The case for primordial black holes as dark matter

Abstract

The aim of this paper is to present the case that stellar mass primordial black holes make up the dark matter component of the Universe. A near critical density of compact bodies implies that most lines of sight will be gravitationally microlensed, and the paper focuses on looking for the predicted effects on quasar brightness and spectral variations. These signatures of microlensing include the shape of the Fourier power spectrum of the light curves, near achromatic and statistically symmetric variations, and the absence of time dilation in the timescale of variability. For spectral changes, as the continuum varies there should be little corresponding change in the strength of the broad lines. In all these cases, the observations are found to be consistent with the predictions for microlensing by a population of stellar mass compact bodies. For multiply lensed quasars where the images vary independently it is shown that stellar populations are too small to produce the observed microlensing effects, implying a population of compact dark matter bodies of around a stellar mass along the line of sight. The most serious objection to dark matter in the form of compact bodies has come from observations of microlensing of stars in the Magellanic Clouds. In this paper the expected event rate is re-analysed using more recent values for the structure and dynamics of the Galactic halo, and it is shown that there is then no conflict with the observations. Finally, the possible identity of a near critical density of dark matter in the form of stellar mass compact bodies is reviewed, with the conclusion that by far the most plausible candidates are primordial black holes formed during the QCD epoch. The overall conclusion of the paper is that primordial black holes should be seen alongside elementary particles as viable dark matter candidates.

16 pages, 11 figures, accepted for publication in MNRAS

References in corpus (39)

• Dark Matter Candidates from Particle Physics and Methods of Detection
• The Milky Way Tomography with SDSS: I. Stellar Number Density Distribution
• The MACHO Project: Microlensing Results from 5.7 Years of LMC Observations
• The Relationship Between Luminosity and Broad-Line Region Size in Active Galactic Nuclei
• The 2dF Galaxy Redshift Survey: correlation functions, peculiar velocities and the matter density of the Universe
• The Milky Way's Circular Velocity Curve to 60 kpc and an Estimate of the Dark Matter Halo Mass from Kinematics of ~2400 SDSS Blue Horizontal Branch Stars
• Resolved Massive Star Clusters in the Milky Way and its Satellites: Brightness Profiles and a Catalogue of Fundamental Parameters
• The MACHO Project LMC Microlensing Results from the First Two Years and the Nature of the Galactic Dark Halo
• Reverberation Mapping of High-Luminosity Quasars: First Results
• Dipole Anisotropy in the COBE DMR First-Year Sky Maps
• The Quasar Accretion Disk Size - Black Hole Mass Relation
• The Quasar Accretion Disk Size -- Black Hole Mass Relation
• A measurement of large-scale peculiar velocities of clusters of galaxies: results and cosmological implications
• Quantitative Interpretation of Quasar Microlensing Light Curves
• The local surface density of disc matter mapped by Hipparcos
• Starcounts Redivivus. IV. Density Laws Through Photometric Parallaxes
• Primordial Black Holes as All Dark Matter
• The Proper Motion of SgrA*: I. First VLBA Results
• Optical Variability in Active Galactic Nuclei: Starbursts or Disk Instabilities?
• Steps Toward Determination of the Size and Structure of the Broad-Line Region in Active Galactic Nuclei. XVI. A Thirteen-Year Study of Spectral Variability in NGC 5548
• Primordial Black Hole Formation during First-Order Phase Transitions
• Non-Gaussian Fluctuations and Primordial Black Holes from Inflation
• Two measures of the shape of the Milky Way's dark halo
• Streaming motions of galaxy clusters within 12000 km/s - V. The peculiar velocity field
• The MACHO Project First Year LMC Results: The Microlensing Rate and the Nature of the Galactic Dark Halo
• Variability-Selected Quasars in MACHO Project Magellanic Cloud Fields
• Cores of Dark Matter Halos Correlate with Disk Scale Lengths
• Vertical distribution of Galactic disk stars : II. The surface mass density in the Galactic plane
• The MACHO Project: Microlensing Detection Efficiency
• Formation of intermediate-mass black holes as primordial black holes in the inflationary cosmology with running spectral index
• Local Surface Density of the Galactic Disk from a 3-D Stellar Velocity Sample
• Timescale of variation and the size of the accretion disc in active galactic nuclei
• Improved Parameters and New Lensed Features for Q0957+561 from WFPC2 Imaging
• Quasar variability: correlations with amplitude
• Theory of Exploring the Dark Halo with Microlensing 1: Power--Law Models
• Spectral Variability of Quasars in the Sloan Digital Sky Survey. II: The C IV Line
• Colour changes in quasar light curves
• Photometric Confirmation of MACHO Large Magellanic Cloud Microlensing Events
• Testing dark matter with high-redshift supernovae

Cited by in corpus (18)

• CMB bounds on disk-accreting massive Primordial Black Holes
• A Lower Bound on the Mass of Cold Thermal Dark Matter from Planck
• Constraints on primordial black holes as dark matter candidates from capture by neutron stars
• Primordial black holes with an accurate QCD equation of state
• Observational Evidence for Primordial Black Holes: A Positivist Perspective
• Massive Primordial Black Holes as Dark Matter and their detection with Gravitational Waves
• Primordial Black Holes
• Imperfect Dark Matter
• The signature of primordial black holes in the dark matter halos of galaxies
• Polarization of a stochastic gravitational wave background through diffusion by massive structures
• Compact bifluid hybrid stars: Hadronic Matter mixed with self-interacting fermionic Asymmetric Dark Matter
• Detecting the Stochastic Gravitational Wave Background from Primordial Black Hole Formation
• On tidal capture of primordial black holes by neutron stars
• New evidence for a cosmological distribution of stellar mass primordial black holes
• How does Clifford algebra show the way to the second quantized fermions with unified spins, charges and families, and with vector and scalar gauge fields beyond the {\it standard model}
• The double quasar Q2138-431: detection of a lensing galaxy
• Evidence for microlensing by primordial black holes in quasar broad emission lines
• Cosmological nanolensing by dense gas clouds