Black hole-neutron star mergers are unlikely multi-messenger sources

Fragione, Giacomo

doi:10.48550/arxiv.2110.09604

Cited by 4 publications

(8 citation statements)

References 60 publications

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“…For example, studies including Zevin et al (2017), Bouffanais et al (2019), Franciolini et al (2021, Ng et al (2021) and Zevin et al (2021) aim to determine the contributions of different formation channels to the observed BHBH population. Further examples include Fragione (2021), which estimates the number of BHNS mergers with an electromagnetic counterpart. Our work shows that uncertainties in both stellar and binary evolution and S(𝑍, 𝑧) modelling can drastically impact the rate and distribution shapes of the BHBH, BHNS and NSNS populations, challenging the ability to draw strong conclusions when only considering a few population synthesis models at this stage.…”

Section: A Realistic View Of Population Synthesis Modelsmentioning

confidence: 99%

Impact of Massive Binary Star and Cosmic Evolution on Gravitational Wave Observations II: Double Compact Object Rates and Properties

Broekgaarden,

Berger,

Stevenson

et al. 2021

Preprint

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Making the most of the rapidly increasing population of gravitational-wave detections of black hole (BH) and neutron star (NS) mergers requires comparing observations with population synthesis predictions. In this work we investigate the combined impact from the key uncertainties in population synthesis modelling of the isolated binary evolution channel: the physical processes in massive binary-star evolution and the star formation history as a function of metallicity, 𝑍, and redshift 𝑧, S(𝑍, 𝑧). Considering these uncertainties we create 560 different publicly available model realizations and calculate the rate and distribution characteristics of detectable BHBH, BHNS, and NSNS mergers. We find that our stellar evolution and S(𝑍, 𝑧) variations can impact the predicted intrinsic and detectable merger rates by factors 10 2 -10 4 . We find that BHBH rates are dominantly impacted by S(𝑍, 𝑧) variations, NSNS rates by stellar evolution variations and BHNS rates by both. We then consider the combined impact from all uncertainties considered in this work on the detectable mass distribution shapes (chirp mass, individual masses and mass ratio). We find that the BHNS mass distributions are predominantly impacted by massive binary-star evolution changes. For BHBH and NSNS we find that both uncertainties are important. We also find that the shape of the delay time and birth metallicity distributions are typically dominated by the choice of S(𝑍, 𝑧) for BHBH, BHNS and NSNS. We identify several examples of robust features in the mass distributions predicted by all 560 models, such that we expect more than 95 percent of BHBH detections to contain a BH 8 M and have mass ratios 4. Our work demonstrates that it is essential to consider a wide range of allowed models to study double compact object merger rates and properties. Conversely, larger observed samples could allow us to decipher currently unconstrained stages of stellar and binary evolution.

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Section: A Realistic View Of Population Synthesis Modelsmentioning

confidence: 99%

Impact of Massive Binary Star and Cosmic Evolution on Gravitational Wave Observations II: Double Compact Object Rates and Properties

Broekgaarden,

Berger,

Stevenson

et al. 2021

Preprint

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show abstract

“…However, disruption occurs only for a small region of BHNS parameter space, when the BH is highly spinning and small, 5 − 10M (see Foucart et al 2018, and §3.1 below). Furthermore, given the LVK population of compact object mergers discovered so far, it is likely that most BHNS mergers will not disrupt the NS (Fragione 2021).…”

Section: Introductionmentioning

confidence: 99%

Multi-Messenger Constraints on Magnetic Fields in Merging Black Hole-Neutron Star Binaries

D'Orazio,

Haiman,

Levin

et al. 2021

Preprint

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The LIGO-Virgo-KAGRA Collaboration recently detected gravitational waves (GWs) from the merger of black-hole-neutron-star (BHNS) binary systems GW200105 and GW200115. No coincident electromagnetic (EM) counterparts were detected. While the mass ratio and BH spin in both systems were not sufficient to tidally disrupt the NS outside of the BH event horizon, other, magnetospheric mechanisms for EM emission exist in this regime and depend sensitively on the NS magnetic field strength. Combining GW measurements with EM flux upper limits, we place upper limits on the NS surface magnetic field strength above which magnetospheric emission models would have generated an observable EM counterpart. We consider fireball models powered by the black-hole battery mechanism, where energy is output in gamma-rays over 1 second. Consistency with no detection by Fermi-GBM or INTEGRAL SPI-ACS constrains the NS surface magnetic field to 10 15 G. Hence, joint GW detection and EM upper limits rule out the theoretical possibility that the NSs in GW200105 and GW200115, and the putative NS in GW190814, retain 10 15 G dipolar magnetic fields until merger. They also rule out formation scenarios where strongly magnetized magnetars quickly merge with BHs. We alternatively rule out operation of the BH-battery powered fireball mechanism in these systems. This is the first multi-messenger constraint on NS magnetic fields in BHNS systems and a novel approach to probe fields at this point in NS evolution. This demonstrates the constraining power that multi-messenger analyses of BHNS mergers have on BHNS formation scenarios, the magnetic-field evolution in NSs, and the physics of BHNS magnetospheric interactions.

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“…The fraction of systems where tidal disruption occurs is still uncertain as it depends on unknown distributions of the binary mass ratio, NS compactness, and BH spin. Still, this fraction is assumed to be small (Zappa et al 2019;Fragione 2021). For example, while BHNS mergers with large aligned BH spins produce the most ejecta mass, high spins do not seem to be consistent with current GW detections (Abbott et al 2021b).…”

Section: Introductionmentioning

confidence: 90%

Investigating the detection rates and inference of gravitational-wave and radio emission from black hole neutron star mergers

Boersma¹,

Leeuwen²

2022

Preprint

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Context. Black hole neutron star (BHNS) mergers have recently been detected through their gravitational-wave (GW) emission. While no electromagnetic emission (EM) has yet been confidently associated with these systems, observing any such emission could provide information on, for example, the neutron star (NS) equation of state (EOS). BHNS mergers could produce EM emission as a short gamma-ray burst (sGRB), and/or an sGRB afterglow upon interaction with the circummerger medium. Aims. Here, we make predictions for the expected detection rates with the Square Kilometre Array Phase 1 (SKA1) of sGRB radio afterglows associated with BHNS mergers. We also investigate the benefits of a multimessenger analysis in inferring the properties of the merging binary. Methods. We simulate a population of BHNS mergers, making use of recent stellar population synthesis results, and estimate their sGRB afterglow flux to obtain the detection rates with SKA1. We investigate how this rate depends on the GW detector sensitivity, the primary black hole spin, and the NS EOS. We then perform a multimessenger Bayesian inference study on a fiducial BHNS merger. We simulate its sGRB afterglow and GW emission, as input to this study, using recent models for both and take systematic errors into account.Results. The expected rates of a combined GW and radio detection with the current generation GW detectors are likely low. Due to the much increased sensitivity of future GW detectors like the Einstein Telescope, the chances of an sGRB localisation and radio detection increase substantially. The unknown distribution of the BH spin has a big influence on the detection rates, however, and it is a large source of uncertainty. Furthermore, for our fiducial BHNS merger we are able to infer both the binary source parameters as well as the parameters of the sGRB afterglow simultaneously, when combining the GW and radio data. The radio data provides useful extra information on the binary parameters such as the mass ratio but this is limited by the systematic errors involved. Conclusions. The probability of finding an sGRB afterglow of a BHNS merger is low in the near future but rises significantly when the next generation GW detectors come online. Combining information from GW data with radio data is crucial to characterise the jet properties. A better understanding of the systematics will further increase the amount of information on the binary parameters that can be extracted from this radio data.

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Black hole-neutron star mergers are unlikely multi-messenger sources

Cited by 4 publications

References 60 publications

Impact of Massive Binary Star and Cosmic Evolution on Gravitational Wave Observations II: Double Compact Object Rates and Properties

Impact of Massive Binary Star and Cosmic Evolution on Gravitational Wave Observations II: Double Compact Object Rates and Properties

Multi-Messenger Constraints on Magnetic Fields in Merging Black Hole-Neutron Star Binaries

Investigating the detection rates and inference of gravitational-wave and radio emission from black hole neutron star mergers

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