - Lewis, J.
AU - Hwang, C. Y.
N1 - Funding Information:
the conclusion that the EUV and soft X-ray spectrali ndicesdo not deviate substantiallyf rom each other for the sampleo f AGN in question.T his data sample representtsh e first seriousa ttemptto addressth e issue of EUV emission from AGN in a statistical senses incethe unique combination of survey and pointed data has resulted in a large dynamic range of count rates (a factor of -50, as is evident from Figure 3) and intrinsic X-ray luminosities (a factor of - 104) for the sourcesF. utureefforts to study the problem will involve enlargemenot f the sample as more AGN are being detecteds erendipitouslyb y EUVE and acquisition of high resolution X-ray spectraf or some of the sourcesb y missions such as ASCA. This work is supportedb y NASA contract NAS5-30180.
PY - 1995
Y1 - 1995
N2 - Active Galactic Nuclei (AGN) emit a substantial fraction of their total radiated power in the EUV passband, because spectroscopically this band is situated at or near the peak of the "big blue bump", which is bounded on either side by the UV and soft X-ray excesses. Owing to the lack of observational data, the shape of AGN spectra in the EUV is not well known. This paper presents broad band (65-190 eV) count rates of 11 AGN detected by the Extreme Ultraviolet Explorer (EUVE). Assuming a power law spectral shape for the EUV and soft X-ray energies, we demonstrate that the photon indices of the sources are considerably steeper than typical AGN indices. For 6 sources where ROSAT data are available to provide a more precise determination of their spectral parameters in the 0.1-2.5 keV range, we have used these parameters to compute predicted EUVE count rates and compared them with the observed values. The two sets of quantities agree to within experimental error. We conclude that there is no evidence of spectral steepening or turn-over of the soft X-ray excess at EUV wavelengths for a sample of AGN which covers a wide range of brightness.
AB - Active Galactic Nuclei (AGN) emit a substantial fraction of their total radiated power in the EUV passband, because spectroscopically this band is situated at or near the peak of the "big blue bump", which is bounded on either side by the UV and soft X-ray excesses. Owing to the lack of observational data, the shape of AGN spectra in the EUV is not well known. This paper presents broad band (65-190 eV) count rates of 11 AGN detected by the Extreme Ultraviolet Explorer (EUVE). Assuming a power law spectral shape for the EUV and soft X-ray energies, we demonstrate that the photon indices of the sources are considerably steeper than typical AGN indices. For 6 sources where ROSAT data are available to provide a more precise determination of their spectral parameters in the 0.1-2.5 keV range, we have used these parameters to compute predicted EUVE count rates and compared them with the observed values. The two sets of quantities agree to within experimental error. We conclude that there is no evidence of spectral steepening or turn-over of the soft X-ray excess at EUV wavelengths for a sample of AGN which covers a wide range of brightness.
UR - http://www.scopus.com/inward/record.url?scp=0042660796&partnerID=8YFLogxK
U2 - 10.1016/0273-1177(95)00049-K
DO - 10.1016/0273-1177(95)00049-K
M3 - 期刊論文
AN - SCOPUS:0042660796
SN - 0273-1177
VL - 16
SP - 81
EP - 84
JO - Advances in Space Research
JF - Advances in Space Research
IS - 3
ER -