THE MOST LUMINOUSz∼ 9-10 GALAXY CANDIDATES YET FOUND: THE LUMINOSITY FUNCTION, COSMIC STAR-FORMATION RATE, AND THE FIRST MASS DENSITY ESTIMATE AT 500 Myr
Year: 2014
Type: article
Abstract: We present the discovery of four surprisingly bright ( H 160 ∼ 26–27 mag AB) galaxy candidates at z ∼ 9–10 in the complete HST CANDELS WFC3/IR GOODS-N imaging data, doubling the number of z ∼ 10 galaxy candidates that are known, just ∼500 Myr after the big bang. Two similarly bright sources are also detected in a reanalysis of the GOODS-S data set. Three of the four galaxies in GOODS-N are significantly detected at 4.5σ–6.2σ in the very deep Spitzer /IRAC 4.5 μm data, as is one of the GOODS-S candidates. Furthermore, the brightest of our candidates (at z = 10.2 ± 0.4) is robustly detected also at 3.6 μm (6.9σ), revealing a flat UV spectral energy distribution with a slope β = −2.0 ± 0.2, consistent with demonstrated trends with luminosity at high redshift. Thorough testing and use of grism data excludes known low-redshift contamination at high significance, including single emission-line sources, but as-yet unknown low redshift sources could provide an alternative solution given the surprising luminosity of these candidates. Finding such bright galaxies at z ∼ 9–10 suggests that the luminosity function for luminous galaxies might evolve in a complex way at z > 8. The cosmic star formation rate density still shows, however, an order-of-magnitude increase from z ∼ 10 to z ∼ 8 since the dominant contribution comes from low-luminosity sources. Based on the IRAC detections, we derive galaxy stellar masses at z ∼ 10, finding that these luminous objects are typically 10 9 M ☉ . This allows for a first estimate of the cosmic stellar mass density at z ∼ 10 resulting in M ☉ Mpc −3 for galaxies brighter than M UV ∼ −18. The remarkable brightness, and hence luminosity, of these z ∼ 9–10 candidates will enable deep spectroscopy to determine their redshift and nature, and highlights the opportunity for the James Webb Space Telescope to map the buildup of galaxies at redshifts much earlier than z ∼ 10.
Source: The Astrophysical Journal
Authors: P. A. Oesch, R. J. Bouwens, G. D. Illingworth, I. Labbé, R. Smit, M. Franx, P. G. van Dokkum, I. Momcheva, M. L. N. Ashby, G. G. Fazio, J.-S. Huang, S. P. Willner, V. Gonzalez, D. Magee, M. Trenti, G. B. Brammer, R. E. Skelton, L. R. Spitler
Institutions: University of California, Santa Cruz, Yale University, Leiden University, Leiden Observatory, Smithsonian Astrophysical Observatory, Center for Astrophysics Harvard & Smithsonian, University of California, Riverside, University of Cambridge, Space Telescope Science Institute, South African Astronomical Observatory, Australian Astronomical Observatory, Macquarie University
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
Awards: PROPOSAL TITLED A PROPOSAL TO INVESTGATE OUTSTAND ING PROBLEMS IN ASTRONOMY BY THE INSTRUMENT DEFIN, G3863383412, G433322167, G4357913612, G4518818167, Programs on Critical Problems in Physics, Astrophysics and Biophysics at the Aspen Center for Physics, G58316358, G6273510985, G7039555113, G767601387
OpenAlex ID: W2131686982