Gabriel B. Brammer

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We present 3D-HST, a near-infrared spectroscopic Treasury program with the Hubble Space Telescope for studying the physical processes that shape galaxies in the distant universe. 3D-HST provides rest-frame optical spectra for a sample of ∼7000 galaxies at 1 < z < 3.5, the epoch when ∼60% of all star formation took place, the number density of quasars(More)
We study the growth of massive galaxies from z = 2 to the present using data from the NOAO/Yale NEWFIRM Medium Band Survey. The sample is selected at a constant number density of n = 2×10−4 Mpc−3, so that galaxies at different epochs can be compared in a meaningful way. We show that the stellar mass of galaxies at this number density has increased by a(More)
Context. Photometric redshifts (photo-z’s) have become an essential tool in extragalactic astronomy. Many current and upcoming observing programmes require great accuracy of photo-z’s to reach their scientific goals. Aims. Here we introduce PHAT, the PHoto-z Accuracy Testing programme, an international initiative to test and compare different methods of(More)
We use a robust sample of 11 z ∼ 7 galaxies (z850-dropouts) to estimate the stellar mass density of the universe when it was only ∼750 Myr old. We combine the very deep optical to near-Infrared photometry from the HST ACS and NICMOS cameras with mid-Infrared Spitzer IRAC imaging available through the GOODS program. After carefully removing the flux from(More)
We present HST/WFC3 grism spectroscopy of the brightest galaxy at z > 1.5 in the GOODS-South WFC3 Early Release Science grism pointing, covering the wavelength range 0.9μm – 1.7μm. The spectrum is of remarkable quality and shows the redshifted Balmer lines Hβ, Hγ, and Hδ in absorption at z = 1.902± 0.002, correcting previous erroneous redshift measurements(More)
We use the optical to mid-infrared coverage of the NEWFIRM Medium-Band Survey (NMBS) to characterize, for the first time, the properties of a mass-complete sample of 14 galaxies at 3.0 z < 4.0 with Mstar > 2.5×1011 M , and to derive significantly more accurate measurements of the high-mass end of the stellar mass function (SMF) of galaxies at 3.0 z < 4.0.(More)
In 1964, Refsdal hypothesized that a supernova whose light traversed multiple paths around a strong gravitational lens could be used to measure the rate of cosmic expansion. We report the discovery of such a system. In Hubble Space Telescope imaging, we have found four images of a single supernova forming an Einstein cross configuration around a redshift z(More)
Supernova “Refsdal,” multiply imaged by cluster MACS1149.5+2223, represents a rare opportunity to make a true blind test of model predictions in extragalactic astronomy, on a timescale that is short compared to a human lifetime. In order to take advantage of this event, we produced seven gravitational lens models with five independent methods, based on(More)
In the cold dark matter cosmology, the baryonic components of galaxies-stars and gas-are thought to be mixed with and embedded in non-baryonic and non-relativistic dark matter, which dominates the total mass of the galaxy and its dark-matter halo. In the local (low-redshift) Universe, the mass of dark matter within a galactic disk increases with disk(More)
In Hubble Space Telescope (HST) imaging taken on 2014 November 10, four images of supernova (SN) “Refsdal” (redshift z=1.49) appeared in an Einstein-cross-like configuration (images S1–S4) around an early-type galaxy in the cluster MACS J1149.5+2223 (z=0.54). Almost all lens models of the cluster have predicted that the SN should reappear within a year(More)