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Post Info TOPIC: Abell 2744
Blobrana


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A2744_YD4
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Oldest dust ever spotted in the universe seen in distant galaxy

Nicolas Laporte at University College London and his colleagues turned ALMA, the Atacama Large Millimeter/submillimeter Array, towards the early universe. They studied a star-forming galaxy called A2744_YD4, whose light dates back to just 200 million years after the birth of the earliest stars.
With a little help from a foreground galaxy cluster called Abell 2744, which acted as a gravitational lens and thus magnified the distant galaxy by a factor of two, Laporte's team discovered the dust. To boot, there's so much of it that it could fill the sun 6 million times over.
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Blobrana


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Ancient Stardust Sheds Light on the First Stars

Astronomers have used ALMA to detect a huge mass of glowing stardust in a galaxy seen when the Universe was only four percent of its present age. This galaxy was observed shortly after its formation and is the most distant galaxy in which dust has been detected. This observation is also the most distant detection of oxygen in the Universe. These new results provide brand-new insights into the birth and explosive deaths of the very first stars.
An international team of astronomers, led by Nicolas Laporte of University College London, have used the Atacama Large Millimeter/submillimeter Array (ALMA) to observe A2744_YD4, the youngest and most remote galaxy ever seen by ALMA. They were surprised to find that this youthful galaxy contained an abundance of interstellar dust - dust formed by the deaths of an earlier generation of stars.
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Blobrana


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Posts: 131433
Date:
MCS J0014.3-3022
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Title: Abell 2744: Too much substructure for Lambda CDM?
Author: J. Schwinn, M. Jauzac, C. M. Baugh, M. Bartelmann, D. Eckert, D. Harvey, P. Natarajan, R. Massey

The massive substructures found in Abell 2744 by Jauzac et al. (2016) present a challenge to the cold dark matter paradigm due to their number and proximity to the cluster centre. We use one of the biggest N-body simulations, the Millennium XXL, to investigate the substructure in a large sample of massive dark matter haloes. A range of effects which influence the comparison with the observations is considered, extending the preliminary evaluation carried out by Jauzac et al. (2016). There are many tens of haloes in the simulation with a total mass comparable with or larger than that of Abell 2744. However, we find no haloes with a number and distribution of massive substructures (> 5 10^13 Msun) that is close to that inferred from the observations of Abell 2744. The application of extreme value statistics suggests that we would need a simulation of at least ten times the volume of the Millennium XXL to find a single dark matter halo with a similar internal structure to Abell 2744. Explaining the distribution of massive substructures in clusters is a new hurdle for hierarchical models to negotiate, which is not weakened by appeals to baryonic physics or uncertainty over the nature of the dark matter particle.

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Blobrana


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RE: Abell 2744
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Cosmic filaments exposed near huge cluster

A new study using ESAs XMM-Newton X-ray observatory has now uncovered a handful of filaments made of galaxies, gas and dark matter that are flowing towards one of the most massive galaxy clusters in the Universe, obtaining the first, unambiguous detection of gas in the cosmic web.
The object of the study is Abell 2744, which has been nicknamed the Pandora Cluster owing to its complex and jumbled structure. It is composed of at least four smaller components that are merging.
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Blobrana


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Hubble Sees 'Ghost Light' From Dead Galaxies

NASA's Hubble Space Telescope has picked up the faint, ghostly glow of stars ejected from ancient galaxies that were gravitationally ripped apart several billion years ago. The mayhem happened 4 billion light-years away, inside an immense collection of nearly 500 galaxies nicknamed "Pandora's Cluster," also known as Abell 2744. The scattered stars are no longer bound to any one galaxy, and drift freely between galaxies in the cluster.
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Blobrana


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Posts: 131433
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Pandora's Cluster
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Hubble Finds Extremely Distant Galaxy through Cosmic Magnifying Glass

Peering through a giant cosmic magnifying glass, NASA's Hubble Space Telescope has spotted a tiny, faint galaxy -- one of the farthest galaxies ever seen. The diminutive object is estimated to be more than 13 billion light-years away.
This galaxy offers a peek back to the very early formative years of the universe and may just be the tip of the iceberg.
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Blobrana


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RE: Abell 2744
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Title: Intra-Cluster Light at the Frontier: Abell 2744
Author: Mireia Montes, Ignacio Trujillo

The ultra-deep multiwavelength HST Frontier Fields coverage of the Abell Cluster 2744 is used to derive the stellar population properties of its intra-cluster light (ICL). The restframe colours of the ICL of this intermediate redshift (z=0.3064) massive cluster are bluer (g-r~0.7; i-J~0.6) than those found in the stellar populations of its main galaxy members (g-r~0.85; i-J~0.75). Based on these colours, we derive the following mean metallicity Z~0.018+-0.003 for the ICL. The ICL age is ~3-5 Gyr younger than the average age of the massive galaxies of the cluster. The fraction of stellar mass in the ICL component comprises at least 6% of the total stellar mass of the galaxy cluster. Our data is consistent with a scenario where the bulk of the ICL of Abell 2744 has been formed relatively recently (z<1). The stellar population properties of the ICL suggest that this diffuse component is mainly the result of the disruption of infalling galaxies with similar characteristics in mass (M*~3x10^{10} Msun) and metallicity than our own Milky Way.

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Blobrana


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Title: Star formation in the massive cluster merger Abell 2744
Author: T.D. Rawle (1), B. Altieri (1), E. Egami (2), P.G. Perez-Gonzalez (3), J. Richard (4), J.S. Santos (5,1), I. Valtchanov (1), G. Walth (2), H. Bouy (6), C.P. Haines (7), N. Okabe (8) ((1) ESAC, ESA, (2) University of Arizona, (3) Universidad Complutense de Madrid, (4) Universite Lyon, (5) Osservatorio Astrofisico di Arcetri, (6) Centro de Astrobiologia, INTA-CSIC, (7) Universidad de Chile, (8) Kavli Institute, University of Tokyo)

We present a comprehensive study of star-forming (SF) galaxies in the HST Frontier Field recent cluster merger A2744 (z=0.308). Wide-field, ultraviolet-infrared (UV-IR) imaging enables a direct constraint of the total star formation rate (SFR) for 53 cluster galaxies, with SFR{UV+IR}=343+/-10 Msun/yr. Within the central 4 arcmin (1.1 Mpc) radius, the integrated SFR is complete, yielding a total SFR{UV+IR}=201+/-9 Msun/yr. Focussing on obscured star formation, this core region exhibits a total SFR{IR}=138+/-8 Msun/yr, a mass-normalised SFR{IR} of Sigma{SFR}=11.2+/-0.7 Msun/yr per 10^14 Msun and a fraction of IR-detected SF galaxies f{SF}=0.080(+0.010,-0.037). Overall, the cluster population at z~0.3 exhibits significant intrinsic scatter in IR properties (total SFR{IR}, Tdust distribution) apparently unrelated to the dynamical state: A2744 is noticeably different to the merging Bullet cluster, but similar to several relaxed clusters. However, in A2744 we identify a trail of SF sources including jellyfish galaxies with substantial unobscured SF due to extreme stripping (SFR{UV}/SFR{IR} up to 3.3). The orientation of the trail, and of material stripped from constituent galaxies, indicates that the passing shock front of the cluster merger was the trigger. Constraints on star formation from both IR and UV are crucial for understanding galaxy evolution within the densest environments.

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Blobrana


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Spitzer Sees the Galactic Dawn with 'Frontier Fields'

NASA's Spitzer Space Telescope, in tandem with other major NASA observatories, has recently embarked on a major new mission to glimpse the universe's very first galaxies. Called Frontier Fields, the project is a collaboration with the Hubble Space Telescope and the Chandra X-ray Observatory. All three telescopes, collectively known as NASA's Great Observatories, are playing indispensable roles in this quest.
Observations of the first Frontier Field cluster, Abell 2744, have been completed. Work is now underway on another cluster and two more are slated for summer. The Abell 2744 effort has already resulted in the discovery of one of the most distant galaxies ever seen, dubbed Abell2744 Y1. This tiny, infant galaxy was witnessed at a time when the 13.8 billion-year-old universe was a mere 650 million years old. Frontier Fields is expected to reveal many other similarly primeval galaxies in the critical galaxy-forming epoch shortly after the Big Bang. 
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Blobrana


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Pandora's Cluster - A Galactic Crash Investigation

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A team of scientists has studied the galaxy cluster Abell 2744, nicknamed Pandora's Cluster. They have pieced together the cluster's complex and violent history using telescopes in space and on the ground, including the Hubble Space Telescope and ESO's Very Large Telescope. Abell 2744 seems to be the result of a simultaneous pile-up of at least four separate galaxy clusters and this complex collision has produced strange effects that have never been seen together before.
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The galaxies in the cluster are clearly visible in the VLT and Hubble images. Although the galaxies are bright they make up less than 5% of the mass there. The rest is gas (around 20%), which is so hot that it shines only in X-rays, and dark matter (around 75%), which is completely invisible. To understand what was going on in the collision the team needed to map the positions of all three types of matter in Abell 2744.
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