Derivation of the core mass -- halo mass relation of fermionic and bosonic dark matter halos from an effective thermodynamical model

Chavanis, Pierre-Henri

doi:10.48550/arxiv.1905.08137

Cited by 4 publications

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“…This makes the core-halo configuration extremely important since it corresponds to the "most probable" configuration of the system (in a thermodynamical sense). Finally, using the "velocity dispersion tracing" relation, we could generalize the core mass -halo mass relation obtained by Schive et al [25] to the case of DM halos made of bosons with attractive or repulsive interaction and to the case of DM halos made of fermions [8,16].…”

Section: Introductionmentioning

confidence: 82%

“…In order to match the characteristics of the smallest halos like dwarf spheroidals (dSphs) that are interpreted as purely quantum objects (see below), the mass of the fermion should be of the order of m ∼ 170 eV/c 2 while the mass of the boson should be of the order of m ∼ 2.92 × 10 −22 eV/c 2 if it has a vanishing * Electronic address: chavanis@irsamc.ups-tlse.fr self-interaction, or lie in the range 2.19 × 10 −22 eV/c 2 < m < 2.92 × 10 −22 eV/c 2 if it has an attractive selfinteraction, and in the range 2.92 × 10 −22 eV/c 2 < m < 1.10×10 −3 eV/c 2 if it has a repulsive self-interaction (see Appendix D of [15] and Ref. [16]). 1 In these quantum models, sufficiently large DM halos have a "core-halo" structure which results from a process of violent collisionless relaxation [20] and gravitational cooling [21][22][23].…”

Section: Introductionmentioning

confidence: 99%

“…They are orders of magnitude that could be improved by making a more detailed comparison with observations. The arguments of [15,16] suggest that the mass of a boson with an attractive self-interaction should be slightly smaller than the mass of a noninteracting boson (m ∼ 2.92 × 10 −22 eV/c 2 ), while the mass of a boson with a repulsive self-interaction can be up to 20 orders of magnitude larger than the mass of a noninteracting boson. As discussed in Appendix D.4 of [15], a mass larger than 2.92 × 10 −22 eV/c 2 could alleviate some tensions with the observations of the Lymanα forest encountered in the noninteracting model.…”

Section: Introductionmentioning

confidence: 99%

“…is of the same order as the velocity dispersion in the halo v 2 v ∼ GM v /r v . In recent papers [8,16], we managed to justify this relation from an effective thermodynamic approach. We considered DM halos with a quantum core and an homogeneous isothermal atmosphere in a box of radius r h .…”

Section: Introductionmentioning

confidence: 99%

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Core mass-halo mass relation of bosonic and fermionic dark matter halos harboring a supermassive black hole

Chavanis

2020

Phys. Rev. D

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We study the core mass -halo mass relation of bosonic dark matter halos, in the form of selfgravitating Bose-Einstein condensates, harbouring a supermassive black hole. We use the "velocity dispersion tracing" relation according to which the velocity dispersion in the core v 2 c ∼ GMc/Rc is of the same order as the velocity dispersion in the halo v 2 h ∼ GM h /r h (this relation can be justified from thermodynamical arguments) and the approximate analytical mass-radius relation of the quantum core in the presence of a central black hole obtained in our previous paper [P.H. Chavanis, Eur. Phys. J. Plus 134, 352 (2019)]. For a given minimum halo mass (M h )min ∼ 10 8 M determined by the observations, the only free parameter of our model is the scattering length as of the bosons (their mass m is then determined by the characteristics of the minimum halo). For noninteracting bosons and for bosons with a repulsive self-interaction, we find that the core mass Mc increases with the halo mass M h and achieves a maximum value (Mc)max at some halo mass (M h ) * before decreasing. The whole series of equilibria is stable. For bosons with an attractive self-interaction, we find that the core mass achieves a maximum value (Mc)max at some halo mass (M h ) * before decreasing. The series of equilibria becomes unstable above a maximum halo mass (M h )max ≥ (M h ) * . In the absence of black hole (M h )max = (M h ) * . At that point, the quantum core (similar to a dilute axion star) collapses. We perform a similar study for fermionic dark matter halos. We find that they behave similarly to bosonic dark matter halos with a repulsive self-interaction, the Pauli principle for fermions playing the role of the repulsive self-interaction for bosons. PACS numbers: 95.30.Sf, 95.35.+d, 98.62.Gq

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Section: Introductionmentioning

confidence: 82%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Core mass-halo mass relation of bosonic and fermionic dark matter halos harboring a supermassive black hole

Chavanis

2020

Phys. Rev. D

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“…In the case of dark matter halos made of fermions (massive neutrinos) or bosons (axions), the gravothermal catastrophe can be stopped or even prevented by quantum mechanics. This leads to a fermion or boson "ball" -forming a bulge -surrounded by an extended halo (quantum core-halo structure) [198,199]. Alternatively, during the gravothermal catastrophe, the system may become relativistic and finally undergo a dynamical instability of general relativistic origin leading to the formation of a supermassive black hole as described in [132,151,161].…”

Section: B Instability At Ec For Globular Clusters and Dark Matter Halosmentioning

confidence: 99%

Caloric curves of classical self-gravitating systems in general relativity

Alberti,

Chavanis

2019

Preprint

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We determine the caloric curves of classical self-gravitating systems at statistical equilibrium in general relativity. In the classical limit, the caloric curves of a self-gravitating gas depend on a unique parameter ν = GN m/Rc 2 , called the compactness parameter, where N is the particle number and R the system's size. Typically, the caloric curves have the form of a double spiral. The "cold spiral", corresponding to weakly relativistic configurations, is a generalization of the caloric curve of nonrelativistic classical self-gravitating systems. The "hot spiral", corresponding to strongly relativistic configurations, is similar (but not identical) to the caloric curve of the ultrarelativistic self-gravitating black-body radiation. We introduce two types of normalization of energy and temperature in order to obtain asymptotic caloric curves describing respectively the cold and the hot spirals in the limit ν → 0. As the number of particles increases, the cold and the hot spirals approach each other, merge at ν S = 0.128, form a loop above νS = 0.1415, reduce to a point at νmax = 0.1764, and finally disappear. Therefore, the double spiral shrinks when the compactness parameter ν increases, implying that general relativistic effects render the system more unstable. We discuss the nature of the gravitational collapse at low and high energies with respect to a dynamical (fast) or a thermodynamical (slow) instability.

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Gravitational phase transitions and instabilities of self-gravitating fermions in general relativity

Chavanis

Alberti

2020

Physics Letters B

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We discuss the occurrence of gravitational phase transitions and instabilities in a gas of selfgravitating fermions within the framework of general relativity. In the classical (nondegenerate) limit, the system undergoes a gravitational collapse at low energies E < Ec and low temperatures T < Tc. This is called "gravothermal catastrophe" in the microcanonical ensemble and "isothermal collapse" in the canonical ensemble. When quantum mechanics is taken into account and when the particle number is below the Oppenheimer-Volkoff limit (N < NOV), complete gravitational collapse is prevented by the Pauli exclusion principle. In that case, the Fermi gas undergoes a gravitational phase transition from a gaseous phase to a condensed phase. The condensed phase represents a compact object like a white dwarf, a neutron star, or a dark matter fermion ball. When N > NOV, there can be a subsequent gravitational collapse below a lower critical energy E < E c or a lower critical temperature T < T c leading presumably to the formation of a black hole. The evolution of the system is different in the microcanonical and canonical ensembles. In the microcanonical ensemble, the system takes a "core-halo" structure. The core consists in a compact quantum object or a black hole while the hot halo is expelled at large distances. This is reminiscent of the red giant structure of low-mass stars or the implosion-explosion of massive stars (supernova). In the canonical ensemble, the system collapses as a whole towards a compact object or a black hole. This is reminiscent of the implosion of supermassive stars (hypernova).PACS numbers: 04.40. Dg, 05.70.Fh, 95.30.Sf, 95.35.+d

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Derivation of the core mass -- halo mass relation of fermionic and bosonic dark matter halos from an effective thermodynamical model

Cited by 4 publications

References 0 publications

Core mass-halo mass relation of bosonic and fermionic dark matter halos harboring a supermassive black hole

Core mass-halo mass relation of bosonic and fermionic dark matter halos harboring a supermassive black hole

Caloric curves of classical self-gravitating systems in general relativity

Gravitational phase transitions and instabilities of self-gravitating fermions in general relativity

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