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Quenching Star Formation in the Green Valley: The Mass Flux at Intermediate Redshifts

Published online by Cambridge University Press:  13 April 2010

Thiago S. Gonçalves
Affiliation:
California Institute of Technology, 1200 E. California Blvd. MC 278-17, Pasadena CA 91107, USA email: [email protected]
D. Christopher Martin
Affiliation:
California Institute of Technology, 1200 E. California Blvd. MC 278-17, Pasadena CA 91107, USA email: [email protected]
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Abstract

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We have obtained several hundred very deep spectra with DEIMOS/Keck in order to estimate the galactic mass flux density at intermediate redshifts (0.6 < z < 0.9) from the "blue cloud" to the red sequence across the so-called “green valley”, the intermediate region in the color-magnitude plot between those two populations. We use spectral indices (specifically Dn(4000) and Hδ, A) to determine star formation histories. Together with an independent measurement of number density of galaxies in each bin of the color-magnitude plot, one can infer the rate at which galaxies from a given sample are transiting through that bin. Measuring this value for all magnitude values, studies at lower redshift determined that the mass flux density in the green valley is comparable to both the mass build-up rate of the red sequence and the mass loss rate from the blue cloud. We show preliminary results for our intermediate redshift sample.

Type
Contributed Papers
Copyright
Copyright © International Astronomical Union 2010

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