The BOSS Emission-line Lens Survey. V. Morphology and Substructure of Lensed Lyα Emitters at Redshift Z ≈ 2.5 in the BELLS GALLERY

Abstract

We present a morphological study of the 17 lensed Lyman-α emitter (LAE) galaxies of the Baryon Oscillation Spectroscopic Survey Emission-Line Lens Survey (BELLS) for the GALaxy-Lyα EmitteR sYstems (BELLS GALLERY) sample. This analysis combines the magnification effect of strong galaxy-galaxy lensing with the high resolution of the Hubble Space Telescope (HST) to achieve a physical resolution of ∼80 pc for this 2 < z < 3 LAE sample, allowing a detailed characterization of the LAE rest-frame ultraviolet continuum surface brightness profiles and substructure. We use lens-model reconstructions of the LAEs to identify and model individual clumps, which we subsequently use to constrain the parameters of a generative statistical model of the LAE population. Since the BELLS GALLERY sample is selected primarily on the basis of Lyman-α emission, the LAEs that we study here are likely to be directly comparable to those selected in wide-field narrow-band LAE surveys, in contrast with the lensed LAEs identified in cluster lensing fields. We find an LAE clumpiness fraction of approximately 88%, significantly higher than found in previous (non-lensing) studies. We find a well-resolved characteristic clump half-light radii of ∼350 pc, a scale comparable to the largest H II regions seen in the local universe. This statistical characterization of LAE surfacebrightness profiles will be incorporated into future lensing analyses using the BELLS GALLERY sample to constrain the incidence of dark-matter substructure in the foreground lensing galaxies.

Observations of the Lyman-α Universe

“…Of course, the morphology of LAEs may not be a simple disk, but a disk-like shape with sub-structures on < 1 pkpc scales that are poorly understood. Clumpy structures are identified in various high-z galaxies including some LAEs (Shibuya et al 2016;Cornachione et al 2018;Ritondale et al 2019). Further studies are needed to test the viewing angle effect of the Lyα escape.…”

Discovering New Strong Gravitational Lenses in the DESI Legacy Imaging Surveys

“…For redshifts beyond the range that lensing galaxies can typically probe, together with high-resolution imaging (from the Hubble Space Telescope, adaptive optics, or the James Webb Space Telescope in the near future), strong lensing as a cosmic telescope magnifies spectral (e.g., Cornachione et al 2018) and spatial features (e.g., Marshall et al 2007;Patrício et al 2019;Vanzella et al 2020) of the lensed distant galaxies, providing the only way to study the morphology and internal structures of galaxies at sub-kiloparsec scales at high redshifts that can extend to z > 2.…”

Holismokes

“…Since these strong lens observations are very powerful, several large surveys including the Sloan Lens ACS (SLACS) survey (Bolton et al 2006;Shu et al 2017), the CFHTLS Strong Lensing Legacy Survey (SL2S; Cabanac et al 2007;Sonnenfeld et al 2015), the Sloan WFC Edge-on Late-type Lens Survey (SWELLS; Treu et al 2011), the BOSS Emission-Line Lens Survey (BELLS; Brownstein et al 2012;Shu et al 2016;Cornachione et al 2018), the Dark Energy Survey (DES; Dark Energy Survey Collaboration 2005; Tanoglidis et al 2021), the Survey of Gravitationally-lensed Objects in HSC Imaging (SuGOHI; Sonnenfeld et al 2018a;Wong et al 2018;Chan et al 2020;Jaelani et al 2020), and surveys in the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS; e.g., Lemon et al 2018;Cañameras et al 2020) have been conducted to find lenses. So far we have detected several thousand lenses, but mainly from the lower redshift regime.…”