We present a comprehensive multiwavelength photometric analysis of the innermost ( \sim 3 \times 3 kpc ^ { 2 } ) 110 globular clusters ( GCs ) of M87 .
Their spectral energy distributions ( SEDs ) were built taking advantage of new ground-based high resolution near-IR imaging aided by adaptive optics at the Very Large Telescope ( VLT ) combined with Hubble Space Telescope ( HST ) ultraviolet–optical archival data .
These GC SEDs are among the best photometrically sampled extragalactic GC SEDs .
To compare with our SEDs we constructed equally sampled SEDs of Milky Way GCs .
Using both these Milky Way cluster templates and different stellar population models , ages of > 10 Gyr and metallicities of [ Fe/H ] \sim - 0.6 dex are consistently inferred for the inner GCs of M87 .
In addition , the metallicity of these GCs is low ( \Delta [ Fe/H ] \sim 0.8 dex ) compared to that of their host galaxy .
These results agree with the idea that the GC formation in M87 ceased earlier than that of the bulk of the stars of the central part of the galaxy .
The ages of the inner GCs of M87 support the idea that these central parts of the galaxy formed first .
Our data do not support evidence of recent wet merging .