scholarly journals Constraining scalar fields with stellar kinematics and collisional dark matter

2010 ◽  
Vol 2010 (11) ◽  
pp. 002-002 ◽  
Author(s):  
Pau Amaro-Seoane ◽  
Juan Barranco ◽  
Argelia Bernal ◽  
Luciano Rezzolla
2011 ◽  
Vol 20 (13) ◽  
pp. 2543-2558 ◽  
Author(s):  
SAMUEL LEPE ◽  
JAVIER LORCA ◽  
FRANCISCO PEÑA ◽  
YERKO VÁSQUEZ

From a variational action with nonminimal coupling with a scalar field and classical scalar and fermionic interaction, cosmological field equations can be obtained. Imposing a Friedmann–Lemaître–Robertson–Walker (FLRW) metric, the equations lead directly to a cosmological model consisting of two interacting fluids, where the scalar field fluid is interpreted as dark energy and the fermionic field fluid is interpreted as dark matter. Several cases were studied analytically and numerically. An important feature of the non-minimal coupling is that it allows crossing the barrier from a quintessence to phantom behavior. The insensitivity of the solutions to one of the parameters of the model permits it to find an almost analytical solution for the cosmological constant type of universe.


2010 ◽  
Vol 105 (5) ◽  
Author(s):  
G. Rybka ◽  
M. Hotz ◽  
L. J Rosenberg ◽  
S. J. Asztalos ◽  
G. Carosi ◽  
...  
Keyword(s):  

2019 ◽  
Vol 28 (15) ◽  
pp. 1950170
Author(s):  
Kui Xiao

The evolutionary pictures for phantom field in loop quantum cosmology are discussed in this paper. Comparing the dynamical behaviors of the phantom field with one of the canonical scalar fields in loop quantum cosmology scenario, we found that the [Formula: see text] phase trajectories are the same, but the [Formula: see text] phase-spaces are very different, and the phantom field with considering potentials can drive neither super inflation nor slow-roll inflation in loop quantum cosmology (LQC) scenario. While the universe is filled with multiple dark fluids, to ensure that the condition [Formula: see text] does not violate, the energy density of dark matter [Formula: see text] and the equation-of-state of phantom field [Formula: see text] should satisfy the condition [Formula: see text] at the bounce point. If this constraint condition holds, the universe can enter an inflationary stage, and it is possible to unify the description of phantom field, dark matter and inflation. We introduced a toy model which has the same form of the general Chaplygin gas to unify the dark energy, dark matter and slow-roll inflation, and the slow-roll inflation of the toy model has also been discussed.


Author(s):  
A. Cabo Montes de Oca ◽  
D. Suarez Fontanella

Static (not stationary) solutions of the Einstein–Klein–Gordon (EKG) equations including matter are obtained for real scalar fields. The scalar field interaction with matter is considered. The introduced coupling allows the existence of static solutions in contraposition with the case of the simpler EKG equations for real scalar fields and gravity. Surprisingly, when the considered matter is a photon-like gas, it turns out that the gravitational field intensity at large radial distances becomes nearly a constant, exerting an approximately fixed force to small bodies at any distance. The effect is clearly related with the massless character of the photon-like field. It is also argued that the gravitational field can generate a bounding attraction, that could avoid the unlimited increase in mass with the radius of the obtained here solution. This phenomenon, if verified, may furnish a possible mechanism for explaining how the increasing gravitational potential associated to dark matter, finally decays at large distances from the galaxies. A method for evaluating these photon bounding effects is just formulated in order to be further investigated.


2019 ◽  
Vol 14 (S353) ◽  
pp. 253-254
Author(s):  
M. Yang ◽  
L. Zhu ◽  
A. Weijmans ◽  
G. van de Ven ◽  
N. F. Boardman ◽  
...  

AbstractWe present a new method to combine cold gas kinematics with the stellar kinematics modelled with the Schwarzschild orbit-superposition technique, and its application to the lenticular galaxy NGC 2974. The combination of stellar and cold gas kinematics significantly improves the constraints on the measured dark matter profile: assuming a generalised NFW halo profile, we find a cuspy inner halo slope for NGC 2974.


2018 ◽  
Vol 168 ◽  
pp. 06002
Author(s):  
Aditya Aravind ◽  
Minglei Xiao ◽  
Jiang-Hao Yu

We discuss the inflationary model presented in [1], involving a gauge singlet scalar field and fermionic dark matter added to the standard model. Either the Higgs or the singlet scalar could play the role of the inflaton, and slow roll is realized through its non-minimal coupling to gravity. The effective scalar potential is stabilized by the mixing between the scalars as well as the coupling with the fermionic field. Mixing of the two scalars also provides a portal to dark matter. Constraints on the model come from perturbativity and stability, collider searches and dark matter constraints and impose a constraining relationship on the masses of dark matter and scalar fields. Inflationary predictions are generically consistent with current Planck data.


2019 ◽  
Vol 880 (2) ◽  
pp. 91 ◽  
Author(s):  
Pieter van Dokkum ◽  
Asher Wasserman ◽  
Shany Danieli ◽  
Roberto Abraham ◽  
Jean Brodie ◽  
...  

2019 ◽  
Vol 885 (2) ◽  
pp. 155 ◽  
Author(s):  
Asher Wasserman ◽  
Pieter van Dokkum ◽  
Aaron J. Romanowsky ◽  
Jean Brodie ◽  
Shany Danieli ◽  
...  

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