Search

We present the results of a systematic search for Lyα emitters (LAEs) at using the HST WFC3 Infrared Spectroscopic Parallel (WISP) Survey. Our total volume over this redshift range is Mpc3, comparable to many of the narrowband surveys despite their larger area coverage. We find two LAEs at z = 6.38 and 6.44 with line luminosities of erg s−1, putting them among the brightest LAEs discovered at these redshifts. Taking advantage of the broad spectral coverage of WISP, we are able to rule out almost all lower-redshift contaminants. The WISP LAEs have a high number density of Mpc−3. We argue that the LAEs reside in megaparsec-scale ionized bubbles that allow the Lyα photons to redshift out of resonance before encountering the neutral intergalactic medium. We discuss possible ionizing sources and conclude that the observed LAEs alone are not sufficient to ionize the bubbles. [ABSTRACT FROM AUTHOR]

Looking for bright galaxies born in the early universe is fundamental to investigating the Epoch of Reionization, the era when the first stars and galaxies ionized the intergalactic medium. We utilize Hubble Space Telescope pure-parallel imaging to select galaxy candidates at a time 500–650 million years after the Big Bang, which corresponds to redshifts z ∼ 8–10. These data come from the Brightest of Reionizing Galaxies Survey (BoRG) Cycle 22 data set, which consists of pure-parallel imaging in ∼90 different lines of sight that sum up to an area of ∼420 arcmin2. This survey uses five filters and has the advantage (compared to the Cycle 21 BoRG program) of including imaging in the JH140 band, covering continuous wavelengths from the visible to near-infrared (λ = 0.35–1.7 μm). This allows us to perform a reliable selection of galaxies at z ≥ 8 using the photometric-redshift technique. We use these galaxy candidates to constrain the bright end of the rest-frame ultraviolet luminosity function in this epoch. These candidates are excellent targets for follow-up observations, particularly with the James Webb Space Telescope. [ABSTRACT FROM AUTHOR]

We present the first results from our survey of the star-forming complex W3, combining VRI photometry with multiobject spectroscopy to identify and characterize the high-mass stellar population across the region. With 79 new spectral classifications, we bring the total number of spectroscopically confirmed O- and B-type stars in W3 to 105. We find that the high-mass slope of the mass function in W3 is consistent with a Salpeter IMF, and that the extinction toward the region is best characterized by an RV of approximately 3.6. B-type stars are found to be more widely dispersed across the W3 giant molecular cloud (GMC) than previously realized: they are not confined to the high-density layer (HDL) created by the expansion of the neighboring W4 H ii region into the GMC. This broader B-type population suggests that star formation in W3 began spontaneously up to 8–10 Myr ago, although at a lower level than the more recent star formation episodes in the HDL. In addition, we describe a method of optimizing sky subtraction for fiber spectra in regions of strong and spatially variable nebular emission. [ABSTRACT FROM AUTHOR]