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Paper: The Star Formation Law in High-Redshift Damped Lyα Systems
Volume: 379, Cosmic Frontiers
Page: 217
Authors: Wolfe, A.M.
Abstract: Application of the Kennicutt-Schmidt law to damped Lyα absorption systems (DLAs) indicates over 6% of the sky should be covered with extend objects brighter than μV = 29 mag arcsec−2 if DLAs at z=[2.5,3.5] undergo in situ star formation. We search the Hubble Ultra Deep Field F606W image for low surface-brightness features. Our search yields upper limits on the comoving SFR density between factors of 30 and 100 below the predicted rates, suggesting a factor of 20 or more reduction in star formation efficiency. We suggest this is due to (a) the low molecular content of the gas, and (b) the increase with redshift of the critical surface density threshold for the Toomre instability. The upper limits on comoving SFR density imply that the observed metallicity and heating rates of DLAs cannot be due to in situ star formation. Rather, they could be due to Lyman Break galaxies centrally located in the DLA gas.
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