From NASA Chandra Blog : “Galaxy Cluster Travels Down an Intergalactic Highway”

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From NASA Chandra Blog


The Northern Clump
Credit:A. Veronica et al X-ray: (Chandra: National Aeronautics Space Agency (US)/Chandra X-ray Center (US)/University of Bonn [Rheinische Friedrich-Wilhelms-Universität Bonn](DE)/;European Space Agency [Agence spatiale européenne][Europäische Weltraumorganisation](EU)/XMM-Newton X-ray Space Telescope (EU)); Optical: DES/Department of Energy (US) /DOE’s Fermi National Accelerator Laboratory (US)/FNAL DECam/Cerro Tololo Inter-American Observatory (CL) (US) /NSF NOIRLab (US)/National Science Foundation (US)/ Association of Universities for Research in Astronomy (US); Radio: CSIRO-Commonwealth Scientific and Industrial Research Organisation (AU)/ASKAP Pathfinder Radio Telescope/Evolutionary Map of the Universe.

Researchers have found a galaxy cluster acting like a passenger on what astronomers are calling an “intergalactic highway.” The cluster is known as the “Northern Clump” and it is located about 690 million light years from Earth. Previously, scientists discovered an enormous filament, a thin strip of very hot gas that stretched for at least 50 million light years. A new study found evidence that the Northern Clump is traveling along this filament, similar to how a car moves along the interstate.

A composite with ESA’s XMM-Newton (blue), Chandra data (purple), optical and infrared data (orange, green, blue), plus radio data from the Evolutionary Map of the Universe survey made by the Australian Square Kilometer Array Pathfinder telescope (red) is shown with an inset with the Chandra data.

Also included is a side-by-side graphic. On the left side of this panel is an optical and infrared image from the Dark Energy Camera in Chile. The right side contains an X-ray image from ESA’s XMM-Newton (blue), with high-precision X-ray data from NASA’s Chandra X-ray Observatory are in the inset (purple).

Credit: X-ray: (Chandra: NASA/CXC/Univ. Bonn/A. Veronica et al; XMM-Newton: ESA/XMM-Newton); Optical: DES/DOE/FNAL/DECam/CTIO/NOIRLab/NSF/AURA; Radio: CSIRO/ASKAP/EMU

Each telescope gives important information about this system. For example, the optical data provides a view of the galaxies in the cluster, while the XMM-Newton data reveal hot gas in the cluster with temperatures of millions of degrees. The Chandra data show hot gas around a supermassive black hole in the middle of a galaxy in the cluster’s center.

Previous observations from the extended ROentgen Survey with an Imaging Telescope Array (eROSITA) have shown that the Northern Clump and a pair of galaxy clusters to the south all lie along an enormous filament of gas. The Northern Clump is moving towards the other clusters and all three will eventually merge with each other. The other two clusters, Abell 3391 and Abell 3395, are not shown in this image.

In the radio data, astronomers found a pair of jets of particles being ejected from regions close to the black hole that point backwards like the braids of a runner. The X-ray shows evidence of a bow shock, like the sonic boom from a supersonic plane, towards the south and a tail of hot gas towards the north that is likely being dragged off the cluster as it moves. The bend in the radio jet and both of these X-ray features are consistent with the cluster traveling south along the filament towards the other two clusters. These results agree with simulations showing that galaxy clusters grow by traveling towards each other along enormous filaments of gas, before colliding and merging.

See the full article here .


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NASA’s Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA’s Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra’s science and flight operations from Cambridge, Mass.

In 1976 the Chandra X-ray Observatory (called AXAF at the time) was proposed to National Aeronautics and Space Administration (US) by Riccardo Giacconi and Harvey Tananbaum. Preliminary work began the following year at NASA’s Marshall Space Flight Center(US) and the Harvard Smithsonian Center for Astrophysics(US) . In the meantime, in 1978, NASA launched the first imaging X-ray telescope, Einstein (HEAO-2), into orbit. Work continued on the AXAF project throughout the 1980s and 1990s. In 1992, to reduce costs, the spacecraft was redesigned. Four of the twelve planned mirrors were eliminated, as were two of the six scientific instruments. AXAF’s planned orbit was changed to an elliptical one, reaching one third of the way to the Moon’s at its farthest point. This eliminated the possibility of improvement or repair by the space shuttle but put the observatory above the Earth’s radiation belts for most of its orbit. AXAF was assembled and tested by TRW (now Northrop Grumman Aerospace Systems) in Redondo Beach, California.

AXAF was renamed Chandra as part of a contest held by NASA in 1998, which drew more than 6,000 submissions worldwide. The contest winners, Jatila van der Veen and Tyrel Johnson (then a high school teacher and high school student, respectively), suggested the name in honor of Nobel Prize–winning Indian-American astrophysicist Subrahmanyan Chandrasekhar. He is known for his work in determining the maximum mass of white dwarf stars, leading to greater understanding of high energy astronomical phenomena such as neutron stars and black holes. Fittingly, the name Chandra means “moon” in Sanskrit.

Originally scheduled to be launched in December 1998, the spacecraft was delayed several months, eventually being launched on July 23, 1999, at 04:31 UTC by Space Shuttle Columbia during STS-93. Chandra was deployed from Columbia at 11:47 UTC. The Inertial Upper Stage’s first stage motor ignited at 12:48 UTC, and after burning for 125 seconds and separating, the second stage ignited at 12:51 UTC and burned for 117 seconds. At 22,753 kilograms (50,162 lb), it was the heaviest payload ever launched by the shuttle, a consequence of the two-stage Inertial Upper Stage booster rocket system needed to transport the spacecraft to its high orbit.

Chandra has been returning data since the month after it launched. It is operated by the SAO at the Chandra X-ray Center in Cambridge, Massachusetts, with assistance from Massachusetts Institute of Technology(US) and Northrop Grumman Space Technology. The ACIS CCDs suffered particle damage during early radiation belt passages. To prevent further damage, the instrument is now removed from the telescope’s focal plane during passages.

Although Chandra was initially given an expected lifetime of 5 years, on September 4, 2001, NASA extended its lifetime to 10 years “based on the observatory’s outstanding results.” Physically Chandra could last much longer. A 2004 study performed at the Chandra X-ray Center indicated that the observatory could last at least 15 years.

In July 2008, the International X-ray Observatory, a joint project between European Space Agency [Agence spatiale européenne][Europäische Weltraumorganisation](EU), NASA and Japan Aerospace Exploration Agency (JAXA) (国立研究開発法人宇宙航空研究開発機構], was proposed as the next major X-ray observatory but was later cancelled. ESA later resurrected a downsized version of the project as the Advanced Telescope for High Energy Astrophysics (ATHENA), with a proposed launch in 2028.

European Space Agency [Agence spatiale européenne][Europäische Weltraumorganisation](EU) Athena spacecraft depiction

On October 10, 2018, Chandra entered safe mode operations, due to a gyroscope glitch. NASA reported that all science instruments were safe. Within days, the 3-second error in data from one gyro was understood, and plans were made to return Chandra to full service. The gyroscope that experienced the glitch was placed in reserve and is otherwise healthy.