Euclid preparation

Abstract

We present a new infrared survey covering the three Euclid deep fields and four other Euclid calibration fields using Spitzer Space Telescope's Infrared Array Camera (IRAC). We combined these new observations with all relevant IRAC archival data of these fields in order to produce the deepest possible mosaics of these regions. In total, these observations represent nearly 11 % of the total Spitzer Space Telescope mission time. The resulting mosaics cover a total of approximately 71.5 deg 2 in the 3.6 and 4.5 µm bands, and approximately 21.8 deg 2 in the 5.8 and 8 µm bands. They reach at least 24 AB magnitude (measured to 5σ, in a 2 . 5 aperture) in the 3.6 µm band and up to ∼ 5 mag deeper in the deepest regions. The astrometry is tied to the Gaia astrometric reference system, and the typical astrometric uncertainty for sources with 16 < [3.6] < 19 is 0 . 15. The photometric calibration is in excellent agreement with previous WISE measurements. We extracted source number counts from the 3.6 µm band mosaics, and they are in excellent agreement with previous measurements. Given that the Spitzer Space Telescope has now been decommissioned, these mosaics are likely to be the definitive reduction of these IRAC data. This survey therefore represents an essential first step in assembling multi-wavelength data on the Euclid deep fields, which are set to become some of the premier fields for extragalactic astronomy in the 2020s.

Illuminating the Dark Side of Cosmic Star Formation. II. A Second Date with RS-NIRdark Galaxies in COSMOS

“…The biggest difference in the photometric depth between our catalog and the COSMOS2020 is in the MIR bands, where IRAC-1 and IRAC-2 maps (Moneti et al 2022) are slightly deeper than the ones we used, as summarized in Table 3. We checked the MIR fluxes of the sources that we have in common with the COSMOS2020 catalog and verified that using the deeper IRAC maps would not change our results.…”

“…15 This is the same UltraVISTA data release as used in the recent COSMOS2020 catalog (Weaver et al 2022). 16 The IRAC maps used in the COSMOS2020 catalog are instead those from Moneti et al (2022): the difference is minimal and only concerns channels 1 and 2, as shown in Figure 3 of Weaver et al (2022).…”

A Machine-learning Approach to Predict Missing Flux Densities in Multiband Galaxy Surveys

“…u-band observations are conducted by the MegaCam instrument at CFHT, and other optical bands (g, r, i, and z) are available from Subaru's HSC imaging. The Spitzer/IRAC channel 1, 2 (ch1, ch2) data are compiled from all the IRAC observations of the COSMOS field (Moneti et al 2022). Near-IR photometry in Y, J, and H bands are obtained from the UltraVISTA survey (McCracken et al 2012).…”

“…H20 will provide u-band observations from the MegaCam instrument on the Canada−France−Hawaii Telescope (CFHT) and g-, r-, i-, and z-band imaging from the Hyper Suprime-Cam (HSC) instrument on the Subaru Telescope over 20 deg 2 of the Euclid deep fields. Spitzer/IRAC observations from the Spitzer Legacy Survey (SLS) are also available in the same fields (Moneti et al 2022). In this paper, we identify the importance of wave bands for an H20+UVISTA-like survey with similar wavelength coverage expected in Euclid deep fields, incorporating the near-IR YJH bands from UltraVISTA (McCracken et al 2012) in addition to the H20 and SLS wave bands.…”

New insights and predictions on high-redshift galaxies from wide-area infrared surveys

“…However, the forthcoming Euclid mission will open up a new era in the search of such objects by mapping a large area of the sky at NIR wavelengths. In addition to its main wide survey, Euclid will perform deep observations of three so-called Euclid Deep Fields, which will encompass a total area of ∼50 deg 2 Moneti et al 2022;McPartland et al, in prep). In the best-case scenario, Euclid Deep sources will have photometric coverage in at most 10-12 filters, and therefore deriving accurate photometric redshifts and galaxy physical parameters will be challenging.…”