SIMBAD references

We discovered a strongly lensed (µ >= 40) Ly α emission at z = 6.629 (S/N ≃ 18) in the MUSE Deep Lensed Field (MDLF) targeting the Hubble Frontier Field (HFF) galaxy cluster MACS J0416. Dedicated lensing simulations imply that the Ly α emitting region necessarily crosses the caustic. The arc-like shape of the Ly α extends 3 arcsec on the observed plane and is the result of two merged multiple images, each one with a de-lensed Ly α luminosity L <= 2.8 x 10⁴⁰ erg s^–1 arising from a confined region (<=150 pc effective radius). A spatially unresolved Hubble Space Telescope(HST) counterpart is barely detected at S/N ≃ 2 after stacking the near-infrared bands, corresponding to an observed (intrinsic) magnitude m₁₅₀₀ >= 30.8 (>=35.0). The inferred rest-frame Ly α equivalent width is EW₀ > 1120 Å if the IGM transmission is T_IGM < 0.5. The low luminosities and the extremely large Ly α EW₀ match the case of a Population III (Pop III) star complex made of several dozens stars (∼10⁴ M_☉) that irradiate an H II region crossing the caustic. While the Ly α and stellar continuum are among the faintest ever observed at this redshift, the continuum and the Ly α emissions could be affected by differential magnification, possibly biasing the EW₀ estimate. The aforementioned tentative HST detection tends to favour a large EW₀, making such a faint Pop III candidate a key target for the James Webb Space Telescope and Extremely Large Telescopes.