Rest-frame UV Properties of Luminous Strong Gravitationally Lensed Ly-alpha Emitters from the BELLS GALLERY Survey

Séminaire IPAG de Ismael Perez-Fournon (Instituto de Astrofísica de Canarias), mercredi 5 février 2020, 11h00, IRAM seminar room

Sloan Digital Sky Survey (SDSS) imaging and spectroscopy have been crucial to identify many types of gravitational lenses up to high redshifts. I will present recent results on the rest-frame UV properties of gravitationally lensed Lyman alpha emitters (LAE) from the BELLS GALLERY survey (Shu et al. 2016a,b, Marques-Chaves et al. 2017, Cornachione et al. 2018, Marques-Chaves et al. 2019) based on the combination of SDSS spectroscopy (for source selection) with HST, William Herschel Telescope and Gran Telescopio Canarias (GTC) follow-up observations. The BELLS GALLERY survey has discovered 187 gravitational lenses in the analysis of 1.4 million BOSS galaxy spectra. These systems consist of massive SDSS Luminous Red Galaxies (LRG) at redshifts of approximately 0.5 strongly lensing LAEs at redshifts from 2–3. The magnification effect from lensing reveals the structure of LAEs below 100 pc scales, providing a detailed look at the sites of the most concentrated unobscured star formation in the universe. A recent study of the HST subsample of 21 sources (Cornachione et al. 2018, Ritondale et al. 2019) shows a LAE clumpiness fraction of approximately 88%, significantly higher than found in previous (non-lensing) studies. We also find a well-resolved characteristic clump half-light radius of 350 pc, a scale comparable to the largest H II regions seen in the local universe. I will present results from the spectroscopic follow-up of BELLS GALLERY lenses with GTC (Marques-Chaves et al. 2019). The combination of SDSS spectroscopy (discovery), the flux boost of the natural lenses (LRGs), the high-resolution HST imaging and the high signal-to-noise optical GTC/OSIRIS spectroscopy offers the unique opportunity to carry out higher signal-to-noise studies than otherwise achievable, providing a close-up look of LAE’s properties during the epoch when cosmic star formation activity was at its peak. I will discuss the plans for mm observations of these lensed LAEs.