As the topics of study of Ly alpha emitters evolve, new selection methods are being developed to find these high redshift galaxies. In this proceedings, three new methods are presented, based on large integral field unit spectrographs, ultradeep slit spectroscopy and serendipitous discoveries. (C) 2009 Elsevier B.V. All rights reserved.

We present the results of Magellan/MMIRS and Keck/NIRSPEC spectroscopy for five Ly alpha emitters (LAEs) at z similar or equal to 2.2 for which high-resolution FUV spectra from Magellan/MagE are available. We detect nebular emission lines including H alpha on the individual basis and low-ionization interstellar (LIS) absorption lines in a stacked FUV spectrum, and measure average offset velocities of the Ly alpha line, Delta v(Ly alpha), and LIS absorption lines, Delta v(abs), with respect to the systemic velocity defined by the nebular lines. For a sample of eight z similar to 2-3 LAEs without active galactic nucleus from our study and the literature, we obtain Delta v(Ly alpha) = 175 +/- 35 km s(-1), which is significantly smaller than that of Lyman-break Galaxies (LBGs), Delta v(Ly alpha) similar or equal to 400 km s(-1). The stacked FUV spectrum gives Delta v(abs) = -179 +/- 73 km s(-1), comparable to that of LBGs. These positive Delta v(Ly alpha) and negative Delta v(abs) suggest that LAEs also have outflows. In contrast to LBGs, however, the LAEs' Delta v(Ly alpha) is as small as |Delta v(abs)|, suggesting low neutral hydrogen column densities. Such a low column density with a small number of resonant scattering may cause the observed strong Ly alpha emission of LAEs. We find an anti-correlation between Ly alpha equivalent width (EW) and Delta v(Ly alpha) in a compilation of LAE and LBG samples. Although its physical origin is not clear, this anti-correlation result appears to challenge the hypothesis that a strong outflow, by means of a reduced number of resonant scattering, produces a large EW. If LAEs at z > 6 have similarly small Delta v(Ly alpha) values, constraints on the reionization history derived from the Ly alpha transmissivity may need to be revised.

We present a statistical study of velocities of Ly alpha, interstellar (IS) absorption, and nebular lines and gas covering fraction for Ly alpha emitters (LAEs) at z similar or equal to 2. We make a sample of 22 LAEs with a large Ly alpha equivalent width (EW) of greater than or similar to 50 angstrom based on our deep Keck/Low Resolution Imaging Spectrometer (LRIS) observations, in conjunction with spectroscopic data from the Subaru/Fiber Multi Object Spectrograph program and the literature. We estimate the average velocity offset of Ly alpha from a systemic redshift determined with nebular lines to be Delta upsilon(Ly alpha) = 234 +/- 9 km s(-1). Using a Kolmogorov-Smirnov test, we confirm the previous claim of Hashimoto et al. that the average Delta upsilon(Ly alpha) of LAEs is smaller than that of Lyman break galaxies (LBGs). Our LRIS data successfully identify blueshifted multiple IS absorption lines in the UV continua of four LAEs on an individual basis. The average velocity offset of IS absorption lines from a systemic redshift is Delta upsilon(IS) = 204 +/- 27 km s(-1), indicating LAEs' gas outflow with a velocity comparable to typical LBGs. Thus, the ratio R-IS(Ly alpha) = Delta upsilon(Ly alpha)/Delta upsilon(IS) of LAEs is around unity, suggestive of low impacts on Ly alpha transmission by resonant scattering of neutral hydrogen in the IS medium. We find an anti-correlation between Ly alpha EW and the covering fraction, f(c), estimated from the depth of absorption lines, where f(c) is an indicator of average neutral hydrogen column density, N-HI. The results of our study support the idea that N-HI is a key quantity determining Ly alpha emissivity.

We present the discovery of two z > 6 quasars, selected as i-band dropouts in the Very Large Telescope Survey Telescope ATLAS survey. Our first quasar has redshift, z = 6.31 +/- 0.03, z-band magnitude, z(AB) = 19.63 +/- 0.08 and rest frame 1450 angstrom absolute magnitude, M-1450 = -27.8 +/- 0.2, making it the joint second most luminous quasar known at z > 6. The second quasar has z = 6.02 +/- 0.03, z(AB) = 19.54 +/- 0.08 and M-1450 = -27.0 +/- 0.1. We also recover a z = 5.86 quasar discovered by Venemans et al., in preparation. To select our quasars, we use a new 3D colour space, combining the ATLAS optical colours with mid-infrared data from the Wide-field Infrared Survey Explorer. We use i(AB) - z(AB) colour to exclude main-sequence stars, galaxies and lower redshift quasars, W1 - W2 to exclude L dwarfs and z(AB) - W2 to exclude T dwarfs. A restrictive set of colour cuts returns only our three high redshift quasars and no contaminants, albeit with a sample completeness of similar to 50 per cent. We discuss how our 3D colour space can be used to reject the majority of contaminants from samples of bright 5.7 < z < 6.3 quasars, replacing follow-up near-infrared photometry, whilst retaining high completeness.

We present the results of an Ly alpha profile analysis of 12 Ly alpha emitters (LAEs) at z similar to 2.2 with high-resolution Ly alpha spectra. We find that all 12 objects have an Ly alpha profile with the main peak redward of the systemic redshift defined by nebular lines, and five have a weak, secondary peak blueward of the systemic redshift (blue bump). The average velocity offset of the red main peak (the blue bump, if any) with respect to the systemic redshift is Delta nu(Ly alpha,r) = 174 +/- 19 km s(-1) (Delta nu(Ly alpha,b) = -316 +/- 45 km s(-1)), which is smaller than (comparable to) that of Lyman break galaxies (LBGs). The outflow velocities inferred from metal absorption lines in three individual and one stacked spectra are comparable to those of LBGs. The uniform expanding shell model constructed by Verhamme et al. reproduces not only the Ly alpha profiles but also other observed quantities, including the outflow velocity and the FWHM. of nebular lines for the non-blue-bump objects. On the other hand, the model predicts too high FWHMs of nebular lines for the blue bump objects, although this discrepancy may disappear if we introduce additional Ly alpha photons produced by gravitational cooling. We show that the small D nu(Ly alpha,r) values of our sample can be explained by low neutral. hydrogen column densities of log(N-H (I)) = 18.9 cm(-2) on average. This value is more than one order of magnitude lower than those of LBGs but is consistent with recent findings that LAEs have high ionization parameters and low H (I) gas masses. This result suggests that low N-H (I) values, giving reduced numbers of resonant scattering of Ly alpha photons, are the key to the strong Ly alpha emission of LAEs.

We present the first results of a survey for high-redshift, z >= 6, quasars using izY multicolour photometric observations from the Dark Energy Survey (DES). Here we report the discovery and spectroscopic confirmation of the Z(AB), Y-AB = 20.2, 20.2 (M-1450 = -26.5) quasar DES J0454-4448 with a redshift of z = 6.09 +/- 0.02 based on the onset of the Ly alpha forest and an H I near zone size of 4.1(-1.2)(+1.1) proper Mpc. The quasar was selected as an i-band drop out with i-z = 2.46 and z(AB) < 21.5 from an area of similar to 300 deg(2). It is the brightest of our 43 candidates and was identified for spectroscopic follow-up solely based on the DES i-z and z-Y colours. The quasar is detected by WISE and has W1(AB) = 19.68. The discovery of one spectroscopically confirmed quasar with 5.7 < z < 6.5 and z(AB) <= 20.2 is consistent with recent determinations of the luminosity function at z similar to 6. DES when completed will have imaged -5000 deg2 to Y-AB = 23.0 (5 sigma point source) and we expect to discover 50-100 new quasars with z > 6 including 3-10 with z > 7 dramatically increasing the numbers of quasars currently known that are suitable for detailed studies.

We investigate the origin of extragalactic continuum emission and its relation to the stellar population of a recently discovered peculiar z = 3.344 Ly alpha emitter. Based on an analysis of the broad-band colours and morphology, we find further support for the idea that the underlying galaxy is being fed by a large-scale (L >= 35 kpc) accretion stream. ArchivalHST images show small-scale (similar to 5 kpc) tentacular filaments converging near a hotspot of star formation, possibly fueled by gas falling in along the filaments. The spectral energy distribution of the tentacles is broadly compatible with either (1) non-ionizing rest-frame far-UV continuum emission from stars formed in a 60 million-year-old starburst; (2) nebular two-photon continuum radiation, arising from collisional excitation cooling; or (3) a recombination spectrum emitted by hydrogen fluorescing in response to ionizing radiation escaping from the galaxy. The latter possibility simultaneously accounts for the presence of asymmetric Ly alpha emission from the large-scale gaseous filament, and the nebular continuum in the smaller scale tentacles as caused by the escape of ionizing radiation from the galaxy. Possible astrophysical explanations for the nature of the tentacles include: a galactic wind powered by the starburst; infalling gas during cold accretion, or tails of interstellar medium dragged out of the galaxy by satellite haloes that have plunged through the main halo. The possibility of detecting extragalactic two-photon continuum emission in space-based, broad-band images suggests a tool for studying the gaseous environment of high-redshift galaxies at much greater spatial detail than possible with Lya or other resonance line emission.

We present multisightline absorption spectroscopy of cool gas around three lensing galaxies at z = 0.4-0.7. These lenses have half-light radii r(e) = 2.6-8 kpc and stellar masses of log M-*/M-circle dot = 10.9-11.4, and therefore resemble nearby passive elliptical galaxies. The lensed QSO sightlines presented here occur at projected distances of d = 3-15 kpc (or d approximate to 1-2 r(e)) from the lensing galaxies, providing for the first time an opportunity to probe both interstellar gas at r similar to r(e) and circumgalactic gas at larger radii r >> r(e) of these distant quiescent galaxies. We observe distinct gas absorption properties among different lenses and among sightlines of individual lenses. Specifically, while the quadruple lens for HE 0435-1223 shows no absorption features to very sensitive limits along all four sightlines, strong MgII, Fe II, Mg I, and Ca II absorption transitions are detected along both sightlines near the double lens for HE 0047-1756, and in one of the two sightlines near the double lens for HE 1104-1805. The absorbers are resolved into 8-15 individual components with a line-of-sight velocity spread of Delta v approximate to 300-600 km s(-1). The large ionic column densities, log N greater than or similar to 14, observed in two components suggest that these may be Lyman limit or damped Ly a absorbers with a significant neutral hydrogen fraction. The majority of the absorbing components exhibit a uniform supersolar Fe/Mg ratio with a scatter of < 0.1 dex across the full Delta v range. Given a predominantly old stellar population in these lensing galaxies, we argue that the observed large velocity width and Fe-rich abundance pattern can be explained by SNe Ia enriched gas at radius r similar to r(e). We show that additional spatial constraints in line-of-sight velocity and relative abundance ratios afforded by a multisightline approach provide a powerful tool to resolve the origin of chemically enriched cool gas in massive haloes.

We present physical properties of spectroscopically confirmed Ly alpha emitters (LAEs) with very large rest-frame Ly alpha equivalent widths EW0(Ly alpha). Although the definition of large EW0(Ly alpha) LAEs is usually difficult due to limited statistical and systematic uncertainties, we identify six LAEs selected from similar to 3000 LAEs at z similar to 2 with reliable measurements of EW0 (Ly alpha) similar or equal to 200-400 angstrom given by careful continuum determinations with our deep photometric and spectroscopic data. These large EW0(Ly alpha) LAEs do not have signatures of AGN, but notably small stellar masses of M star = 10(7-8)M(circle dot) and high specific star formation rates (star formation rate per unit galaxy stellar mass) of similar to 100 Gyr(-1). These LAEs are characterized by the median values of L(Ly alpha) = 3.7 x 10(42) erg s(-1) and M-UV = -18.0 as well as the blue UV continuum slope of beta = -2.5 +/- 0.2 and the low dust extinction E(B -V)(star) = 0.02(-0.02)(+0.04), which indicate a high median Lya escape fraction of f(esc)(Ly alpha) = 0.68 +/- 0.30. This large f(esc)(Ly alpha) value is explained by the low H (I) column density in the interstellar medium which is consistent with full width at half-maximum (FWHM) of the Ly alpha line, FWHM(Ly alpha) = 212 +/- 32 km s(-1), significantly narrower than those of small EW0(Ly alpha) LAEs. Based on the stellar evolution models, our observational constraints of the large EW0 (Ly alpha), the small beta, and the rest-frame He (II) EW imply that at least a half of our large EW0(Ly alpha) LAEs would have young stellar ages of less than or similar to 20 Myr and very low metallicities of Z < 0.02 Z(circle dot) regardless of the star formation history.