Librería Samer Atenea
Librería Aciertas (Toledo)
Kálamo Books
Librería Perelló (Valencia)
Librería Elías (Asturias)
Donde los libros
Librería Kolima (Madrid)
Librería Proteo (Málaga)
We study the properties of star-forming galaxies at redshift z~2, anera in which a substantial fraction of the stellar mass in theuniverse formed. Using 114 near-IR spectra of the H-alpha and [N II]emission lines and model spectral energy distributions fit torest-frame UV through IR photometry, we examine the galaxies’ starformation properties, dynamical masses and velocity dispersions,spatially resolved kinematics, outflow properties, and metallicitiesas a function of stellar mass and age. While the stellar masses ofthe galaxies in our sample vary by a factor of ~500, dynamical massesfrom H-alpha velocity dispersions and indirect estimates of gas massesimply that the variation of stellar mass is due as much to theevolution of the stellar population and the conversion of gas intostars as to intrinsic differences in the total masses of the galaxies.About 10% of the galaxies are apparently young starbursts with highgas fractions, caught just as they have begun to convert large amountsof gas into stars. Using the [N II]/H-alpha ratio of compositespectra to estimate the average oxygen abundance, we find a monotonicincrease in metallicity with stellar mass. From the estimated gasfractions, we conclude that the observed mass-metallicity relation isprimarily driven by the increase in metallicity as gas is converted tostars. The picture that emerges is of galaxies with a broad range instellar population properties, from young galaxies with ages of a fewtens of Myr, stellar masses M~10^9 Msun, and metallicities Z~ 1/3Zsun, to massive objects with M*~10^11 Msun, Z~Zsun, and ages as oldas the universe allows. All, however, are rapidly star-forming, powergalactic-scale outflows, and have masses in gas and stars of at least~10^10 Msun, in keeping with their likely role as the progenitors ofelliptical galaxies seen today.
