Мақола

UV Star Formation Rates in the Local Universe

Samir SalimCurrent address: National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719R. Michael RichDepartment of Physics and Astronomy, University of California, Los Angeles, CA 90095Stephane CharlotInstitut d’Astrophysique de Paris, CNRS, 98 bis Boulevard Arago, F-75014 Paris, FranceJarle BrinchmannCentro de Astrofísica da Universidade do Porto, Rua das Estrelas, 4150-762 Porto, PortugalBenjamin D. JohnsonDepartment of Astronomy, Columbia University, New York, NY 10027David SchiminovichDepartment of Astronomy, Columbia University, New York, NY 10027Mark SeibertObservatories of the Carnegie Institution of Washington, 813 Santa Barbara Street, Pasadena, CA 91101Ryan MalleryDepartment of Physics and Astronomy, University of California, Los Angeles, CA 90095Timothy M. HeckmanDepartment of Physics and Astronomy, Johns Hopkins University, Homewood Campus, Baltimore, MD 21218Karl ForsterCalifornia Institute of Technology, MC 405-47, 1200 East California Boulevard, Pasadena, CA 91125Peter G. FriedmanCalifornia Institute of Technology, MC 405-47, 1200 East California Boulevard, Pasadena, CA 91125D. Christopher MartinCalifornia Institute of Technology, MC 405-47, 1200 East California Boulevard, Pasadena, CA 91125Patrick MorrisseyCalifornia Institute of Technology, MC 405-47, 1200 East California Boulevard, Pasadena, CA 91125Susan G. NeffLaboratory for Astronomy and Solar Physics, NASA Goddard Space Flight Center, Greenbelt, MD 20771Todd SmallCalifornia Institute of Technology, MC 405-47, 1200 East California Boulevard, Pasadena, CA 91125Ted K. WyderCalifornia Institute of Technology, MC 405-47, 1200 East California Boulevard, Pasadena, CA 91125Luciana BianchiCenter for Astrophysical Sciences, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218Jose DonasLaboratoire d’Astrophysique de Marseille, BP 8, Traverse du Siphon, 13376 Marseille Cedex 12, FranceYoung‐Wook LeeCenter for Space Astrophysics, Yonsei University, Seoul 120-749, KoreaBarry F. MadoreObservatories of the Carnegie Institution of Washington, 813 Santa Barbara Street, Pasadena, CA 91101Bruno MilliardLaboratoire d’Astrophysique de Marseille, BP 8, Traverse du Siphon, 13376 Marseille Cedex 12, FranceAlex S. SzalayDepartment of Physics and Astronomy, Johns Hopkins University, Homewood Campus, Baltimore, MD 21218Barry Y. WelshSpace Sciences Laboratory, University of California, Berkeley, 601 Campbell Hall, Berkeley, CA 94720Sukyoung K. YiCenter for Space Astrophysics, Yonsei University, Seoul 120-749, Korea

2007en

ABI

Аннотация

We measure star formation rates (SFRs) of ≈50,000 optically selected galaxies in the local universe (z ≈ 0.1)—from gas-rich dwarfs to massive ellipticals. We obtain dust-corrected SFRs by fitting the GALEX (ultraviolet) and SDSS photometry to a library of dust-attenuated population synthesis models. For star-forming galaxies, our UV-based SFRs compare remarkably well with those from SDSS-measured emission lines (Hα). Deviations from perfect agreement are shown to be due to differences in the dust attenuation estimates. In contrast to Hα measurements, UV provides reliable SFRs for galaxies with weak Hα, and where Hα is contaminated with AGN emission (1/2 of the sample). Using full-SED SFRs, we calibrate a simple prescription that uses GALEX far- and near-UV magnitudes to produce dust-corrected SFRs for normal star-forming galaxies. The specific SFR is considered as a function of stellar mass for (1) star-forming galaxies with no AGNs, (2) those hosting an AGN, and (3) galaxies without Hα emission. We find that the three have distinct star formation histories, with AGNs lying intermediate between the star-forming and the quiescent galaxies. Star-forming galaxies without an AGN lie on a relatively narrow linear sequence. Remarkably, galaxies hosting a strong AGN appear to represent the massive continuation of this sequence. On the other hand, weak AGNs, while also massive, have lower SFRs, sometimes extending to the realm of quiescent galaxies. We propose an evolutionary sequence for massive galaxies that smoothly connects normal star-forming galaxies to quiescent galaxies via strong and weak AGNs. We confirm that some galaxies with no Hα show signs of star formation in the UV. We derive a cosmic star formation density at z = 0.1 with significantly smaller total error than previous measurements.

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DOI: 10.1086/519218

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