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Primordial black holes (PBHs), possibly constituting a non-negligible fraction of dark matter (DM), might be responsible for a number of gravitational-wave events detected by LIGO/Virgo/KAGRA. In this paper, we simulate the evolution of PBH binaries in DM halos and calculate their merger rate up to redshift of 10. We assume that DM halos are made entirely by a combination of single PBHs and PBH binaries. We present the resulting merger rates from the two main channels that lead to merging PBH binaries: two-body captures and binary-single interactions. We account for alternative assumptions on the dark matter halo mass-concentration relationship versus redshift. We also study what impact the PBH mass distribution, centered in the stellar-mass range, has on the PBH merger rate that the ground-based gravitational-wave observatories can probe. We find that, under reasonable assumptions on the abundance of PBH binaries relative to single PBHs, the binary-single interaction rates can be dominant over the two-body capture channel. Our work studies in detail the dynamics of PBHs inside DM halos, advancing our understanding on how the current gravitational-wave events constrain the properties of PBHs. Moreover, we make predictions in a redshift range to be probed by future observatories.
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Search for subsolar-mass black hole binaries in the second part of Advanced LIGO’s and Advanced Virgo’s third observing run
ABSTRACT We describe a search for gravitational waves from compact binaries with at least one component with mass $0.2$$–$$1.0 \, \mathrm{M}_\odot$$ and mass ratio q ≥ 0.1 in Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO) and Advanced Virgo data collected between 2019 November 1, 15:00 utc and 2020 March 27, 17:00 utc. No signals were detected. The most significant candidate has a false alarm rate of $$0.2 \, \rm {yr}^{-1}$$. We estimate the sensitivity of our search over the entirety of Advanced LIGO’s and Advanced Virgo’s third observing run, and present the most stringent limits to date on the merger rate of binary black holes with at least one subsolar-mass component. We use the upper limits to constrain two fiducial scenarios that could produce subsolar-mass black holes: primordial black holes (PBH) and a model of dissipative dark matter. The PBH model uses recent prescriptions for the merger rate of PBH binaries that include a rate suppression factor to effectively account for PBH early binary disruptions. If the PBHs are monochromatically distributed, we can exclude a dark matter fraction in PBHs $$f_\mathrm{PBH} \gtrsim \, 0.6$$ (at 90 per cent confidence) in the probed subsolar-mass range. However, if we allow for broad PBH mass distributions, we are unable to rule out fPBH = 1. For the dissipative model, where the dark matter has chemistry that allows a small fraction to cool and collapse into black holes, we find an upper bound fDBH < 10−5 on the fraction of atomic dark matter collapsed into black holes.
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- Award ID(s):
- 2110594 2110360 2207594 2011865 2011334 2308693 2207728 2110460 2308881 2207999 2110181
- PAR ID:
- 10439484
- Date Published:
- Journal Name:
- Monthly Notices of the Royal Astronomical Society
- Volume:
- 524
- Issue:
- 4
- ISSN:
- 0035-8711
- Page Range / eLocation ID:
- 5984 to 5992
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract The possible existence of primordial black holes in the stellar-mass window has received considerable attention because their mergers may contribute to current and future gravitational-wave detections. Primordial black hole mergers, together with mergers of black holes originating from Population III stars, are expected to dominate at high redshifts ( z ≳ 10). However, the primordial black hole merger rate density is expected to rise monotonically with redshift, while Population III mergers can only occur after the birth of the first stars. Next-generation gravitational-wave detectors such as the Cosmic Explorer (CE) and Einstein Telescope (ET) can access this distinctive feature in the merger rates as functions of redshift, allowing for direct measurement of the abundance of the two populations and hence for robust constraints on the abundance of primordial black holes. We simulate four months’ worth of data observed by a CE-ET detector network and perform hierarchical Bayesian analysis to recover the merger rate densities. We find that if the universe has no primordial black holes with masses of ( 10 M ⊙ ) , the projected upper limit on their abundance f PBH as a fraction of dark matter energy density may be as low as f PBH ∼ ( 10 − 5 ) , about two orders of magnitude lower than the current upper limits in this mass range. If instead f PBH ≳ 10 −4 , future gravitational-wave observations would exclude f PBH = 0 at the 95% credible interval.more » « less
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A<sc>bstract</sc> Primordial black holes (PBHs) formed during first-order phase transitions provide a powerful link between the early-universe microphysics and observable signatures today, including dark matter and gravitational waves. In this work we develop a unified description of PBH formation based on the Israel junction conditions, which capture collapse dynamics without relying on conventional overdensity or pressure-balance arguments. As a first application, we show that exotic objects such as Fermi-balls can collapse into PBHs even when most of the vacuum energy is trapped in solitonic cores, leading to a different gravitational-wave signal relative to vacuum-only scenarios. As a second application, we study multiple phase transitions in a hidden sector, which generate correlated gravitational-wave spectra and PBH abundances across transitions. Our framework, while analytically controlled, is broadly applicable to hidden-sector models with general vacuum, radiation, and matter contributions. We present the resulting predictions for PBH mass spectra, dark matter fractions, and gravitational-wave signals, highlighting parameter regions that remain open in current searches and motivating future probes.more » « less
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Abstract Primordial black holes (PBHs), theorized to have originated in the early Universe, are speculated to be a viable form of dark matter. If they exist, they should be detectable through photometric and astrometric signals resulting from gravitational microlensing of stars in the Milky Way. Population Synthesis for Compact-object Lensing Events, orPopSyCLE, is a simulation code that enables users to simulate microlensing surveys, and is the first of its kind to include both photometric and astrometric microlensing effects, which are important for potential PBH detection and characterization. To estimate the number of observable PBH microlensing events, we modifyPopSyCLEto include a dark matter halo consisting of PBHs. We detail our PBH population model, and demonstrate ourPopSyCLE+ PBH results through simulations of the Optical Gravitational Lensing Experiment-IV (OGLE-IV) and Nancy Grace Roman Space Telescope (Roman) microlensing surveys. We provide a proof-of-concept analysis for adding PBHs intoPopSyCLE, and thus include many simplifying assumptions, such asfDM, the fraction of dark matter composed of PBHs, and , mean PBH mass. Assuming M⊙, we find ∼3.6fDMtimes as many PBH microlensing events than stellar evolved black hole events, a PBH average peak Einstein crossing time of ∼91.5 days, estimate on order of 102fDMPBH events within the 8 yr OGLE-IV results, and estimate Roman to detect ∼1000fDMPBH microlensing events throughout its planned microlensing survey.more » « less
- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.1093/mnras/stad588
