Table 5.
Results of the mass models.
| (1) | (2) | (3) | (4) | (5) | (6) | (7) | (8) | (9) |
|---|---|---|---|---|---|---|---|---|
| ID | Colour | Models | Comments |  |
M/LDisc | M/LBulge | Rc | σ |
| Symb. | (M⊙/L⊙) | (M⊙/L⊙) | (kpc) | (km s−1) | ||||
| (a) | y ⋆ | BFM (2) | M/LDisc(r) & M/LBulge c-fix | 12.8 | 1.5–0.5 | 3.76 | 2.4 |
142 |
| (b) | w + | BFM (4) | 13.2 | 2.8 |
2.8 |
2.3 |
139 |
|
| (c) | OfR | MDM ((a) 2/4) | M/LDisc ≥ M/LBulge | (a) 8.2/9.3 | 20.2 |
0.0 |
∞ | 0 |
| (d) | OfR | BFM (4) | M/LDisc ≥ M/LBulge | 7.8 | 15.8 |
0.0 |
4.2 |
85 |
| (e) | o ▫ | BFM (4) | M/LDisc(r) ≥ M/LBulge | 7.6 | (b) 9.7 |
0.0 |
5.9 |
115 |
| (f) | b ⋆ | BFM (2) | M/LDisc & M/LBulge c-fix | 13.0 | 1.0 | 3.76 | 2.4 |
144 |
| (g) | lb ⋆ | BFM (3) | M/LBulge c-fix | 12.8 | 3.7 |
3.76 | 3.0 |
135 |
| (h) | dg ▫ | MBM (3) | 16.6 | 2.6 |
6.0 | 4.6 |
137 |
|
| (i) | g ° | MBM (2) | Bulge only | 24.8 | – | 9.0 | 15.2 |
119 |
| (j) | l ° | MDM (2) | Disc only | 32.2 | 9.0 | – | 13.0 |
121 |
| (k) | v ° | BFM (3) | Bulge only | 12.7 | – | 3.1 |
2.2 |
137 |
| (l) | p ° | BFM (3) | Disc only | 13.5 | 2.3 |
– | 1.9 |
142 |
| (m) (c) | OfR | BFM (2) | (a) & IllustrisTNG100 | – | 1.5–0.5 | 3.76 | 3(hs)–4(ls) | 298(hs)–307(ls) |
| (n) (c) | OfR | BFM (4) | (b) & IllustrisTNG100 | – | 0(ls)–2(hs) | 0(ls)–6(hs) | 2(ls)–5(hs) | 298(ls)–305(hs) |
Notes. Column (1): identification of the model. Column (2): colours (y: yellow; w: white; OfR: model not plotted because out of the figure range; o: orange; b: blue; lb: light blue; dg: dark green; g: green; l: lime; v: violet; and p: pink) and symbols (⋆ for models using the mass-to-light ratio computed from the colour indexes and ° for models with only one baryonic component, a disc or a bulge) used in Fig. 12 to locate the results of the mass models. Column (3): BFM, MBM, and MDM means, respectively, best-fit model, maximum bulge model, and maximum disc model. The number after the model indicates the number of free parameters of the fit. Column (4): comments on the models. In all the models, except in (c), (d), (e), (i), and (k), the condition M/LDisc ≤ M/LBulge is imposed; “c-fix” means that mass-to-light ratios have been fixed using the colour indexes (which is not the case when the mass-to-light ratio is fixed in cases of MDM or MBM); M/LDisc(r) means that the mass-to-light ratio is a function of the radius as reported in Fig. 9, while M/LBulge and M/LDisc mean that the mass-to-light ratio is fixed along the radius. Disc only means that all the stars are distributed in a flat disc component only and bulge only means that all the stars are in a spherical bulge component only. Column (5): best (minimal) reduced chi-square value. Columns (6 and 7): M/LDisc and M/LBulge are the disc and bulge mass-to-light ratios, respectively. Columns (8 and 9): Rc and σ are the core radius and velocity dispersion of the DM halo, respectively.
For models (c), two different degrees of freedom provide two different reduced χ2 values but identical baryonic and halo parameters.
For model (e), M/LDisc varies with radius as determined from colour indexes in Sect. 5.2 and that the value is the scaling factor with respect to M/LDisc plotted on Fig. 9, rather than a value in M⊙/L⊙.
Models (m) and (n) correspond to the IllustrisTNG100 RC shown in Fig. 8 instead of the observed RC. We consider the same BFM as for models (a) and (b), respectively; (ls) and (hs) in Cols. (6) to (9) mean “low slope” and “high slope”, respectively, they correspond to the inner slope of the RC until the radius where the IllustrisTNG100 RC begins. No value of χ2 or uncertainties are given because they depend on different Illustris uncertainties from those in the observations.
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