The Kormendy relation of massive elliptical galaxies at z  1.5: evidence for size evolution

Abstract

We present the morphological analysis based on HST-NIC2 (0.075 arcsec pixel −1 ) images in the F160W filter of a sample of nine massive field (>10 11 M ) galaxies spectroscopically classified as early-types at 1.2 < z < 1.7. Our analysis shows that all of them are bulgedominated systems. In particular, six of them are well fitted by a de Vaucouleurs profile (n = 4) suggesting that they can be considered pure elliptical galaxies. The remaining three galaxies are better fitted by a Sérsic profile with index 1.9 < n fit < 2.3 suggesting that a disc-like component could contribute up to 30 per cent to the total light of these galaxies. We derived the effective radius R e and the mean surface brightness (SB) μ e within R e of our galaxies and we compared them with those of early-types at lower redshifts. We find that the SB μ e of our galaxies should get fainter by 2.5 mag from z ∼ 1.5 to ∼0 to match the SB of the local ellipticals with comparable R e , that is, the local Kormendy relation. Luminosity evolution without morphological changes can only explain half of this effect, as the maximum dimming expected for an elliptical galaxy is ∼1.6 mag in this redshift range. Thus, other parameters, possibly structural, may undergo evolution and play an important role in reconciling models and observations. Hypothesizing an evolution of the effective radius of galaxies we find that R e should increase by a factor of 1.5 from z ∼ 1.5 to ∼0.

Cluster galaxies in XMMU J2235-2557: galaxy population properties in most massive environments atz ~ 1.4

“…On the other hand, it is interesting to remember that the structural properties of such massive objects might be different from those of similar galaxies in the local Universe. As pointed out in several studies (e.g., Daddi et al 2005;Trujillo et al 2006bTrujillo et al ,a, 2007Longhetti et al 2007;Cimatti et al 2008;Buitrago et al 2008;Damjanov et al 2009;Rettura et al 2010;Williams et al 2010;Taylor et al 2010, and references therein), massive early-type galaxies at high redshift appear to be (on average) more compact than their local counterparts, their size being smaller than that of local early-types of comparable mass (but see also results and discussion in e.g. Mancini et al 2010;Onodera et al 2010;Valentinuzzi et al 2010;Saracco et al 2010, and references therein).…”

Galaxy And Mass Assembly (GAMA): $\mathcal {M_\star }\text{--}R_{\rm e}$ relations ofz= 0 bulges, discs and spheroids

“…Daddi et al 2005;Longhetti et al 2007;van Dokkum et al 2008;Trujillo et al 2006Trujillo et al , 2007. This itself is not a problem since an evolution in the M − Re relation is expected due to galaxies at later times being formed through less dissipative events (i.e.…”

Sizes, colour gradients and resolved stellar mass distributions for the massive cluster galaxies in XMMUJ2235-2557 atz= 1.39

“…Previous studies suggest that massive passive galaxies have grown by a factor of ∼ 2 in size since z ∼ 1 (e.g. Trujillo et al 2006b;Longhetti et al 2007;Cimatti et al 2008;van der Wel et al 2008;Saglia et al 2010;Beifiori et al 2014), and a factor of ∼ 4 since z ∼ 2 (e.g. Trujillo et al 2007;Buitrago et al 2008;van Dokkum et al 2008;Newman et al 2012;Szomoru, Franx & van Dokkum 2012;Barro et al 2013;van der Wel et al 2014).…”