Characterizing the galaxy shape effect on the Euclid slitless spectroscopy using simulations

Abstract: The next generation of wide spectroscopic surveys such as Euclid will scan the sky in the near-infrared to obtain both photometry and spectroscopy. For this purpose, the Euclid telescope will rely on a Near-Infrared Spectrometer and Photometer (NISP) instrument whose spectroscopic channel has been designed to operate in slitless configuration. This powerful and easy to operate configuration makes it possible to avoid any prior selection on the targeted galaxies while covering the entire field of view. Beyond the observed flux of the galaxy, the detector capabilities will strongly depend on the shape of the galaxy, which gets convolved with the galaxy spectra. To test the effect of the galaxy shape on the quality of the Euclid slitless spectra, we have performed simulations testing potentially impactful morphological parameters. We then characterized the effect of the disk half-light radius on the quality of the Euclid slitless spectra.