(2016) 'Sizes, colour gradients and resolved stellar mass distributions for the massive cluster galaxies in XMMUJ2235-2557 at z = 1.39.', Monthly notices of the Royal Astronomical Society., 458 (3). pp. 3181-3209. Further information on publisher's website: Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. ABSTRACTWe 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 nearinfrared Hubble Space Telescope 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% 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 * /L H 160 and (z 850 − H 160 ) and use these to derive mass-weighted Sérsic fits: the mass-weighted sizes are ∼ 41% smaller than their restframe r-band counterparts compared with an average of ∼ 12% at z ∼ 0. We attribute this evolution to the evolution in the M * /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 semi-major axis (a), with ∇ age = d log(age)/d log(a) ∼ −0.33, while the survival of weaker colour gradients in old, local galaxies implies that metallicity gradients are also required, with ∇ Z = d log(Z)/d log(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.

We present the analysis of the fundamental plane (FP) for a sample of 19 massive red-sequence galaxies (M > 4 × 10 10 M ) in 3 known overdensities at 1.39 < z < 1.61 from the KMOS Cluster Survey, a guaranteed time program with spectroscopy from the K-band Multi-Object Spectrograph (KMOS) at the VLT and imaging from the Hubble Space Telescope. As expected, we find that the FP zero-point in B band evolves with redshift, from the value 0.443 of Coma to −0.10 ± 0.09, −0.19 ± 0.05, −0.29 ± 0.12 for our clusters at z = 1.39, z = 1.46, and z = 1.61, respectively. For the most massive galaxies (log M /M > 11) in our sample, we translate the FP zero-point evolution into a mass-to-light-ratio M/L evolution finding ∆ log M/L B = (−0.46 ± 0.10)z, ∆ log M/L B = (−0.52 ± 0.07)z, to ∆ log M/L B = (−0.55 ± 0.10)z, respectively. We assess the potential contribution of the galaxies structural and stellar velocity dispersion evolution to the evolution of the FP zeropoint and find it to be ∼6-35% of the FP zero-point evolution. The rate of M/L evolution is consistent with galaxies evolving passively. By using single stellar population models, we find an average age of 2.33 +0.86 −0.51 Gyr for the log M /M > 11 galaxies in our massive and virialized cluster at z = 1.39, 1.59 +1.40 −0.62 Gyr in a massive but not virialized cluster at z = 1.46, and 1.20 +1.03 −0.47 Gyr in a protocluster at z = 1.61. After accounting for the difference in the age of the Universe between redshifts, the ages of the galaxies in the three overdensities are consistent within the errors, with possibly a weak suggestion that galaxies in the most evolved structure are older.

We present integral field spectroscopy of 10 early-type galaxies in the nearby, low-mass, Fornax cluster, from which we derive spatially resolved stellar kinematics. Based on the morphologies of their stellar velocity maps we classify 2/10 galaxies as slow rotators, with the remaining 8 galaxies fast rotators.Supplementing our integral field observations with morphological and kinematic data from the literature, we analyse the 'kinematic' type of all 30 galaxies in the Fornax cluster brighter than M K = −21.5 mag (M * ∼ 6 × 10 9 M ). Our sample's slow rotator fraction within one virial radius is 7 +4 −6 per cent. 13 +8 −6 per cent of the early-type galaxies are slow rotators, consistent with the observed fraction in other galaxy aggregates. The fraction of slow rotators in Fornax varies with cluster-centric radius, rising to 16 +11 −8 per cent of all kinematic types within the central 0.2 virial radii, from 0 per cent in the cluster outskirts.We find that, even in mass-matched samples of slow and fast rotators, slow rotators are found preferentially at higher projected environmental density than fast rotators. This demonstrates that dynamical friction alone cannot be responsible for the differing distributions of slow and fast rotators. For dynamical friction to play a significant role, slow rotators must reside in higher mass sub-halos than fast rotators and/or form in the centres of groups before being accreted on to the cluster.

We present near‐infrared (NIR) adaptive optics‐assisted spectroscopic observations of the CO (Δμ= 2) absorption bands towards the centre of the giant elliptical galaxy NGC 1399. The observations were made with NAOS‐CONICA (on the European Southern Observatory's Very Large Telescope) and have a full width at half‐maximum resolution of 0.15 arcsec (14 pc). Kinematic analysis of the observations reveals a decoupled core and strongly non‐Gaussian line‐of‐sight velocity profiles in the central 0.2 arcsec (19 pc). NIR imaging also indicates an asymmetric elongation of the central isophotes in the same region. We use spherical orbit‐superposition models to interpret the kinematics, using a set of orthogonal ‘eigen‐velocity profiles’ that allow us to fit models directly to spectra. The models require a central black hole of mass 1.2+0.5−0.6× 109 M⊙, with a strongly tangentially biased orbit distribution in the inner 40 pc.

We present spatially resolved measurements of the stellar initial mass function (IMF) in NGC 1399, the largest elliptical galaxy in the Fornax Cluster. Using data from the Multi Unit Spectroscopic Explorer (MUSE) and updated state-of-the-art stellar population synthesis models from Conroy et al. (2018), we use full spectral fitting to measure the low-mass IMF, as well as a number of individual elemental abundances, as a function of radius in this object. We find that the IMF in NGC 1399 is heavier than the Milky Way in its centre and remains radially constant at a super-salpeter slope out to 0.7 R e . At radii larger than this, the IMF slope decreases to become marginally consistent with a Milky Way IMF just beyond R e . The inferred central V-band M/L ratio is in excellent agreement with the previously reported dynamical M/L measurement from Houghton et al. (2006). The measured radial form of the M/L ratio may be evidence for a two-phase formation in this object, with the central regions forming differently to the outskirts. We also report measurements of a spatially resolved filament of ionised gas extending 4 (404 pc at D L = 21.1 Mpc) from the centre of NGC 1399, with very narrow equivalent width and low velocity dispersion (65 ± 14 kms −1 ). The location of the emission, combined with an analysis of the emission line ratios, leads us to conclude that NGC 1399's AGN is the source of ionising radiation.