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

Fig. 3.3.— Histogram of the observed cumulative LF of resolved sources in our analysis
sample. The continuous curve is the sum of the best-fit LMXB LFs (eq. 3.1) and
the expected background source counts. The vertical line indicates the completeness
limit of our sample.
power law is not required by the fits, the total luminosity of all of the sources diverges
at the high-luminosity limit for the best-fit LF. The lack of very bright sources (beyond
those observed) in NGC 1600 can be explained by Poisson fluctuations; however, it
seems likely either that the correct underlying LF of the sources in NGC 1600 is a bit
steeper than the best-fit value or that it steepens or has a cut-off at high luminosities
beyond those observed.
Early-type galaxies tend to have broken or cutoff power-law LFs with the break
or cutoff occurring well below the luminosities measured in NGC 1600, while star-
forming galaxies tend to have single power-law LFs that extend to low luminosities
(Sarazin et al. 2001; Blanton et al. 2001; Finoguenov & Jones 2002; Zezas & Fabbiano
2002; Jeltema et al. 2003; Chapter 2; Randall et al. 2004). The high luminosities of
the sources in NGC 1600 make it difficult to directly compare its LF with those of
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