Cosmology

Abstract:

This paper describes the VIS processing function (VIS PF) of the Euclid ground segment pipeline, which processes and calibrates raw data from the VIS camera. We present the algorithms used in each processing element along with a description of the on-orbit performance of VIS PF based on performance verification and Q1 datasets. We demonstrate that the principal performance metrics (image quality, astrometric accuracy, photometric calibration) are within pre-launch specifications. The image-to-image photometric scatter is less than 0.8% and absolute astrometric accuracy compared to Gaia is 5 mas. Image quality is stable over all Q1 images, with a full width at half maximum (FWHM) of 0 . ″ 16. The stacked images (combining four nominal and two short exposures) reach I E = 25.6 (10 σ , measured as the variance of 1 . ″ 3 diameter apertures). We also describe quality control metrics provided with each image, and an appendix provides a detailed description of the provided data products. The excellent quality of these images demonstrates the immense potential of Euclid VIS data for weak lensing. VIS data covering most of the extragalactic sky will provide a lasting high-resolution atlas of the Universe.

Abstract:

Abstract:

JWST has discovered an early period of galaxy formation that was more vigorous than expected, which has challenged our understanding of the early Universe. In this work, we present the longest spectroscopic integration ever acquired by JWST/MIRI (tobs ≈ 51 hr). This spectrum covers the brightest rest-frame optical nebular emission lines for the luminous galaxy JADES-GS-z14-0 at z = 14.18. Most notably, we detect [O III]λλ4959, 5007 at ≈14σ and Hα at ≈4σ with these ultradeep observations. These lines reveal that JADES-GS-z14-0 has low dust attenuation with a recent star formation rate of SFR ≈ 8 ± 2M⊙ yr−1, star formation rate surface density of ΣSFR ≈ 20 ± 5M⊙ yr−1 kpc−2, and ionizing photon production efficiency of ξion ≈ 1025.3±0.1 Hz erg−1. Using standard strong-line diagnostics, we infer a gas-phase oxygen abundance of log10(O/H)+12≈7.5±0.2 (≈6%Z⊙), carbon-to-oxygen ratio of [C/O] ≈ −0.4 ± 0.2, ionization parameter of log10(U)≳−2.4 , and density of nH ≈ 690 ± 200 cm−3. Using detailed photoionization modeling, we instead derive log10(O/H)+12≈8.5−0.4+0.4 (≈60%Z⊙), log10(U)≈−1.4−0.4+0.3 , and nH≈540−320+520cm−3 . The inferred properties of JADES-GS-z14-0 are similar to those measured for similarly luminous galaxies at z > 10 with previous MIRI/Spectroscopy, such as GHZ2/GLASSz12, GN-z11, and MACS0647-JD1. These results suggest extreme ionization conditions and rapid metal enrichment less than 300 Myr after the Big Bang. Existing simulations are unable to reproduce the empirical and inferred properties of JADES-GS-z14-0. This work demonstrates an important step toward understanding the formation of the first stars and heavy elements in the Universe. Future work will focus on the detection of the rest-frame optical continuum and its interpretation for the stellar population properties of JADES-GS-z14-0.

Abstract:

We present a catalogue of H i sources extracted from the MIGHTEE survey data cubes covering the COSMOS field. The catalogue contains 293 sources in the redshift range of . In addition to H i masses and velocity widths, the catalogue includes optical through near-infrared photometry and inferred stellar masses and star-formation rates. The quantity of sources in the H i catalogue acquired through untargeted source finding is greatly influenced by the source finding methods used. This study therefore also provides a well-characterized expected completeness of the detected sample of galaxies based on their properties, informing of any detection biases, inferred through a comparative study of different source finding algorithms. We have tested the performance of widely-used source finders: pybdsf, profound, and sofia, along with new source finder leshi, focusing exclusively on H i source detection rather than source characterization in the first instance. The source finders were tested by injecting a sample of simulated galaxies divided into narrow bins of mass, inclination and distance into a MeerKAT data cube. The results inform the source finding strategies for the MeerKAT International GigaHertz Tiered Extragalactic Exploration (MIGHTEE) survey, as well as upcoming SKAO surveys.

Abstract:

ATLAS (Asteroid Terrestrial Last Alert System) is a time-domain survey using four telescopes, covering the entire sky. It has observed 8378 spectroscopically confirmed Type Ia supernovae (SNe Ia), with thousands of cosmology-grade light curves (to be released as TITAN DR1). To prepare this massive, low-redshift dataset for cosmology, we evaluate and cross-calibrate ATLAS forced photometry using tertiary stars from the DES (Dark Energy Survey) Y6 release. The 5000 deg2 DES footprint overlaps regions both in and out of the PS1 (Pan-STARRS DR1) footprint, allowing tests of the primary calibrator for the ATLAS Refcat2 catalog. Initial offsets are at the ∼40 mmag scale. To improve this, we determine Δ zero-point offsets for two cases: (1) pixel-to-pixel offsets within individual CCDs (reduced from ∼8 to ∼4 mmag rms) and (2) chip-to-chip offsets across the nine CCDs and filters (reduced from ∼17 to ∼3 mmag rms). We also identify the largest systematic uncertainty as a transmission-function color dependence, requiring shifts in the assumed ATLAS filters at the ∼30 mmag level if uncorrected. We validate our calibration using (a) CALSPEC standards, (b) an independent tertiary catalog, and (c) distance moduli of cross-matched SNe Ia, all showing improved consistency. Overall, we estimate combined calibration-related systematics at the ∼5–10 mmag level, supporting competitive cosmological constraints with the TITAN SN Ia dataset.