Astronomy and Astrophysics – Astrophysics
Scientific paper
1996-05-21
Astronomy and Astrophysics
Astrophysics
8 pages LaTex file; mn.sty macro (enclosed), 5 LaTex Tables, 12 Postscript figures; accepted for publication in MNRAS
Scientific paper
Using a sample of 63 AGNs extracted from the $Einstein$ Extended Medium Sensitivity Survey (EMSS), we study the X-ray spectral properties of X-ray selected AGN in the 0.1$-$2.4 keV ROSAT band. These objects are all the EMSS AGN detected with more than 300 net counts in ROSAT PSPC images available from the public archive (as of May 31, 1995). A Maximum-Likelihood analysis is used to find the mean power-law spectral index $<\alpha_p>$ and the intrinsic dispersion $\sigma_p$. We find $<\alpha_p>$=1.42 with $\sigma_p$=0.44. This value is significantly steeper ($\Delta \alpha \sim$0.4) than the mean $Einstein$/IPC spectral index obtained applying the ML analysis on the whole sample of EMSS AGN. This result shows that the soft excess already noted in optically selected AGN is present also in X-ray selected AGN. The relatively high value obtained for the intrinsic dispersion confirms that in the soft band AGN are characterized by a variety of spectral indices and the increase with respect to results obtained from the analysis of Einstein data ($\Delta \sigma_p \sim$0.16) suggests a further broadening of the spectral index distribution as one moves to softer energies. A comparison between the mean spectral index of Radio-quiet and Radio-loud subsamples shows that the mean index of the RL sample is flatter than that of RQ, both in the IPC ($\Delta \alpha \sim$0.3) and in the PSPC ($\Delta \alpha \sim$0.4) data. This suggests that the additional X-ray component in RL AGN dominates the X-ray emission of RL AGN over almost two decades of energy ($\sim$0.1$-$10 keV).
Ciliegi Paolo
Maccacaro Tommaso
No associations
LandOfFree
The X-ray spectral properties of X-ray selected AGN : ROSAT spectra of EMSS AGN does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with The X-ray spectral properties of X-ray selected AGN : ROSAT spectra of EMSS AGN, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The X-ray spectral properties of X-ray selected AGN : ROSAT spectra of EMSS AGN will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-315191