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Hercules–Corona Borealis Great Wall

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Hercules-Corona Borealis Great Wall
Gamma-ray bursts are powerful bright events that can be used as tracers of matter decoupling in the far distant universe. The gamma-ray burst shown here is an impression of GRB 080319B.
Observation data (Epoch J2000)
Constellation(s)Hercules and Corona Borealis[1]
Major axis3 Gpc (9,785 Mly)[2]
Redshift1.6 to 2.1[2]
Distance9.612 to 10.538 billion light-years (light travel distance)[3]
15.049 to 17.675 billion light-years
(present comoving distance)[3]

The Hercules-Corona Borealis Great Wall is an immense superstructure of galaxies that measures more than 10 billion light years across.[1][2] It is the largest and the most massive structure known in the observable universe.

This huge structure was discovered in November 2013 by a mapping of gamma ray bursts that occurs in the distant universe.[1][2] The astronomers used data from the Swift Gamma-Ray Burst Mission.

Characteristics

The said structure is a galactic filament,[2] or a huge group of galaxies assembled by gravity. It is about 10 billion light-years (3 Gpc) at its longest dimension, by 7.2 billion light-years (2.2 Gpc; 150,000 km/s in redshift space) on the other,[2] and is the largest known structure in the universe. It is at redshift 1.6-2.1, corresponding to a distance of approximately 10 billion light-years away,[2] and is located in the sky in the direction of the constellations Hercules and Corona Borealis.[1]

Discovery

The Swift Satellite, through which data collected through it helped to trace the Hercules-Corona Borealis Great Wall.

Gamma-ray bursts are some of the most powerful events in the known universe. They are very luminous flashes of gamma rays of distant, massive stars rotating at very high speeds. Gamma-ray bursts are exponentially rare; only one happens in an average galaxy like the Milky Way every a few million years. Therefore, gamma-ray bursts can be indicators of galaxies as standard candles to track down traces of matter decoupling in such a region of the universe.

In a survey done in 2012,[2] in the College of Charleston in South Carolina, the sky was subdivided into 9 parts with 31 GRB's each. In one radial part, 14 out of the 31 GRB's in the region are concentrated in an area 45° wide, with average redshifts ~1.5 to ~2.0. Therefore, if many GRB's occurred in the region, it must be a decoupling of thousands, or possibly, millions of galaxies.

Homogeneity problem

According to the cosmological principle, at sufficiently large scales, the universe is approximately homogeneous, meaning that the random fluctuations in quantities such as the matter density between different regions of the universe are small. However, the appropriate definition depends on the context in which it is used. Yadav et al suggested that the tips of the scales might be as well to 260/h Mpc.[4] Some scientists say that the maximum sizes of structures was somewhere around 70-130/h Mpc based on the measure of the homogeneity scale.[5][6][7] No structures are expected to be larger than the scale since the current evolutionary theories of the formation of the universe do not accept objects larger than the scale.

The Sloan Great Wall, discovered in 2003, is 1.37 billion light years across,[8] and is marginally larger than the scale.

The Huge-LQG (Huge Large Quasar Group), discovered in 2012, is 4 billion light years across.[9] However, long range correlations provide evidences of the impossibility of this structure.[10]

The Hercules-Corona Borealis Great Wall, is more than 8 times larger than the scale,[1] and so greatly exceeds the homogeneity scale.

Evolutionary problem

The structure also poses a problem to the current models of the universe's evolution. At a distance of 10 billion light-years means that we see the structure as it was 10 billion years ago, or roughly 3.79 billion years after the Big Bang. A structure 10 billion light-years wide found so early in the universe is an extreme inacceptance to the cosmological model of evolution. The structure was itself too big, and too complex, to exist so early in the universe. There is currently no idea of how such a structure has evolved.[1]

See also

References

  1. ^ a b c d e f "Universe's Largest Structure is a Cosmic Conundrum". discovery. 2013-11-19. Retrieved 2013-11-22. {{cite web}}: |first= missing |last= (help)
  2. ^ a b c d e f g h Horvath I., Hakkila J. (2013). "The largest structure of the Universe, defined by Gamma-Ray Bursts". arXiv:1311.1104. Bibcode:2013arXiv1311.1104H. {{cite journal}}: Cite journal requires |journal= (help); Unknown parameter |coauthors= ignored (|author= suggested) (help)
  3. ^ a b "Redshift-distance relation".
  4. ^ Yadav, Jaswant (25 February 2010). "Fractal dimension as a measure of the scale of homogeneity". Monthly notices of the Royal Astronomical Society. 405 (3): 2009–2015. arXiv:1001.0617. Bibcode:2010MNRAS.405.2009Y. doi:10.1111/j.1365-2966.2010.16612.x. Retrieved 15 January 2013. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  5. ^ Hogg, D.W. et al., (May 2005) "Cosmic Homogeneity Demonstrated with Luminous Red Galaxies". The Astrophysical Journal 624: 54-58. arXiv:astro-ph/0411197. Bibcode:2005ApJ...624...54H. doi:10.1086/429084.
  6. ^ Scrimgeour, Morag I. et al., (May 2012) "The WiggleZ Dark Energy Survey: the transition to large-scale cosmic homogeneity". Monthly Notices of the Royal Astronomical Society 425 (1): 116-134. arXiv:1205.6812. Bibcode: 2012MNRAS.425...116S. doi: 10.1111/j.1365-2966.2012.21402.x.
  7. ^ Nadathur, Seshadri, (July 2013) "Seeing patterns in noise: gigaparsec-scale 'structures' that do not violate homogeneity". Monthly Notices of the Royal Astronomical Society in press. arXiv:1306.1700. Bibcode: 2013MNRAS.tmp.1690N. doi: 10.1093/mnras/stt1028.
  8. ^ Gott, J. Richard, III; et al. (2005). "A Map of the Universe". The Astrophysical Journal. 624 (2): 463–484. arXiv:astro-ph/0310571. Bibcode:2005ApJ...624..463G. doi:10.1086/428890Template:Inconsistent citations {{cite journal}}: Unknown parameter |month= ignored (help)CS1 maint: multiple names: authors list (link) CS1 maint: postscript (link)
  9. ^ Clowes, Roger; Harris; Raghunathan; Campusano; Soechting; Graham (2012-01-11). "A structure in the early Universe at z ∼ 1.3 that exceeds the homogeneity scale of the R-W concordance cosmology". Monthly notices of the royal astronomical society. 1211 (4): 6256. arXiv:1211.6256. Bibcode:2012arXiv1211.6256C. doi:10.1093/mnras/sts497. Retrieved 14 January 2013. {{cite journal}}: Check date values in: |year= / |date= mismatch (help); Unknown parameter |coauthors= ignored (|author= suggested) (help)CS1 maint: unflagged free DOI (link)
  10. ^ Gaite, Jose, Dominguez, Alvaro and Perez-Mercader, Juan (August 1999) "The fractal distribution of galaxies and the transition to homogeneity". The Astrophysical Journal 522: L5-L8. arXiv:astroph/9812132. Bibcode: 1999ApJ...522L...5G. doi: 10.1086/312204.
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