4 Erratum: Comparison of the results with those of Young et al. (1995)

At this point we should note an error in Table 3 of Curran et al. (2000): When calculating the global CO luminosity values using the global fluxes of Young et al. (1995), we multiplied these over the whole flux region, when in actual fact these should be multiplied over the source size (where the flux falls to 50%). Unfortunately this is not available in Young et al. (1995) but the diameter within which 70% of the flux is contained is given, allowing us to assign upper limits to their results. These are compared with our results in Table 4.

 

 

Table 4: The global CO $1\rightarrow 0$ luminosities [ $\times 10^{3}$ K km s^-1 kpc²] compared with those of Young et al. (1995) (Young)

NGC	1068	2273	5033	6814	7469
Our	2.4	$\approx$0.08	$0.6\pm0.01$	$\approx$0.42	$2.00\pm0.09$
Young	<4	<0.04	<1.7	<0.45	$1.9\pm0.3$

Note that for NGC 1068 the Young et al. (1995) observation is over a diameter of 84'' and hence captures most of the flux (Fig. 1). This can be seen in their value of $120\pm40$ K km s^-1, cf. ours of 133 K km s^-1 for the global integrated intensity.

NGC 2273 is only observed over a diameter of 30'', although it appears that most of the flux is sampled, $3.8\pm0.7$ K km s^-1, cf. our value of $\approx$4 K km s^-1 for the global integrated intensity.

NGC 5033 is observed over a diameter of 96'' and our map (Fig. 4) suggests that there may be emission beyond this.

NGC 6814 is over a diameter of 78'' which is a similar region to where we find emission (Fig. 6).

For completeness, our previous value for NGC 7469 (Curran et al. 2000), was correct as the source is distant (v=4900 km s^-1) and so the flux contained within the central beam (diameter 10 kpc) determines the global luminosity. Thus with the exception of NGC 2273, the remaining results are at least consistent with those of Young et al. (1995).