The Redshift Evolution of Extended Ly <i>α</i> Emission in HETDEX. I. Imaging Methods and Emission Measurements
Abstract We investigate extended Ly α emission using integral-field unit (IFU) data from the Hobby–Eberly Telescope Dark Energy Experiment (or HETDEX). We apply the modified Shepard method to image 106,853 Ly α emitters (LAEs) and median-stack them as functions of rest-frame Ly α equivalent width (EW), Ly α line flux, and redshift to obtain accurate flux measurements for the faintest Ly α detections. After careful consideration of point-spread function, centroiding, IFU correlation, and signal-to-noise ratio errors, we calculate that the one-dimensional exponential scale lengths of our LAEs range from ∼3.0 to 7.1 kpc. The scale lengths show a slight negative correlation with the Ly α EW, with lower-EW sources having higher scale lengths. We also detect positive correlations between the scale length of the sample and its Ly α flux and luminosity within flux- and luminosity-binned subsamples. Overall, we find evidence for a decrease in Ly α halo size with increasing redshift. We discuss the mechanisms that could be powering these halos and driving their complex evolution.
Authors
- Brianna D. McKay (ORCID: https://orcid.org/0000-0002-1952-3245)
- Robin Ciardullo (ORCID: https://orcid.org/0000-0002-1328-0211)
- Daniel J. Farrow (ORCID: https://orcid.org/0000-0003-2575-0652)
- C X Liu
- Dustin Davis (ORCID: https://orcid.org/0000-0002-8925-9769)
- Sarah Tuttle (ORCID: https://orcid.org/0000-0002-7327-565X)
- Chris Byrohl (ORCID: https://orcid.org/0000-0002-0885-8090)
- Steven L. Finkelstein (ORCID: https://orcid.org/0000-0001-8519-1130)
- Karl Gebhardt (ORCID: https://orcid.org/0000-0002-8433-8185)
- Erin Mentuch Cooper (ORCID: https://orcid.org/0000-0002-2307-0146)
- Gregory R. Zeimann (ORCID: https://orcid.org/0000-0003-2307-0629)
Institutions
- Pennsylvania State University (US)
- Kavli Institute for the Physics and Mathematics of the Universe (JP)
- Yunnan University (CN)
- University of Hull (GB)
- Heidelberg University (DE)
- Canada–France–Hawaii Telescope (US)
- Seattle University (US)
- Heidelberg Institute for Theoretical Studies (DE)
- The University of Tokyo (JP)
- The University of Texas at Austin (US)
Publication Details
- Journal
- The Astrophysical Journal
- Published
- 2026-04-14
- DOI
- https://doi.org/10.3847/1538-4357/ae4de7
- Primary Topic
- Galaxies: Formation, Evolution, Phenomena
- Type
- article
- Field-Weighted Citation Impact
- 0.00
Funders
- National Science Foundation
- University of Texas at Austin
- Missouri University of Science and Technology
- University of Oxford
- Georg-August-Universität Göttingen
- University of Tokyo
- Ludwig-Maximilians-Universität München
- Leibniz-Institut für Astrophysik Potsdam
- Max-Planck-Institut für Astrophysik
- Department of Mechanical Engineering, University of Texas at Austin
- U.S. Air Force
- Leibniz-Gemeinschaft
- Air Force Research Laboratory