Difference between revisions of "Large Scale Structure of the cosmos"
m (Text replacement - "http://" to "https://") |
|||
| Line 1: | Line 1: | ||
[[File:lighterstill.jpg]] | [[File:lighterstill.jpg]] | ||
| − | In [[physical]] [[cosmology]], the '''large-scale structure''' of the [[universe]] refers to the characterization of [[observable]] [[distributions]] of [[matter]] and [[light]] on the largest scales (typically on the order of billions of [[light-years]]). Sky surveys and mappings of the various [ | + | In [[physical]] [[cosmology]], the '''large-scale structure''' of the [[universe]] refers to the characterization of [[observable]] [[distributions]] of [[matter]] and [[light]] on the largest scales (typically on the order of billions of [[light-years]]). Sky surveys and mappings of the various [https://en.wikipedia.org/wiki/Wavelength wavelength bands] of [https://en.wikipedia.org/wiki/Electromagnetic_radiation electromagnetic radiation] (in particular 21-cm emission) have yielded much [[information]] on the [[content]] and [[character]] of the universe's [[structure]]. The [[organization]] of structure appears to follow as a [[hierarchical]] model with organization up to the scale of [[superclusters]] and filaments. Larger than this, there seems to be no continued structure, a [[phenomenon]] which has been referred to as the ''End of Greatness''. |
[[File:Universe_Reference_Map650.jpg|center|frame]] | [[File:Universe_Reference_Map650.jpg|center|frame]] | ||
| − | The [[organization]] of [[structure]] arguably begins at the [[stellar]] level, though most cosmologists rarely address [ | + | The [[organization]] of [[structure]] arguably begins at the [[stellar]] level, though most cosmologists rarely address [https://en.wikipedia.org/wiki/Astrophysics astrophysics] on that scale. [[Stars]] are organised into [[galaxies]], which in turn form [https://en.wikipedia.org/wiki/Groups_and_clusters_of_galaxies clusters] and [[superclusters]] that are separated by immense voids, creating a vast foam-like structure sometimes called the "cosmic web". Prior to [https://www.wikipedia.org/wiki/1989 1989], it was commonly assumed that virialized [[galaxy]] clusters were the largest structures in [[existence]], and that they were [[distributed]] more or less [[uniformly]] throughout the universe in every direction. However, based on [https://en.wikipedia.org/wiki/Redshift_survey redshift survey data], in 1989 Margaret Geller and John Huchra discovered the "[https://en.wikipedia.org/wiki/Great_Wall_(astronomy) Great Wall]," a sheet of galaxies more than 500 million light-years long and 200 million wide, but only 15 million [[light-years]] thick. The existence of this structure escaped notice for so long because it requires locating the position of galaxies in three dimensions, which involves combining location information about the galaxies with distance information from redshifts. In April 2003, another large-scale structure was discovered, the [https://en.wikipedia.org/wiki/Sloan_Great_Wall Sloan Great Wall]. In August 2007, a possible supervoid was detected in the constellation Eridanus.[1] It coincides with the '[https://en.wikipedia.org/wiki/WMAP_cold_spot WMAP Cold Spot]', a cold region in the microwave sky that is highly improbable under the currently favored cosmological model. This supervoid could cause the cold spot, but to do so it would have to be improbably big, possibly a billion light-years across. |
| − | In more recent studies the universe appears as a collection of giant bubble-like voids separated by sheets and [ | + | In more recent studies the universe appears as a collection of giant bubble-like voids separated by sheets and [https://en.wikipedia.org/wiki/Galaxy_filament filaments of galaxies], with the [[superclusters]] appearing as occasional [[relatively]] dense nodes. This network is clearly visible in the [https://en.wikipedia.org/wiki/2dF_Galaxy_Redshift_Survey 2dF Galaxy Redshift Survey]. In the figure a 3-D reconstruction of the inner parts of the survey is shown, revealing an impressive view on the cosmic structures in the nearby universe. Several superclusters stand out, such as the Sloan Great Wall, the largest structure in the universe known to date. |
[[File:Superclusters_atlasoftheuniverse.gif|center|frame]] | [[File:Superclusters_atlasoftheuniverse.gif|center|frame]] | ||
| − | At the [[center]] of the [ | + | At the [[center]] of the [https://en.wikipedia.org/wiki/Hydra_supercluster Hydra supercluster] there is a [[gravitational]] [[anomaly]], known as the [https://en.wikipedia.org/wiki/Great_Attractor Great Attractor], which affects the [[motion]] of galaxies over a region hundreds of millions of [[light-years]] across. These galaxies are all [https://en.wikipedia.org/wiki/Redshift redshifted], in accordance with [https://en.wikipedia.org/wiki/Hubble%27s_law Hubble's law], indicating that they are receding from us and from each other, but the variations in their redshift are sufficient to reveal the [[existence]] of a concentration of [[mass]] equivalent to tens of thousands of galaxies. |
| − | The Great Attractor, discovered in 1986, lies at a distance of between 150 million and 250 million [[light-years]] (250 million is the most recent estimate), in the direction of the [ | + | The Great Attractor, discovered in 1986, lies at a distance of between 150 million and 250 million [[light-years]] (250 million is the most recent estimate), in the direction of the [https://en.wikipedia.org/wiki/Hydra_(constellation) Hydra] and [https://en.wikipedia.org/wiki/Centaurus Centaurus] constellations. In its vicinity there is a preponderance of large old galaxies, many of which are colliding with their neighbours, and/or radiating large amounts of radio waves. |
| − | In 1987 Astronomer R. Brent Tully of the University of Hawaii’s Institute of Astronomy identified what he called the [ | + | In 1987 Astronomer R. Brent Tully of the University of Hawaii’s Institute of Astronomy identified what he called the [https://en.wikipedia.org/wiki/Pisces-Cetus_Supercluster_Complex Pisces-Cetus Supercluster Complex], a [[structure]] which he said was one billion [[light years]] long and 150 million light years across.[https://en.wikipedia.org/wiki/Large-scale_structure_of_the_cosmos] |
==See also== | ==See also== | ||
*'''''[[Part 1|Central and Superuniverse]]''''' | *'''''[[Part 1|Central and Superuniverse]]''''' | ||
| Line 29: | Line 29: | ||
*F. Sylos Labini, M. Montuori and L. Pietronero (1998). "Scale-invariance of galaxy clustering". Physics Reports 293: 61-226. doi:10.1023/B:GERG.0000006699.45969.49. arΧiv:astro-ph/9711073v1. Retrieved 2009-12-22. | *F. Sylos Labini, M. Montuori and L. Pietronero (1998). "Scale-invariance of galaxy clustering". Physics Reports 293: 61-226. doi:10.1023/B:GERG.0000006699.45969.49. arΧiv:astro-ph/9711073v1. Retrieved 2009-12-22. | ||
==External links== | ==External links== | ||
| − | *[ | + | *[https://www.mpa-garching.mpg.de/galform/millennium/ "Millennium Simulation" of structure forming] Max Planck Institute of Astrophysics, Garching, Germany |
| − | * [ | + | * [https://apod.nasa.gov/apod/ap071107.html The Sloan Great Wall: Largest Known Structure?] on [https://apod.nasa.gov APOD] |
| − | *[ | + | *[https://www.space.gs/17-apr-2007-ras.html Hubble, VLT and Spitzer Capture Galaxy Formation in the Early Universe.] |
[[Category: Cosmology]] | [[Category: Cosmology]] | ||
[[Category: Astronomy]] | [[Category: Astronomy]] | ||
Latest revision as of 01:21, 13 December 2020
In physical cosmology, the large-scale structure of the universe refers to the characterization of observable distributions of matter and light on the largest scales (typically on the order of billions of light-years). Sky surveys and mappings of the various wavelength bands of electromagnetic radiation (in particular 21-cm emission) have yielded much information on the content and character of the universe's structure. The organization of structure appears to follow as a hierarchical model with organization up to the scale of superclusters and filaments. Larger than this, there seems to be no continued structure, a phenomenon which has been referred to as the End of Greatness.
The organization of structure arguably begins at the stellar level, though most cosmologists rarely address astrophysics on that scale. Stars are organised into galaxies, which in turn form clusters and superclusters that are separated by immense voids, creating a vast foam-like structure sometimes called the "cosmic web". Prior to 1989, it was commonly assumed that virialized galaxy clusters were the largest structures in existence, and that they were distributed more or less uniformly throughout the universe in every direction. However, based on redshift survey data, in 1989 Margaret Geller and John Huchra discovered the "Great Wall," a sheet of galaxies more than 500 million light-years long and 200 million wide, but only 15 million light-years thick. The existence of this structure escaped notice for so long because it requires locating the position of galaxies in three dimensions, which involves combining location information about the galaxies with distance information from redshifts. In April 2003, another large-scale structure was discovered, the Sloan Great Wall. In August 2007, a possible supervoid was detected in the constellation Eridanus.[1] It coincides with the 'WMAP Cold Spot', a cold region in the microwave sky that is highly improbable under the currently favored cosmological model. This supervoid could cause the cold spot, but to do so it would have to be improbably big, possibly a billion light-years across.
In more recent studies the universe appears as a collection of giant bubble-like voids separated by sheets and filaments of galaxies, with the superclusters appearing as occasional relatively dense nodes. This network is clearly visible in the 2dF Galaxy Redshift Survey. In the figure a 3-D reconstruction of the inner parts of the survey is shown, revealing an impressive view on the cosmic structures in the nearby universe. Several superclusters stand out, such as the Sloan Great Wall, the largest structure in the universe known to date.
At the center of the Hydra supercluster there is a gravitational anomaly, known as the Great Attractor, which affects the motion of galaxies over a region hundreds of millions of light-years across. These galaxies are all redshifted, in accordance with Hubble's law, indicating that they are receding from us and from each other, but the variations in their redshift are sufficient to reveal the existence of a concentration of mass equivalent to tens of thousands of galaxies.
The Great Attractor, discovered in 1986, lies at a distance of between 150 million and 250 million light-years (250 million is the most recent estimate), in the direction of the Hydra and Centaurus constellations. In its vicinity there is a preponderance of large old galaxies, many of which are colliding with their neighbours, and/or radiating large amounts of radio waves.
In 1987 Astronomer R. Brent Tully of the University of Hawaii’s Institute of Astronomy identified what he called the Pisces-Cetus Supercluster Complex, a structure which he said was one billion light years long and 150 million light years across.[1]
See also
Further reading
- Vicent J. Martínez, Jean-Luc Starck, Enn Saar, David L. Donoho, Simon Reynolds, Pablo de la Cruz, and Silvestre Paredes (nov 2005). "Morphology Of The Galaxy Distribution From Wavelet Denoising". The Astrophysical Journal 634: 744-755. doi:10.1086/497125. arΧiv:astro-ph/0508326. Retrieved 2009-12-22.
- J. R. Mureika and C. C. Dyer (2005-05-17). "Multifractal Analysis of Packed Swiss Cheese Cosmologies". Classical and Quantum Gravity. v1. arΧiv:gr-qc/0505083. Retrieved 2009-12-22.
- Mureika, J. R. and Dyer, C. C. (jan 2004). "Review: Multifractal Analysis of Packed Swiss Cheese Cosmologies". General Relativity and Gravitation 36: 151-184. doi:10.1023/B:GERG.0000006699.45969.49. arΧiv:gr-qc/0505083. Retrieved 2009-12-22.
- Gott, III, J. R. et al. (may 2005). "A Map of the Universe". The Astrophysical Journal 624: 463-484. doi:10.1086/428890. arΧiv:astro-ph/0310571. Retrieved 2009-12-22.
- F. Sylos Labini, M. Montuori and L. Pietronero (1998). "Scale-invariance of galaxy clustering". Physics Reports 293: 61-226. doi:10.1023/B:GERG.0000006699.45969.49. arΧiv:astro-ph/9711073v1. Retrieved 2009-12-22.
External links
- "Millennium Simulation" of structure forming Max Planck Institute of Astrophysics, Garching, Germany
- The Sloan Great Wall: Largest Known Structure? on APOD
- Hubble, VLT and Spitzer Capture Galaxy Formation in the Early Universe.
