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Articoli di riviste sul tema "Missing mass (Astronomy)"

Autore: Grafiati

Pubblicato: 4 giugno 2021

Ultima modifica: 31 gennaio 2023

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1

Malkov, O. Yu. "Local missing mass." Astrophysics 37, no. 3 (July 1994): 256–60. http://dx.doi.org/10.1007/bf02058781.

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2

Visser, Matt. "Is the ?missing mass? really missing?" General Relativity and Gravitation 20, no. 1 (January 1988): 77–81. http://dx.doi.org/10.1007/bf00759258.

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3

Atkins, Chris. "The missing mass." Physics World 34, no. 10 (December 1, 2021): 25v. http://dx.doi.org/10.1088/2058-7058/34/10/32.

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In response to the Lateral Thoughts quiz “Sporting chance”, in which question 8 asked for a rough estimate of the theoretical maximum height a pole vaulter could jump, and why the actual world record is slightly above this.

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4

Petit, J. P. "The missing-mass problem." Il Nuovo Cimento B 109, no. 7 (July 1994): 697–709. http://dx.doi.org/10.1007/bf02722527.

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5

Krishan, V. "Rotation curves of galaxies: Missing mass or missing physics." Pramana 49, no. 1 (July 1997): 147–54. http://dx.doi.org/10.1007/bf02856345.

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6

Schatzman, E. "Missing mass or dark matter?" International Journal of Theoretical Physics 28, no. 9 (September 1989): 1169–71. http://dx.doi.org/10.1007/bf00670357.

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7

Surdin, M. "The Missing Mass of the Universe." Physics Essays 13, no. 1 (March 2000): 130–31. http://dx.doi.org/10.4006/1.3025419.

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8

Trippe, Sascha. "The ‘Missing Mass Problem’ in Astronomy and the Need for a Modified Law of Gravity." Zeitschrift für Naturforschung A 69, no. 3-4 (April 1, 2014): 173–87. http://dx.doi.org/10.5560/zna.2014-0003.

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Since the 1930s, astronomical observations have accumulated evidence that our understanding of the dynamics of galaxies and groups of galaxies is grossly incomplete: assuming the validity of Newton’s law of gravity on astronomical scales, the observed mass (stored in stars and interstellar gas) of stellar systems can account only for roughly 10% of the dynamical (gravitating) mass required to explain the high velocities of stars in those systems. The standard approach to this ‘missing mass problem’ has been the postulate of ‘dark matter’, meaning an additional, electromagnetically dark, matter component that provides the missing mass. However, direct observational evidence for dark matter has not been found to date. More importantly, astronomical observations obtained during the last decade indicate that dark matter cannot explain the kinematics of galaxies. Multiple observations show that the discrepancy between observed and dynamical mass is a function of gravitational acceleration (or field strength) but not of other parameters (size, rotation speed, etc.) of a galaxy; the mass discrepancy appears below a characteristic and universal acceleration aM = (1:1±0:1) · 10-10 ms-2 (Milgrom’s constant). Consequently, the idea of a modified law of gravity, specifically the ansatz of modified Newtonian dynamics (MOND), is becoming increasingly important in astrophysics. MOND has successfully predicted various important empirical relations of galaxy dynamics, including the famous Tully-Fisher and Faber-Jackson relations. MOND is found to be consistent with stellar dynamics from binary stars to clusters of galaxies, thus covering stellar systems spanning eight orders of magnitude in size and 14 orders of magnitude in mass. These developments have the potential to initiate a paradigm shift from dark matter to a modified law of gravity as the physical mechanism behind the missing mass problem.

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9

Gorjup, Niko, and Amrit Sorli. "SMBH relativistic mass and missing dark matter." Advanced Studies in Theoretical Physics 16, no. 4 (2022): 291–97. http://dx.doi.org/10.12988/astp.2022.91963.

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10

Cook, Richard I., and I. P. Dell'Antonio. "THE MISSING WEAK LENSING MASS IN A781." Astrophysical Journal 750, no. 2 (April 25, 2012): 153. http://dx.doi.org/10.1088/0004-637x/750/2/153.

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11

Mossel, Elchanan, and Mesrob I. Ohannessian. "On the Impossibility of Learning the Missing Mass." Entropy 21, no. 1 (January 2, 2019): 28. http://dx.doi.org/10.3390/e21010028.

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This paper shows that one cannot learn the probability of rare events without imposing further structural assumptions. The event of interest is that of obtaining an outcome outside the coverage of an i.i.d. sample from a discrete distribution. The probability of this event is referred to as the “missing mass”. The impossibility result can then be stated as: the missing mass is not distribution-free learnable in relative error. The proof is semi-constructive and relies on a coupling argument using a dithered geometric distribution. Via a reduction, this impossibility also extends to both discrete and continuous tail estimation. These results formalize the folklore that in order to predict rare events without restrictive modeling, one necessarily needs distributions with “heavy tails”.

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12

Walker, Phil. "Magnetism and the missing mass of the universe." Physics World 8, no. 9 (September 1995): 19. http://dx.doi.org/10.1088/2058-7058/8/9/13.

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13

Krauss, Lawrence, and Michael S. Turner. "Quintessence: The Mystery of Missing Mass in the Universe." Physics Today 53, no. 9 (September 2000): 65–66. http://dx.doi.org/10.1063/1.1325241.

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14

Bahcall, J. N., and S. Casertano. "Some possible regularities in the missing mass problem." Astrophysical Journal 293 (June 1985): L7. http://dx.doi.org/10.1086/184480.

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15

Kleyna, Jan T., Mark I. Wilkinson, N. Wyn Evans, and Gerard Gilmore. "Ursa Major: A Missing Low-Mass CDM Halo?" Astrophysical Journal 630, no. 2 (August 19, 2005): L141—L144. http://dx.doi.org/10.1086/491654.

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16

Santander-García, Miguel, David Jones, Javier Alcolea, Roger Wesson, and Valentín Bujarrabal. "The missing mass conundrum of post-common-envelope planetary nebulae." Proceedings of the International Astronomical Union 14, S343 (August 2018): 239–43. http://dx.doi.org/10.1017/s1743921318005495.

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AbstractMost planetary nebulae (PNe) show beautiful, axisymmetric morphologies despite their progenitor stars being essentially spherical. Angular momentum provided by a close binary companion is widely invoked as the main agent that would help eject an axisymmetric nebula, after a brief phase of engulfment of the secondary within the envelope of the Asymptotic Giant Branch (AGB) star, known as a common envelope (CE). The evolution on the AGB would thus be interrupted abruptly, its (still quite) massive envelope fully ejected to form the PN, which should be more massive than a PN coming from the same star were it single. We test this hypothesis by deriving the ionised+molecular masses of a pilot sample of post-CE PNe and comparing them to a regular PNe sample. We find the mass of post-CE PNe to be actually lower, on average, than their regular counterparts, raising some doubts on our understanding of these intriguing objects.

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17

Stuckey, W. M., Timothy McDevitt, A. K. Sten, and Michael Silberstein. "Could GR contextuality resolve the missing mass problem?" International Journal of Modern Physics D 27, no. 14 (October 2018): 1847018. http://dx.doi.org/10.1142/s0218271818470181.

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In Newtonian gravity, mass is an intrinsic property of matter, while in general relativity (GR), mass is a contextual property of matter, e.g. when two different GR spacetimes are adjoined. Herein, we explore the possibility that the astrophysical missing mass attributed to nonbaryonic dark matter (DM) actually obtains because we have been assuming the Newtonian intrinsic view of mass rather than the GR contextual view. Perhaps we should model astrophysical phenomena via combined GR spacetimes to better account for their complexity. Accordingly, we consider a GR ansatz in fitting galactic rotation curve data (THINGS), X-ray cluster mass profile data (ROSAT/ASCA), and CMB angular power spectrum data (Planck 2015) without DM. We find that our fits compare well with both modified gravity programs and DM programs.

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18

Bardalez Gagliuffi, Daniella C., Jacqueline K. Faherty, Adam C. Schneider, Aaron Meisner, Dan Caselden, Guillaume Colin, Sam Goodman, et al. "WISEA J083011.95+283716.0: A Missing Link Planetary-mass Object." Astrophysical Journal 895, no. 2 (June 5, 2020): 145. http://dx.doi.org/10.3847/1538-4357/ab8d25.

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19

Eggen, Olin J. "The Sirius Supercluster and Missing Mass near the Sun." Astronomical Journal 116, no. 2 (August 1998): 782–88. http://dx.doi.org/10.1086/300465.

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20

Read, J. I., M. I. Wilkinson, N. Wyn Evans, G. Gilmore, and Jan T. Kleyna. "The mass of dwarf spheroidal galaxies and the missing satellite problem." Proceedings of the International Astronomical Union 1, no. C198 (March 2005): 235–39. http://dx.doi.org/10.1017/s1743921305003807.

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21

Fattahi, Azadeh, Julio F. Navarro, and Carlos S. Frenk. "The missing dwarf galaxies of the Local Group." Monthly Notices of the Royal Astronomical Society 493, no. 2 (February 10, 2020): 2596–605. http://dx.doi.org/10.1093/mnras/staa375.

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ABSTRACT We study the Local Group (LG) dwarf galaxy population predicted by the APOSTLE ΛCDM cosmological hydrodynamics simulations. These indicate that: (i) the total mass within 3 Mpc of the Milky Way–Andromeda mid-point (M3Mpc) typically exceeds ∼3 times the sum of the virial masses (M200crit) of the two primaries and (ii) the dwarf galaxy formation efficiency per unit mass is uniform throughout the volume. This suggests that the satellite population within the virial radii of the Milky Way and Andromeda should make up fewer than one third of all LG dwarfs within 3 Mpc. This is consistent with the fraction of observed LG galaxies with stellar mass $M_*\gt 10^7\, {\rm M}_\odot$ that are satellites (12 out of 42; i.e. 28 per cent). For the APOSTLE galaxy mass–halo mass relation, the total number of such galaxies further suggests an LG mass of $M_{\rm 3 Mpc}\sim 10^{13}\, {\rm M}_\odot$. At lower galaxy masses, however, the observed satellite fraction is substantially higher (42 per cent for $M_*\gt 10^5\, { \mathrm{ M}}_\odot$). If this is due to incompleteness in the field sample, then ∼50 dwarf galaxies at least as massive as the Draco dwarf spheroidal must be missing from the current LG field dwarf inventory. The incompleteness interpretation is supported by the pronounced flattening of the LG luminosity function below $M_*\sim 10^7\, {\rm M}_\odot$, and by the scarcity of low surface brightness LG field galaxies compared to satellites. The simulations indicate that most missing dwarfs should lie near the virial boundaries of the two LG primaries, and predict a trove of nearby dwarfs that await discovery by upcoming wide-field imaging surveys.

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22

Datta, B., C. Sivaram, and S. K. Ghosh. "Neutral fermions as the missing mass matter in galactic halos." Astrophysics and Space Science 111, no. 2 (April 1985): 413–17. http://dx.doi.org/10.1007/bf00649981.

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23

Peterson, R. C. "Radial velocities of remote globular clusters - Stalking the missing mass." Astrophysical Journal 297 (October 1985): 309. http://dx.doi.org/10.1086/163529.

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24

Melott, A. L., and D. N. Schramm. "Can 'warm' particles provide the missing mass in dwarf galaxies?" Astrophysical Journal 298 (November 1985): 1. http://dx.doi.org/10.1086/163583.

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25

Valtonen, M. J., and G. G. Byrd. "Redshift asymmetries in systems of galaxies and the missing mass." Astrophysical Journal 303 (April 1986): 523. http://dx.doi.org/10.1086/164100.

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26

Sukhbold, Tuguldur, and Scott Adams. "Missing red supergiants and carbon burning." Monthly Notices of the Royal Astronomical Society 492, no. 2 (January 10, 2020): 2578–87. http://dx.doi.org/10.1093/mnras/staa059.

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ABSTRACT Recent studies on direct imaging of Type II core-collapse supernova progenitors indicate a possible threshold around MZAMS ∼ 16–20 M⊙, where red supergiants (RSG) with larger birth masses do not appear to result in supernova explosions and instead implode directly into a black hole. In this study, we argue that it is not a coincidence that this threshold closely matches the critical transition of central carbon burning in massive stars from the convective to radiative regime. In lighter stars, carbon burns convectively in the centre and result in compact final pre-supernova cores that are likely to result in explosions, while in heavier stars after the transition, it burns as a radiative flame and the stellar cores become significantly harder to explode. Using the $\rm {\small {kepler}}$ code we demonstrate the sensitivity of this transition to the rate of 12C(α, γ)16O reaction and the overshoot mixing efficiency, and we argue that the upper mass limit of exploding RSG could be employed to constrain uncertain input physics of massive stellar evolution calculations. The initial mass corresponding to the central carbon burning transition range from 14 to 26 M⊙ in recently published models from various groups and codes, and only a few are in agreement with the estimates inferred from direct imaging studies.

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27

McGaugh, Stacy S. "The Halo by Halo Missing Baryon Problem." Proceedings of the International Astronomical Union 3, S244 (June 2007): 136–45. http://dx.doi.org/10.1017/s1743921307013920.

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AbstractThe global missing baryon problem – that the sum of observed baryons falls short of the number expected form BBN – is well known. In addition to this, there is also a local missing baryon problem that applies to individual dark matter halos. This halo by halo missing baryon problem is such that the observed mass fraction of baryons in individual galaxies falls short of the cosmic baryon fraction. This deficit is a strong function of circular velocity. I give an empirical estimate of this function, and note the presence of a critical scale of ~ 900 km s−1 therein. I also briefly review Ωb from BBN, highlighting the persistent tension between lithium and the CMB, and discuss some pros and cons of individual galaxies and clusters of galaxies as potential reservoirs of dark baryons.

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28

Silverman, M. P., and R. L. Mallett. "Cosmic degenerate matter: a possible solution to the problem of missing mass." Classical and Quantum Gravity 18, no. 4 (February 2, 2001): L37—L42. http://dx.doi.org/10.1088/0264-9381/18/4/101.

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29

Atkins, Chris. "Clearing the bar." Physics World 34, no. 11 (December 1, 2021): 28v. http://dx.doi.org/10.1088/2058-7058/34/11/36.

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30

Sanders, R. H. "Missing Mass as Evidence for Modified Newtonian Dynamics at Low Accelerations." Modern Physics Letters A 18, no. 27 (September 7, 2003): 1861–75. http://dx.doi.org/10.1142/s0217732303011770.

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Milgrom has proposed that the appearance of discrepancies between the Newtonian dynamical mass and the directly observable mass in astronomical systems could be due to a breakdown of Newtonian dynamics in the limit of low accelerations rather than the presence of unseen matter. Milgrom's hypothesis, modified Newtonian dynamics or MOND, has been remarkably successful in explaining systematic properties of spiral and elliptical galaxies and predicting in detail the observed rotation curves of spiral galaxies with only one additional parameter — a critical acceleration which is on the order of the cosmologically interesting value of cH0. Here we review the empirical successes of this idea and discuss its possible extension to cosmology and structure formation.

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31

FARZAN, YASAMAN. "A FRAMEWORK TO SIMULTANEOUSLY EXPLAIN TINY NEUTRINO MASS AND HUGE MISSING MASS PROBLEM OF THE UNIVERSE." Modern Physics Letters A 25, no. 25 (August 20, 2010): 2111–20. http://dx.doi.org/10.1142/s0217732310034018.

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A minimalistic scenario is developed to explain dark matter and tiny but nonzero neutrino masses. A new scalar called SLIM plays the role of the dark matter. Neutrinos achieve Majorana mass through a one-loop diagram. This scenario can be realized for both real and complex SLIM. Simultaneously explaining the neutrino mass and dark matter abundance constrains the scenario. In particular for real SLIM, an upper bound of a few MeV on the masses of the new particles and a lower bound on their coupling is obtained which make the scenario testable. The low energy scenario can be embedded within various SU (2)× U (1) symmetric models. A specific example is introduced and its phenomenological consequences are discussed.

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32

Khoze, V. A., A. D. Martin, and M. G. Ryskin. "Double-diffractive processes in high-resolution missing-mass experiments at the Tevatron." European Physical Journal C 19, no. 3 (March 2001): 477–83. http://dx.doi.org/10.1007/s100520100637.

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33

Krasnov, Kirill, and Yuri Shtanov. "Non-metric gravity: II. Spherically symmetric solution, missing mass and redshifts of quasars." Classical and Quantum Gravity 25, no. 2 (December 20, 2007): 025002. http://dx.doi.org/10.1088/0264-9381/25/2/025002.

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34

Fielder, Catherine E., Yao-Yuan Mao, Jeffrey A. Newman, Andrew R. Zentner, and Timothy C. Licquia. "Predictably missing satellites: subhalo abundances in Milky Way-like haloes." Monthly Notices of the Royal Astronomical Society 486, no. 4 (April 17, 2019): 4545–68. http://dx.doi.org/10.1093/mnras/stz1098.

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ABSTRACT On small scales there have been a number of claims of discrepancies between the standard cold dark matter (CDM) model and observations. The ‘missing satellites problem’ infamously describes the overabundance of subhaloes from CDM simulations compared to the number of satellites observed in the Milky Way. A variety of solutions to this discrepancy have been proposed; however, the impact of the specific properties of the Milky Way halo relative to the typical halo of its mass has yet to be explored. Motivated by recent studies that identified ways in which the Milky Way is atypical, we investigate how the properties of dark matter haloes with mass comparable to our Galaxy’s – including concentration, spin, shape, and scale factor of the last major merger – correlate with the subhalo abundance. Using zoom-in simulations of Milky Way-like haloes, we build two models of subhalo abundance as functions of host halo properties. From these models we conclude that the Milky Way most likely has fewer subhaloes than the average halo of the same mass. We expect up to 30 per cent fewer subhaloes with low maximum rotation velocities ($V_{\rm max}^{\rm sat} \sim 10$ km s−1) at the 68 per cent confidence level and up to 52 per cent fewer than average subhaloes with high rotation velocities ($V_{\rm max}^{\rm sat} \gtrsim 30$ km s−1, comparable to the Magellanic Clouds) than would be expected for a typical halo of the Milky Way’s mass. Concentration is the most informative single parameter for predicting subhalo abundance. Our results imply that models tuned to explain the missing satellites problem assuming typical subhalo abundances for our Galaxy may be overcorrecting.

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35

Clowe, Douglas, Maxim Markevitch, Maruša Bradač, Anthony H. Gonzalez, Sun Mi Chung, Richard Massey, and Dennis Zaritsky. "ON DARK PEAKS AND MISSING MASS: A WEAK-LENSING MASS RECONSTRUCTION OF THE MERGING CLUSTER SYSTEM A520,." Astrophysical Journal 758, no. 2 (October 8, 2012): 128. http://dx.doi.org/10.1088/0004-637x/758/2/128.

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36

Boothroyd, Arnold I., I. J. Sackmann, and William A. Fowler. "Our sun. II - Early mass loss of 0.1 solar mass and the case of the missing lithium." Astrophysical Journal 377 (August 1991): 318. http://dx.doi.org/10.1086/170361.

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37

Merritt, Allison, Annalisa Pillepich, Pieter van Dokkum, Dylan Nelson, Lars Hernquist, Federico Marinacci, and Mark Vogelsberger. "A missing outskirts problem? Comparisons between stellar haloes in the Dragonfly Nearby Galaxies Survey and the TNG100 simulation." Monthly Notices of the Royal Astronomical Society 495, no. 4 (May 4, 2020): 4570–604. http://dx.doi.org/10.1093/mnras/staa1164.

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ABSTRACT Low surface brightness galactic stellar haloes provide a challenging but promising path towards unravelling the past assembly histories of individual galaxies. Here, we present detailed comparisons between the stellar haloes of Milky Way-mass disc galaxies observed as part of the Dragonfly Nearby Galaxies Survey (DNGS) and stellar mass-matched galaxies in the TNG100 run of the IllustrisTNG project. We produce stellar mass maps as well as mock g- and r-band images for randomly oriented simulated galaxies, convolving the latter with the Dragonfly point spread function (PSF) and taking care to match the background noise, surface brightness limits, and spatial resolution of DNGS. We measure azimuthally averaged stellar mass density and surface brightness profiles, and find that the DNGS galaxies generally have less stellar mass (or light) at large radii (&gt;20 kpc) compared to their mass-matched TNG100 counterparts, and that simulated galaxies with similar surface density profiles tend to have low accreted mass fractions for their stellar mass. We explore potential solutions to this apparent ‘missing outskirts problem’ by implementing several ad hoc adjustments within TNG100 at the stellar particle level. Although we are unable to identify any single adjustment that fully reconciles the differences between the observed and simulated galaxy outskirts, we find that artificially delaying the disruption of satellite galaxies and reducing the spatial extent of in-situ stellar populations result in improved matches between the outer profile shapes and stellar halo masses, respectively. Further insight can be achieved with higher resolution simulations that are able to better resolve satellite accretion, and with larger samples of observed galaxies.

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38

Chen, Jacqueline, Samuel K. Lee, Francisco-Javier Castander, José Maza, and Paul L. Schechter. "MISSING LENSED IMAGES AND THE GALAXY DISK MASS IN CXOCY J220132.8-320144." Astrophysical Journal 769, no. 1 (May 6, 2013): 81. http://dx.doi.org/10.1088/0004-637x/769/1/81.

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39

Posti, Lorenzo, Filippo Fraternali, and Antonino Marasco. "Peak star formation efficiency and no missing baryons in massive spirals." Astronomy & Astrophysics 626 (June 2019): A56. http://dx.doi.org/10.1051/0004-6361/201935553.

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It is commonly believed that galaxies use, throughout Hubble time, a very small fraction of the baryons associated with their dark matter halos to form stars. This so-called low star formation efficiency f⋆ ≡ M⋆/fbMhalo, where fb ≡ Ωb/Ωc is the cosmological baryon fraction, is expected to reach its peak at nearly L* (at efficiency ≈20%) and decline steeply at lower and higher masses. We have tested this using a sample of nearby star-forming galaxies, from dwarfs (M⋆ ≃ 107 M⊙) to high-mass spirals (M⋆ ≃ 1011 M⊙) with HI rotation curves and 3.6 μm photometry. We fit the observed rotation curves with a Bayesian approach by varying three parameters, stellar mass-to-light ratio Υ⋆, halo concentration c, and mass Mhalo. We found two surprising results: (1) the star formation efficiency is a monotonically increasing function of M⋆ with no sign of a decline at high masses, and (2) the most massive spirals (M⋆ ≃ 1−3 × 1011 M⊙) have f⋆ ≈ 0.3−1, i.e. they have turned nearly all the baryons associated with their halos into stars. These results imply that the most efficient galaxies at forming stars are massive spirals (not L* galaxies); they reach nearly 100% efficiency, and thus once both their cold and hot gas is considered in the baryon budget, they have virtually no missing baryons. Moreover, there is no evidence of mass quenching of the star formation occurring in galaxies up to halo masses of a few × 1012 M⊙.

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40

Jenkovszky, L. L., O. E. Kuprash, and V. K. Magas. "Low-mass Diffraction Dissociation at the LHC. Role of the Background." Ukrainian Journal of Physics 56, no. 7 (February 9, 2022): 738. http://dx.doi.org/10.15407/ujpe56.7.738.

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A dual model with a nonlinear proton Regge trajectory in the missing mass (M2X) channel is constructed. A background based on a direct-channel exotic trajectory, developed and applied earlier for the inclusive electron-proton cross section description in the nucleon resonance region, is used. The parameters of the model are determined from the extrapolations to earlier experiments. Predictions for the low-mass (2 < M2X < 8 GeV2) diffraction dissociation cross sections at the LHC energies are given.

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41

JIANG, XIAODONG. "A SEARCH FOR NEUTRAL BARYON RESONANCES BELOW PION THRESHOLD." International Journal of Modern Physics A 20, no. 08n09 (April 10, 2005): 1947–50. http://dx.doi.org/10.1142/s0217751x05023700.

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The reaction p(e,e′π+)X0 was studied with two high resolution magnetic spectrometers to search for narrow baryon resonances. A missing mass resolution of 2.0 MeV was achieved. A search for structures in the mass region of 0.97<MX0<1.06 GeV yielded no significant signal. The yield ratio of p(e,e′π+)X0/p(e,e′π+)n was determined to be (-0.35±0.35)×10-3 at 1.004 GeV and (0.34±0.42)×10-3 at 1.044 GeV. This measurement clearly demonstrated the potential of high resolution missing mass searches in coincidence experiments.

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42

LIMA, JOSÉ A. S., and LUCIO MARASSI. "MASS FUNCTION OF HALOS: A NEW ANALYTICAL APPROACH." International Journal of Modern Physics D 13, no. 07 (August 2004): 1345–49. http://dx.doi.org/10.1142/s0218271804005511.

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A generalization of the Press–Schechter (PS) formalism yielding the mass function of bound structures in the Universe is given. The extended formula is based on a power law distribution which encompasses the Gaussian PS formula as a special case. The new method keeps the original analytical simplicity of the PS approach and also solves naturally its main difficult (the missing factor 2) for a given value of the free parameter.

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43

Ruiz, María Teresa. "Do Low Luminosity Stars Matter?" Proceedings of the International Astronomical Union 5, H15 (November 2009): 47–60. http://dx.doi.org/10.1017/s1743921310008185.

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AbstractHistorically, low luminosity stars have attracted very little attention, in part because they are difficult to see except with large telescopes, however, by neglecting to study them we are leaving out the vast majority of stars in the Universe. Low mass stars evolve very slowly, it takes them trillions of years to burn their hydrogen, after which, they just turn into a He white dwarf, without ever going through the red giant phase. This lack of observable evolution partly explains the lack of interest in them. The search for the “missing mass” in the galactic plane turned things around and during the 60s and 70s the search for large M/L objects placed M-dwarfs and cool WDs among objects of astrophysical interest. New fields of astronomical research, like BDs and exoplanets appeared as spin-offs from efforts to find the “missing mass”. The search for halo white dwarfs, believed to be responsible for the observed microlensing events, is pursued by several groups. The progress in these last few years has been tremendous, here I present highlights some of the great successes in the field and point to some of the still unsolved issues.

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44

Bournaud, Frederic. "Tidal Dwarf Galaxies and Missing Baryons." Advances in Astronomy 2010 (2010): 1–7. http://dx.doi.org/10.1155/2010/735284.

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Tidal dwarf galaxies form during the interaction, collision, or merger of massive spiral galaxies. They can resemble “normal” dwarf galaxies in terms of mass, size, and become dwarf satellites orbiting around their massive progenitor. They nevertheless keep some signatures from their origin, making them interesting targets for cosmological studies. In particular, they should be free from dark matter from a spheroidal halo. Flat rotation curves and high dynamical masses may then indicate the presence of an unseen component, and constrain the properties of the “missing baryons,” known to exist but not directly observed. The number of dwarf galaxies in the Universe is another cosmological problem for which it is important to ascertain if tidal dwarf galaxies formed frequently at high redshift, when the merger rate was high, and many of them survived until today. In this paper, “dark matter” is used to refer to the nonbaryonic matter, mostly located in large dark halos, that is, CDM in the standard paradigm, and “missing baryons” or “dark baryons” is used to refer to the baryons known to exist but hardly observed at redshift zero, and are a baryonic dark component that is additional to “dark matter”.

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45

Hawkins, Michael, and Charles Alcock. "Hunting Down the Universe: The Missing Mass, Primordial Black Holes, and Other Dark Matters." Physics Today 51, no. 7 (July 1998): 72. http://dx.doi.org/10.1063/1.882307.

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46

BAYIN, SELÇUK Ş. "MISSING MASS AND THE ACCELERATION OF THE UNIVERSE: IS QUINTESSENCE THE ONLY EXPLANATION?" International Journal of Modern Physics D 11, no. 10 (December 2002): 1523–29. http://dx.doi.org/10.1142/s0218271802002839.

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Detailed observations of the temperature fluctuations in the microwave background radiation indicate that we live in an open universe. From the size of these fluctuations, it is concluded that the geometry of the universe is quite close to Euclidean. In terms Friedmann models, this implies a mass density within 10% of the critical density required for a flat universe. Observed mass can only account for 30% of this mass density. Recently, an outstanding observation revealed that cosmos is accelerating. This motivated some astronomers to explain the missing 70% as some exotic dark energy called quintessence. In this essay, we present an alternative explanation to these cosmological issues in terms of the Friedmann Thermodynamics. This model has the capability of making definite predictions about the geometry of the universe, the missing mass problem, and the acceleration of the universe in-line with the recent findings. For future observations, we also predict where this model will start differing from the quintessence models.

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47

Stierwalt, Sabrina. "ALFALFA in the Leo Region: Looking for Missing Satellites in HI." Proceedings of the International Astronomical Union 3, S244 (June 2007): 385–86. http://dx.doi.org/10.1017/s1743921307014391.

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AbstractThe location of two nearby galaxy groups within ~20 Mpc in the Leo region allows for a detailed study of low-mass galaxies. A catalog of HI line detections in Leo (9h36m < α < 11h36m, +8° < δ < +16°) has been made from the blind HI survey ALFALFA. More sensitive single-pixel Arecibo observations targeted Leo dwarf candidates noted optically by Karachentsev et al. 2004 (K04) to determine group members and allow for a comparison of HI and optically-selected samples. This presentation highlights the differences between the two samples and the significant contribution blind HI surveys can make to the missing satellites problem.

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48

Rigby, J. R., and G. H. Rieke. "Missing Massive Stars in Starbursts: Stellar Temperature Diagnostics and the Initial Mass Function." Astrophysical Journal 606, no. 1 (May 2004): 237–57. http://dx.doi.org/10.1086/382776.

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49

Muzzio, Juan C., Victor H. Dessaunet, and M. Marcela Vergne. "Tidal stripping and accretion in clusters of galaxies with smoothly distributed missing mass." Astrophysical Journal 313 (February 1987): 112. http://dx.doi.org/10.1086/164952.

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50

Rusin, David, and Chung-Pei Ma. "Constraints on the Inner Mass Profiles of Lensing Galaxies from Missing Odd Images." Astrophysical Journal 549, no. 1 (March 1, 2001): L33—L37. http://dx.doi.org/10.1086/319129.

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