Physical Sciences and Mathematics | Open Access Articles

Candels: The Contribution Of The Observed Galaxy Population To Cosmic Reionization, Steven L. Finkelstein, Casey Papovich, Russel E, Ryan Jr., Andreas H. Pawlik, Mark Dickinson, Henry C. Ferguson, Kristian Finlator, Anton M. Koekemoer, Mauro Giavalisco, Mauro Giavalisco, Asantha Cooray, James S. Dunlop, Sandy M. Faber, Norman A. Grogin, Dale D. Kocevski, Jeffrey A. Newman

Mauro Giavalisco

We present measurements of the specific ultraviolet luminosity density from a sample of 483 galaxies at 6 . z . 8. These galaxies were selected from new deep near-infrared Hubble Space Telescope imaging from the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey, Hubble UltraDeep Field 2009 and WFC3 Early Release Science programs. In contrast to the majority of previous analyses, which assume that the distribution of galaxy ultraviolet (UV) luminosities follows a Schechter distribution, and that the distribution continues to luminosities far below our observable limit, we investigate the contribution to reionization from galaxies which we can observe, free from …

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The Evolution Of The Galaxy Rest-Frame Ultraviolet Luminosity Function Over The First Two Billion Years, Steven L. Finkelstein, Russell E. Ryan Jr., Casey Papovich, Mark Dickinson, Mimi Song, Rachel Somerville, Herny C. Ferguson, Brett Salmon, Mauro Giavalisco, Anton M. Koekemoer, Matthew L. N. Ashby, Peter Behroozi, Marco Castellano, James S. Dunlop, Sandy M. Faber, Giovanni G. Fazio, Adriano Fontana, Norman A. Grogin, Nimish Hathi, Jason Jaacks, Dale D. Kocevski, Rachel Livermore, Ross J. Mclure, Emiliano Merlin, Bahram Mobasher, Jeffrey A. Newman, Marc Rafelski, Vithal Tilvi, S.P. Willner

Mauro Giavalisco

No abstract provided.

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On The Stellar Populations And Evolution Of Star-Forming Galaxies At 6.3 < Z < 8.6, Steven L. Finkelstein, Casey Papovich, Mauro Giavalisco, Naveen A. Reddy, Henry C. Ferguson, Anton M. Koekemoer, Mark Dickinson

Mauro Giavalisco

We study the physical characteristics of galaxies at 6.3 < z < 8.6, selected from deep near-infrared imaging with the Wide Field Camera 3 (WFC3) on board the Hubble Space Telescope. Accounting for the photometric scatter using simulations, galaxies at z ~ 7 have bluer UV colors compared to typical local starburst galaxies at > 4 sigma confidence. Although these colors necessitate young ages (<100 Myr), low or zero dust attenuation, and low metallicities, these are explicable by normal (albeit unreddened) stellar populations, with no evidence for near-zero metallicities and/or top-heavy initial mass functions. The age of the Universe at these redshifts limits the amount of stellar mass in late-type populations, and the WFC3 photometry implies galaxy stellar masses ~ 10^8 - 10^9 Msol for Salpeter initial mass functions to a limiting magnitude of M_1500 ~ -18. The masses of ``characteristic'' (L*) z > 7 galaxies are smaller than those of L* Lyman break galaxies (LBGs) at lower redshifts, and are comparable to less evolved galaxies selected on the basis of their Lyman alpha emission at 3 < z < 6, implying that the 6.3 < z < 8.6 galaxies are the progenitors of more evolved galaxies at lower redshifts. We estimate that Lyman alpha emission is able to contribute to the observed WFC3 colors of galaxies at these redshifts, with an estimated typical line flux of ~ 10^-18 erg s^-1 cm^-2, roughly a factor of four below currently planned surveys. The integrated UV specific luminosity for the detected galaxies at z ~ 7 and z ~ 8 is within factors of a few of that required to reionize the IGM assuming low clumping factors, implying that in order to reionize the Universe galaxies at these redshifts have a high ( ~ 50%) escape fraction of Lyman continuum photons, possibly substantiated by the very blue colors of this population.

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Star-Forming Or Starbursting? The Ultraviolet Conundrum, M Boquien, D Calzetti, R Kennicutt, D Dale, C Engelbracht, Kd Gordon, S Hong, Jc Lee, J Portouw

Astronomy Department Faculty Publication Series

Compared to starburst galaxies, normal star-forming galaxies have been shown to display a much larger dispersion of the dust attenuation at fixed reddening through studies of the IRX-β diagram (the IR/UV ratio "IRX" versus the UV color "β"). To investigate the causes of this larger dispersion and attempt to isolate second parameters, we have used GALEX UV, ground-based optical, and Spitzer infrared imaging of eight nearby galaxies, and examined the properties of individual UV and 24 μm selected star-forming regions. We concentrated on star-forming regions, in order to isolate simpler star formation histories than those that characterize whole galaxies. We …

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Comparison Of H Alpha And Uv Star Formation Rates In The Local Volume: Systematic Discrepancies For Dwarf Galaxies, Jc Lee, Ag De Paz, C Tremonti, Rc Kennicutt, S Salim, M Bothwell, D Calzetti, J Dalcanton, D Dale, C Engelbracht, Sjjg Funes, B Johnson, S Sakai, E Skillman, L Van Zee, F Walter, D Weisz

Astronomy Department Faculty Publication Series

Using a complete sample of ~300 star-forming galaxies within 11 Mpc of the Milky Way, we evaluate the consistency between star formation rates (SFRs) inferred from the far ultraviolet (FUV) non-ionizing continuum and Hα nebular emission, assuming standard conversion recipes in which the SFR scales linearly with luminosity at a given wavelength. Our analysis probes SFRs over 5 orders of magnitude, down to ultra-low activities on the order of ~10-4 M sun yr-1. The data are drawn from the 11 Mpc Hα and Ultraviolet Galaxy Survey (11HUGS), which has obtained Hα fluxes from ground-based narrowband imaging, and UV fluxes from …

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Observations Of Starburst Galaxies With Far-Ultraviolet Spectrographic Explorer: Galactic Feedback In The Local Universe, Jp Grimes, T Heckman, A Aloisi, D Calzetti, C Leitherer, Cl Martin, G Meurer, K Sembach, D Strickland

Astronomy Department Faculty Publication Series

We have analyzed FUSE (905-1187 Å) spectra of a sample of 16 local starburst galaxies. These galaxies cover almost three orders of magnitude in star-formation rates and over two orders of magnitude in stellar mass. Absorption features from the stars and interstellar medium are observed in all the spectra. The strongest interstellar absorption features are generally blue-shifted by ~ 50-300 km s–1, implying the almost ubiquitous presence of starburst-driven galactic winds in this sample. The outflow velocites increase with both the star-formation rate and the star-formation rate per unit stellar mass, consistent with a galactic wind, driven by the population …

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Mauro Giavalisco

Mauro Giavalisco

On The Stellar Populations And Evolution Of Star-Forming Galaxies At 6.3 < Z < 8.6, Steven L. Finkelstein, Casey Papovich, Mauro Giavalisco, Naveen A. Reddy, Henry C. Ferguson, Anton M. Koekemoer, Mark Dickinson

Mauro Giavalisco

Star-Forming Or Starbursting? The Ultraviolet Conundrum, M Boquien, D Calzetti, R Kennicutt, D Dale, C Engelbracht, Kd Gordon, S Hong, Jc Lee, J Portouw

Astronomy Department Faculty Publication Series

Astronomy Department Faculty Publication Series

Observations Of Starburst Galaxies With Far-Ultraviolet Spectrographic Explorer: Galactic Feedback In The Local Universe, Jp Grimes, T Heckman, A Aloisi, D Calzetti, C Leitherer, Cl Martin, G Meurer, K Sembach, D Strickland

Astronomy Department Faculty Publication Series