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New Insight on Galaxy Formation and Evolution from Keck Spectroscopy of the Hawaii Deep Fields
We present the results of spectroscopic studies with the LRIS spectrograph on Keck of two of the Hawaii deep survey fields. The 393 objects observed cover an area of 26.2 square arcmin and constitute
Caltech Faint Galaxy Redshift Survey. X. A Redshift Survey in the Region of the Hubble Deep Field North
A redshift survey has been carried out in the region of the Hubble Deep Field North using the Low Resolution Imaging Spectrograph (LRIS) at the Keck Observatory. The resulting redshift catalog, which
The Minimum Universal Metal Density between Redshifts of 1.5 and 5.5
It appears that the Lyα forest is becoming thick at a redshift of about 5.5, cutting off the higher redshift intergalactic medium from view in neutral hydrogen. However, the effects of star formation
The Evolution of the Intergalactic Medium Transmission to Redshift 6
We have measured the transmission of the Lyα forest produced by neutral hydrogen scattering in the intergalactic medium between redshifts 2 and 6.3 using high signal-to-noise, high-resolution (R ≥
Metal enrichment and ionization balance in the Lyman alpha forest at z = 3
The recent discovery of carbon in close to half of the low neutral hydrogen column density [$N({\rm H~I}) > 3\ten{14}\cm2$] Lyman forest clouds toward $z \sim 3$ quasars has challenged the widely
We have measured the redshift evolution of the density of Lyman limit systems (LLSs) in the intergalactic medium over the redshift range 0 < z < 6. We have used two new quasar samples to (1) improve
The Distribution of column densities and b values in the Lyman-alpha forest
We describe the properties of the Ly$\alpha$ forest in the column density range $\nhi \geq 2\times10^{12}$ cm$^{-2}$ based on 1056 lines in the wavelength range 4300--5100\AA measured in extremely
The Redshift Evolution of the Ly alpha Forest
We have analyzed the properties of low column density Lyman alpha forest clouds (12.8 < log N_HI < 16.0) toward 5 QSOs at different redshifts, using high signal-to-noise data from the HIRES
Resolving the Structure of Ionized Helium in the Intergalactic Medium with the Far Ultraviolet Spectroscopic Explorer
The presence of He ii Lyα absorbers with no H icounterparts indicates that structure is present even in low-density regions, consistent with theoretical predictions of structure formation through gravitational instability.