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The study of galaxy formation and evolution is concerned with the processes that formed a heterogeneous universe from a homogeneous beginning, the formation of the first galaxies, the way galaxies change over time, and the processes that have generated the variety of structures observed in nearby galaxies. Galaxy formation is hypothesized to occur from structure formation theories, as a result of tiny quantum fluctuations in the aftermath of the Big Bang. The simplest model in general agreement with observed phenomena is the Lambda-CDM model—that is, clustering and merging allows galaxies to accumulate mass, determining both their shape and structure. Hydrodynamics simulation, which simulates both baryons and dark matter, is widely used to study galaxy formation and evolution.
In modern physical cosmology, the cosmological principle is the notion that the spatial distribution of matter in the universe is uniformly isotropic and homogeneous when viewed on a large enough scale, since the forces are expected to act equally throughout the universe on a large scale, and should, therefore, produce no observable inequalities in the large-scale structuring over the course of evolution of the matter field that was initially laid down by the Big Bang.
The Giant Metrewave Radio Telescope (GMRT), located near Narayangaon, Pune in India, is an array of thirty fully steerable parabolic radio telescopes of 45 metre diameter, observing at metre wavelengths. It is the largest and most sensitive radio telescope array in the world at low frequencies. It is operated by the National Centre for Radio Astrophysics (NCRA), a part of the Tata Institute of Fundamental Research, Mumbai. It was conceived and built under the direction of Govind Swarup during 1984 to 1996. It is an interferometric array with baselines of up to 25 kilometres (16 mi). It was recently upgraded with new receivers, after which it is also known as the upgraded Giant Metrewave Radio Telescope (uGMRT).
The Lambda-CDM, Lambda cold dark matter, or ΛCDM model is a mathematical model of the Big Bang theory with three major components:
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- the postulated cold dark matter, denoted by CDM
- ordinary matter
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9 Pegasi is a supergiant star in the constellation Pegasus. Its apparent magnitude is 4.35.
The Huge Large Quasar Group, is a possible structure or pseudo-structure of 73 quasars, referred to as a large quasar group, that measures about 4 billion light-years across. At its discovery, it was identified as the largest and the most massive known structure in the observable universe, though it has been superseded by the Hercules–Corona Borealis Great Wall at 10 billion light-years. There are also issues about its structure.
The Clowes–Campusano LQG is a large quasar group, consisting of 34 quasars and measuring about 2 billion light-years across. It is one of the largest known superstructures in the observable universe. It is located near the larger Huge-LQG. It was discovered by the astronomers Roger Clowes and Luis Campusano in 1991.
The KBC Void is an immense, comparatively empty region of space, named after astronomers Ryan Keenan, Amy Barger, and Lennox Cowie, who studied it in 2013. The existence of a local underdensity has been the subject of many pieces of literature and research articles.
References
- 1 2 3 4 5 6 Clowes, Roger G.; Campusano, Luis E.; Graham, Matthew J. & Söchting, Ilona K. (2012). "Two close large quasar groups of size ∼ 350 Mpc at: Two close large quasar groups". Monthly Notices of the Royal Astronomical Society. 419 (1): 556–565. arXiv: 1108.6221 . Bibcode:2012MNRAS.419..556C. doi: 10.1111/j.1365-2966.2011.19719.x . S2CID 31553670.
- ↑ Yadav, Jaswant K.; Bagla, J. S. & Khandai, Nishikanta (April 2010). "Fractal dimension as a measure of the scale of homogeneity: 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 . S2CID 118603499.
- ↑ Hogg, David W.; Eisenstein, Daniel J.; Blanton, Michael R.; Bahcall, Neta A.; Brinkmann, J.; Gunn, James E.; Schneider, Donald P. (2005). "Cosmic Homogeneity Demonstrated with Luminous Red Galaxies". The Astrophysical Journal. 624 (1): 54–58. arXiv: astro-ph/0411197 . Bibcode:2005ApJ...624...54H. doi:10.1086/429084. ISSN 0004-637X. S2CID 15957886.
- ↑ Scrimgeour, Morag I.; Davis, Tamara; Blake, Chris; et al. (2012). "The WiggleZ Dark Energy Survey: the transition to large-scale cosmic homogeneity: Cosmic homogeneity in the WiggleZ survey". 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 . S2CID 19959072.
- ↑ Nadathur, Seshadri (2013). "Seeing patterns in noise: gigaparsec-scale 'structures' that do not violate homogeneity". Monthly Notices of the Royal Astronomical Society. 434 (1): 398–406. arXiv: 1306.1700 . Bibcode:2013MNRAS.434..398N. doi: 10.1093/mnras/stt1028 . ISSN 0035-8711.
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