1D: Single disk fits

Our additionally added very late-type and low-mass galaxies FGC 2339 and IC 5249 could not be fitted with the 2D Two Disk fit or the 1D Constrained Two Disk fit. This is not due to a lack of a second vertical component. As we could see in NGC 1886 J it would still give fit results. In both galaxies a vertical structure is visible. Although it is faint for FGC 2339, both seem to have a too flat second component. This makes it hard for the fitting function, as it has to sum two exponential functions and gives higher scaleheight values tot the second component to describe it, after which it will start to increase rapidly to unphysical values. A similar thing happened to the scalelength of both the thin and the thick disk, showing that the intensity stays rather flat over radius. This behaviour was in strong contrast to the Two Disk model's ability to fit the other sample galaxies without problems, confirming the vertical structures seen to be thick disks. Thus the only remaining option to be able to present quantitative numbers is the 1D Single Disk fit.
Only two parameters are needed to fit with the 1D Single Disk fit, $\mu_0$ and $z_0$. For FGC 2339 $f_b$ was set to 1.10 and we used an $z_{\textrm{\scriptsize min}}$ of 1.5 arcseconds to avoid the inner flattening; for IC 5249 $f_b$ was set to 1.08 and a $z_{\textrm{\scriptsize min}}$ of 2.5 arcseconds was used. Tables 13A and 13B show the fit results of each cut of the quadrazised average galaxy, for FGC 2339 and IC 5249 respectively. See Appendix A for plots of the vertical profiles and the single disk fit. The quadrasized average was chosen because it would constrain $z_0$ better in its variation and due to the flat radial behaviour of the thin and thick disk intensity the vertical structure will not disappear at higher radius because of the $\mu_\textrm{\scriptsize cut}$ value. For the fit equation 5 was used. The fitting was done with the Levenberg-Marquardt least-squares algorithm, weigthed with the average magnitude error for each datapoint.
The values for $z_0$ remain reasonably constant, giving a median of 2.1 $\pm$ 0.1 arcseconds for FGC 2339 and 3.7 $\pm$ 0.1 arcseconds for IC 5249. What shows most notably is the very slow increase of $\mu_0$ over the radius for both galaxies, showing the intensity remains almost flat over the radius of the galaxy. This confirms the 'flat' behaviour of the radial parameters in the 2D Two Disk fit, making it clear that one cannot use this fitting model for these galaxies. The $\chi^2$ values are all quite high, showing that the 1D One Disk fit is not capable of doing a good fit and confirming the existence of a distinct vertical structure, which could not be described by a thick disk.

TABLE 13

1D ONE DISK FIT RESULTS

A: FGC 2339 R
[$''$]	[$''$]	[mag/$\Box ''$]
2.43	1.94	20.27	29.35
3.24	1.96	20.31	21.68
4.32	2.02	20.37	18.91
5.40	2.07	20.44	19.55
6.48	2.12	20.53	14.89
7.56	2.14	20.60	24.43
8.91	2.17	20.67	16.02
10.53	2.20	20.75	16.68
12.15	2.21	20.79	9.40
13.77	2.18	20.82	10.15
15.93	2.13	20.84	20.66
18.09	1.97	20.80	28.98
20.25	1.97	20.87	34.54
22.95	1.88	20.78	28.04
25.65	1.71	20.61	27.05

B: IC 5249 R
[$''$]	[$''$]	[mag/$\Box ''$]
34.29	3.75	21.25	18.35
37.53	3.83	21.33	41.74
41.04	3.70	21.31	29.72
44.82	3.77	21.39	36.82
49.14	3.68	21.04	25.14
53.46	3.68	21.44	31.03
58.32	3.70	21.05	27.72
63.72	3.77	21.58	40.35
69.12	3.60	21.52	16.46
75.33	4.02	21.67	191.71

Figure 7: 1D Fit on the first profile of the lower north-west quadrant of IC 3322A J. The black dots are the actual data. The red line is the 1D Constrained Two Disk fit, the blue line is the Generalized Gaussian fit.