Age and metallicity gradients support hierarchical formation for M87

作者：Montes Mireia^*; Trujillo Ignacio; Prieto M Almudena; Acosta Pulido Jose A

来源：Monthly Notices of the Royal Astronomical Society, 2014, 439(1): 990-1002.

DOI：10.1093/mnras/stu037

• techniques: high angular resolution
• galaxies: evolution
• galaxies: formation
• galaxies: individual: M87
• galaxies: photometry

In order to probe the inside-out formation of the most massive galaxies in the Universe, we have explored the radial (0.1 less than or similar to R less than or similar to 8 kpc) variation of the spectral energy distribution of M87 from UV to IR. For this purpose, we have combined high-resolution data in 16 different bands. Our analysis indicate that the age of the stellar population of M87 remains almost unchanged with radius. However, the metallicity ([Z/H]) profile presents three different zones: the innermost kpc shows a plateau with supersolar metallicity, followed by a decline in metallicity down to 5 kpc and another plateau afterwards. The size of the inner plateau is similar to the expected size (Re) of an object with the predicted mass of M87 at z = 2. The global [Z/H] gradient is -0.26 +/- 0.10, similar to those found in other nearby massive ellipticals. The observed change in the stellar population of M87 is consistent with a rapid formation of the central part (R less than or similar to 5 kpc) of this galaxy followed by the accretion of the outer regions through the infall of more metal-poor material.

• 出版日期2014-3