THE EVOLUTION OF THE FAINT END OF THE UV LUMINOSITY FUNCTION DURING THE PEAK EPOCH OF STAR FORMATION $(1\lt z\lt 3)$*

Anahita Alavi; Brian Siana; Johan Richard; Marc Rafelski; Mathilde Jauzac; Marceau Limousin; William R. Freeman; Claudia Scarlata; Brant Robertson; Daniel P. Stark; Harry I. Teplitz; Vandana Desai

doi:10.3847/0004-637X/832/1/56

THE EVOLUTION OF THE FAINT END OF THE UV LUMINOSITY FUNCTION DURING THE PEAK EPOCH OF STAR FORMATION $(1\lt z\lt 3)$ ^*

Anahita Alavi¹, Brian Siana¹, Johan Richard², Marc Rafelski^3,4, Mathilde Jauzac^4,5,6, Marceau Limousin⁸, William R. Freeman¹, Claudia Scarlata⁸, Brant Robertson⁹, Daniel P. Stark¹⁰, Harry I. Teplitz¹², and Vandana Desai¹²

Published 2016 November 17 • © 2016. The American Astronomical Society. All rights reserved.
The Astrophysical Journal, Volume 832, Number 1 Citation Anahita Alavi et al 2016 ApJ 832 56 DOI 10.3847/0004-637X/832/1/56

Download Article PDF

Article metrics

2571 Total downloads

Permissions

Get permission to re-use this article

Author affiliations

¹ Department of Physics and Astronomy, University of California, Riverside, CA 92521, USA

² Centre de Recherche Astrophysique de Lyon, Université Lyon 1, 9 Avenue Charles André, F-69561 Saint Genis Laval Cedex, France

³ Goddard Space Flight Center, Code 665, Greenbelt, MD 20771, USA

⁴ Space Telescope Science Institute, Baltimore, MD, USA

⁵ Centre for Extragalactic Astronomy, Department of Physics, Durham University, Durham DH1 3LE, UK

⁶ Institute for Computational Cosmology, Durham University, South Road, Durham DH1 3LE, UK

⁷ Astrophysics and Cosmology Research Unit, School of Mathematical Sciences, University of KwaZulu-Natal, Durban 4041, South Africa

⁸ Aix Marseille Univ, CNRS, LAM, Laboratoire d'Astrophysique de Marseille, Marseille, France

⁹ Minnesota Institute for Astrophysics, University of Minnesota, Minneapolis, MN 55455, USA

¹⁰ Department of Astronomy and Astrophysics, University of California, Santa Cruz, 1156 High Street, Santa Cruz, CA 95064,USA

¹¹ Department of Astronomy, Steward Observatory, University of Arizona, 933 North Cherry Avenue, Rm N204, Tucson, AZ 85721, USA

¹² Infrared Processing and Analysis Center, Caltech, Pasadena, CA 91125, USA

ORCID iDs

Anahita Alavi https://orcid.org/0000-0002-8630-6435

Brian Siana https://orcid.org/0000-0002-4935-9511

Johan Richard https://orcid.org/0000-0001-5492-1049

Marc Rafelski https://orcid.org/0000-0002-9946-4731

Claudia Scarlata https://orcid.org/0000-0002-9136-8876

Brant Robertson https://orcid.org/0000-0002-4271-0364

Harry I. Teplitz https://orcid.org/0000-0002-7064-5424

Dates

Received 2016 June 4
Revised 2016 September 6
Accepted 2016 September 13
Published 2016 November 17

Keywords

galaxies: evolution; galaxies: high-redshift; galaxies: luminosity function, mass function

Journal RSS

Create or edit your corridor alerts

What are corridors?

ABSTRACT

We present a robust measurement of the rest-frame UV luminosity function (LF) and its evolution during the peak epoch of cosmic star formation at $1\lt z\lt 3$ . We use our deep near-ultraviolet imaging from WFC3/UVIS on the Hubble Space Telescope and existing Advanced Camera for Surveys (ACS)/WFC and WFC3/IR imaging of three lensing galaxy clusters, Abell 2744 and MACS J0717 from the Hubble Frontier Field survey and Abell 1689. Combining deep UV imaging and high magnification from strong gravitational lensing, we use photometric redshifts to identify 780 ultra-faint galaxies with ${M}_{\mathrm{UV}}\lt -12.5$ AB mag at $1\lt z\lt 3$ . From these samples, we identified five new, faint, multiply imaged systems in A1689. We run a Monte Carlo simulation to estimate the completeness correction and effective volume for each cluster using the latest published lensing models. We compute the rest-frame UV LF and find the best-fit faint-end slopes of $\alpha =-1.56\pm 0.04$ , $\alpha =-1.72\pm 0.04$ , and $\alpha =-1.94\pm 0.06$ at $1.0\lt z\lt 1.6$ , $1.6\lt z\lt 2.2$ , and $2.2\lt z\lt 3.0$ , respectively. Our results demonstrate that the UV LF becomes steeper from $z\sim 1.3$ to $z\sim 2.6$ with no sign of a turnover down to ${M}_{\mathrm{UV}}=-14$ AB mag. We further derive the UV LFs using the Lyman break "dropout" selection and confirm the robustness of our conclusions against different selection methodologies. Because the sample sizes are so large and extend to such faint luminosities, the statistical uncertainties are quite small, and systematic uncertainties (due to the assumed size distribution, for example) likely dominate. If we restrict our analysis to galaxies and volumes above $\gt 50 \%$ completeness in order to minimize these systematics, we still find that the faint-end slope is steep and getting steeper with redshift, though with slightly shallower (less negative) values ( $\alpha =-1.55\pm 0.06$ , −1.69 ± 0.07, and −1.79 ± 0.08 for $z\sim 1.3$ , 1.9, and 2.6, respectively). Finally, we conclude that the faint star-forming galaxies with UV magnitudes of $-18.5\lt {M}_{\mathrm{UV}}\lt -12.5$ covered in this study produce the majority (55%–60%) of the unobscured UV luminosity density at $1\lt z\lt 3$ .

Export citation and abstract BibTeX RIS

Previous article in issue

Next article in issue

Footnotes

*
Some of the data presented herein were obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W.M. Keck Foundation.
13
To be consistent with other studies, we quote these limits in terms of ${L}_{z=3}^{* }$ , i.e., ${M}_{1700,{AB}}^{* }=-21.07$ , from Steidel et al. (1999).
14
https://archive.stsci.edu/prepds/frontier/
15
http://www.stsci.edu/hst/wfc3/tools/cte_tools
16
The normalized median absolute deviation is defined as ${\sigma }_{\mathrm{NMAD}}=1.48\times \mathrm{median}(| {\rm{\Delta }}z-\mathrm{median}({\rm{\Delta }}z)| /(1+z))$ (Ilbert et al. 2006; Brammer et al. 2008). Unlike the usual standard deviation, ${\sigma }_{\mathrm{NMAD}}$ is not sensitive to the presence of outliers.
17
We define the faint galaxies based on the limiting magnitude used in our sample selection criteria (see Section 6). They are defined to have a signal-to-noise ratio (S/N) < 5 in either detection filter or the rest-frame 1500 Å filter.
18
The Q parameter (see Equation (8) in Brammer et al. 2008) combines the reduced- ${\chi }^{2}$ of the fitting procedure with the width of the $68 \%$ confidence interval of the redshift probability distribution function to present an estimate of the reliability of the output redshift.
19
https://archive.stsci.edu/prepds/frontier/lensmodels/
20
https://projets.lam.fr/projects/lenstool/wiki
21
We note that for the same experiment, the effective volumes of the LBG samples (see Appendix B) show slightly larger change at bright luminosities. This can be understood by considering that the color–color criteria select against very reddened galaxies. However, our final estimates of the best-fit LFs (for both sample selections) are robust against these different initial assumptions of dust reddening distribution.
22
The circularized effective radius is defined as ${r}_{e}={r}_{e,\mathrm{major}}\sqrt{q}$ , where ${r}_{e,\mathrm{major}}$ is the half-light radius along the semimajor axis and q is the axis ratio. The circularized radius has been extensively used in other high-redshift size measurements (e.g., Mosleh et al. 2012; Ono et al. 2013).
23
In the future, when we complete the UV survey of HFFs, we will add four more clusters and consequently triple our sample size at z = 2.6. Therefore, our number density measurement for bright galaxies at this redshift will be more accurate.