scholarly journals Constraining primordial black holes in dark matter with kinematics of dwarf galaxies

2019 ◽  
Vol 99 (12) ◽  
Author(s):  
Bo-Qiang Lu ◽  
Yue-Liang Wu
Keyword(s):  
Black Holes ◽  
Dark Matter ◽  
Dwarf Galaxies ◽  
Primordial Black Holes

scholarly journals Improved constraints from ultra-faint dwarf galaxies on primordial black holes as dark matter

2020 ◽  
Vol 492 (4) ◽  
pp. 5247-5260 ◽  
Author(s):  
Jakob Stegmann ◽  
Pedro R Capelo ◽  
Elisa Bortolas ◽  
Lucio Mayer
Keyword(s):  
Black Holes ◽  
Dark Matter ◽  
Gravitational Waves ◽  
Lognormal Distribution ◽  
Dwarf Galaxies ◽  
Relaxation Processes ◽  
Primordial Black Holes ◽  
Stellar Component ◽  
Stellar Velocity ◽  
Velocity Dispersions

ABSTRACT Soon after the recent first ever detection of gravitational waves from merging black holes it has been suggested that their origin is primordial. Appealingly, a sufficient number of primordial black holes (PBHs) could also partially or entirely constitute the dark matter (DM) in our Universe. However, recent studies on PBHs in ultra-faint dwarf galaxies (UFDGs) suggest that they would dynamically heat up the stellar component due to two-body relaxation processes. From the comparison with the observed stellar velocity dispersions and the stellar half-light radii, it was claimed that only PBHs with masses $\lesssim 10\, {\rm M}_\odot$ can significantly contribute to the DM. In this work, we improve the latter constraints by considering the largest observational sample of UFDGs and by allowing the PBH masses to follow an extended (lognormal) distribution. By means of collisional Fokker–Planck simulations, we explore a wide parameter space of UFDGs containing PBHs. The analysis of the half-light radii and velocity dispersions resulting from the simulations leads to three general findings that exclude PBHs with masses $\sim \mathcal {O}(1\operatorname{-}100)\, {\rm M}_\odot {}$ from constituting all of the DM: (i) we identify a critical sub-sample of UFDGs that only allows for $\sim \mathcal {O}(1)\, {\rm M}_\odot$ PBH masses; (ii) for any PBH mass, there is an UFDG in our sample that disfavours it; (iii) the spatial extensions of a majority of simulated UFDGs containing PBHs are too large to match the observed.

scholarly journals Cusp-to-core transition in low-mass dwarf galaxies induced by dynamical heating of cold dark matter by primordial black holes

2020 ◽  
Vol 492 (4) ◽  
pp. 5218-5225
Author(s):  
Pierre Boldrini ◽  
Yohei Miki ◽  
Alexander Y Wagner ◽  
Roya Mohayaee ◽  
Joseph Silk ◽  
...  
Keyword(s):  
Black Holes ◽  
Dark Matter ◽  
Time Scale ◽  
Mass Fraction ◽  
Cold Dark Matter ◽  
Dwarf Galaxies ◽  
Dwarf Galaxy ◽  
Initial Density ◽  
Primordial Black Holes ◽  
Low Mass

ABSTRACT We performed a series of high-resolution N-body simulations to examine whether dark matter candidates in the form of primordial black holes (PBHs) can solve the cusp–core problem in low-mass dwarf galaxies. If some fraction of the dark matter in low-mass dwarf galaxies consists of PBHs and the rest is cold dark matter, dynamical heating of the cold dark matter by the PBHs induces a cusp-to-core transition in the total dark matter profile. The mechanism works for PBHs in the 25–100 M⊙ mass window, consistent with the Laser Interferometer Gravitational-Wave Observatory (LIGO) detections, but requires a lower limit on the PBH mass fraction of 1 ${{\rm per\ cent}}$ of the total dwarf galaxy dark matter content. The cusp-to-core transition time-scale is between 1 and 8 Gyr. This time-scale is also a constant multiple of the relaxation time between cold dark matter particles and PBHs, which depends on the mass, the mass fraction, and the scale radius of the initial density profile of PBHs. We conclude that dark matter cores occur naturally in haloes composed of cold dark matter and PBHs, without the need to invoke baryonic processes.

scholarly journals NANOGrav Data Hints at Primordial Black Holes as Dark Matter

2021 ◽  
Vol 126 (4) ◽  
Author(s):  
V. De Luca ◽  
G. Franciolini ◽  
A. Riotto
Keyword(s):  
Black Holes ◽  
Dark Matter ◽  
Primordial Black Holes

scholarly journals A constraint on light primordial black holes from the interstellar medium temperature

2021 ◽  
Author(s):  
Hyungjin Kim
Keyword(s):  
Black Holes ◽  
Dark Matter ◽  
Dwarf Galaxy ◽  
Dark Matter Candidate ◽  
Primordial Black Hole ◽  
Primordial Black Holes ◽  
Substantial Fraction ◽  
Interstellar Gas ◽  
Medium Temperature ◽  
Fast Electrons

Abstract Primordial black holes are a viable dark matter candidate. They decay via Hawking evaporation. Energetic particles from the Hawking radiation interact with interstellar gas, depositing their energy as heat and ionization. For a sufficiently high Hawking temperature, fast electrons produced by black holes deposit a substantial fraction of energy as heat through the Coulomb interaction. Using the dwarf galaxy Leo T, we place an upper bound on the fraction of primordial black hole dark matter. For M < 5 × 10−17M⊙, our bound is competitive with or stronger than other bounds.

scholarly journals Primordial black holes from the QCD epoch: linking dark matter, baryogenesis, and anthropic selection

2020 ◽  
Vol 501 (1) ◽  
pp. 1426-1439
Author(s):  
Bernard Carr ◽  
Sebastien Clesse ◽  
Juan García-Bellido
Keyword(s):  
Black Holes ◽  
Dark Matter ◽  
Selection Effect ◽  
Mass Function ◽  
Baryon Asymmetry ◽  
Primordial Black Holes ◽  
Cosmological Horizon ◽  
Chandrasekhar Limit ◽  
The Universe ◽  
Characteristic Mass

ABSTRACT If primordial black holes (PBHs) formed at the quark-hadron epoch, their mass must be close to the Chandrasekhar limit, this also being the characteristic mass of stars. If they provide the dark matter (DM), the collapse fraction must be of order the cosmological baryon-to-photon ratio ∼10−9, which suggests a scenario in which a baryon asymmetry is produced efficiently in the outgoing shock around each PBH and then propagates to the rest of the Universe. We suggest that the temperature increase in the shock provides the ingredients for hotspot electroweak baryogenesis. This also explains why baryons and DM have comparable densities, the precise ratio depending on the size of the PBH relative to the cosmological horizon at formation. The observed value of the collapse fraction and baryon asymmetry depends on the amplitude of the curvature fluctuations that generate the PBHs and may be explained by an anthropic selection effect associated with the existence of galaxies. We propose a scenario in which the quantum fluctuations of a light stochastic spectator field during inflation generate large curvature fluctuations in some regions, with the stochasticity of this field providing the basis for the required selection. Finally, we identify several observational predictions of our scenario that should be testable within the next few years. In particular, the PBH mass function could extend to sufficiently high masses to explain the black hole coalescences observed by LIGO/Virgo.

scholarly journals Primordial black holes as dark matter: converting constraints from monochromatic to extended mass distributions

2018 ◽  
Vol 2018 (01) ◽  
pp. 004-004 ◽  
Author(s):  
Nicola Bellomo ◽  
José Luis Bernal ◽  
Alvise Raccanelli ◽  
Licia Verde
Keyword(s):  
Black Holes ◽  
Dark Matter ◽  
Primordial Black Holes ◽  
Mass Distributions
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