de La Vieuville, G.; Bina, D.; Pello, R.; Mahler, G.; Richard, J.; Drake, A. B.; Herenz, E. C.; Bauer, F. E.; Clément, B.; Lagattuta, D.; Laporte, N.; Martinez, J.
Contact. This paper presents the results obtained with the Multi-Unit Spectroscopic Explorer (MUSE) at the ESO Very Large Telescope on the faint end of the Lyman-alpha luminosity function (LF) based on deep observations of four lensing clusters. The goal of our project is to set strong constraints on the relative contribution of the Lyman-alpha emitter (LAE) population to cosmic reionization. Aims. The precise aim of the present study is to further constrain the abundance of LAEs by taking advantage of the magnification provided by lensing clusters to build a blindly selected sample of galaxies which is less biased than current blank field samples in redshift and luminosity. By construction, this sample of LAEs is complementary to those built from deep blank fields, whether observed by MUSE or by other facilities, and makes it possible to determine the shape of the LF at fainter levels, as well as its evolution with redshift. Methods. We selected a sample of 156 LAEs with redshifts between 2.9 ≤ z ≤ 6.7 and magnification-corrected luminosities in the range 39 ≲ log LLyα [erg s−1] ≲43. To properly take into account the individual differences in detection conditions between the LAEs when computing the LF, including lensing configurations, and spatial and spectral morphologies, the non-parametric 1/Vmax method was adopted. The price to pay to benefit from magnification is a reduction of the effective volume of the survey, together with a more complex analysis procedure to properly determine the effective volume Vmax for each galaxy. In this paper we present a complete procedure for the determination of the LF based on IFU detections in lensing clusters. This procedure, including some new methods for masking, effective volume integration and (individual) completeness determinations, has been fully automated when possible, and it can be easily generalized to the analysis of IFU observations in blank fields. Results. As a result of this analysis, the Lyman-alpha LF has been obtained in four different redshift bins: 2.9 < z < 6, 7, 2.9 < z < 4.0, 4.0 < z < 5.0, and 5.0 < z < 6.7 with constraints down to log LLyα = 40.5. From our data only, no significant evolution of LF mean slope can be found. When performing a Schechter analysis also including data from the literature to complete the present sample towards the brightest luminosities, a steep faint end slope was measured varying from α = −1.69−0.08+0.08 to α = −1.87−0.12+0.12 between the lowest and the highest redshift bins. Conclusions. The contribution of the LAE population to the star formation rate density at z ∼ 6 is ≲50% depending on the luminosity limit considered, which is of the same order as the Lyman-break galaxy (LBG) contribution. The evolution of the LAE contribution with redshift depends on the assumed escape fraction of Lyman-alpha photons, and appears to slightly increase with increasing redshift when this fraction is conservatively set to one. Depending on the intersection between the LAE/LBG populations, the contribution of the observed galaxies to the ionizing flux may suffice to keep the universe ionized at z ∼ 6.
Astronomy & Astrophysics
We thank the anonymous referee for their critical review and useful suggestions. This work has been carried out thanks to the support of the OCEVU Labex (ANR-11-LABX-0060) and the A*MIDEX project (ANR-11-IDEX-0001-02) funded by the “Investissements d’Avenir” French government programme managed by the ANR. Partially funded by the ERC starting grant CALENDS (JR, VP, BC, JM), the Agence Nationale de la recherche bearing the reference ANR-13-BS05-0010-02 (FOGHAR), and the “Programme National de Cosmologie and Galaxies” (PNCG) of CNRS/INSU, France. GdV, RP, JR, GM, JM, BC, and VP also acknowledge support by the Programa de Cooperacion Cientifica – ECOS SUD Program C16U02. NL acknowledges funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No 669253), ABD acknowledges support from the ERC advanced grant “Cosmic Gas”. LW acknowledges support by the Competitive Fund of the Leibniz Association through grant SAW-2015-AIP-2, and TG acknowledges support from the European Research Council under grant agreement ERC-stg-757258 (TRIPLE).. Based on observations made with ESO Telescopes at the La Silla Paranal Observatory under programme IDs 060.A-9345, 094.A-0115, 095.A-0181, 096.A-0710, 097.A0269, 100.A-0249, and 294.A-5032. Also based on observations obtained with the NASA/ESA Hubble Space Telescope, retrieved from the Mikulski Archive for Space Telescopes (MAST) at the Space Telescope Science Institute (STScI). STScI is operated by the Association of Universities for Research in Astronomy, Inc. under NASA contract NAS 5-26555. This research made use of Astropy, a community-developed core Python package for Astronomy (Astropy Collaboration 2013). All plots in this paper were created using Matplotlib (Hunter 2007).
de La Vieuville G, Bina D, Pello R, et al. Faint end of the z ∼ 3–7 luminosity function of Lyman-alpha emitters behind lensing clusters observed with MUSE. Astronomy & Astrophysics. 2019;628. doi:10.1051/0004-6361/201834471
de La Vieuville, G., Bina, D., Pello, R., Mahler, G., Richard, J., Drake, A. B., … Soucail, G. (2019). Faint end of the z ∼ 3–7 luminosity function of Lyman-alpha emitters behind lensing clusters observed with MUSE. Astronomy & Astrophysics. EDP Sciences. https://doi.org/10.1051/0004-6361/201834471
La Vieuville, G. de, D. Bina, R. Pello, G. Mahler, J. Richard, A. B. Drake, E. C. Herenz, et al. “Faint End of the z ∼ 3–7 Luminosity Function of Lyman-Alpha Emitters behind Lensing Clusters Observed with MUSE.” Astronomy & Astrophysics. EDP Sciences, 2019. https://doi.org/10.1051/0004-6361/201834471.
G. de La Vieuville et al., “Faint end of the z ∼ 3–7 luminosity function of Lyman-alpha emitters behind lensing clusters observed with MUSE,” Astronomy & Astrophysics, vol. 628. EDP Sciences, 2019.
de La Vieuville G, Bina D, Pello R, Mahler G, Richard J, Drake AB, Herenz EC, Bauer FE, Clément B, Lagattuta D, Laporte N, Martinez J, Patrício V, Wisotzki L, Zabl J, Bouwens RJ, Contini T, Garel T, Guiderdoni B, Marino RA, Maseda MV, Matthee JJ, Schaye J, Soucail G. 2019. Faint end of the z ∼ 3–7 luminosity function of Lyman-alpha emitters behind lensing clusters observed with MUSE. Astronomy & Astrophysics. 628, A3.
de La Vieuville, G., et al. “Faint End of the z ∼ 3–7 Luminosity Function of Lyman-Alpha Emitters behind Lensing Clusters Observed with MUSE.” Astronomy & Astrophysics, vol. 628, A3, EDP Sciences, 2019, doi:10.1051/0004-6361/201834471.