Related papers: Mission: Impossible (Escape from the Lyman Limit)
We present UV spectroscopy from HST/GHRS and reanalyze existing H_alpha images of the quasar/galaxy pair 3C 232/NGC 3067 and of the halo gas associated with NGC 3067. The spectra permit measurement of, or limits on, the column densities of…
We present a sample of 407 z~3 Lyman break galaxies (LBGs) to a limiting isophotal u-band magnitude of 27.6 mag in the Hubble Ultra Deep Field (UDF). The LBGs are selected using a combination of photometric redshifts and the u-band drop-out…
We present the results of the deepest search to date for star-forming galaxies beyond a redshift z~8.5 utilizing a new sequence of near-infrared Wide Field Camera 3 images of the Hubble Ultra Deep Field. This `UDF12' campaign completed in…
We compute the ionizing radiation field at low redshift, arising from Seyferts, QSOs, and starburst galaxies. This calculation combines recent Seyfert luminosity functions, extrapolated ultraviolet fluxes from our IUE-AGN database, and a…
A significant fraction of the high-redshift galaxies show strong Lyman emission lines. For redshifts z>5, most known galaxies belong to this class. However, so far not much is known about the physical structure and nature of these objects.…
The sky-averaged (global) 21-cm signal is a powerful probe of the intergalactic medium (IGM) prior to the completion of reionization. However, it has so far been unclear that even in the best case scenario, in which the signal is accurately…
We have recently discovered five Lyman continuum leaking galaxies at z~0.3, selected for their compactness, intense star-formation, and high [OIII]/[OII] ratio (Izotov et al. 2016ab). Here we derive their ionizing photon production…
We use a large sample of galaxies at z~3 to establish a relationship between reddening, neutral gas covering fraction (fcov(HI)), and the escape of ionizing photons at high redshift. Our sample includes 933 galaxies at z~3, 121 of which…
We use very large cosmological Smoothed-Particle-Hydrodynamics simulations to study the properties of high redshift Lyman-alpha emitters (LAEs). We identify star-forming galaxies at z=3.1 in a cosmological volume of 100 h^-1Mpc on a side.…
We cross-match the two currently largest all-sky photometric catalogs, mid-infrared WISE and SuperCOSMOS scans of UKST/POSS-II photographic plates, to obtain a new galaxy sample that covers 3pi steradians. In order to characterize and…
The demographics of the production and escape of ionizing photons from UV-faint early galaxies is a key unknown in discovering the primary drivers of reionization. With the advent of JWST it is finally possible to observe the rest-frame…
We present a catalog of photometry and photometric redshifts of 335 faint objects in the HDF-S NICMOS field. The analysis is based on (1) infrared images obtained with the Hubble Space Telescope (HST) using the Near Infrared Camera and…
We have developed a method for selecting the most luminous galaxies detected by IRAS based on their extreme values of R, the ratio of 60 micron and B-band luminosity. These objects have optical counterparts that are close to or below the…
We examine the relationship between galaxies and the intergalactic medium at z < 1 using a group of three closely spaced background QSOs with z_em ~1 observed with the Hubble Space Telescope. Using a new grouping algorithm, we identify…
We present new Hubble Space Telescope/Wide Field Camera 3 imaging of 25 extremely luminous (-23.2 < M_ UV < -21.2) Lyman-break galaxies (LBGs) at z ~ 7. The sample was initially selected from 1.65 deg^2 of ground-based imaging in the…
The lack of success of Lyman-alpha searches for high-redshift (z>2) field galaxies may be due to extinction by dust, suggesting that surveys based on lines of longer wavelength, particularly H-alpha, may be more effective. To test the dust…
We publicly release a new sample of $34$ medium resolution quasar spectra at $5.77\leq z_{\rm em}\leq6.54$ observed with the Echellette Spectrograph and Imager (ESI) on the Keck telescope. This quasar sample represents an ideal laboratory…
The UltraViolet Imaging of the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey Fields (UVCANDELS) survey is a Hubble Space Telescope (HST) Cycle-26 Treasury Program, allocated in total 164 orbits of primary Wide-Field Camera…
Aims: We present an analysis of the Lyman continuum (LyC) escape fraction of high redshift galaxies using an analytic post-processing approach. Methods: We apply the model to 600,000 galaxies of the Illustris TNG50 simulation in the…
We describe an ongoing experiment to search for the meta-galactic Lyman-continuum background at z~2-3. We are obtaining one of the deepest optical spectra ever, using LRIS/Keck-II to search for the fluorescent Ly-alpha emission from…