Paola Oliva-Altamirano edited section_Introduction_label_sec_intro__.tex  almost 9 years ago

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\\\\  The recent accretion history of galaxies can be read through their stellar population gradients. In the canonical scenario, a galaxy's initial metallicity gradient is set by an initial starburst at $z\geq3$ and the metallicity decreases in the outskirts, as metallicity follows the changes in the gravitational potential \citep{SCOTT09, MCDERMID12}. This gradient can be disrupted by violent merging events (major mergers), or reinforced by minor mergers \citep{KOBAYASHI04, SPOLAOR09, COOPER10,PIPINO10}. \citet{HIRSCHMANN14} analysed the stellar populations of 10 massive halos ($10^{12}<$~M$_{\rm halo}<10^{13}$~M$_{\odot}$) from the high-resolution cosmological simulation of \citet{HIRSCHMANN13}. They found that major mergers do flatten the metallicity gradients. If, as predicted, BCGs have an active merger history, including several major mergers, they would be expected to have shallower metallicity gradients than lower mass galaxies. However, long-slit observations to date suggest that they have a wide range of gradients \citep{BROUGH07,LOUBSER12}.   \\\\  Integral Field Unit (IFU) spectroscopy is a valuable tool to explore the spatially-resolved kinematics and stellar populations of galaxies. The SAURON \citep{ZEEUW02} and ATLAS$^{3D}$ \citep{CAPPELLARI11a} surveys have used IFU spectroscopy to explore a significant sample of early-type galaxies in the local Universe. \citet{KUNTSCHNER10} and \citet{ATLAS3D} presented the stellar population analysis of the SAURON and ATLAS$^{3D}$ samples, respectively, finding that 40 per cent of the galaxies typically show contributions from young stellar populations connected to low mass, fast rotator systems. In contrast, they find that slow rotators are generally consistent with old ($\geq 10$ Gyr) stellar populations. The most massive systems (stellar mass $\geq 10^{10.5}$M$_{\odot}$) have the flattest metallicity gradients. However, the ATLAS$^{3D}$ sample contains 21 galaxies with dynamical masses greater than $10^{11.3}$M$_{\odot}$, and only one of those is a BCG (M87). \\\\  \citet{JIMMY13} analysed the kinematics and photometry of a sample of 10 BCGs observed with the VIMOS IFU, of which 4 have close massive companions. If BCGs were the product of many minor mergers they would be expected to be slow-rotating galaxies. \citet{JIMMY13} found that 30 per cent of the BCGs in their sample are fast rotators. The simulations of \citet{NAAB13}, predict that angular momentum mostly depends on the gas content of the galaxies involved in the interaction, suggesting that the slow or fast rotation could be a temporary state. \citet{JIMMY13}, also find through photometric analysis \citep[$G-M_{20}$;][]{LOTZ08} that 40 per cent of the galaxies in the sample have undergone a minor merger within the last 0.2 Gyr.