Luminosity Function

The luminosity function of the Kuiper belt has, until recently, not been well constrained near . This is due to the small areas covered by most surveys to limiting magnitudes . Using the data from this survey and previous work, new constraints were determined on the luminosity function of the Kuiper belt near . Table 3 shows the constraints on the sky surface density of Kuiper belt objects using data from this work, Kowal (1989), Luu and Jewitt (1988), Levison and Duncan (1990), Jewitt and Luu (1995), Irwin et al. (1995), Jewitt et al. (1996) and Jewitt et al. (1998). Upper limits and error margins were calculated with Poisson statistics. Upper limits are 99% confidence limits and error margins have 68% confidence. It should be noted that the sky surface density does not always equal the number of detections divided by the survey area due to the decrease of detection efficiency with magnitude. In particular, Jewitt et al. (1998) has an detection efficiency at but this decreases to by . Pluto has been excluded from the analysis as it is 8 magnitudes brighter than any known Kuiper belt object. As Table 3 includes data from surveys with different limiting magnitudes, the number of objects detected does not always increase with limiting magnitude.

Table 3. Sky Surface Density of Kuiper Belt Objects.

	Area	Detections
	()
18.5	6800	0
19.5	393	0
21.0	69	2
22.0	41.6	7
23.2	10.2	16
24.2	5.1	20
24.8	1.2	7

 

  
Figure 1: Sky Surface Density of Kuiper Belt Objects.

Figure 1 is plot of the sky surface density of Kuiper belt objects near the ecliptic. The detections of bright Kuiper Belt objects by Jewitt et al. (1998) indicate that a break in the luminosity of the Kuiper Belt is not required unless the photographic survey by Kowal (1989) had a high detection efficiency to the limiting magnitude stated by Kowal or Irwin et al. (1995). A CCD survey of would provide a much improved estimate of the population of bright Kuiper Belt objects and possibly detect a break in the luminosity function.

© Copyright Astronomical Society of Australia 1997