The European Organisation for Astronomical Research in the Southern Hemisphere, commonly referred to as the European Southern Observatory (ESO), is an intergovernmental research organisation made up of 16 member states for ground-based astronomy. Created in 1962, ESO has provided astronomers with state-of-the-art research facilities and access to the southern sky. The organisation employs about 730 staff members and receives annual member state contributions of approximately €162 million. Its observatories are located in northern Chile.ESO has built and operated some of the largest and most technologically advanced telescopes. These include the 3.6 m New Technology Telescope, an early pioneer in the use of active optics, and the Very Large Telescope (VLT), which consists of four individual 8.2 m telescopes and four smaller auxiliary telescopes which can all work together or separately. The Atacama Large Millimeter Array observes the universe in the millimetre and submillimetre wavelength ranges, and is the world's largest ground-based astronomy project to date. It was completed in March 2013 in an international collaboration by Europe (represented by ESO), North America, East Asia and Chile.Currently under construction is the Extremely Large Telescope. It will use a 39.3-metre-diameter segmented mirror, and become the world's largest optical reflecting telescope when operational in 2024. Its light-gathering power will allow detailed studies of planets around other stars, the first objects in the universe, supermassive black holes, and the nature and distribution of the dark matter and dark energy which dominate the universe.ESO's observing facilities have made astronomical discoveries and produced several astronomical catalogues. Its findings include the discovery of the most distant gamma-ray burst and evidence for a black hole at the centre of the Milky Way. In 2004, the VLT allowed astronomers to obtain the first picture of an extrasolar planet (2M1207b) orbiting a brown dwarf 173 light-years away. The High Accuracy Radial Velocity Planet Searcher (HARPS) instrument installed on the older ESO 3.6 m telescope led to the discovery of extrasolar planets, including Gliese 581c—one of the smallest planets seen outside the Solar System.
JWST observations have revealed a population of high-redshift “little red dots” (LRDs) that challenge conventional active galactic nucleus (AGN) models. We report the discovery of three local LRDs at z = 0.1–0.2, initially selected from the Sloan Digital Sky Survey database, with follow-up optical/near-IR spectroscopy and photometry. They exhibit properties fully consistent with those of high-redshift LRDs, including broad hydrogen and helium emission lines, compact morphologies, V-shaped UV-optical spectral energy distribution, declining near-IR continua, and no significant variability. Two sources were targeted but not detected in X-rays with statistical significance. All three sources show blue-shifted He i absorption, while two exhibit H α and Na D absorption lines. We detect full Balmer and Paschen line series in all three objects, along with abundant narrow [Fe ii ] emission in two. The emission-line analyses suggest narrow lines originate from AGN-powered, metal-poor regions with minimal dust; broad lines come from inner regions with exceptionally high density or atypical dust properties; and [Fe ii ] emission arises from dense gas between broad- and narrow-line regions. One of our objects, J1025+1402 (nicknamed “The Egg”), shows extremely high equivalent width Na D, K i , and Ca ii triplet absorption lines, along with other potential low-ionization absorption features, suggesting the presence of a cool (∼5000 K), metal-enriched gas envelope. The optical/near-IR continua of these LRDs are also consistent with theoretical models featuring an atmosphere around black holes (BHs). The Wide-field Infrared Survey Explorer–detected IR emission is consistent with weak dust emission of T ∼ 10 ^2 –10 ^3 K. We propose a conceptual model consisting of a largely thermalized cool-gas envelope surrounding the central BH and an extended emission-line region with high-density outflowing gas to explain the observed properties of these local LRDs.
The James Webb Space Telescope (JWST) hosts a non-redundant Aperture Masking Interferometer (AMI) in its Near Infrared Imager and Slitless Spectrograph (NIRISS) instrument, providing the only dedicated interferometric facility aboard - magnitudes more precise than any interferometric experiment previously flown. However, the performance of AMI (and other high resolution approaches such as kernel phase) in recovery of structure at high contrasts has not met design expectations. A major contributing factor has been the presence of uncorrected detector systematics, notably charge migration effects in the H2RG sensor, and insufficiently accurate mask metrology. Here we present Amigo, a data-driven calibration framework and analysis pipeline that forward-models the full JWST AMI system - including its optics, detector physics, and readout electronics - using an end-to-end differentiable architecture implemented in the Jax framework and in particular exploiting the partial differential partial derivative $\partial$ Lux optical modelling package. Amigo directly models the generation of up-the-ramp detector reads, using an embedded neural sub-module to capture non-linear charge redistribution effects, enabling the optimal extraction of robust observables, for example kernel amplitudes and phases, while mitigating systematics such as the brighter-fatter effect. We demonstrate Amigo's capabilities by recovering the AB Dor AC binary from commissioning data with high-precision astrometry, and detecting both HD 206893 B and the inner substellar companion HD 206893 c: a benchmark requiring contrasts approaching 10 mag at separations of only 100 mas. These results exceed outcomes from all published pipelines and re-establish AMI as a viable competitor for imaging at high contrast at the diffraction limit. Amigo is publicly available as open-source software community resource Amigo logo .
This paper accompanies Data Release 4 of the James Webb Space Telescope (JWST) Advanced Deep Extragalactic Survey, which presents the full NIRSpec spectroscopy of the survey. We provide spectra of 5190 targets across Great Observatories Origins Deep Survey (GOODS)-North and GOODS-South (including the Hubble Ultra Deep Field), observed with the low-dispersion ( R approximate to 30-300) prism and three medium-resolution ( R approximate to 1000 ) gratings spanning 0 . 8 < lambda < 5 . 5 & micro;m; 2654 were also observed with the higher resolution ( R approximate to 2700 ) G395H grating. The tiered survey design obtained less than or similar to 20 h exposures for ' 700 galaxies in the Deep and Ultra Deep tiers, and shallower observations ( ' 1-3 h per setting) of > 4400 galaxies in the Medium tiers. Targets were selected from photometric redshifts or colours, with priority given to rest-UV-selected galaxies at z > 5 . 7 and F444W-selected galaxies at 1 . 5 < z < 5 . 7 . We describe the full target selection and present spectroscopic redshifts and success rates. In total, we obtain robust redshifts for 3297 galaxies, including 396 at z > 5 . 7 and 2545 at 1 . 5 < z < 5 . 7 . To facilitate uniform analyses, we define 'gold' subsamples based on UV-and F444W-selection. Using the parent samples and redshift success rates, we construct rest-UV luminosity functions at 6 less than or similar to z less than or similar to 9 from the Medium-and Deep-JWST tiers. Our number densities agree well with previous determinations from both photometric and spectroscopic samples, with modest interloper fractions confirming the reliability of photometric UV-bright galaxy selections at these redshifts.
The high electron temperature in galaxy clusters (> 1 keV or > 10(7) K) leads to corrections at the level of a few percent in their thermal Sunyaev-Zeldovich effect signatures. Both the size and frequency dependence of these corrections, which are known as relativistic temperature corrections, depend upon the temperature of the objects. In this work we exploit this effect to measure the average temperature of a stack of Compton-y selected clusters. Specifically, we apply the "spectroscopic method" and search for the temperature that best fits the clusters' signal measured at frequencies from 30 to 545 GHz by the Atacama Cosmology Telescope and Planck satellite. We measure the average temperature of clusters detected in the Atacama Cosmology Telescope maps to be 8.5 + 2.4 keV, with an additional systematic error of comparable amplitude dominated by passband uncertainty. Upcoming surveys, such as the Simons Observatory and CMB-S4, have the potential to dramatically improve upon these measurements and thereby enable precision studies of cluster temperatures with millimeter observations. The key challenge for future observations will be mitigating instrumental systematic effects, which already limit this analysis.
We investigate the evolution of the bar fraction and length using an extended James Webb Space Telescope NIRCam imaging data set of galaxies at 1 <= z <= 4. We assess the wavelength dependence of the bar fraction and bar length evolution by selecting a nearly mass-complete CEERS disc sample and performing visual classifications on the short (F200W) and long (F356W + F444W) wavelength channels. A similar bar fraction is observed for both samples, and combined, we find a declining bar fraction from 0.16(-0.03)(+0.03) to 0.07(-0.01)(+0.03) over the redshift range. No evolution in the F356W + F444W bar length is measured, with a mean of 3.6 kpc. A slight increase of similar to 1 kpc towards z = 1 is measured in the F200W sample, with a mean of 2.9 kpc. We find that the correlation between bar length and galaxy mass, for massive galaxies at z < 1, is unseen at z > 1. By incorporating barred galaxies at z < 1, we show that there is a modest increase in the bar length (approximate to 2 kpc) towards z = 0, but bars longer than approximate to 8 kpc are only found at z < 1. We show that bars and discs grow in tandem, for the bar length normalized by disc size does not evolve. Not only is a significant population of bars forming beyond z = 1, but our results also show that some of these bars are as long and strong as the average bar at z approximate to 0.
