VIMOS mosaic integral-field spectroscopy of the bulge and disk of the early-type galaxy NGC 4697

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We present an integral field study of the internal structure, kinematics and stellar population of the almost edge-on, intermediate luminosity (L*) elliptical galaxy NGC 4697. We build extended 2-dimensional (2D) maps of the stellar kinematics and line-strengths of the galaxy up to 0.7 effective radii (Reff) using a mosaic of 8 VIMOS (VIsible Multi-Objects Spectrograph on the VLT) integral-field unit pointings. We find clear evidence for a rotation-supported structure along the major axis from the 2D kinematical maps, confirming the previous classification of this system as a `fast-rotator'. We study the correlations between the third and fourth Gauss-Hermite moments of the line-of-sight velocity distribution (LOSVD) h₃ and h₄ with the rotation parameter (V/σ), and compare our findings to hydrodynamical simulations. We find remarkable similarities to predictions from gas-rich mergers. Based on photometry, we perform a bulge/disk decomposition and study the stellar population properties of the two components. The bulge and the disk show different stellar populations, with the stars in the bulge being older (age bulge=13.5⁺¹.⁴₋₁.₄ Gyr, age disk=10.5⁺¹.⁶₋₂.₀Gyr) and more metal-poor ([M/H]bulge = -0.17⁺⁰.¹²₋₀.₁, [M/H]disk=-0.03⁺⁰.⁰²₋₀.₁). The evidence of a later-formed, more metal-rich disk embedded in an older, more metal-poor bulge, together with the LOSVD structure, supports a mass assembly scenario dominated by gas-rich minor mergers and possibly with a late gas-rich major merger that left a previously rapidly rotating system unchanged. The bulge and the disk do not show signs of different stellar Initial Mass Function slopes, and both match well with a Milky Way-like IMF.