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Table 2.

Summary of the constraints on the typical mergers that caused the decrease in the ordered rotation of ETGs.

Observation Time sincetransformation [Gyr] Indicates minormergers? Indicates wetmergers? From oursample?
Tidal disturbances > 4 n n Y
KDCs < 12? n n Y
KDCs + tidal disturbances > 4 n n Y
Stellar age + α-elements (massive ETGs) > 10 n Y Y
Galaxy counts at high z > 8–9 n n n
Ellipticities of massive quenched galaxies at high z > 10 n n n
Sérsic indices of massive quenched galaxies at high z > 12 n n n
Luminosities, surface brightnesses and effective radii of brightest cluster galaxies at high z > 10 n n n
Inner phot. profiles (low environmental density) > 10 n Y Y
Dust lanes > 1 n n Y
Effective radii > 12 n Y Y
Metallicity gradients Y n Y

Notes. Observation: The observable providing constraints on the properties of mergers that caused the kinematic transformation. The order is as discussed in the text. Time since transformation: The typical time of the kinematic transformation implied by the given observable. A question mark indicates a speculative estimate. Indicates minor mergers? and Indicates wet mergers?: The columns show whether the given observable implies that the mergers causing the kinematic transformation were minor or wet, respectively. The symbols “Y” and “n” indicate yes and no, respectively. None of the observing facts considered in this study indicate that the mergers were major or dry. From our sample?: Indicates whether the given observational data are those analyzed in this paper or come from literature, with the meaning of symbols as before. The data from literature sources might be less telling for the galaxy sample investigated in this paper.

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