scholarly journals MOND fiducial specific angular momentum of disc galaxies

2021 ◽  
Vol 104 (6) ◽  
Author(s):  
Mordehai Milgrom
Keyword(s):  
Angular Momentum ◽  
Disc Galaxies

scholarly journals Angular Momentum Accretion onto Disc Galaxies

2018 ◽  
Vol 14 (A30) ◽  
pp. 228-232
Author(s):  
Filippo Fraternali ◽  
Gabriele Pezzulli
Keyword(s):  
Angular Momentum ◽  
Star Formation ◽  
Momentum Distribution ◽  
Intergalactic Medium ◽  
Star Forming ◽  
Gas Accretion ◽  
Hot Corona ◽  
Inside Out ◽  
Disc Galaxies ◽  
Hubble Time

AbstractThroughout the Hubble time, gas makes its way from the intergalactic medium into galaxies fuelling their star formation and promoting their growth. One of the key properties of the accreting gas is its angular momentum, which has profound implications for the evolution of, in particular, disc galaxies. Here, we discuss how to infer the angular momentum of the accreting gas using observations of present-day galaxy discs. We first summarize evidence for ongoing inside-out growth of star forming discs. We then focus on the chemistry of the discs and show how the observed metallicity gradients can be explained if gas accretes onto a disc rotating with a velocity 20 – 30% lower than the local circular speed. We also show that these gradients are incompatible with accretion occurring at the edge of the discs and flowing radially inward. Finally, we investigate gas accretion from a hot corona with a cosmological angular momentum distribution and describe how simple models of rotating coronae guarantee the inside-out growth of disc galaxies.

scholarly journals Stellar bars in counter-rotating dark matter haloes: the role of halo orbit reversals

2019 ◽  
Vol 489 (3) ◽  
pp. 3102-3115 ◽  
Author(s):  
Angela Collier ◽  
Isaac Shlosman ◽  
Clayton Heller
Keyword(s):  
Dark Matter ◽  
Angular Momentum ◽  
Galaxy Evolution ◽  
Secular Evolution ◽  
Resonant Interactions ◽  
Disc Galaxies ◽  
Simulation Time ◽  
Lindblad Resonance ◽  
Inner Lindblad Resonance

Abstract Disc galaxies can exchange angular momentum and baryons with their host dark matter (DM) haloes. These haloes possess internal spin, λ, which is insignificant rotationally but does affect interactions between the baryonic and DM components. While statistics of prograde and retrograde spinning haloes in galaxies is not available at present, the existence of such haloes is important for galaxy evolution. In the previous works, we analysed dynamical and secular evolution of stellar bars in prograde spinning haloes and the DM response to the bar perturbation, and found that it is modified by the resonant interactions between the bar and the DM halo orbits. In this work, we follow the evolution of stellar bars in retrograde haloes. We find that this evolution differs substantially from evolution in rigid unresponsive haloes, discussed in the literature. First, we confirm that the bar instability is delayed progressively along the retrograde λ sequence. Secondly, the bar evolution in the retrograde haloes differs also from that in the prograde haloes, in that the bars continue to grow substantially over the simulation time of 10 Gyr. The DM response is also substantially weaker compared to this response in the prograde haloes. Thirdly, using orbital spectral analysis of the DM orbital structure, we find a phenomenon we call the orbit reversal – when retrograde DM orbits interact with the stellar bar, reverse their streaming and precession, and become prograde. This process dominates the inner halo region adjacent to the bar and allows these orbits to be trapped by the bar, thus increasing efficiency of angular momentum transfer by the inner Lindblad resonance. We demonstrate this reversal process explicitly in a number of examples.

scholarly journals Angular momentum-related probe of cold gas deficiencies

2020 ◽  
Vol 493 (4) ◽  
pp. 5024-5037
Author(s):  
Jie Li ◽  
Danail Obreschkow ◽  
Claudia Lagos ◽  
Luca Cortese ◽  
Charlotte Welker ◽  
...  
Keyword(s):  
Angular Momentum ◽  
Velocity Dispersion ◽  
Virgo Cluster ◽  
Atomic Fraction ◽  
Cluster Galaxies ◽  
Nearby Galaxies ◽  
The Stability ◽  
Baryonic Mass ◽  
Log Ratio ◽  
Disc Galaxies

ABSTRACT Recent studies of neutral atomic hydrogen (H i) in nearby galaxies found that all field disc galaxies are H i saturated, in that they carry roughly as much H i as permitted before this gas becomes gravitationally unstable. By taking this H i saturation for granted, the atomic gas fraction fatm of galactic discs can be predicted as a function of the stability parameter q = jσ/(GM), where M and j are the baryonic mass and specific angular momentum of the disc and σ is the H i velocity dispersion (Obreschkow et al. 2016). The log-ratio Δfq between this predictor and the observed atomic fraction can be seen as a physically motivated ‘H i deficiency’. While field disc galaxies have Δfq ≈ 0, objects subject to environmental removal of H i are expected to have Δfq > 0. Within this framework, we revisit the H i deficiencies of satellite galaxies in the Virgo cluster and in clusters of the EAGLE simulation. We find that observed and simulated cluster galaxies are H i deficient and that Δfq slightly increases when getting closer to the cluster centres. The Δfq values are similar to traditional H i deficiency estimators, but Δfq is more directly comparable between observations and simulations than morphology-based–deficiency estimators. By tracking the simulated H i deficient cluster galaxies back in time, we confirm that Δfq ≈ 0 until the galaxies first enter a halo with $M_{\rm halo}\gt 10^{13}\rm M_{\odot }$, at which moment they quickly lose H i by environmental effects. Finally, we use the simulation to investigate the links between Δfq and quenching of star formation.

scholarly journals A tight angular-momentum plane for disc galaxies

2021 ◽  
Author(s):  
P. E. Mancera Piña ◽  
L. Posti ◽  
G. Pezzulli ◽  
F. Fraternali ◽  
S. M. Fall ◽  
...  
Keyword(s):  
Angular Momentum ◽  
Momentum Plane ◽  
Angular Momentum Plane ◽  
Disc Galaxies

scholarly journals The baryonic specific angular momentum of disc galaxies

2021 ◽  
Author(s):  
P. E. Mancera Piña ◽  
L. Posti ◽  
F. Fraternali ◽  
E. A K. Adams ◽  
T. Oosterloo
Keyword(s):  
Angular Momentum ◽  
Disc Galaxies

Angular Momentum in the Formation of Disc Galaxies

2004 ◽  
Vol 21 (3) ◽  
pp. 588-591 ◽  
Author(s):  
Luo Zhi-Jian ◽  
Shu Cheng-Gang
Keyword(s):  
Angular Momentum ◽  
Disc Galaxies

scholarly journals COMMISSION 7: CELESTIAL MECHANICS AND DYNAMICAL ASTRONOMY

2008 ◽  
Vol 4 (T27A) ◽  
pp. 12-22
Author(s):  
Joseph A. Burns ◽  
Zoran Knežević ◽  
Andrea Milani ◽  
David Vokrouhlický ◽  
Evangelia Athanassoula ◽  
...  
Keyword(s):  
Angular Momentum ◽  
Celestial Mechanics ◽  
Configuration Space ◽  
Temporal Evolution ◽  
Dark Halo ◽  
Relative Importance ◽  
Secular Evolution ◽  
Resonant Orbits ◽  
Dynamical Astronomy ◽  
Disc Galaxies

The interplay of the disc and the dark halo resonances governs the secular evolution of disc galaxies, and the properties of their bar component (Athanassoula 2002). Martinez-Valpuestaet al. (2006), Ceverino & Klypin (2007) and Athanassoula (2007b) confirm and extend this work. Ceverino & Klypin (2007) calculate the orbital frequencies of each particle over the whole temporal evolution, and thus find much broader frequency peaks. In all cases, it is the same resonances that come into play, and, as in Athanassoula 2002, the angular momentum is emitted by near-resonant material in the bar region and absorbed by near-resonant material in the halo and the outer disc. The relative importance of each resonance, however, varies from one case to another. Furthermore, the second and third of the above mentioned studies examine the location of resonant orbits in configuration space and find compatible results.

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