Explore the vast range of titles available.

Two extremely massive galaxies are seen 800 million years after the Big Bang, showing the rapid growth of early structure and marking the most massive halo known in that era. A massive galaxy in the early Universe The most massive galaxies in the early Universe were very rare objects and observing them during their growing stage is a challenge. Daniel Marrone and collaborators report observations of one of them less than 800 million years after the Universe began, which high-resolution imaging reveals to in fact be a closely interacting pair of galaxies. The larger one is forming stars at a rate of 2,900 solar masses per year, and contains 270 billion solar masses of gas. The rapid star formation was probably triggered by the interaction with its close companion, whose properties are closer to those of galaxies observed in the nearby Universe. According to the current understanding of cosmic structure formation, the precursors of the most massive structures in the Universe began to form shortly after the Big Bang, in regions corresponding to the largest fluctuations in the cosmic density field 1 , 2 , 3 . Observing these structures during their period of active growth and assembly—the first few hundred million years of the Universe—is challenging because it requires surveys that are sensitive enough to detect the distant galaxies that act as signposts for these structures and wide enough to capture the rarest objects. As a result, very few such objects have been detected so far 4 , 5 . Here we report observations of a far-infrared-luminous object at redshift 6.900 (less than 800 million years after the Big Bang) that was discovered in a wide-field survey 6 . High-resolution imaging shows it to be a pair of extremely massive star-forming galaxies. The larger is forming stars at a rate of 2,900 solar masses per year, contains 270 billion solar masses of gas and 2.5 billion solar masses of dust, and is more massive than any other known object at a redshift of more than 6. Its rapid star formation is probably triggered by its companion galaxy at a projected separation of 8 kiloparsecs. This merging companion hosts 35 billion solar masses of stars and has a star-formation rate of 540 solar masses per year, but has an order of magnitude less gas and dust than its neighbour and physical conditions akin to those observed in lower-metallicity galaxies in the nearby Universe 7 . These objects suggest the presence of a dark-matter halo with a mass of more than 100 billion solar masses, making it among the rarest dark-matter haloes that should exist in the Universe at this epoch.

Massive galaxy clusters have been found that date to times as early as three billion years after the Big Bang, containing stars that formed at even earlier epochs1,2,3. The high-redshift progenitors of these galaxy clusters—termed ‘protoclusters’—can be identified in cosmological simulations that have the highest overdensities (greater-than-average densities) of dark matter4,5,6. Protoclusters are expected to contain extremely massive galaxies that can be observed as luminous starbursts7. However, recent detections of possible protoclusters hosting such starbursts8,9,10,11 do not support the kind of rapid cluster-core formation expected from simulations12: the structures observed contain only a handful of starbursting galaxies spread throughout a broad region, with poor evidence for eventual collapse into a protocluster. Here we report observations of carbon monoxide and ionized carbon emission from the source SPT2349-56. We find that this source consists of at least 14 gas-rich galaxies, all lying at redshifts of 4.31. We demonstrate that each of these galaxies is forming stars between 50 and 1,000 times more quickly than our own Milky Way, and that all are located within a projected region that is only around 130 kiloparsecs in diameter. This galaxy surface density is more than ten times the average blank-field value (integrated over all redshifts), and more than 1,000 times the average field volume density. The velocity dispersion (approximately 410 kilometres per second) of these galaxies and the enormous gas and star-formation densities suggest that this system represents the core of a cluster of galaxies that was already at an advanced stage of formation when the Universe was only 1.4 billion years old. A comparison with other known protoclusters at high redshifts shows that SPT2349-56 could be building one of the most massive structures in the Universe today.

In the past decade, our understanding of how stars and galaxies formed during the first 5 billion years after the Big Bang has been revolutionized by observations that leverage gravitational lensing by intervening masses, which act as natural cosmic telescopes to magnify background sources. Previous studies have harnessed this effect to probe the distant Universe at ultraviolet, optical, infrared and millimetre wavelengths1,2,3,4,5,6. However, strong-lensing studies of young, star-forming galaxies have never extended into X-ray wavelengths, which uniquely trace high-energy phenomena. Here, we report an X-ray detection of star formation in a highly magnified, strongly lensed galaxy. This lensed galaxy, seen during the first third of the history of the Universe, is a low-mass, low-metallicity starburst with elevated X-ray emission, and is a likely analogue to the first generation of galaxies. Our measurements yield insight into the role that X-ray emission from stellar populations in the first generation of galaxies may play in reionizing the Universe. This observation paves the way for future strong-lensing-assisted X-ray studies of distant galaxies reaching orders of magnitude below the detection limits of current deep fields, and previews the depths that will be attainable with future X-ray observatories.

Change history: In this Letter, the Acknowledgements section should have included the following sentence: “The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.”. This omission has been corrected online.

We present preliminary results from an on-going program that aims at mapping the intracluster medium (ICM) temperature of high redshift galaxy clusters from the MaDCoWS sample using a joint analysis of shallow X-ray data obtained by Chandra and high angular resolution Sunyaev-Zel’dovich (SZ) observations realized with the NIKA2 and MUSTANG-2 cameras. We also present preliminary results from an on-going Open Time program within the NIKA2 collaboration that aims at mapping the ICM temperature of a galaxy cluster at z = 0.45 from the resolved detection of the relativistic corrections to the SZ spectrum. These studies demonstrate how high angular resolution SZ observations will play a major role in the coming decade to push the investigation of ICM dynamics and non-gravitational processes to high redshift before the next generation X-ray observatories come into play.

We present the results of the analysis of the very massive cluster MOO J1142+1527 at a redshift z = 1.2 based on high angular resolution NIKA2 Sunyaev-Zel’dovich (SZ) and Chandra X-ray data. This multi-wavelength analysis enables us to estimate the shape of the temperature profile with unprecedented precision at this redshift and to obtain a map of the gas entropy distribution averaged along the line of sight. The comparison between the cluster morphological properties observed in the NIKA2 and Chandra maps together with the analysis of the entropy map allows us to conclude that MOOJ1142+1527 is an on-going merger hosting a cool-core at the position of the X-ray peak. This work demonstrates how the addition of spatially-resolved SZ observations to low signal-to-noise X-ray data can bring valuable insights on the intracluster medium thermodynamic properties at z > 1.

A spectroscopic redshift survey of extraordinarily bright millimetre-wave-selected sources of carbon monoxide line emission — originating from star-forming molecular gas — shows that at least ten of these sources lie at redshifts greater than four, indicating that the fraction of dusty starburst galaxies at high redshifts is greater than previously thought. ALMA focused on star-forming galaxies Luminous, dusty, starburst galaxies were abundant in the early Universe, but it has been difficult to measure the complete redshift distribution of these objects, especially at the highest redshifts. The ALMA interferometer in Chile, now coming on-stream, provides high-resolution imaging at the millimetre/submillimetre wavelengths at which star-forming gases are best observed. Using ALMA, Joaquin Vieira and co-workers targeted carbon monoxide line emissions from gravitationally lensed galaxies discovered in a wide-field survey using the South Pole Telescope. The ten z > 4 objects revealed in this work more than double the number of spectroscopically confirmed, ultra-luminous galaxies discovered at extreme redshifts. Two sources at z = 5.7 are among the most distant ultra-luminous starburst galaxies known, seen as they were about a billion years after the Big Bang. In the past decade, our understanding of galaxy evolution has been revolutionized by the discovery that luminous, dusty starburst galaxies were 1,000 times more abundant in the early Universe than at present 1 , 2 . It has, however, been difficult to measure the complete redshift distribution of these objects, especially at the highest redshifts ( z  > 4). Here we report a redshift survey at a wavelength of three millimetres, targeting carbon monoxide line emission from the star-forming molecular gas in the direction of extraordinarily bright millimetre-wave-selected sources. High-resolution imaging demonstrates that these sources are strongly gravitationally lensed by foreground galaxies. We detect spectral lines in 23 out of 26 sources and multiple lines in 12 of those 23 sources, from which we obtain robust, unambiguous redshifts. At least 10 of the sources are found to lie at z  > 4, indicating that the fraction of dusty starburst galaxies at high redshifts is greater than previously thought. Models of lens geometries in the sample indicate that the background objects are ultra-luminous infrared galaxies, powered by extreme bursts of star formation.

X-ray, optical and infrared observations reveal a very high rate of star formation in the core of an extremely luminous galaxy cluster; this starburst seems to be triggered by a cooling flow of the dense intracluster plasma. A cool-running galaxy cluster Theory predicts that the hot intracluster plasma in the cores of some galaxy clusters is dense enough to cool radiatively during the cluster's lifetime. This should lead to continuous 'cooling flows' of gas sinking towards the cluster centre, yet until now no substantial cooling flow had been observed. New optical and X-ray observations of the galaxy cluster SPT-CLJ2344-424316 at z = 0.596 reveal it to be exceptionally luminous, with a remarkably strong cooling flow equivalent to more than 3,000 solar masses per year. The central galaxy of the cluster appears to be experiencing a massive starburst, which suggests that the feedback source thought to be responsible for preventing runaway cooling in nearby cool-core clusters is not yet established in this cluster. In the cores of some clusters of galaxies the hot intracluster plasma is dense enough that it should cool radiatively in the cluster’s lifetime 1 , 2 , 3 , leading to continuous ‘cooling flows’ of gas sinking towards the cluster centre, yet no such cooling flow has been observed. The low observed star-formation rates 4 , 5 and cool gas masses 6 for these ‘cool-core’ clusters suggest that much of the cooling must be offset by feedback to prevent the formation of a runaway cooling flow 7 , 8 , 9 , 10 . Here we report X-ray, optical and infrared observations of the galaxy cluster SPT-CLJ2344-4243 (ref. 11 ) at redshift z = 0.596. These observations reveal an exceptionally luminous (8.2 × 10 45  erg s −1 ) galaxy cluster that hosts an extremely strong cooling flow (around 3,820 solar masses a year). Further, the central galaxy in this cluster appears to be experiencing a massive starburst (formation of around 740 solar masses a year), which suggests that the feedback source responsible for preventing runaway cooling in nearby cool-core clusters may not yet be fully established in SPT-CLJ2344-4243. This large star-formation rate implies that a significant fraction of the stars in the central galaxy of this cluster may form through accretion of the intracluster medium, rather than (as is currently thought) assembling entirely via mergers.

Computers have assisted people with disabilities in all phases of life and have helped increase opportunities for them to become more productive members of society. Rehabilitation service providers can offer improved services with greater knowledge of computer assistive technology. This article discusses computer adaptations and alternative input devices (e.g., alternative computer keyboards, switches, mouse modifications, eye-tracking devices), alternative input processing aids (e.g., word prediction, reading and writing aids, electronic reference tools), and alternative output (e.g., motor, visual, auditory, and tactile representation) to facilitate use of computers by persons who have disabilities.

The South Pole Telescope (SPT) is a 10 meter telescope operating at mm wavelengths. It has recently completed a three-band survey covering 2500 sq. degrees. One of the survey's main goals is to detect galaxy clusters using Sunyaev-Zeldovich effect and use these clusters for a variety of cosmological and astrophysical studies such as the dark energy equation of state, the primordial non-gaussianity and the evolution of galaxy populations. Since 2005, we have been engaged in a comprehensive optical and near-infrared followup program (at wavelengths between 0.4 and 5 μm) to image high-significance SPT clusters, to measure their photometric redshifts, and to estimate the contamination rate of the candidate lists. These clusters are then used for various cosmological and astrophysical studies.