All Figures

	Figure 1: Illustrated are colours which were used to select globular cluster candidates as a function of age and metallicity and taken from model predictions of Maraston (2005). Upper and lower colour cuts are indicated as horizontal lines. Curves in left panels are parametrized by metallicity, curves in right panels are parametrized by age and indicated accordingly.
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In the text

Figure 2: The behavior of Lick Balmer indices as a function the horizontal branch morphology (HBR). This parameter is defined in Lee et al. (1994) as HBR (B-R)/(B+V+R), where B and R are the number of stars blue-wards and red wards of the instability strip. V is the number of variable stars inside the instability strip. HBR = 1 indicates an entirely blue and HBR = -1and entirely red horizontal branch. Here we plot data for globular clusters in the Milky Way ( squares: data from Puzia et al. 2002 and Trager et al. 1998), M 31 ( invertedtriangles: Puzia et al. 2005, Rich et al. 2003, and Trager et al. 1998), and the Large Magellanic Cloud triangles: Beasley et al. 2002b). Filled symbols show globular clusters with a metallicity [Z/H] -0.6 (note, all have HBR = -1). NGC 6388 and NGC 6441 are indicated by stars at HBR = -0.7. A small arrow at each panel's right ordinate indicates the most extreme Balmer index value for globular clusters with [Z/H] > -0.6. Several clusters show a tendency for higher Balmer indices at HBR  -0.5. Their deviations from the overall sequence are .

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In the text

Figure 3: Influence of [/Fe] variations on age-metallicity diagnostic grids. Panel  a): H vs. Fe. Lines show model predictions (Thomas et al. 2003,2004) for stellar populations with metallicities [Z/H] = -2.25 to 0.67 dex and two ages 13 (solid lines) and 3 Gyr (dot-dashed lines) parametrized for three different [/Fe] ratios 0.0, 0.3, and 0.5 dex. Panel  b) shows the same model predictions for H vs. [MgFe], while panel  c) illustrates the changes in the H vs. Mgb grid. The other panels show the predicted variations for higher-order Balmer line age/metallicity diagnostic grids.

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In the text

Figure 4: Passband definitions for Balmer-line, Mgb, Fe5270, and Fe5335 Lick indices with their feature and adjacent continuum passbands. The over-plotted spectrum is a high-S/N spectrum of the Galactic globular cluster NGC 6284 (Puzia et al. 2002). The resolution is 7 Å and was left untouched to keep satellite lines visible. Line data were taken from Reader & Corliss (1981), data for molecular bands are from Rosen (1952). Note the large number of satellite lines which are included in the passband definitions.

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In the text

Figure 5: Computed vs. measured photometric colors for our sample globular clusters. Computed colors were derived from spectroscopic ages and metallicities using the SSP models of Maraston (2005). The circles show all selected globular clusters for which optical/near-infrared colors were obtained (see Paper I for details). Solid circles show the high-quality sample, which was selected by a more constrained error cut (see text for details). Errorbars indicate 1- uncertainties.

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In the text

Figure 6: Age-metallicity diagnostic plots (panels a)- e)) constructed from Balmer indices H , H, H , H , and H  vs. [MgFe] for high-quality globular cluster spectra (solid dots). Open circles show our remaining selected globular cluster data. SSP models of Thomas et al. (2004) have been over-plotted for [/Fe] = 0.3, metallicities [Z/H] = -2.25, -1.35, -0.80, -0.33, 0.00, 0.35, and 0.67 dex (dotted lines), and ages 15, 10, 5, 3, 2, 1 (solid lines). The red dotted line is an interpolated iso-metallicity track for [Z/H] = -0.8. The blue solid line is the 5 Gyr isochrone, and is used to split between old and young globular clusters. A dashed isochrone illustrates the Balmer index strengths for a 15 Gyr old stellar population with an entirely red horizontal-branch morphology. The [/Fe] diagnostic plot (panel  f)) shows the mean iron index Fe as a function of Mg2. SSP models of Thomas et al. (2003,2004) with constant [/Fe] ratios have been over-plotted for [Z/H] between -2.25 and +0.67 dex and two ages 13 ( solid lines) and 3 Gyr ( dotted lines) with various [/Fe] ratios 0.0, +0.3,and +0.5 dex.

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In the text

Figure 7: Histograms for ages, metallicities, and [/Fe] ratios for globular clusters in early-type galaxies. The panels in the left column show distribution of each parameter for all selected (hatched histograms), outliers in diagnostic plots (double-hatched histograms), and high-quality data (solid histograms). Each panel in the right column illustrates a correlation of two of these parameters for the high-quality sub-sample. Dashed lines in the correlation plots show weighted least-square fits.

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In the text

Figure 8: Top row: comparison of globular cluster ages and metallicities in our sample galaxies with those in a simulated host galaxy with a similar luminosity (mass). All globular cluster in our sample are shown as hatched histograms, outliers in diagnostic plots are indicated by double-hatched histograms (see Sect. 4.2), and high-quality data is shown as solid histograms. Observed and simulated globular cluster samples were split into metal-poor and metal-rich globular clusters at [Z/H] = -0.9 and the shading is accordingly transfered to the age distribution plot. Bottom row: average ages and metallicities of simulated globular cluster systems in faint and bright host galaxies. All predictions were taken from Beasley et al. (2002a).

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In the text