PhD Thesis (PDF) - Department of Astronomy - University of Virginia

NGC 4697 to convert the observed source count rates into unabsorbed X-ray
(0.3–10 keV) luminosities (LX). The fluxes were corrected for exposure (including
vignetting), the time dependent QE degradation of the ACIS-S3 chip, and the PSF
fraction of source counts within the region used to extract the counts. The indi-
vidual conversion factors from observed count rates were 1.18, 1.50, 1.46, 1.46, and
1.47 × 10 41 ergs count −1 for a typical source. We list the individual luminosities of
Observations 0784 (A), 4727 (B), 4728 (C), 4729 (D), and 4730 (E) in columns 2–6
of Table 5.6.
In Figure 5.7, we display the individual observation LFs of the sources in the
Analysis Sample within a < 220 ′′ . We calculate the probability the LFs of each pair
of observations are drawn from the same population using the two-sample K-S test.
Since PKS range from 0.33 (0784 versus 4727) to 0.94 (4729 versus 4730), we believe
that the LFs do not change significantly on our inter-observation timescales, which
vary from 11 d to 4.6 yr.
We combined the luminosities from all of the different observations; as before, we
included the effects of varying exposure (including vignetting), the time dependent
QE degradation of the ACIS-S3 chip, and the PSF fraction of source counts within
the region used to extract the counts. We give this luminosity, combining all five
observations, as Lall in Table 5.7 (column 4).
One can compare Lall to the individual luminosities using χ 2 to test if the indi-
vidual values are all consistent with a constant luminosity. In Figure 5.8, we display
the LF of sources with a < 220 ′′ and a < 90% probability of being variable. We fit
this LF (for the 68 sources in the Analysis Sample, Lall > 1.4 × 10 37 ergs s −1 ) using
the same techniques we have used previously (Paper I; Paper II; Blanton et al. 2001;
Irwin et al. 2002). Since the average completeness correction factor in the Analysis
169