Constraining Lyman-alpha spatial offsets at 3 < z < 5.5 from VANDELS slit spectroscopy
- Hoag, A ORCID Department of Physics and Astronomy, University of California, Los Angeles, CA 90095-1547, USA
- Treu, T Department of Physics and Astronomy, University of California, Los Angeles, CA 90095-1547, USA
- Pentericci, L INAF, Osservatorio Astronomico di Roma, via Frascati 33, I-00078 Monteporzio Catone, Italy
- Amorin, R Departamento de Física y Astronomía, Universidad de La Serena, Av. Juan Cisternas 1200 Norte, La Serena, Chile
- Bolzonella, M INAF, Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, via Gobetti 93/3, I-40129 Bologna, Italy
- Bradač, M ORCID Department of Physics, University of California, Davis, 1 Shields Ave, Davis, CA 95616, USA
- Castellano, M INAF, Osservatorio Astronomico di Roma, via Frascati 33, I-00078 Monteporzio Catone, Italy
- Cullen, F Institute for Astronomy, University of Edinburgh, Royal Observatory, Edinburgh EH9 3HJ, UK
- Fynbo, J P U The Cosmic Dawn Center, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen Ø, Denmark
- Garilli, B INAF, Istituto di Astrofisica Spaziale e Fisica Cosmica Milano, via Bassini 15, I-20133 Milano, Italy
- Guaita, L Núcleo de Astronomia, Facultad de Ingeniería, Universidad Diego Portales, Av. Ejército 441, Santiago, Chile
- Hathi, N ORCID Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
- Henry, A Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
- Jones, T ORCID Department of Physics, University of California, Davis, 1 Shields Ave, Davis, CA 95616, USA
- Mason, C ORCID Harvard-Smithsonian Center for Astrophysics, 60 Garden St, Cambridge, MA 02138, USA
- McLeod, D Institute for Astronomy, University of Edinburgh, Royal Observatory, Edinburgh EH9 3HJ, UK
- McLure, R Institute for Astronomy, University of Edinburgh, Royal Observatory, Edinburgh EH9 3HJ, UK
- Morishita, T Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
- Pozzetti, L INAF, Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, via Gobetti 93/3, I-40129 Bologna, Italy
- Schaerer, D Institut de Recherche en Astrophysique et Planétologie CNRS, IRAP, 14 Avenue E. Belin, F-31400 Toulouse, France
- Schmidt, K B Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16, D-14482 Potsdam, Germany
- Talia, M ORCID Department of Physics and Astronomy (DIFA), University of Bologna, Via Gobetti 93/2, I-40129 Bologna, Italy
- Thomas, R European Southern Observatory, Avenida Alonso de Cordova 3107, Vitacura, 19001 Casilla, Santiago de Chile, Chile
- 2019-7-1
Published in:
- Monthly Notices of the Royal Astronomical Society. - Oxford University Press (OUP). - 2019, vol. 488, no. 1, p. 706-719
English
Abstract
We constrain the distribution of spatially offset Lyman-alpha emission (Ly α) relative to rest-frame ultraviolet emission in ∼300 high redshift (3 < z < 5.5) Lyman-break galaxies (LBGs) exhibiting Ly α emission from VANDELS, a VLT/VIMOS slit-spectroscopic survey of the CANDELS Ultra Deep Survey and Chandra Deep Field South fields (≃0.2 deg2 total). Because slit spectroscopy only provides one spatial dimension, we use Bayesian inference to recover the underlying two-dimensional Ly α spatial offset distribution. We model the distribution using a two-dimensional circular Gaussian, defined by a single parameter σr,Ly α, the standard deviation expressed in polar coordinates. Over the entire redshift range of our sample (3 < z < 5.5), we find $\sigma _{r,\mathrm{Ly}\,\alpha }=1.70^{+0.09}_{-0.08}$ kpc ($68\hbox{ per cent}$ conf.), corresponding to ∼0${^{\prime\prime}_{.}}$25 at 〈z〉 = 4.5. We also find that σr,Ly α decreases significantly with redshift. Because Ly α spatial offsets can cause slit losses, the decrease in σr,Ly α with redshift can partially explain the increase in the fraction of Ly α emitters observed in the literature over this same interval, although uncertainties are still too large to reach a strong conclusion. If σr,Ly α continues to decrease into the reionization epoch, then the decrease in Ly α transmission from galaxies observed during this epoch might require an even higher neutral hydrogen fraction than what is currently inferred. Conversely, if spatial offsets increase with the increasing opacity of the intergalactic medium, slit losses may explain some of the drop in Ly α transmission observed at z > 6. Spatially resolved observations of Ly α and UV continuum at 6 < z < 8 are needed to settle the issue.
- Language
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- English
- Open access status
- green
- Identifiers
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- DOI 10.1093/mnras/stz1768
- ISSN 0035-8711
- Persistent URL
- https://sonar.ch/global/documents/170959
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