Details

Autor(en) / Beteiligte

• Chan, Jeffrey C. C
• Beifiori, Alessandra
• Mendel, J. Trevor
• Saglia, Roberto P
• Bender, Ralf
• Fossati, Matteo
• Galametz, Audrey
• Wegner, Michael
• Wilman, David J
• Cappellari, Michele
• Davies, Roger L
• Houghton, Ryan C. W
• Prichard, Laura J
• Lewis, Ian J
• Sharples, Ray
• Stott, John P

Titel

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

Ist Teil von

• Monthly notices of the Royal Astronomical Society, 2016-05, Vol.458 (3), p.3181-3209

Ort / Verlag

London: Oxford University Press

Erscheinungsjahr

2016

Link zum Volltext

Quelle

Electronic Journals Library

Beschreibungen/Notizen

• We analyse the sizes, colour gradients and resolved stellar mass distributions for 36 massive and passive galaxies in the cluster XMMUJ2235-2557 at z = 1.39 using optical and near-infrared Hubble Space Telescope (HST) imaging. We derive light-weighted Sérsic fits in five HST bands (i 775, z 850, Y 105, J 125, H 160), and find that the size decreases by ∼20 per cent going from i 775 to H 160 band, consistent with recent studies. We then generate spatially resolved stellar mass maps using an empirical relationship between $M_{{\ast }}/L_{H_{160}}$ and (z 850 − H 160) and use these to derive mass-weighted Sérsic fits: the mass-weighted sizes are ∼41 per cent smaller than their rest-frame r-band counterparts compared with an average of ∼12 per cent at z ∼ 0. We attribute this evolution to the evolution in the $M_{{\ast }}/L_{H_{160}}$ and colour gradient. Indeed, as expected, the ratio of mass-weighted to light-weighted size is correlated with the M */L gradient, but is also mildly correlated with the mass surface density and mass-weighted size. The colour gradients (∇ z − H ) are mostly negative, with a median value of ∼0.45 mag dex−1, twice the local value. The evolution is caused by an evolution in age gradients along the semimajor axis (a), with ∇age = dlog (age)/dlog (a) ∼− 0.33, while the survival of weaker colour gradients in old, local galaxies implies that metallicity gradients are also required, with ∇ Z  = dlog (Z)/dlog (a) ∼− 0.2. This is consistent with recent observational evidence for the inside–out growth of passive galaxies at high redshift, and favours a gradual mass growth mechanism, such as minor mergers.