The ultraviolet properties of star-forming galaxies - I. HST WFC3 observations of very high redshift galaxies
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 417:1 (2011) 717-729
The WFC3 infrared spectroscopic parallel (WISP) survey
Astrophysical Journal 723:1 (2010) 104-115
Abstract:
We present the WFC3 Infrared Spectroscopic Parallel (WISP) Survey. WISP is obtaining slitless, near-infrared grism spectroscopy of ∼90 independent, high-latitude fields by observing in the pure-parallel mode with the Wide Field Camera Three on the Hubble Space Telescope for a total of ∼250 orbits. Spectra are obtained with the G102 (λ = 0.8-1.17 μm, R ∼ 210) and G141 grisms (λ = 1.11-1.67 μm, R ∼ 130), together with direct imaging in the J and H bands (F110W and F140W, respectively). In the present paper, we present the first results from 19 WISP fields, covering approximately 63 arcmin2. For typical exposure times (∼6400 s in G102 and ∼2700 s in G141), we reach 5σ detection limits for emission lines of f ∼ 5 × 10 -17 erg s-1 cm-2 for compact objects. Typical direct imaging 5σ limits are 26.3 and 26.1 mag. (AB) in F110W and F140W, respectively. Restricting ourselves to the lines measured with the highest confidence, we present a list of 328 emission lines, in 229 objects, in a redshift range 0.3 < z < 3. The single-line emitters are likely to be a mix of Hα and [O III]5007,4959 Å, with Hα predominating. The overall surface density of high-confidence emission-line objects in our sample is approximately 4 per arcmin2. These first fields show high equivalent width sources, active galactic nucleus, and post-starburst galaxies. The median observed star formation rate (SFR) of our Hα-selected sample is 4 M⊙ yr-1. At intermediate redshifts, we detect emission lines in galaxies as faint as H140 ∼ 25, or M R < - 19, and are sensitive to SFRs down to less than 1M ⊙ yr-1. The slitless grisms on WFC3 provide a unique opportunity to study the spectral properties of galaxies much fainter than L* at the peak of the galaxy assembly epoch. © 2010. The American Astronomical Society.2D kinematics and physical properties of z ∼ 3 star-forming galaxies
Monthly Notices of the Royal Astronomical Society 401:3 (2010) 1657-1669
Abstract:
We present results from a study of the kinematic structure of star-forming galaxies at redshift z ∼ 3 selected in the VIMOS VLT Deep Survey (VVDS), using integral field spectroscopy of rest-frame optical nebular emission lines, in combination with rest-frame UV spectroscopy, ground-based optical/near-IR and Spitzer photometry. We also constrain the underlying stellar populations to address the evolutionary status of these galaxies. We infer the kinematic properties of four galaxies: VVDS-20298666, VVDS-020297772, VVDS-20463884 and VVDS-20335183 with redshifts z = 3.2917, 3.2878, 3.2776 and 3.7062, respectively. While VVDS-20463884 presents an irregular velocity field with a peak in the local velocity dispersion of the galaxy shifted from the centre of the galaxy, VVDS-20298666 has a well-resolved gradient in velocity over a distance of ∼4.5 kpc with a peak-to-peak amplitude of v = 91 km s -1. We discovered that the nearby galaxy, VVDS-020297772 (which shows traces of active galactic nucleus activity), is in fact a companion at a similar redshift with a projected separation of 12 kpc. In contrast, the velocity field of VVDS-020335183 seems more consistent with a merger on a rotating disc. However, all of the objects have a high local velocity dispersion (σ ∼ 60-70 km s-1), which gives v/σ ≲ 1. It is unlikely that these galaxies are a dynamically cold rotating disc of ionized gas. © 2009 RAS.GRB 090426: The environment of a rest-frame 0.35-s gamma-ray burst at a redshift of 2.609
Monthly Notices of the Royal Astronomical Society 401:2 (2010) 963-972
Abstract:
We present the discovery of an absorption-line redshift of z = 2.609 for GRB 090426, establishing the first firm lower limit to a redshift for a gamma-ray burst (GRB) with an observed duration of <2 s. With a rest-frame burst duration of T90z = 0.35 s and a detailed examination of the peak energy of the event, we suggest that this is likely (at >90 per cent confidence) a member of the short/hard phenomenological class of GRBs. From analysis of the optical-afterglow spectrum we find that the burst originated along a very low H i column density sightline, with NH i < 3.2 × 1019 cm-2. Our GRB 090426 afterglow spectrum also appears to have weaker low-ionization absorption (Si ii, C ii) than ∼95 per cent of previous afterglow spectra. Finally, we also report the discovery of a blue, very luminous, star-forming putative host galaxy (∼2L *) at a small angular offset from the location of the optical afterglow. We consider the implications of this unique GRB in the context of burst duration classification and our understanding of GRB progenitor scenarios. © 2009 RAS.Keck spectroscopy of faint 3 < z < 7 Lyman break galaxies - I. New constraints on cosmic reionization from the luminosity and redshift-dependent fraction of Lyman α emission
Monthly Notices of the Royal Astronomical Society 408:3 (2010) 1628-1648