arXiv subjects

Louis Gabarra

Publications and source records attributed to Louis Gabarra.

5 recordsLinked to original sources

arXiv2026

A SHARP Look at Quenching and Bulge-Disk Growth in Massive Galaxies at Cosmic Noon

The physical mechanisms that quench star formation in massive galaxies remain poorly understood. At cosmic noon (1 3x sharper than JWST) and broad near-IR wavelength coverage with 12-IFU multiplexing. This will enable, for the first time, a simultaneous bulge-disk decomposition of stellar populations and spatially resolved mapping of ionised gas in massive galaxies (log $M_*/M_{\odot}\geq 11$) at 2.2 15-20 per spectral resolution element, on the inner bulge, and outer disk extracted spectral continuum, and S/N>5 for nebular lines ([OII], H$\beta$, [OIII], H$\alpha$) on sub-kpc scales. These observations will allow us to reconstruct independent bulge and disk star-formation histories, ages, metallicities, and $\alpha$-enhancements, while mapping spatially resolved star formation, gas kinematics, and feedback-driven outflows. By directly comparing the timing of bulge growth and star-formation suppression across galaxy components, this programme will test whether quenching proceeds inside-out, distinguish fast and slow quenching pathways, and link structural transformation to feedback processes in the most massive galaxies at cosmic noon.

astro-ph.GA↗

arXiv2024

Data analysis of the NISP instrument for the Euclid mission: from the first validation tests on ground up to the verification phase after launch

The Euclid telescope, launched from Cape Canaveral on July 1st, 2023, is dedicated to studying dark matter and dark energy from its orbit at the Sun-Earth Lagrangian point L2. It is equipped with two instruments: the visual imager (VIS) and the Near-Infrared Spectrometer and Photometer (NISP). The Euclid Wide Survey (Scaramella et al. 2022) will cover approximately 14500 deg2 of the extragalactic sky, and will be complemented by the Euclid Deep Survey that will cover about 40 deg2 and achieve two magnitudes fainter depth. Several ground-test campaigns were performed to assess NISP instrument basic functionalities and performances, some highlights will be reviewed in this thesis. The analysis comprises two key aspects: the evaluation of NISP image data acquired during ground-tests and during commissioning, and the verification of instrument performance in spectroscopic mode through the use of pixel-level simulated images. The analysis includes the characterisation of NISP detectors, from instrumental background to point-spread function (PSF) evaluations, confirming that NISP performance is well within the Euclid requirement. We introduce a calibration methodology to estimate the filter wheel assembly position from PSF distortions that have been successfully applied during the commissioning and will continue to be used during the mission for calibration purpose. Additionally, we investigated noise events that occur during image acquisition, with a particular focus on \v{S}snowballs\v{S} and cosmic ray tracks. Finally, we present a spectroscopic pixel-level simulation campaign of the NISP instrument, where spectral energy distributions were generated and processed by the Euclid spectroscopic channel simulator.

astro-ph.IM↗

arXiv2023

Construction of spectral libraries of star-forming galaxies at $0.3\leq z \leq 2.5$

Spectral energy distribution (SED) models of galaxies at $0.3\leq z \leq 2.5$ were constructed to be processed by the Euclid spectroscopic channel simulator in order to investigate the \Euclid Near-Infrared Spectrometer and Photometer (NISP) capabilities. We developed a solid methodology to build a realistic and representative synthetic SED library of star-forming galaxies, including reliable emission line fluxes and widths. The construction of the SEDs consists in computing the continuum using the Bruzual \& Charlot (2003) models, calling out SED fitting parameters available in publicly released multi-wavelength catalogues. Emission lines were added using empirical and theoretical relations.

astro-ph.GA↗

arXiv2023

Pre-launch optical verification of the Euclid NISP instrument and comparison with simulated images

To characterise the NISP (Near-Infrared Spectrometer and Photometer) instrument optical capability before the launch of the \Euclid telescope to orbit, foreseen in 2023, data analysis of ground-based tests and Monte Carlo simulations that mimic the expected NISP performance were carried out. Pre-launch test data were analysed to assess the fulfilment of the mission specifications in terms of Point Spread Function (PSF), set at EE50(PSF)$\,\leq 0.3$ arcseconds, and with a spectral resolution below 16 angstroms per pixel. We also provide a first comparison between real images from the ground-based tests with simulated ones. We confirm the high optical quality of the NISP instrument, fulfilling the mission specifications in terms of PSF and spectral dispersion with a good agreement between the different test campaigns. We validated the PSF and spectral dispersion provided by the NISP simulator, a crucial aspect to validate the consistency between real and simulated images.

astro-ph.IM↗

arXiv2023

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

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.

astro-ph.GA↗