Spatially Resolved Emission of a High-Redshift Dla Galaxy With the Keck/Osiris Ifu

Abstract

We present the first Keck/OSIRIS infrared IFU observations of a high redshift damped Lyman−α (DLA) galaxy detected in the line of sight to a background quasar. By utilizing the Laser Guide Star Adaptive Optics (LGSAO) to reduce the quasar PSF to FWHM∼ 0.15 , we were able to search for and map the foreground DLA emission free from the quasar contamination. We present maps of the Hα and [O III] λλ5007, 4959 emission of DLA2222−0946 at a redshift of z ∼ 2.35. From the composite spectrum over the Hα emission region we measure a star formation rate of 9.5 ± 1.0 M year −1 and a dynamical mass, M dyn = 6.1 × 10 9 M . The average star formation rate surface density is Σ SF R = 0.55 M yr −1 kpc −2 , with a central peak of 1.7 M yr −1 kpc −2 . Using the standard Kennicutt-Schmidt relation, this corresponds to a gas mass surface density of Σ gas = 243 M pc −2 . Integrating over the size of the galaxy we find a total gas mass of M gas = 4.2 × 10 9 M . We estimate the gas fraction of DLA2222−0946 to be f gas ∼ 40%. We detect [N II]λ6583 emission at 2.5σ significance with a flux corresponding to a metallicity of 75% solar. Comparing this metallicity with that derived from the low-ion absorption gas ∼6 kpc away, ∼30% solar, indicates possible evidence for a metallicity gradient or enriched in/outflow of gas. Kinematically, both Hα and [O III] emission show relatively constant velocity fields over the central galactic region. While we detect some red and blueshifted clumps of emission, they do not correspond with rotational signatures that support an edge-on disk interpretation.

Directly imaging damped Ly α galaxies at z > 2 – III. The star formation rates of neutral gas reservoirs at z ∼ 2.7

“…Fynbo et al 2011Fynbo et al , 2013Péroux et al 2011Péroux et al , 2012Noterdaeme et al 2012a;Bouché et al 2013;Jorgenson & Wolfe 2014), has yielded 11 DLA galaxies currently known at z > 1.9. In Table 2, we present a summary of the properties of these confirmed DLA galaxies.…”

Starburst–AGN mixing – II. Optically selected active galaxies

“…Yuan et al (2011) measure the gradient in the gas-phase metal abundance of a lensed galaxy at z = 1.49 using laser guide star (LGS) AO observations from the OSIRIS IFU on Keck II. Jorgenson & Wolfe (2014) also use OSIRIS data to construct maps of the Hα and [O III] lines for a Lyα-emitter at z ∼ 2.2, and Nesvadba et al (2007) present an argument for the existence of a starburst-driven wind in a sub-millimetre galaxy at z ∼ 2.56 using deep NIR IFU data from SPIFFI on the VLT. These works highlight the growing potential to use the spatial variation of emission line fluxes and ratios as diagnostics for the principle ionization sources of high redshift galaxies.…”

Galaxy counterparts of metal-rich damped Lyα absorbers: the case of J205922.4−052842★

“…Smith, Cohen & Bradley 1986;Møller & Warren 1993;Kulkarni et al 2001;Fumagalli et al 2014) and integral field spectroscopy (e.g. Christensen et al 2007;Péroux et al 2011;Bouché et al 2012;Jorgenson & Wolfe 2014). Despite the much larger number of systems being observed, between 1986 and 2010 the galaxy counterparts of only two bona fide DLAs were identified (Møller, Fynbo & Fall 2004; but see also Krogager et al 2012;Christensen et al 2014).…”