Small-scale structure and 21cm fluctuations by primordial black holes

Gong, Jinn Ouk; Kitajima, Naoya

doi:10.1088/1475-7516/2017/08/017

Cited by 49 publications

(52 citation statements)

References 76 publications

(117 reference statements)

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“…Consequently, this term would only be relevant if minihalos gave sizable contributions, or if one considers extremely heavy PBHs (however it is worth noting that there unavoidably exists uncertainty in the high redshift halo mass function within ΛCDM which could produce degenerate effects to minihalos). While previous work has claimed that the enhanced number density of minihalos, produced by viable populations of PBHs, could give rise to an observable signal [119,120], we show here that these calculations had not self-consistently accounted for the global heating of the IGM, which significantly raises the Jeans mass and tends to suppress the minihalo contribution. Thus, the dominant effect on the 21cm power spectrum arises exclusively from the modifications to the heating and ionization of the IGM.…”

Section: Results and Conclusioncontrasting

confidence: 76%

“…Within the context of ΛCDM, minihalos contribute minimally to the 21cm signal [138] (the signal is expected to be at the level of O(1) mK in ΛCDM). However, it has been argued that the enhancement in the number density of these halos by a population of PBHs can make their contribution observable [119,120]. We address this claim in Section III.3, and show that the contribution of minihalos is typically suppressed when the global effects of accretion are self-consistently included in the calculation.…”

Section: The Effects Of Primordial Black Holesmentioning

confidence: 87%

“…Since star-forming halos are expected to produce the dominant 21cm signal in the epochs of interest, one is naively driven to conclude that the Poisson noise in the power spectrum is not relevant and can be neglected (even though, we have included it in the calculation of the global signal). It was recently argued [119,120], however, that the enhanced number density of minihalos arising from the shot noise induced by ∼ O(M ) PBHs could sufficiently elevate the contribution of minihalos to a discernible level. We briefly outline the formalism for estimating the minihalo contribution below, and show that the computation of Ref.…”

Section: Iii3 Shot Noisementioning

confidence: 99%

“…Studies have been performed in the context of various dark matter candidates, for example, illustrating unprecedented sensitivity to a wide array of dark matter candidates . Existing works looking into the effects of PBHs in 21cm cosmology have independently focused on understanding the effects arising from PBH accretion on the globally averaged signal [118], Poisson-noise on the power spectrum [119,120], and local modifications to the medium around PBHs on the globally averaged signal and the angular power spectrum [121,122]. In this work, we compare and contrast these three effects in the context of O(M ) PBHs, illustrating that the only process relevant for M PBH 10 3 M is the heating and ionization of the IGM arising from X-rays produced during accretion.…”

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confidence: 99%

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Constraining the primordial black hole abundance with 21-cm cosmology

et al. 2019

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The discoveries of a number of binary black hole mergers by LIGO and VIRGO has reinvigorated the interest that primordial black holes (PBHs) of tens of solar masses could contribute non-negligibly to the dark matter energy density. Should even a small population of PBHs with masses O(M ) exist, they could profoundly impact the properties of the intergalactic medium and provide insight into novel processes at work in the early Universe. We demonstrate here that observations of the 21cm transition in neutral hydrogen during the epochs of reionization and cosmic dawn will likely provide one of the most stringent tests of solar mass PBHs. In the context of 21cm cosmology, PBHs give rise to three distinct observable effects: (i) the modification to the primordial power spectrum (and thus also the halo mass function) induced by Poisson noise, (ii) a uniform heating and ionization of the intergalactic medium via X-rays produced during accretion, and (iii) a local modification to the temperature and density of the ambient medium surrounding isolated PBHs. Using a four-parameter astrophysical model, we show that experiments like SKA and HERA could potentially improve upon existing constraints derived using observations of the cosmic microwave background by more than one order of magnitude. I. INTRODUCTIONThe canonical cosmological model assumes that dark matter is comprised of a cold gas of weakly interacting particles. Despite its simplicity, this minimal scenario provides an excellent fit to both cosmic microwave background (CMB) and large-scale structure measurements [1][2][3][4]. However, a precise understanding of the fundamental nature of dark matter is missing and remains at the forefront in the current list of unsolved problems in modern physics.Although dark matter is usually interpreted in terms of a new elementary particle, other alternatives exist. Black holes (BHs) produced prior to big bang nucleosynthesis (BBN), i.e., primordial black holes (PBHs), represent such an alternative -remarkably, this solution is as old as particle dark matter [5]. In particular, this scenario has recently attracted much attention [6][7][8][9][10][11][12] in the context of the LIGO and VIRGO discoveries of several binary BH mergers [13][14][15][16][17].The idea that PBHs could be formed by strong accretion during the radiation-dominated epoch was first introduced five decades ago [18]. It was later suggested that initial fluctuations in the early Universe could give rise to a large number of gravitationally collapsed objects with masses above the Planck mass [19], that however, would not grow substantially by accretion [20]. Very light PBHs would not survive until the present epoch, though; the prediction that any BH should emit particles with a black body spectrum [21,22] implies that PBHs with masses below 10 −18 M (with M the Sun's mass) would have evaporated on cosmological times scales [21][22][23]. While the evaporation of such light PBHs would have interesting observational consequences [24][25][26], only heavier PBHs coul...

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Section: Results and Conclusioncontrasting

confidence: 76%

Section: The Effects Of Primordial Black Holesmentioning

confidence: 87%

Section: Iii3 Shot Noisementioning

confidence: 99%

mentioning

confidence: 99%

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Constraining the primordial black hole abundance with 21-cm cosmology

et al. 2019

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“…The impact of Poisson noise from PBHs in the small-scale Lyman-α forest power spectrum has been recently utilized to constrain massive PBHs (m PBH > 60M ) [52]. Both the Poisson noise and accretion methods have promise for future -and current -21 cm observations [53][54][55]. Furthermore, microlensing searches [56] have constrained PBH masses in the planetary-to-stellar-mass window by monitoring stars in the Large Magellanic Cloud (MACHO [57,58], EROS-2 [59]) and the Galactic Bulge [60].…”

Section: Introductionmentioning

confidence: 99%

Revisiting constraints on asteroid-mass primordial black holes as dark matter candidates

Montero-Camacho

Fang

Vasquez

et al. 2019

J. Cosmol. Astropart. Phys.

240

193

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As the only dark matter candidate that does not invoke a new particle that survives to the present day, primordial black holes (PBHs) have drawn increasing attention recently. Up to now, various observations have strongly constrained most of the mass range for PBHs, leaving only small windows where PBHs could make up a substantial fraction of the dark matter. Here we revisit the PBH constraints for the asteroid-mass window, i.e., the mass range 3.5 × 10 −17 M < m PBH < 4 × 10 −12 M . We revisit 3 categories of constraints.(1) For optical microlensing, we analyze the finite source size and diffractive effects and discuss the scaling relations between the event rate, m PBH and the event duration. We argue that it will be difficult to push the existing optical microlensing constraints to much lower m PBH . (2) For dynamical capture of PBHs in stars, we derive a general result on the capture rate based on phase space arguments. We argue that survival of stars does not constrain PBHs, but that disruption of stars by captured PBHs should occur and that the asteroidmass PBH hypothesis could be constrained if we can work out the observational signature of this process. (3) For destruction of white dwarfs by PBHs that pass through the white dwarf without getting gravitationally captured, but which produce a shock that ignites carbon fusion, we perform a 1+1D hydrodynamic simulation to explore the post-shock temperature and relevant timescales, and again we find this constraint to be ineffective. In summary, we find that the asteroid-mass window, which was previously constrained due to femtolensing, WD survival, optical microlensing, and neutron star capture is no longer constrained. Hence, the asteroid-mass window remains open for PBHs to account for all the dark matter.

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Seven hints for primordial black hole dark matter

Clesse

García-Bellido

2018

Physics of the Dark Universe

218

200

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Seven observations point towards the existence of primordial black holes (PBH), constituting the whole or an important fraction of the dark matter in the Universe: the mass and spin of black holes detected by Advanced LIGO/VIRGO, the detection of micro-lensing events of distant quasars and stars in M31, the non-detection of ultra-faint dwarf satellite galaxies with radius below 15 parsecs, evidences for core galactic dark matter profiles, the correlation between X-ray and infrared cosmic backgrounds, and the existence of super-massive black holes very early in the Universe's history. Some of these hints are newly identified and they are all intriguingly compatible with the reconstructed broad PBH mass distribution from LIGO events, peaking on PBH mass mPBH ≈ 3M and passing all other constraints on PBH abundances. PBH dark matter also provides a new mechanism to explain the mass-to-light ratios of dwarf galaxies, including the recent detection of a diffuse galaxy not dominated by dark matter. Finally we conjecture that between 0.1% and 1% of the events detected by LIGO will involve a PBH with a mass below the Chandrasekhar mass, which would unambiguously prove the existence of PBH.

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Small-scale structure and 21cm fluctuations by primordial black holes

Cited by 49 publications

References 76 publications

Constraining the primordial black hole abundance with 21-cm cosmology

Constraining the primordial black hole abundance with 21-cm cosmology

Revisiting constraints on asteroid-mass primordial black holes as dark matter candidates

Seven hints for primordial black hole dark matter

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