Stacy McGaugh

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Stacy McGaugh
Born (1964-01-11) January 11, 1964 (age 60)
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

<span class="mw-page-title-main">Dark matter</span> Concept in cosmology

In astronomy, dark matter is a hypothetical form of matter that does not interact with light or other electromagnetic radiation. Dark matter is implied by gravitational effects which cannot be explained by general relativity unless more matter is present than can be observed. 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 formation and evolution</span>

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.

<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 a widely verified empirical relationship between the mass or intrinsic luminosity of a spiral galaxy and its asymptotic rotation velocity or emission line width. Since the observed brightness of a galaxy is distance-dependent, the relationship can be used to estimate distances to galaxies from measurements of their rotational velocity.

A galactic halo is an extended, roughly spherical component of a galaxy which extends beyond the main, visible component. Several distinct components of a galaxy comprise its halo:

The cuspy halo problem is 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").

<span class="mw-page-title-main">Lambda-CDM model</span> Model of Big Bang cosmology

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, denoted by CDM
  3. ordinary matter

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.

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<span class="mw-page-title-main">Satellite galaxy</span> Galaxy that orbits a larger galaxy due to gravitational attraction

A satellite galaxy is a smaller companion galaxy that travels on bound orbits within the gravitational potential of a more massive and luminous host galaxy. Satellite galaxies and their constituents are bound to their host galaxy, in the same way that planets within the Solar System are gravitationally bound to the Sun. While most satellite galaxies are dwarf galaxies, satellite galaxies of large galaxy clusters can be much more massive. The Milky Way is orbited by about fifty satellite galaxies, the largest of which is the Large Magellanic Cloud.

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

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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 theory that proposes a modification of Newton's second law to account for observed properties of galaxies. Its primary motivation is to explain galaxy rotation curves without invoking dark matter, and is one of the most well-known theories of this class. However, it has not gained widespread acceptance, with the majority of astrophysicists supporting the Lambda-CDM model as providing the better fit to observations.

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 "AQUAdratic Lagrangian", stemming from the fact that, in contrast to Newtonian gravity, the proposed Lagrangian is non-quadratic in the potential gradient .

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

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<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. 109. IOP Publishing: 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. 15 (1). Springer Science and Business Media LLC: 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. 523 (2). IOP Publishing: 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. 380. IOP Publishing: 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. 533 (2). IOP Publishing: 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. 523 (2). IOP Publishing: 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. 541 (2). IOP Publishing: 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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