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Using the Subaru Telescope, a team of astronomers led by JunToshikawa (The Graduate University for Advanced Studies, Japan),Dr. Nobunari Kashikawa (National Astronomical Observatory ofJapan), and Dr. Kazuaki Ota (Kyoto University) has discovered themost distant protocluster of galaxies ever found--one that existedless than one billion years after the Big Bang. Since protoclusters are ancestors of today's massive clusters ofgalaxies, this discovery of a protocluster in the early Universeadvances our understanding of how large-scale structures form andhow galaxies evolve. The nearby or "local" universe, an area that extends about 380million light-years away from Earth, contains many galaxy clusters,i.e., gravitationally bound groups of about 100 to more than 1000galaxies. These clusters are connected with each other and make up a hugenetwork of galaxies called the "large-scale structure" of theUniverse. Such configurations raise fundamental questions: When andhow did these structures form in the history of the Universe? Astronomers think that the Universe started out as an almosthomogeneous mass that spread uniformly. Small fluctuations in theinitial mass distribution increased by gravity over the 13.7billion years of the Universe's age and produced the recent arrayof clusters. Because clusters contain a larger number of old and massivegalaxies than those found in isolated galaxies, astronomersspeculate that developing clusters may significantly affect theevolution of their member galaxies. Therefore, understanding the details of cluster formation (Note 1)is an essential step in addressing key issues of structureformation and galaxy evolution. A necessary part of this process isan investigation of all stages of cluster formation from beginningto end, which is why the current team gave particular emphasis tostudying the birth of clusters. The team focused on this phase of cluster formation by searchingvery distant galaxies that existed in the early Universe. Suchobservations present challenges for a couple of reasons. First, thelight from more distant galaxies is faint and difficult to detect.Second, protoclusters in the early Universe are rare. The use of the Subaru Telescope allowed the team to overcome thesedifficulties. The telescope not only has an 8.2 m primary mirrorwith large light-gathering power but also offers the advantage ofthe Subaru Prime Focus Camera (Suprime-Cam) with a wide-fieldimaging capability. These features are particularly beneficial fordiscovering faint and rare objects in the distant Universe. The team chose to observe the Subaru Deep Field, a 0.25square-degree-wide field in the northern sky near the constellationComa Barenices. The Subaru Deep Field is one of the most suitable regions forfinding protoclusters in the early Universe; the area is not onlydeep and wide but has been intensively observed with the SubaruTelescope, which has detected very faint galaxies. When the team searched for distant galaxies in the Subaru DeepField and investigated their distribution, they found a region witha surface number density five times greater than the average (Fig.1). The astronomers then used Subaru's Faint Object Camera andSpectrograph (FOCAS) to conduct a spectroscopic observation, whichconfirmed that most of the galaxies located in the highly denseregion lay in a narrow area in the line-of-sight. Thisconcentration of galaxies could not be explained by chance. On the basis of their observations with the Subaru Telescope, theteam confirmed the existence of a protocluster 12.72 billion yearsago (Fig. 2)--the most distant protocluster found with its distanceestablished by spectroscopic observations (Note 2). The astronomers were able to directly observe this cluster ofgalaxies at an early stage in galaxy evolution, when structureswere beginning to form in the early Universe. This discovery willbe an important step on the way to understanding structureformation and galaxy evolution. Although the team also investigated the properties of the galaxiesin the protocluster (Note 3), they did not find a significantdifference between the protocluster galaxies and other galaxies inthe field. The astronomers speculate that the characteristic features ofcluster galaxies in the nearby Universe occurred in later stages ofcluster development, not during their birth (Note 4). Closeexamination of the internal structure of the protocluster showedthat it could consist of subgroups of galaxies, merging together toform a more massive cluster (Note 5). The team will continue their research with the Subaru Telescope'sforthcoming Hyper-Suprime Camera (HSC), which has an imagingcapability with a field of view seven times wider than Suprime-Cam. The astronomers expect to use HSC to reveal how many protoclustersexisted in the early Universe and to provide a better picture ofprotoclusters in general. Toshikawa summarized the team's intent:"By continually working to find such distant protoclusters, we canunderstand cluster formation more clearly." These results were published in the May 1, 2012, edition of theAstrophysical Journal. This research was supported by The JapanSociety for the Promotion of Science through Grant-in-Aid forScientific Research 23340050. I am an expert from leduvflashlight.com, while we provides the quality product, such as China 3.7 Volt Lithium Battery , Led UV Flashlight Manufacturer, Led UV Flashlight,and more.
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