Mass limits for dark clusters of degenerate fermions

Membrado, M.; Pacheco, A. F.

doi:10.1051/0004-6361/201219985

Cited by 2 publications

(4 citation statements)

References 86 publications

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“…In 2013, we dealt with dark haloes composed of degenerate fermions to reproduce rotation velocities of galaxies (Membrado & Pacheco 2013), and tried to use them to describe haloes of dispersion-supported dwarf stellar system. We chose the ultrafaint Milky Way satellite galaxy Segue 1 (Simon et al 2011;Martinez et al 2011).…”

Section: Application To Dark Halos Of Dsph Galaxiesmentioning

confidence: 99%

“…In Membrado & Pacheco (2013), we applied a dark halo made of collisionless Newtonian bosons to the ultra-faint Milky Way satellite galaxy Segue 1 (Simon et al 2011;Martinez et al 2011). We saw that when taking its half-light radius, r 1/2 , as the radius that covers 99% of the dark assembly mass, the Segue 1 mass at r 1/2 can be reproduced.…”

Section: Introductionmentioning

confidence: 99%

“…In this paper, we have retaken and extended the calculation made in Membrado & Pacheco (2013) to 19 dSph galaxies. We have dealt with a sphere of self-gravitating bosons as in Membrado et al (1989), but have assumed the presence of dark energy.…”

Section: Introductionmentioning

confidence: 99%

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Bose–Einstein condensate haloes embedded in dark energy

Membrado

Pacheco

2018

A&A

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Context. We have studied clusters of self-gravitating collisionless Newtonian bosons in their ground state and in the presence of the cosmological constant to model dark haloes of dwarf spheroidal (dSph) galaxies. Aims. We aim to analyse the influence of the cosmological constant on the structure of these systems. Observational data of Milky Way dSph galaxies allow us to estimate the boson mass. Methods. We obtained the energy of the ground state of the cluster in the Hartree approximation by solving a variational problem in the particle density. We have also developed and applied the virial theorem. Dark halo models were tested in a sample of 19 galaxies. Galaxy radii, 3D deprojected half-light radii, mass enclosed within them, and luminosity-weighted averages of the square of line-of-sight velocity dispersions are used to estimate the particle mass. Results. Cosmological constant repulsive effects are embedded in one parameter ξ. They are appreciable for ξ > 10−5. Bound structures appear for ξ ≤ ξc = 1.65 × 10−4, what imposes a lower bound for cluster masses as a function of the particle mass. In principle, these systems present tunnelling through a potential barrier; however, after estimating their mean lifes, we realize that their existence is not affected by the age of the Universe. When Milky Way dSph galaxies are used to test the model, we obtain 3.5−1.0+1.3 × 10−22 eV for the particle mass and a lower limit of 5.1−2.8+2.2 × 106 M⊙ for bound haloes. Conclusions. Our estimation for the boson mass is in agreement with other recent results which use different methods. From our particle mass estimation, the treated dSph galaxies would present dark halo masses ~5–11 ×107 M⊙. With these values, they would not be affected by the cosmological constant (ξ < 10−8). However, dark halo masses smaller than 107 M⊙ (ξ > 10−5) would already feel their effects. Our model that includes dark energy allows us to deal with these dark haloes. Assuming quantities averaged in the sample of galaxies, 10−5 < ξ ≤ ξc dark haloes would contain stars up to ~8–15 kpc with luminosities ~9–4 ×103 L⊙. Then, their observation would be complicated. The comparison of our lower bound for dark halo masses with other bounds based on different arguments, leads us to think that the cosmological constant is actually the responsible of limiting the halo mass.

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Section: Application To Dark Halos Of Dsph Galaxiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Bose–Einstein condensate haloes embedded in dark energy

Membrado

Pacheco

2018

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“…In previous papers (Membrado & Pacheco 2012, 2013), we applied this upper limit to spheres of self-gravitating fermions, or bosons, in the ground state, which are quantum systems. These spheres simulated clusters of dark matter.…”

Section: The Effect Of the Cosmological Constant On Bound Non-relativmentioning

confidence: 99%

Effects of the cosmological constant on cold dark matter clusters

Membrado

Pacheco

2014

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Context. Cold dark matter inhomogeneities are considered in a homogeneous background of matter, radiation, and the cosmological constant in a flat universe. Aims. We investigate the influence of the cosmological constant on the non-linear collapse of cold dark matter clusters. Methods. For simplicity, a spherical infall model has been used to describe the collapse of non-relativistic mass shells; besides, an average distribution of density around a cluster of galaxies has been taken. We have found that there is a limit to the mass of the average cluster, which is able to virialize; its value is {M VIR } MAX = 8.1 × 10 14 M . As expected, we found that shells present null proper acceleration at redshift values that are smaller than 0.755. Conclusions. We have noticed that the cosmological constant imposes an upper limit for the mass enclosed by shells, which are able to reach zero proper velocity. Hence, this mass is the maximum mass of the virialized core, {M VIR } MAX . For the average cluster addressed in this work, the value is 2.34 times the mass of the virialized core at present. Shells enclosing masses M > {M VIR } MAX achieve zero proper acceleration and speed up, moving away from the virialized core, and never reach a turn-around point. Shells with M {M VIR } MAX show zero proper aceleration at redshifts close to that at which the universe background acceleration is null. Finally, we have found that the relation between shell proper velocities and their radii can be adjusted by a straight line at z = 0 and from approximately 20 up to 40 Mpc; however, this line does not intercept the origin as velocities due to the Hubble flux do.

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Mass limits for dark clusters of degenerate fermions

Cited by 2 publications

References 86 publications

Bose–Einstein condensate haloes embedded in dark energy

Bose–Einstein condensate haloes embedded in dark energy

Effects of the cosmological constant on cold dark matter clusters

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