Euclid preparation

Abstract

Context. While Euclid is an ESA mission specifically designed to investigate the nature of dark energy and dark matter, the planned unprecedented combination of survey area (∼15 000 deg2), spatial resolution, low sky-background, and depth also make Euclid an excellent space observatory for the study of the low surface brightness Universe. Scientific exploitation of the extended low surface brightness structures requires dedicated calibration procedures that are yet to be tested. Aims. We investigate the capabilities of Euclid to detect extended low surface brightness structure by identifying and quantifying sky-background sources and stray-light contamination. We test the feasibility of generating sky flat-fields to reduce large-scale residual gradients in order to reveal the extended emission of galaxies observed in the Euclid survey. Methods. We simulated a realistic set of Euclid/VIS observations, taking into account both instrumental and astronomical sources of contamination, including cosmic rays, stray-light, zodiacal light, interstellar medium, and the cosmic infrared background, while simulating the effects of background sources in the field of view. Results. We demonstrate that a combination of calibration lamps, sky flats, and self-calibration would enable recovery of emission at a limiting surface brightness magnitude of μlim = 29.5−0.27+0.08 mag arcsec−2 (3σ, 10 × 10 arcsec2) in the Wide Survey, and it would reach regions deeper by 2 mag in the Deep Surveys. Conclusions.Euclid/VIS has the potential to be an excellent low surface brightness observatory. Covering the gap between pixel-to-pixel calibration lamp flats and self-calibration observations for large scales, the application of sky flat-fielding will enhance the sensitivity of the VIS detector at scales larger than 1″, up to the size of the field of view, enabling Euclid to detect extended surface brightness structures below μlim = 31 mag arcsec−2 and beyond.

Re-weighting dark matter in disc galaxies: a new general relativistic observational test

“…Because of the DM relevance in our understanding of the laws of nature, it is then of paramount importance to fully characterise such elusive component of our Universe, making sure to maximise the outcome of the available indirect astrophysical and cosmological tests. Indeed, the characterization of the nature of DM through the study of the large scale distribution of galaxies is one of the scientific drivers of the medium-class ESA mission Euclid (Laureijs et al 2011;Borlaff 2022). With the present study we demonstrate that a fully general relativistic (GR) description of individual disc galaxies can also be used to improve considerably our estimates of their DM content.…”

Constraining the shape of dark matter haloes with globular clusters

“…Chaturvedi et al 2022), and even in the M81/M82/NGC3077 system of galaxies (Chies-Santos et al 2022). When compared to the X-ray surface brightness distribution, the GCs in the Abell 1689 cluster show more substructure (Alamo-Martínez et al 2013), but those in Virgo show a similar distribution to the hot gas (Durrell et al 2014). These intergalactic GCs are thus also likely an outcome of the hierarchical build-up of their current halo: these objects were stripped from their host galaxies as they were accreted, and so they now populate the outskirts of the halo.…”

“…Alamo-Martínez et al 2013;Alamo-Martínez & Blakeslee 2017), in the Virgo cluster (e.g. Durrell et al 2014), in the Perseus cluster (e.g. Harris et al 2020b), in the Fornax cluster (e.g.…”

Towards a data-driven model of the sky from low Earth orbit as observed by the Hubble Space Telescope

“…It also includes other bright astronomical sources like stars (e.g. Borlaff et al 2021), which we do not address in this work specifically.…”

“…For example, Murthy (2014) use archival imaging products from the GALEX space telescope to find two components in the UV sky: one that is time-variable symmetrical in intensity about the local midnight of the orbiting observatory, and one that is proportional to the angle between the Sun and the observed field. Borlaff et al (2021) used Hubble Space Telescope (HST) stray light information in the Hubble Ultra Deep Field (HUDF) to better inform sky estimates for future missions such as Euclid and JWST.…”