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Post Info TOPIC: Phoenix Cluster
Blobrana


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Posts: 131433
Date:
SPT-CL J2344-4243
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Black-Hole-Powered Jets Forge Fuel for Star Formation

Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) have discovered a surprising connection between a supermassive black hole and the galaxy where it resides.
Powerful radio jets from the black hole - which normally suppress star formation - are stimulating the production of cold gas in the galaxy's extended halo of hot gas. This newly identified supply of cold, dense gas could eventually fuel future star birth as well as feed the black hole itself.
The researchers used ALMA to study a galaxy at the heart of the Phoenix Cluster, an uncommonly crowded collection of galaxies about 5.7 billion light-years from Earth.
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Blobrana


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RE: Phoenix Cluster
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Title: An HST/WFC3-UVIS View of the Starburst in the Cool Core of the Phoenix Cluster
Authors: Michael McDonald, Bradford Benson, Sylvain Veilleux, Marshall W. Bautz, Christian L. Reichardt

We present the results of Hubble Space Telescope Wide Field Camera 3 observations of the core of the Phoenix Cluster (SPT-CLJ2344-4243) in five broadband filters spanning rest-frame 1000-5500A. These observations reveal complex, filamentary blue emission, extending for >40 kpc from the brightest cluster galaxy. We observe an underlying, diffuse population of old stars, following an r^1/4 distribution, confirming that this system is somewhat relaxed. The spectral energy distribution in the inner part of the galaxy, as well as along the extended filaments, is a smooth continuum and is consistent with that of a star-forming galaxy, suggesting that the extended, filamentary emission is not due to a large-scale highly-ionised outflow from the central AGN, but rather a massive population of young stars. We estimate an extinction-corrected star formation rate of 798 ±42 Msun/yr, consistent with our earlier work based on low spatial resolution ultraviolet, optical, and infrared imaging. We argue that such a high star formation rate is not the result of a merger, as it would require >10 mergers with gas-rich galaxies and there is no evidence for such multiple merger events. Instead, we propose that the high X-ray cooling rate of ~2850 Msun/yr is the origin of the cold gas reservoir. The combination of such a high cooling rate and the relatively weak radio source in the cluster core suggests that feedback has been unable to halt runaway cooling in this system, leading to this tremendous burst of star formation.

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Blobrana


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Posts: 131433
Date:
SPT-CLJ2344-4243
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Title: A Massive, Cooling-Flow-Induced Starburst in the Core of a Highly Luminous Galaxy Cluster
Authors: M. McDonald, M. Bayliss, B. A. Benson, R. J. Foley, J. Ruel, P. Sullivan, S. Veilleux, K. A. Aird, M. L. N. Ashby, M. Bautz, G. Bazin, L. E. Bleem, M. Brodwin, J. E. Carlstrom, C. L. Chang, H. M. Cho, A. Clocchiatti, T. M. Crawford, A. T. Crites, T. de Haan, S. Desai, M. A. Dobbs, J. P. Dudley, E. Egami, W. R. Forman, G. P. Garmire, E. M. George, M. D. Gladders, A. H. Gonzalez, N. W. Halverson, N. L. Harrington, F. W. High, G. P. Holder, W. L. Holzapfel, S. Hoover, J. D. Hrubes, C. Jones, M. Joy, R. Keisler, L. Knox, A. T. Lee, E. M. Leitch, J. Lieu, M. Lueker, D. Luong-Van, A. Mantz, D. P. Marrone, J. J. McMahon, J. Mehl, S. S. Meyer, E. D. Miller, L. Mocanu, J. J. Mohr, T. E. Montroy, S. S. Murray, T. Natoli, S. Padin, T. Plagge, C. Pryke, T. D. Rawle, C. L. Reichardt, A. Rest, M. Rex, et al. (23 additional authors not shown)

In the cores of some galaxy clusters the hot intracluster plasma is dense enough that it should cool radiatively in the cluster's lifetime, leading to continuous "cooling flows" of gas sinking towards the cluster center, yet no such cooling flow has been observed. The low observed star formation rates and cool gas masses for these "cool core" clusters suggest that much of the cooling must be offset by astrophysical feedback to prevent the formation of a runaway cooling flow. Here we report X-ray, optical, and infrared observations of the galaxy cluster SPT-CLJ2344-4243 at z = 0.596. These observations reveal an exceptionally luminous (L_2-10 keV = 8.2 x 10^45 erg/s) galaxy cluster which hosts an extremely strong cooling flow (dM/dt = 3820 ± 530 solar masses/yr). Further, the central galaxy in this cluster appears to be experiencing a massive starburst (740 ± 160 solar masses/yr), 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 via accretion of the intracluster medium, rather than the current picture of central galaxies assembling entirely via mergers.

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Blobrana


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Posts: 131433
Date:
RE: Phoenix Galaxy Cluster
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Galaxy cluster's 'starburst' surprises astronomers

Astronomers have seen a huge galaxy cluster doing what until now was only theorised to happen: making new stars.
Most galaxy clusters - the largest structures in the Universe - are "red and dead", having long since produced all the stars they can make.
But cluster formation should, according to theory, include a cooling phase, resulting in blue light from new stars.
Writing in Nature, researchers say they have seen evidence that the enormous Phoenix cluster makes 740 stars a year.
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Blobrana


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Posts: 131433
Date:
Phoenix Cluster
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Phoenix Cluster Sets Record Pace at Forming Stars

Stars are forming in the Phoenix cluster at the highest rate ever observed for the middle of a galaxy cluster. The object also is the most powerful producer of X-rays of any known cluster and among the most massive. The data also suggest the rate of hot gas cooling in the central regions of the cluster is the largest ever observed.
The Phoenix cluster is located about 5.7 billion light years from Earth. It is named not only for the constellation in which it is located, but also for its remarkable properties.
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Blobrana


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Posts: 131433
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Most massive and luminous galaxy cluster identified

As vast as the Milky Way may seem, our sprawling galaxy is but a speck next to the largest structures in the universe: galaxy clusters - collections of hundreds to thousands of galaxies bound together by gravity. At the heart of most galaxy clusters sit massive old galaxies, within which only a few new stars are born each year.
Now a multi-institution team led by MIT researchers has identified a galaxy cluster seven billion light-years away that dwarfs most known clusters, churning out a dazzling 740 new stars per year in the central galaxy. The galaxy cluster is among the most massive and most luminous in the universe. While scientists have formally catalogued the cluster by the name SPT-CLJ2344-4243, the MIT-led group has a more informal moniker: the Phoenix cluster, named after the constellation in which it resides.
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Position (J2000): RA 23h 44m 42.00s | Dec -42° 42' 52.60"



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