Stacy McGaugh

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Stacy McGaugh
Born (1964-01-11) January 11, 1964 (age 59)
NationalityAmerican
Alma mater MIT (S.B. 1985),
Princeton and the University of Michigan (Ph.D. 1992)
Scientific career
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Institutions

Stacy McGaugh (born January 11, 1964) is an American astronomer and professor in the Department of Astronomy at Case Western Reserve University in Cleveland, Ohio. His fields of specialty include low surface brightness galaxies, [1] galaxy formation and evolution, [2] tests of dark matter [3] and alternative hypotheses, [4] [5] and measurements of cosmological parameters. [6]

Contents

Stacy McGaugh was an undergraduate student at MIT (S.B. 1985) and a graduate student at Princeton and the University of Michigan (Ph.D. 1992). He held postdoctoral appointments at Cambridge University, the Carnegie Institution of Washington, and Rutgers University before joining the faculty of the University of Maryland in 1998. He moved to Case Western in 2012. He is married with two children. He is a Distinguished Alumnus of Flint (Michigan) Northern High School (2001) and of the Astronomy Department of the University of Michigan (2013).

Known in the field of extragalactic astronomy for his early work on Low Surface Brightness Galaxies [7] and the elemental abundances in HII Regions, [8] McGaugh has also contributed to the study of the kinematics of galaxies, being among the first to point out that low surface brightness galaxies are dark matter dominated and that they pose the cuspy halo problem. [9] He also coined the expression "baryonic Tully–Fisher relation. [10] " He predicted the first to second peak amplitude ratio of the acoustic power spectrum of the Cosmic microwave background radiation. [11] [12] McGaugh found surprising support for the Modified Newtonian dynamics proposed by Mordehai Milgrom as an alternative to Dark matter in his work on Low Surface Brightness Galaxies. [13] [14] This has proven to be very controversial since it implies the non-existence of the non-baryonic dark matter that is central to physical cosmology. Nevertheless, his predictions for the mass distribution of the Milky Way [15] and the velocity dispersions of the dwarf Spheroidal satellites of the Andromeda spiral galaxy [16] have largely been confirmed by subsequent observations. [17] [18]

In 2016 McGaugh, Lelli, and Schombert reported a correlation between a radial acceleration relation (RAR) found among galactic rotation curves and the baryonic Tully-Fisher relation's prediction for galactic rotation curves. [19] According to Paranjape and Sheth, this RAR has important implications for the ΛCDM paradigm and alternative gravity theories. [20]

See also

Related Research Articles

In astronomy, dark matter is a hypothetical form of matter that appears not to interact with light or the electromagnetic field. Dark matter is implied by gravitational effects which cannot be explained by general relativity unless more matter is present than can be seen. Such effects occur in the context of formation and evolution of galaxies, gravitational lensing, the observable universe's current structure, mass position in galactic collisions, the motion of galaxies within galaxy clusters, and cosmic microwave background anisotropies.

<span class="mw-page-title-main">Galaxy rotation curve</span> Observed discrepancy in galactic angular momenta

The rotation curve of a disc galaxy is a plot of the orbital speeds of visible stars or gas in that galaxy versus their radial distance from that galaxy's centre. It is typically rendered graphically as a plot, and the data observed from each side of a spiral galaxy are generally asymmetric, so that data from each side are averaged to create the curve. A significant discrepancy exists between the experimental curves observed, and a curve derived by applying gravity theory to the matter observed in a galaxy. Theories involving dark matter are the main postulated solutions to account for the variance.

In cosmology and physics, cold dark matter (CDM) is a hypothetical type of dark matter. According to the current standard model of cosmology, Lambda-CDM model, approximately 27% of the universe is dark matter and 68% is dark energy, with only a small fraction being the ordinary baryonic matter that composes stars, planets, and living organisms. Cold refers to the fact that the dark matter moves slowly compared to the speed of light, giving it a vanishing equation of state. Dark indicates that it interacts very weakly with ordinary matter and electromagnetic radiation. Proposed candidates for CDM include weakly interacting massive particles, primordial black holes, and axions.

<span class="mw-page-title-main">Tully–Fisher relation</span> Trend in astronomy

In astronomy, the Tully–Fisher relation (TFR) is an empirical relationship between the mass or intrinsic luminosity of a spiral galaxy and its asymptotic rotation velocity or emission line width. It was first published in 1977 by astronomers R. Brent Tully and J. Richard Fisher. The luminosity is calculated by multiplying the galaxy's apparent brightness by , where is its distance from Earth, and the spectral-line width is measured using long-slit spectroscopy.

The cuspy halo problem refers to a discrepancy between the inferred dark matter density profiles of low-mass galaxies and the density profiles predicted by cosmological N-body simulations. Nearly all simulations form dark matter halos which have "cuspy" dark matter distributions, with density increasing steeply at small radii, while the rotation curves of most observed dwarf galaxies suggest that they have flat central dark matter density profiles ("cores").

The Lambda-CDM, Lambda cold dark matter or ΛCDM model is a mathematical model of the Big Bang theory with three major components:

  1. a cosmological constant denoted by lambda (Λ) associated with dark energy,
  2. the postulated cold dark matter, and
  3. ordinary matter.
<span class="mw-page-title-main">Metallicity</span> Relative abundance of heavy elements in a star or other astronomical object

In astronomy, metallicity is the abundance of elements present in an object that are heavier than hydrogen and helium. Most of the normal currently detectable matter in the universe is either hydrogen or helium, and astronomers use the word "metals" as a convenient short term for "all elements except hydrogen and helium". This word-use is distinct from the conventional chemical or physical definition of a metal as an electrically conducting solid. Stars and nebulae with relatively high abundances of heavier elements are called "metal-rich" in astrophysical terms, even though many of those elements are nonmetals in chemistry.

A dark galaxy is a hypothesized galaxy with no stars. They received their name because they have no visible stars but may be detectable if they contain significant amounts of gas. Astronomers have long theorized the existence of dark galaxies, but there are no confirmed examples to date. Dark galaxies are distinct from intergalactic gas clouds caused by galactic tidal interactions, since these gas clouds do not contain dark matter, so they do not technically qualify as galaxies. Distinguishing between intergalactic gas clouds and galaxies is difficult; most candidate dark galaxies turn out to be tidal gas clouds. The best candidate dark galaxies to date include HI1225+01, AGC229385, and numerous gas clouds detected in studies of quasars.

<span class="mw-page-title-main">Galactic disc</span> Component of disc galaxies comprising gas and stars

A galactic disc is a component of disc galaxies, such as spiral galaxies, lenticular galaxies, and the Milky Way. Galactic discs consist of a stellar component and a gaseous component. The stellar population of galactic discs tend to exhibit very little random motion with most of its stars undergoing nearly circular orbits about the galactic center. Discs can be fairly thin because the disc material's motion lies predominantly on the plane of the disc. The Milky Way's disc, for example, is approximately 1 kly thick, but thickness can vary for discs in other galaxies.

In astronomy, the intracluster medium (ICM) is the superheated plasma that permeates a galaxy cluster. The gas consists mainly of ionized hydrogen and helium and accounts for most of the baryonic material in galaxy clusters. The ICM is heated to temperatures on the order of 10 to 100 megakelvins, emitting strong X-ray radiation.

<span class="mw-page-title-main">Bullet Cluster</span> Two colliding clusters of galaxies in constellation Carina

The Bullet Cluster consists of two colliding clusters of galaxies. Strictly speaking, the name Bullet Cluster refers to the smaller subcluster, moving away from the larger one. It is at a comoving radial distance of 1.141 Gpc.

The Freeman law is a statement in astronomy which says that disk galaxies have the same surface brightness, Σ at the center. It was described in 1970 by Ken Freeman.

Modified Newtonian dynamics (MOND) is a hypothesis that proposes a modification of Newton's second law to account for observed properties of galaxies. It is an alternative to the hypothesis of dark matter in terms of explaining why galaxies do not appear to obey the currently understood laws of physics.

AQUAL is a theory of gravity based on Modified Newtonian Dynamics (MOND), but using a Lagrangian. It was developed by Jacob Bekenstein and Mordehai Milgrom in their 1984 paper, "Does the missing mass problem signal the breakdown of Newtonian gravity?". "AQUAL" stands for "A QUAdratic Lagrangian".

<span class="mw-page-title-main">Void (astronomy)</span> Vast empty spaces between filaments with few or no galaxies

Cosmic voids are vast spaces between filaments, which contain very few or no galaxies. The cosmological evolution of the void regions differs drastically from the evolution of the Universe as a whole: there is a long stage when the curvature term dominates, which prevents the formation of galaxy clusters and massive galaxies. Hence, although even the emptiest regions of voids contain more than ~15% of the average matter density of the Universe, the voids look almost empty to an observer.

Crater 2 is a low-surface-brightness dwarf satellite galaxy of the Milky Way, located approximately 380,000 ly from Earth. Its discovery in 2016 revealed significant gaps in astronomers' understanding of galaxies possessing relatively small half-light diameters and suggested the possibility of many undiscovered dwarf galaxies orbiting the Milky Way. Crater 2 was identified in imaging data from the VST ATLAS survey.

<span class="mw-page-title-main">Georges Meylan</span> Swiss astronomer

Georges Meylan is a Swiss astronomer, born on July 31, 1950, in Lausanne, Switzerland. He was the director of the Laboratory of Astrophysics of the Swiss Federal Institute of Technology (EPFL) in Lausanne, Switzerland, and now a professor emeritus of astrophysics and cosmology at EPFL. He is still active in both research and teaching.

<span class="mw-page-title-main">NGC 720</span> Galaxy in the constellation Cetus

NGC 720 is an elliptical galaxy located in the constellation Cetus. It is located at a distance of circa 80 million light years from Earth, which, given its apparent dimensions, means that NGC 720 is about 110,000 light years across. It was discovered by William Herschel on October 3, 1785. The galaxy is included in the Herschel 400 Catalogue. It lies about three and a half degrees south and slightly east from zeta Ceti.

<span class="mw-page-title-main">NGC 4302</span> Galaxy in the constellation Coma Berenices

NGC 4302 is an edge-on spiral galaxy located about 55 million light-years away in the constellation Coma Berenices. It was discovered by astronomer William Herschel on April 8, 1784 and is a member of the Virgo Cluster.

References

  1. ↑ Bothun, G.; Impey, C.; McGaugh, S. (1997). "Low-Surface-Brightness Galaxies: Hidden Galaxies Revealed". Publications of the Astronomical Society of the Pacific. IOP Publishing. 109: 745. Bibcode:1997PASP..109..745B. doi:10.1086/133941. ISSN   0004-6280.
  2. ↑ McGaugh, S.S. (1998) "How Galaxies Don't Form"
  3. ↑ McGaugh, Stacy S.; de Blok, W. J. G. (May 20, 1998). "Testing the Dark Matter Hypothesis with Low Surface Brightness Galaxies and Other Evidence". The Astrophysical Journal. 499 (1): 41–65. arXiv: astro-ph/9801123 . Bibcode:1998ApJ...499...41M. doi:10.1086/305612. ISSN   0004-637X. S2CID   16131617.
  4. ↑ Sanders, Robert H.; McGaugh, Stacy S. (2002). "Modified Newtonian Dynamics as an Alternative to Dark Matter". Annual Review of Astronomy and Astrophysics. 40 (1): 263–317. arXiv: astro-ph/0204521 . Bibcode:2002ARA&A..40..263S. doi:10.1146/annurev.astro.40.060401.093923. ISSN   0066-4146. S2CID   13216648.
  5. ↑ Famaey, Benoît; McGaugh, Stacy S. (September 7, 2012). "Modified Newtonian Dynamics (MOND): Observational Phenomenology and Relativistic Extensions". Living Reviews in Relativity. Springer Science and Business Media LLC. 15 (1): 10. arXiv: 1112.3960 . Bibcode:2012LRR....15...10F. doi: 10.12942/lrr-2012-10 . ISSN   2367-3613. PMC   5255531 . PMID   28163623.
  6. ↑ McGaugh, Stacy S. (October 1, 1999). "Distinguishing between Cold Dark Matter and Modified Newtonian Dynamics: Predictions for the Microwave Background". The Astrophysical Journal. IOP Publishing. 523 (2): L99–L102. arXiv: astro-ph/9907409 . Bibcode:1999ApJ...523L..99M. doi:10.1086/312274. ISSN   0004-637X. S2CID   51842057.
  7. ↑ McGaugh, Stacy S. (1994). "Oxygen abundances in low surface brightness disk galaxies". The Astrophysical Journal. 426: 135. arXiv: astro-ph/9311064 . Bibcode:1994ApJ...426..135M. doi:10.1086/174049. ISSN   0004-637X. S2CID   119364496.
  8. ↑ McGaugh, Stacy S. (1991). "H II region abundances - Model oxygen line ratios". The Astrophysical Journal. IOP Publishing. 380: 140. Bibcode:1991ApJ...380..140M. doi:10.1086/170569. ISSN   0004-637X.
  9. ↑ de Blok, W. J. G.; McGaugh, S. S.; van der Hulst, J. M. (October 21, 1996). "H I observations of low surface brightness galaxies: probing low-density galaxies". Monthly Notices of the Royal Astronomical Society. 283 (1): 18–54. arXiv: astro-ph/9605069 . Bibcode:1996MNRAS.283...18D. doi:10.1093/mnras/283.1.18. ISSN   0035-8711.
  10. ↑ McGaugh, S. S.; Schombert, J. M.; Bothun, G. D.; de Blok, W. J. G. (April 20, 2000). "The Baryonic Tully-Fisher Relation". The Astrophysical Journal. IOP Publishing. 533 (2): L99–L102. arXiv: astro-ph/0003001 . Bibcode:2000ApJ...533L..99M. doi:10.1086/312628. ISSN   0004-637X. PMID   10770699. S2CID   103865.
  11. ↑ McGaugh, Stacy S. (October 1, 1999). "Distinguishing between Cold Dark Matter and Modified Newtonian Dynamics: Predictions for the Microwave Background". The Astrophysical Journal. IOP Publishing. 523 (2): L99–L102. arXiv: astro-ph/9907409 . Bibcode:1999ApJ...523L..99M. doi:10.1086/312274. ISSN   0004-637X. S2CID   51842057.
  12. ↑ McGaugh, Stacy S. (October 1, 2000). "Boomerang Data Suggest a Purely Baryonic Universe". The Astrophysical Journal. IOP Publishing. 541 (2): L33–L36. arXiv: astro-ph/0008188 . Bibcode:2000ApJ...541L..33M. doi:10.1086/312902. ISSN   0004-637X. S2CID   51805379.
  13. ↑ McGaugh, Stacy S.; de Blok, W. J. G. (May 20, 1998). "Testing the Hypothesis of Modified Dynamics with Low Surface Brightness Galaxies and Other Evidence". The Astrophysical Journal. 499 (1): 66–81. arXiv: astro-ph/9801102 . Bibcode:1998ApJ...499...66M. doi:10.1086/305629. ISSN   0004-637X. S2CID   18901029.
  14. ↑ McGaugh, Stacy S. (March 21, 2011). "Novel Test of Modified Newtonian Dynamics with Gas Rich Galaxies". Physical Review Letters. 106 (12): 121303. arXiv: 1102.3913 . Bibcode:2011PhRvL.106l1303M. doi:10.1103/physrevlett.106.121303. ISSN   0031-9007. PMID   21517295. S2CID   1427896.
  15. ↑ McGaugh, Stacy S. (August 10, 2008). "Milky Way Mass Models and MOND". The Astrophysical Journal. 683 (1): 137–148. arXiv: 0804.1314 . Bibcode:2008ApJ...683..137M. doi:10.1086/589148. ISSN   0004-637X. S2CID   16366091.
  16. ↑ McGaugh, Stacy; Milgrom, Mordehai (March 4, 2013). "Andromeda Dwarfs in Light of Modified Newtonian Dynamics". The Astrophysical Journal. 766 (1): 22. arXiv: 1301.0822 . Bibcode:2013ApJ...766...22M. doi:10.1088/0004-637x/766/1/22. ISSN   0004-637X. S2CID   118576979.
  17. ↑ Bovy, Jo; Rix, Hans-Walter (December 2, 2013). "A direct dynamical measurement of the Milky Way's disk surface density profile, disk scale length, and dark matter profile at 4 kpc < R < 9 kpc". The Astrophysical Journal. 779 (2): 115. arXiv: 1309.0809 . Bibcode:2013ApJ...779..115B. doi:10.1088/0004-637x/779/2/115. ISSN   0004-637X. S2CID   118440232.
  18. ↑ McGaugh, Stacy; Milgrom, Mordehai (September 16, 2013). "Andromeda Dwarfs in Light of MOND. II. Testing Prior Predictions". The Astrophysical Journal. 775 (2): 139. arXiv: 1308.5894 . Bibcode:2013ApJ...775..139M. doi:10.1088/0004-637x/775/2/139. ISSN   0004-637X. S2CID   53006824.
  19. ↑ McGaugh, Stacy S.; Lelli, Federico; Schombert, James M. (2016). "Radial Acceleration Relation in Rotationally Supported Galaxies". Physical Review Letters. 117 (20): 201101. arXiv: 1609.05917 . Bibcode:2016PhRvL.117t1101M. doi:10.1103/PhysRevLett.117.201101. PMID   27886485. S2CID   34521243.
  20. ↑ Paranjape, Aseem; Sheth, Ravi K. (2021). "The radial acceleration relation in a ΛCDM universe". Monthly Notices of the Royal Astronomical Society. 507: 632–650. arXiv: 2102.13116 . doi:10.1093/mnras/stab2141. arXiv preprint
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