Open AccessHα Spectroscopy of Galaxies atz> 2: Kinematics and Star Formation
Author(s) -
Dawn K. Erb,
Alice E. Shapley,
Charles C. Steidel,
Max Pettini,
Kurt L. Adelberger,
Matthew P. Hunt,
A. F. M. Moorwood,
JeanGabriel Cuby
Publication year - 2003
Publication title -
the astrophysical journal
Language(s) - English
Resource type - Journals
eISSN - 1538-4357
pISSN - 0004-637X
DOI - 10.1086/375316
Subject(s) - physics , astrophysics , galaxy , redshift , velocity dispersion , emission spectrum , star formation , spectroscopy , astronomy , luminous infrared galaxy , virial theorem , spectral line
We present near-infrared spectroscopy of H-alpha emission lines in a sampleof 16 star-forming galaxies at redshifts 2.04e10 M_sun. One-dimensional velocity dispersions for the 16 galaxies rangefrom ~50 to ~260 km/s, and in cases where we have both virial masses implied bythe velocity dispersions and dynamical masses derived from the spatiallyextended emission lines, they are in rough agreement. We compare our kinematicresults to similar measurements made at z~3, and find that both the observedrotational velocities and velocity dispersions tend to be larger at z~2 than atz~3. We find a mean SFR_H-alpha of 16 M_sun/yr and an averageSFR_H-alpha/SFR_UV ratio of 2.4, without correcting for extinction. We seemoderate evidence for an inverse correlation between the UV continuumluminosity and the ratio SFR_H-alpha/SFR_UV, such as might be observed if theUV-faint galaxies suffered greater extinction. We discuss the effects of dustand star formation history on the SFRs, and conclude that extinction is themost likely explanation for the discrepancy between the two SFRs.Comment: 20 pages, 9 figures. Accepted by Ap
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