Hakim Atek

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Exploiting the power of gravitational lensing, the Hubble Frontier Fields (HFF) program aims at observing six massive galaxy clusters to explore the distant universe far beyond the limits of blank field surveys. Using the complete Hubble Space Telescope observations of the first HFF cluster A2744, we report the detection of 50 galaxy candidates at z ∼ 7 and(More)
Aims. The Aim of our study is to understand the variety of observed Lyα line profiles and strengths in Lyman Break Galaxies (LBGs) and Lyα emitters (LAEs), the physical parameters governing them, and hence to derive constraints on the gas and dust content and stellar populations of these objects. Methods. Using our 3D Lyα radiation transfer code including(More)
Context. The Lyman-alpha (Lyα) recombination line is a fundamental tool for galaxy evolution studies and modern observational cosmology. However, subsequent interpretations are still prone to a number of uncertainties. Besides numerical efforts, empirical data are urgently needed for a better understanding of the Lyα escape process. Aims. We empirically(More)
We use a joint optical/X-ray analysis to constrain the geometry and history of the ongoing merging event in the massive galaxy cluster MACSJ0416.1−2403 (z = 0.397). Our investigation of cluster substructure rests primarily on a combined strongand weak-lensing mass reconstruction based on the deep, high-resolution images obtained for the Hubble Frontier(More)
Context. Lyman-alpha (Lyα) is now widely used to investigate the galaxy formation and evolution in the high redshift universe. . However, without a rigorous understanding of the processes which regulate the Lyα escape fraction, physical interpretations of high-z observations remain questionable. Aims. To examine six nearby star-forming galaxies to(More)
Context. Among the different observational techniques used to select high-redshift galaxies, the hydrogen recombination line Lymanalpha (Lyα) is of particular interest because it gives access to the measurement of cosmological quantities such as the star formation rate (SFR) of distant galaxy populations. However, interpreting this line and calibrating such(More)
We present reduced and calibrated high resolution Lyman-alpha (Lyα) images for a sample of six local star forming galaxies. Targets were selected to represent a range in luminosity and metallicity and to include both known Lyα emitters and non-emitters. Far ultraviolet imaging was carried out with the Solar Blind Channel of the Advanced Camera for Surveys(More)
We combine HST G102 & G141 NIR grism spectroscopy with HST/WFC3-UVIS, HST/WFC3IR and Spitzer/IRAC[3.6μm] photometry to assemble a sample of massive (log(Mstar/M⊙) ∼ 11.0) and quenched galaxies at z ∼ 1.5. Our sample of 41 galaxies is the largest with G102+G141 NIR spectroscopy for quenched sources at these redshifts. In contrast to the local Universe, z ∼(More)
We present results from near-infrared spectroscopy of 26 emission-line galaxies at z ∼ 2.2 and z ∼ 1.5 obtained with the Folded-port InfraRed Echellette (FIRE) spectrometer on the 6.5-meter Magellan Baade telescope. The sample was selected from the WFC3 Infrared Spectroscopic Parallels (WISP) survey, which uses the near-infrared grism of the Hubble Space(More)
We present the first robust measurement of the high redshift mass-metallicity (MZ) relation at 10 . M/M⊙ . 10 , obtained by stacking spectra of 83 emission-line galaxies with secure redshifts between 1.3 . z . 2.3. For these redshifts, infrared grism spectroscopy with the Hubble Space Telescope Wide Field Camera 3 is sensitive to the R23 metallicity(More)