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The modern merger hypothesis offers a method of forming a new elliptical galaxy through merging two equal-mass, gas-rich disc galaxies fuelling a nuclear starburst followed by efficient quenching and dynamical stabilization. A key prediction of this scenario is a central concentration of young stars during the brief phase of morphological transformation from highly disturbed remnant to new elliptical galaxy. To test this aspect of the merger hypothesis, we use integral field spectroscopy to track the stellar Balmer absorption and 4000-Å break strength indices as a function of galactic radius for 12 massive (M* = 1010⊙), nearby (z = 0.03), visually-selected plausible new ellipticals with blue-cloud optical colours and varying degrees of morphological peculiarities. We find that these index values and their radial dependence correlate with specific morphological features such that the most disturbed galaxies have the smallest 4000-Å break strengths and the largest Balmer absorption values. Overall, two-thirds of our sample are inconsistent with the predictions of the modern merger hypothesis. Of these eight, half exhibit signatures consistent with recent minor merger interactions. The other half have star formation histories similar to local, quiescent early-type galaxies. Of the remaining four galaxies, three have the strong morphological disturbances and star-forming optical colours consistent with being remnants of recent, gas-rich major mergers, but exhibit a weak, central burst consistent with forming ~5 per cent of their stars. The final galaxy possesses spectroscopic signatures of a strong, centrally concentrated starburst and quiescent core optical colours indicative of recent quenching (i.e. a post-starburst signature) as prescribed by the modern merger hypothesis. [ABSTRACT FROM AUTHOR]

We present: (i) a kinematic and morphological study of the giant Lyα nebula associated with the radio galaxy based on integral field spectroscopic Visible Multiobject Spectrograph (VIMOS) data from the Very Large Telescope (VLT), and (ii) a photometric study of the host (proto?) galaxy based on Spitzer Space Telescope data. The galaxy appears to be embedded in a giant (≳120 kpc) gas reservoir that surrounds it completely. The kinematic properties of the nebula suggest that it is a rotating structure, which would imply a lower limit to the dynamical mass of . An alternate scenario is that the gas is infalling. Such a process would be able to initiate and sustain significant central starburst activity, although it is likely to contribute with less than 10 per cent of the total stellar mass. The near- to mid-infrared spectral energy distribution of the radio galaxy suggests the existence of a reddened, , evolved stellar population of age ≳1.8 Gyr and mass . The implied formation redshift is . This stellar mass is similar to the stellar masses found for massive early-type galaxies at in deep, near-infrared surveys. [ABSTRACT FROM AUTHOR]