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Using photometric redshifts we determine the galaxy population of the clusters of galaxies Cl0016+16 at , Cl1600+41 at , Cl1601+42 at and MS1008–1224 at . Comparing the clusters, we find no evidence for a universal shape of the total luminosity function (LF) at these redshifts. When dividing the LFs into spectral types, we find that the LF of the early-type galaxies alone can be described by a Gaussian, while the LF of the late-type galaxies is well fitted by a Schechter function, suggesting that the separate LFs for different populations may be universal. The difference in the total LFs can mainly be attributed to the varying relative normalization of these populations, implying that clusters with an abundant population of late-type galaxies also have steeper faint-end slopes. In MS1008–1224 we detect a faint blue population that dominates over a population with colours consistent with dwarf ellipticals, opposite to clusters at lower redshift. Compared to low-redshift clusters, we find that a general fading of the late-type population by ∼2 mag and the early-type population by ∼1 mag describes the evolution from to well. As a consequence of the different early-type and late-type LFs and their dependence on cluster radius, the fraction of blue cluster galaxies, as measured by the Butcher–Oemler effect, differs between the clusters and depends on limiting magnitude and radius. We find a correlation between the dwarf-to-giant ratio and the surface density, indicating that the high-density environment in the cluster cores is hostile to dwarf galaxies. [ABSTRACT FROM AUTHOR]

Photometric redshifts are used to determine the rest-frame luminosity function (LF) of both early- and late-type galaxies to M ∼ -17.6 for the cluster C1 1601+42 at z = 0.54. The total LF shows a steep faint-end slope α ∼ -1.4, indicating the existence of a population of numerous dwarf galaxies. Luminous galaxies, with M ≤-19.5 are mostly red, early-type galaxies, with a LF best described by a Gaussian. Faint galaxies are predominantly blue, late-type galaxies, well fitted by a Schechter function with α ∼ -1.7. Compared with clusters at lower redshift, the steepening of the faint end starts at brighter magnitudes for C1 1601+42, which may indicate a brightening of the present-day dwarf population relative to the giant population with increasing redshift. Early-type galaxies are centrally concentrated, and dominate the core region, implying that the radial gradient of early-type galaxies seen in local clusters is already established at z ∼ 0.5. Bright, late-type galaxies are rare, consistent with a decrease in star formation in field galaxies as they are accreted on to the cluster, while faint, blue galaxies are evenly distributed across the cluster, except for a depletion in the core region. The blue fraction is f ∼ 0.15, which is somewhat lower than the Butcher -- Oemler average at z ∼ 0.5. The value of is found to increase with limiting magnitude and with radius from the centre. [ABSTRACT FROM AUTHOR]

Hubble Space Telescope and ground-based observations of the Type IIn supernova (SN) 2010jl are analyzed, including photometry and spectroscopy in the ultraviolet, optical, and near-IR bands, 26-1128 days after first detection. At maximum, the bolometric luminosity was ∼3 × 1043 erg s–1 and even at 850 days exceeds 1042 erg s–1. A near-IR excess, dominating after 400 days, probably originates in dust in the circumstellar medium (CSM). The total radiated energy is ≳ 6.5 × 1050 erg, excluding the dust component. The spectral lines can be separated into one broad component that is due to electron scattering and one narrow with expansion velocity ∼100 km s–1 from the CSM. The broad component is initially symmetric around zero velocity but becomes blueshifted after ∼50 days, while remaining symmetric about a shifted centroid velocity. Dust absorption in the ejecta is unlikely to explain the line shifts, and we attribute the shift instead to acceleration by the SN radiation. From the optical lines and the X-ray and dust properties, there is strong evidence for large-scale asymmetries in the CSM. The ultraviolet lines indicate CNO processing in the progenitor, while the optical shows a number of narrow coronal lines excited by the X-rays. The bolometric light curve is consistent with a radiative shock in an r–2 CSM with a mass-loss rate of . The total mass lost is ≳ 3 M☼. These properties are consistent with the SN expanding into a CSM characteristic of a luminous blue variable progenitor with a bipolar geometry. The apparent absence of nuclear processing is attributed to a CSM that is still opaque to electron scattering. [ABSTRACT FROM AUTHOR]