Search

We assess the feasibility of detecting star formation in damped Lyman-$\alpha$ systems (DLAs) at z > 1 through near-infrared spectroscopy using the forthcoming integral field units on 8 m-class telescopes. Although their relation to galaxies is not well established, high-z DLAs contain most of the neutral gas in the Universe, and this reservoir is depleted with time - presumably through star formation. Line emission should be an indicator of star formation activity, but searches based on Lyman-$\alpha$ are unreliable because of the selective extinction of this resonant UV line. Using more robust lines such as H$\alpha$ forces a move to the near-infrared at z > 1. For line emission searches, spectroscopy is more sensitive than imaging, but previous long-slit spectroscopic searches have been hampered by the likelihood that any star forming region in the DLA galaxy disk would fall outside the narrow slit. The new integral field units such as CIRPASS on Gemini will cover sufficient solid angles to intercept these, even in the extreme case of large galactic disks at high redshift. On an 8 m-class telescope, star formation rates of $ < 1M_{\odot}$yr-1 will be reached at $z\approx 1.4$ with H$\alpha$ in the H-band. Such star formation rates are well below L* for the high-z Lyman-break population, and are comparable locally to the luminous giant H II complexes in M 101. It appears that instruments such as CIRPASS on Gemini will have both the sensitivity and the survey area to measure star formation rates in z > 1 DLAs. These observations will probe the nature of damped Lyman-$\alpha$ systems and address their relation to galaxies. [ABSTRACT FROM AUTHOR]

We assess the feasibility of detecting star formation in damped Lyman-$\alpha$ systems (DLAs) at z > 1 through near-infrared spectroscopy using the forthcoming integral field units on 8 m-class telescopes. Although their relation to galaxies is not well established, high-z DLAs contain most of the neutral gas in the Universe, and this reservoir is depleted with time - presumably through star formation. Line emission should be an indicator of star formation activity, but searches based on Lyman-$\alpha$ are unreliable because of the selective extinction of this resonant UV line. Using more robust lines such as H$\alpha$ forces a move to the near-infrared at z > 1. For line emission searches, spectroscopy is more sensitive than imaging, but previous long-slit spectroscopic searches have been hampered by the likelihood that any star forming region in the DLA galaxy disk would fall outside the narrow slit. The new integral field units such as CIRPASS on Gemini will cover sufficient solid angles to intercept these, even in the extreme case of large galactic disks at high redshift. On an 8 m-class telescope, star formation rates of $ < 1 M_\odot$ yr-1 will be reached at $z \approx 1.4$ with H$\alpha$ in the H-band. Such star formation rates are well below L* for the high-z Lyman-break population, and are comparable locally to the luminous giant H II complexes in M 101. It appears that instruments such as CIRPASS on Gemini will have both the sensitivity and the survey area to measure star formation rates in z > 1 DLAs. These observations will probe the nature of damped Lyman-$\alpha$ systems and address their relation to galaxies. [ABSTRACT FROM AUTHOR]

We report results from the first 1000 square arc-minutes of the Las Campanas IR survey. We have imaged 1 square degree of high latitude sky in six distinct fields to a $5\sigma$ H-band depth of 20.5 (Vega). Optical imaging in the V,R,I, and z' bands allow us to select color subsets and photometric-redshift-defined shells. We show that the angular clustering of faint red galaxies ( 18 < H < 20.5, I - H > 3) is an order of magnitude stronger than that of the complete H-selected field sample. We employ three approaches to estimate n(z) in order to invert $w(\theta)$ to derive r0. We find that our n(z) is well described by a Gaussian with $ < z > = 1.2, \sigma (z) = 0.15$. From this we derive a value for r0 of 7+2-1 co-moving h-1Mpc at < z > = 1.2. This is a factor of $\sim 2$ larger than the clustering length for Lyman break galaxies and is similar to the expectation for early type galaxies at this epoch. [ABSTRACT FROM AUTHOR]

We present the results of the analysis of the chemical abundances and kinematics in a high-redshift damped Ly-$\alpha$ (DLA) system towards the quasar APM BR J0307-4945 observed during the Commissioning of UVES on the 8.2m ESO VLT Kueyen telescope at Cerro Paranal Observatory. With a redshift zabs = 4.466 and a total neutral hydrogen column density log N(H I) = $20.67\pm 0.09$, it is the most distant DLA system known to the present date, observed when the Universe was as young as 1.3Assuming H0 = 60 km s-1 Mpc $^{-1},\Omega_0 = 0.4,\Lambda_0 = 0.6$ Gyr. [ABSTRACT FROM AUTHOR]

We present a search for spatial and redshift correlations in a 2 Å resolution spectroscopic survey of the Ly$\alpha$ forest at 2.15 < z < 3.37 toward ten QSOs within a 1$^\circ$ diameter field. We find a 3.2$\sigma$ signal for correlations of the Ly$\alpha$ absorption line wavelengths between different lines of sight over 2.60 < z < 3.26. We conclude that a significant fraction of the Ly-$\alpha$ forest arises in structures whose correlation length extends at least over 30 arcmin ($\sim$ 26 h-1 comoving Mpc at z = 2.6 for $H_0 \equiv$ 100h km s-1 Mpc-1,$\Omega$ = 1.0, $\Lambda$ = 0). [ABSTRACT FROM AUTHOR]