Articles de revues : « Compact binary mergers »

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Beniamini, Paz, et Tsvi Piran. « Ultrafast Compact Binary Mergers ». Astrophysical Journal 966, n^o 1 (23 avril 2024) : 17. http://dx.doi.org/10.3847/1538-4357/ad32cd.

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Abstract The duration of orbital decay induced by gravitational waves (GWs) is often the bottleneck of the evolutionary phases going from star formation to a merger. We show here that kicks imparted to the newly born compact object during the second collapse generically result in a GW merger time distribution behaving like dN / d log t ∝ t 2 / 7 at short durations, leading to ultrafast mergers. Namely, a nonnegligible fraction of neutron star binaries, formed in this way, will merge on a timescale as short as 10 Myr, and a small fraction will merge even on a timescale less than 10 kyr. The results can be applied to different types of compact binaries. We discuss here the implications for binary neutron star mergers. These include unique short gamma-ray bursts (GRBs), eccentric and misaligned mergers, r-process enrichment in the very early Universe and in highly star-forming regions, and possible radio precursors. Interestingly, we conclude that among the few hundred short GRBs detected so far, a few must have formed via this ultrafast channel.

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Nitz, Alexander H., Collin D. Capano, Sumit Kumar, Yi-Fan Wang, Shilpa Kastha, Marlin Schäfer, Rahul Dhurkunde et Miriam Cabero. « 3-OGC : Catalog of Gravitational Waves from Compact-binary Mergers ». Astrophysical Journal 922, n^o 1 (1 novembre 2021) : 76. http://dx.doi.org/10.3847/1538-4357/ac1c03.

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Abstract We present the third open gravitational-wave catalog (3-OGC) of compact-binary coalescences, based on the analysis of the public LIGO and Virgo data from 2015 through 2019 (O1, O2, O3a). Our updated catalog includes a population of 57 observations, including 4 binary black hole mergers that had not been previously reported. This consists of 55 binary black hole mergers and the 2 binary neutron star mergers, GW170817 and GW190425. We find no additional significant binary neutron star or neutron star–black hole merger events. The most confident new detection is the binary black hole merger GW190925_232845, which was observed by the LIGO–Hanford and Virgo observatories with  astro > 0.99 ; its primary and secondary component masses are 20.2 − 2.5 + 3.9 M ⊙ and 15.6 − 2.6 + 2.1 M ⊙ , respectively. We estimate the parameters of all binary black hole events using an up-to-date waveform model that includes both subdominant harmonics and precession effects. To enable deep follow up as our understanding of the underlying populations evolves, we make available our comprehensive catalog of events, including the subthreshold population of candidates, and the posterior samples of our source parameter estimates.

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Hamilton, Chris, et Roman R. Rafikov. « Anatomy of a Slow Merger : Dissecting Secularly Driven Inspirals of LIGO/Virgo Gravitational Wave Sources ». Astrophysical Journal 939, n^o 1 (1 novembre 2022) : 48. http://dx.doi.org/10.3847/1538-4357/ac93f6.

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Abstract The dozens of compact object mergers detected by LIGO/Virgo raise a key theoretical question: how do initially wide binaries shrink sufficiently quickly that they are able to merge via gravitational wave (GW) radiation within a Hubble time? One promising class of answers involves secular driving of binary eccentricity by some external tidal perturbation. This perturbation can arise due to the presence of a tertiary point mass, in which case the system exhibits Lidov-Kozai (LK) dynamics, or it can stem from the tidal field of the stellar cluster in which the binary orbits. While these secular tide-driven mechanisms have been studied exhaustively in the case of no GW emission, when GWs are included the dynamical behavior is still incompletely understood. In this paper we consider compact object binaries driven to merger via high-eccentricity excitation by (doubly averaged, test-particle quadrupole level) cluster tides—which includes LK-driven mergers as a special case—and include the effects of both general relativistic precession and GW emission. We provide for the first time an analytical understanding of the different evolutionary stages of the binary’s semimajor axis, secular oscillation timescale, and phase-space structure all the way to merger. Our results will inform future population synthesis calculations of compact object binary mergers from hierarchical triples and stellar clusters.

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Lee, Chang‐Hwan, Hong‐Jo Park et Gerald E. Brown. « Mergers of Binary Compact Objects ». Astrophysical Journal 670, n^o 1 (20 novembre 2007) : 741–46. http://dx.doi.org/10.1086/521947.

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Domainko, W., et M. Ruffert. « Remnants of compact binary mergers ». Advances in Space Research 41, n^o 3 (janvier 2008) : 518–22. http://dx.doi.org/10.1016/j.asr.2006.11.030.

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Dobie, Dougal, Tara Murphy, David L. Kaplan, Kenta Hotokezaka, Juan Pablo Bonilla Ataides, Elizabeth K. Mahony et Elaine M. Sadler. « Radio afterglows from compact binary coalescences : prospects for next-generation telescopes ». Monthly Notices of the Royal Astronomical Society 505, n^o 2 (22 mai 2021) : 2647–61. http://dx.doi.org/10.1093/mnras/stab1468.

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ABSTRACT The detection of gravitational waves from a neutron star merger, GW170817, marked the dawn of a new era in time-domain astronomy. Monitoring of the radio emission produced by the merger, including high-resolution radio imaging, enabled measurements of merger properties including the energetics and inclination angle. In this work, we compare the capabilities of current and future gravitational wave facilities to the sensitivity of radio facilities to quantify the prospects for detecting the radio afterglows of gravitational wave events. We consider three observing strategies to identify future mergers – wide field follow-up, targeting galaxies within the merger localization and deep monitoring of known counterparts. We find that while planned radio facilities like the Square Kilometre Array will be capable of detecting mergers at gigaparsec distances, no facilities are sufficiently sensitive to detect mergers at the range of proposed third-generation gravitational wave detectors that would operate starting in the 2030s.

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Oh, Madeline, Maya Fishbach, Chase Kimball, Vicky Kalogera et Christine Ye. « The Role of Natal Kicks in Forming Asymmetric Compact Binary Mergers ». Astrophysical Journal 953, n^o 2 (1 août 2023) : 152. http://dx.doi.org/10.3847/1538-4357/ace349.

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Abstract In their most recent observing run, the LIGO-Virgo-KAGRA Collaboration observed gravitational waves from compact binary mergers with highly asymmetric mass ratios, including both binary black holes (BBHs) and neutron star-black holes (NSBHs). It appears that NSBHs with mass ratios q ≃ 0.2 are more common than equally asymmetric BBHs, but the reason for this remains unclear. We use the binary population synthesis code cosmic to investigate the evolutionary pathways leading to the formation and merger of asymmetric compact binaries. We find that within the context of isolated binary stellar evolution, most asymmetric mergers start off as asymmetric stellar binaries. Because of the initial asymmetry, these systems tend to first undergo a dynamically unstable mass transfer phase. However, after the first star collapses into a compact object, the mass ratio is close to unity and the second phase of mass transfer is usually stable. According to our simulations, this stable mass transfer fails to shrink the orbit enough on its own for the system to merge. Instead, the natal kick received by the second-born compact object during its collapse is key in determining how many of these systems can merge. For the most asymmetric systems with mass ratios of q ≤ 0.1, the merging systems in our models receive an average kick magnitude of 255 km s−1 during the second collapse, while the average kick for non-merging systems is 59 km s−1. Because lower mass compact objects, like neutron stars, are expected to receive larger natal kicks than higher mass BHs, this may explain why asymmetric NSBH systems merge more frequently than asymmetric BBH systems.

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Rowlinson, A., et G. E. Anderson. « Constraining coherent low-frequency radio flares from compact binary mergers ». Monthly Notices of the Royal Astronomical Society 489, n^o 3 (19 août 2019) : 3316–33. http://dx.doi.org/10.1093/mnras/stz2295.

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ABSTRACT The presence and detectability of coherent radio emission from compact binary mergers (containing at least one neutron star) remains poorly constrained due to large uncertainties in the models. These compact binary mergers may initially be detected as short gamma-ray bursts or via their gravitational wave emission. Several radio facilities have developed rapid response modes enabling them to trigger on these events and search for this emission. For this paper, we constrain this coherent radio emission using the deepest available constraints for GRB 150424A, which were obtained via a triggered observation with the Murchison Widefield Array. We then expand this analysis to determine the properties of magnetar merger remnants that may be formed via a general population of binary neutron star mergers. Our results demonstrate that many of the potential coherent emission mechanisms that have been proposed for such events can be detected or very tightly constrained by the complementary strategies used by the current generation of low-frequency radio telescopes.

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Glanz, Hila, et Hagai B. Perets. « Simulations of common envelope evolution in triple systems : circumstellar case ». Monthly Notices of the Royal Astronomical Society 500, n^o 2 (21 octobre 2020) : 1921–32. http://dx.doi.org/10.1093/mnras/staa3242.

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ABSTRACT The dynamical evolution of triple stellar systems could induce the formation of compact binaries and binary mergers. Common envelope (CE) evolution, which plays a major role in the evolution of compact binary systems, can similarly play a key role in the evolution of triples. Here, we use hydrodynamical simulations coupled with few-body dynamics to provide the first detailed models of the triple common envelope (TCE) evolution. We focus on the circumstellar case, where the envelope of an evolved giant engulfs a compact binary orbiting the giant, which then in-spirals into the core of the evolved star. Through our exploratory modelling, we find several possible outcomes of such TCE: the merger of the binary inside the third star’s envelope; the disruption of the in-spiralling binary following its plunge, leading to a chaotic triple dynamics of the stellar core and the two components of the former disrupted binary. The chaotic evolution typically leads to the in-spiral and merger of at least one of the former binary components with the core, and sometimes to the ejection of the second, or alternatively its further now-binary CE evolution. The in-spiral in TCE leads to overall slower in-spiral, larger mass ejection, and the production of more aspherical remnant, compared with a corresponding binary case of similar masses, due to the energy/momentum extraction from the inner-binary. We expect TCE to play a key role in producing various types of stellar-mergers and unique compact binary systems, and potentially induce transient electromagnetic and gravitational wave sources.

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Trani, Alessandro A. « Do three-body encounters in galactic nuclei affect compact binary merger rates ? » Proceedings of the International Astronomical Union 14, S351 (mai 2019) : 174–77. http://dx.doi.org/10.1017/s174392131900721x.

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AbstractHigh-density cusps of compact remnants are expected to form around supermassive black holes (SMBHs) in galactic nuclei via dynamical friction and two-body relaxation. Due to the high density, binaries in orbit around the SMBH can frequently undergo close encounters with compact remnants from the cusp. This can affect the gravitational wave merger rate of compact binaries in galactic nuclei. We investigated this process by means of high accuracy few-body simulations, performed with a novel Monte Carlo approach. We find that, around a SgrA*-like SMBH, three-body encounters increase the number of mergers by a factor of 3. This occurs because close encounters can reorient binaries with respect to their orbital plane around the SMBH, increasing the number of Kozai-Lidov induced mergers. We obtain a binary black hole merger rate of ГMW = 1.6 × 10−6 yr−1 per Milky Way-like nucleus.

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Deng, Can-Min. « The mass, spin, and rotational energy of the remnant black holes from compact binary mergers ». Monthly Notices of the Royal Astronomical Society 497, n^o 1 (9 juillet 2020) : 643–47. http://dx.doi.org/10.1093/mnras/staa1998.

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ABSTRACT Recently, many gravitational wave events from compact binary mergers have been detected by LIGO. Determining the final mass and spin of the remnant black holes (RBHs) is a fundamental issue and is also important in astrophysics. In this paper, unified models for predicting the final mass and spin of the RBHs from compact binary mergers is proposed. The models achieve a good accuracy within the parameter range of interest. In addition, the rotational energy of the RBHs is also studied that relevant to the electromagnetic counterparts of the mergers. It is found the distribution of the rotational energy of the RBHs from different types of mergers of compact binary has its own characteristics, which might help identify the electromagnetic counterparts associated with the mergers.

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Riley, Jeff, et Ilya Mandel. « Surrogate Forward Models for Population Inference on Compact Binary Mergers ». Astrophysical Journal 950, n^o 2 (1 juin 2023) : 80. http://dx.doi.org/10.3847/1538-4357/accf90.

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Abstract Rapidly growing catalogs of compact binary mergers from advanced gravitational wave detectors allow us to explore the astrophysics of massive stellar binaries. Merger observations can constrain the uncertain parameters that describe the underlying processes in the evolution of stars and binary systems in population models. In this paper, we demonstrate that binary black hole populations—in particular, their detection rates, chirp masses, and redshifts—can be used to measure cosmological parameters describing the redshift-dependent star formation rate and metallicity distribution. We present a method that uses artificial neural networks to emulate binary population synthesis computer models, and construct a fast, flexible, parallelizable surrogate model that we use for inference.

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Michaely, Erez, et Hagai B. Perets. « High rate of gravitational waves mergers from flyby perturbations of wide black hole triples in the field ». Monthly Notices of the Royal Astronomical Society 498, n^o 4 (9 septembre 2020) : 4924–35. http://dx.doi.org/10.1093/mnras/staa2720.

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ABSTRACT Ultrawide triple black holes (TBHs; with an outer orbit >103 au) in the field can be considerably perturbed by flyby encounters with field stars through the excitation of their outer orbit eccentricities. We study the cumulative effect of such flybys, and show them to be conductive for the production of gravitational-wave (GW) sources. Flyby encounters with TBHs can destabilize them, leading to binary–single resonant encounters between the outer black hole (BH) and the inner binary. These encounters can result in either a prompt GW merger of two of the TBH components during the resonant phase, or the disruption of the TBH. In the latter case, a more compact binary is left behind, while the third BH is ejected. Such compact remnant binaries may still inspiral through GW emission, producing delayed GW mergers, with a significant fraction of these merging in less than a Hubble time. We find a volumetric merger rate of ∼3–10 Gpc−3 yr−1 contributed by the (former) prompt-merger TBH channel and ${\sim} 100\!-\!250\,{\rm {\rm Gpc^{-3}\,yr^{-1}}}$ contributed by the (latter) delayed-merger TBH channel. The prompt channel gives rise to eccentric mergers in the aLIGO band, while the majority of the delayed GW mergers are circularized when enter the aLIGO band. We find the total eccentric volumetric merger rate to be ∼1–10 Gpc−3 yr−1 from both channels. We expect these mergers to show no significant spin–orbit alignment, and uniform delay-time distribution.

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Nitz, Alexander H., Sumit Kumar, Yi-Fan Wang, Shilpa Kastha, Shichao Wu, Marlin Schäfer, Rahul Dhurkunde et Collin D. Capano. « 4-OGC : Catalog of Gravitational Waves from Compact Binary Mergers ». Astrophysical Journal 946, n^o 2 (30 mars 2023) : 59. http://dx.doi.org/10.3847/1538-4357/aca591.

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Abstract We present the fourth Open Gravitational-wave Catalog (4-OGC) of binary neutron star (BNS), binary black hole (BBH), and neutron star–black hole (NSBH) mergers. The catalog includes observations from 2015 to 2020 covering the first through third observing runs (O1, O2, O3a, and O3b) of Advanced LIGO and Advanced Virgo. The updated catalog includes seven BBH mergers that were not previously reported with high significance during O3b for a total of 94 observations: 90 BBHs, 2 NSBHs, and 2 BNSs. The most confident new detection, GW200318_191337, has component masses 49.1 − 12.0 + 16.4 M ⊙ and 31.6 − 11.6 + 12.0 M ⊙ ; its redshift of 0.84 − 0.35 + 0.4 (90% credible interval) may make it the most distant merger so far. We estimate the merger rate of BBH sources, assuming a power-law mass distribution containing an additive Gaussian peak, to be 16.5 − 6.2 + 10.4 ( 25.0 − 8.0 + 12.6 ) Gpc−3 yr−1 at a redshift of z = 0 (0.2). For BNS and NSBH sources, we estimate a merger rate of 200 − 148 + 309 Gpc−3 yr−1 and 19 − 14 + 30 Gpc−3 yr−1, respectively, assuming the known sources are representative of the total population. We provide reference parameter estimates for each of these sources using an up-to-date model accounting for instrumental calibration uncertainty. The corresponding data release also includes our full set of subthreshold candidates.

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Rosswog, Stephan. « The multi-messenger picture of compact binary mergers ». International Journal of Modern Physics D 24, n^o 05 (18 mars 2015) : 1530012. http://dx.doi.org/10.1142/s0218271815300128.

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In the last decade, enormous progress has been achieved in the understanding of the various facets of coalescing double neutron star and neutron black hole binary systems. One hopes that the mergers of such compact binaries can be routinely detected with the advanced versions of the ground-based gravitational wave detector facilities, maybe as early as in 2016. From the theoretical side, there has also been mounting evidence that compact binary mergers could be major sources of heavy elements and these ideas have gained recent observational support from the detection of an event that has been interpreted as a "macronova", an electromagnetic transient powered by freshly produced, radioactively decaying heavy elements. In addition, compact binaries are the most plausible triggers of short gamma-ray bursts (sGRBs) and the last decade has witnessed the first detection of a sGRB afterglow and subsequent observations have delivered a wealth of information on the environments in which such bursts occur. To date, compact binary mergers can naturally explain most — though not all — of the observed sGRB properties. This paper reviews major recent developments in various areas related to compact binary mergers.

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Zevin, Michael, Anya E. Nugent, Susmita Adhikari, Wen-fai Fong, Daniel E. Holz et Luke Zoltan Kelley. « Observational Inference on the Delay Time Distribution of Short Gamma-Ray Bursts ». Astrophysical Journal Letters 940, n^o 1 (1 novembre 2022) : L18. http://dx.doi.org/10.3847/2041-8213/ac91cd.

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Abstract The delay time distribution of neutron star mergers provides critical insights into binary evolution processes and the merger rate evolution of compact object binaries. However, current observational constraints on this delay time distribution rely on the small sample of Galactic double neutron stars (with uncertain selection effects), a single multimessenger gravitational wave event, and indirect evidence of neutron star mergers based on r-process enrichment. We use a sample of 68 host galaxies of short gamma-ray bursts to place novel constraints on the delay time distribution and leverage this result to infer the merger rate evolution of compact object binaries containing neutron stars. We recover a power-law slope of α = − 1.83 − 0.39 + 0.35 (median and 90% credible interval) with α < −1.31 at 99% credibility, a minimum delay time of t min = 184 − 79 + 67 Myr with t min > 72 Myr at 99% credibility, and a maximum delay time constrained to t max > 7.95 Gyr at 99% credibility. We find these constraints to be broadly consistent with theoretical expectations, although our recovered power-law slope is substantially steeper than the conventional value of α = −1, and our minimum delay time is larger than the typically assumed value of 10 Myr. Pairing this cosmological probe of the fate of compact object binary systems with the Galactic population of double neutron stars will be crucial for understanding the unique selection effects governing both of these populations. In addition to probing a significantly larger redshift regime of neutron star mergers than possible with current gravitational wave detectors, complementing our results with future multimessenger gravitational wave events will also help determine if short gamma-ray bursts ubiquitously result from compact object binary mergers.

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Radice, David, Sebastiano Bernuzzi et Albino Perego. « The Dynamics of Binary Neutron Star Mergers and GW170817 ». Annual Review of Nuclear and Particle Science 70, n^o 1 (19 octobre 2020) : 95–119. http://dx.doi.org/10.1146/annurev-nucl-013120-114541.

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With the first observation of a binary neutron star merger through gravitational waves and light, GW170817, compact binary mergers have now taken the center stage in nuclear astrophysics. They are thought to be one of the main astrophysical sites of production of r-process elements, and merger observations have become a fundamental tool to constrain the properties of matter. Here, we review our current understanding of the dynamics of neutron star mergers in general and of GW170817 in particular. We discuss the physical processes governing the inspiral, merger, and postmerger evolution, and we highlight the connections between these processes, the dynamics, and the multimessenger observables. Finally, we discuss open questions and issues in the field and the need to address them through a combination of better theoretical models and new observations.

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Klencki, J., M. Moe, W. Gladysz, M. Chruslinska, D. E. Holz et K. Belczynski. « Impact of inter-correlated initial binary parameters on double black hole and neutron star mergers ». Astronomy & ; Astrophysics 619 (novembre 2018) : A77. http://dx.doi.org/10.1051/0004-6361/201833025.

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The distributions of the initial main-sequence binary parameters are one of the key ingredients in obtaining evolutionary predictions for compact binary (BH–BH/BH–NS/NS–NS) merger rates. Until now, such calculations were done under the assumption that initial binary parameter distributions were independent. For the first time, we implement empirically derived inter-correlated distributions of initial binary parameters primary mass (M1), mass ratio (q), orbital period (P), and eccentricity (e). Unexpectedly, the introduction of inter-correlated initial binary parameters leads to only a small decrease in the predicted merger rates by a factor of ≲2–3 relative to the previously used non-correlated initial distributions. The formation of compact object mergers in the isolated classical binary evolution favours initial binaries with stars of comparable masses (q ≈ 0.5–1) at intermediate orbital periods (log P (days) = 2–4). New distributions slightly shift the mass ratios towards lower values with respect to the previously used flat q distribution, which is the dominant effect decreasing the rates. New orbital periods (∼1.3 more initial systems within log P (days) = 2–4), together with new eccentricities (higher), only negligibly increase the number of progenitors of compact binary mergers. Additionally, we discuss the uncertainty of merger rate predictions associated with possible variations of the massive-star initial mass function (IMF). We argue that evolutionary calculations should be normalized to a star formation rate (SFR) that is obtained from the observed amount of UV light at wavelength 1500 Å (an SFR indicator). In this case, contrary to recent reports, the uncertainty of the IMF does not affect the rates by more than a factor of ∼2. Any change to the IMF slope for massive stars requires a change of SFR in a way that counteracts the impact of IMF variations on compact object merger rates. In contrast, we suggest that the uncertainty in cosmic SFR at low metallicity can be a significant factor at play.

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Piran, T., E. Nakar et S. Rosswog. « The electromagnetic signals of compact binary mergers ». Monthly Notices of the Royal Astronomical Society 430, n^o 3 (14 février 2013) : 2121–36. http://dx.doi.org/10.1093/mnras/stt037.

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Nakar, Ehud. « The electromagnetic counterparts of compact binary mergers ». Physics Reports 886 (novembre 2020) : 1–84. http://dx.doi.org/10.1016/j.physrep.2020.08.008.

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Tanaka, Masaomi. « Kilonova/Macronova Emission from Compact Binary Mergers ». Advances in Astronomy 2016 (2016) : 1–12. http://dx.doi.org/10.1155/2016/6341974.

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We review current understanding of kilonova/macronova emission from compact binary mergers (mergers of two neutron stars or a neutron star and a black hole). Kilonova/macronova is emission powered by radioactive decays ofr-process nuclei and it is one of the most promising electromagnetic counterparts of gravitational wave sources. Emission from the dynamical ejecta of ~0.01M⊙is likely to have a luminosity of ~1040–1041 erg s−1with a characteristic timescale of about 1 week. The spectral peak is located in red optical or near-infrared wavelengths. A subsequent accretion disk wind may provide an additional luminosity or an earlier/bluer emission if it is not absorbed by the precedent dynamical ejecta. The detection of near-infrared excess in short GRB 130603B and possible optical excess in GRB 060614 supports the concept of the kilonova/macronova scenario. At 200 Mpc distance, a typical peak brightness of kilonova/macronova with0.01M⊙ejecta is about 22 mag and the emission rapidly fades to >24 mag within ~10 days. Kilonova/macronova candidates can be distinguished from supernovae by (1) the faster time evolution, (2) fainter absolute magnitudes, and (3) redder colors. Since the high expansion velocity (v~0.1–0.2c) is a robust outcome of compact binary mergers, the detection of smooth spectra will be the smoking gun to conclusively identify the gravitational wave source.

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Fields, Jacob, Aviral Prakash, Matteo Breschi, David Radice, Sebastiano Bernuzzi et André da Silva Schneider. « Thermal Effects in Binary Neutron Star Mergers ». Astrophysical Journal Letters 952, n^o 2 (31 juillet 2023) : L36. http://dx.doi.org/10.3847/2041-8213/ace5b2.

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Abstract We study the impact of finite-temperature effects in numerical-relativity simulations of binary neutron star mergers with microphysical equations of state and neutrino transport in which we vary the effective nucleon masses in a controlled way. We find that, as the specific heat is increased, the merger remnants become colder and more compact due to the reduced thermal pressure support. Using a full Bayesian analysis, we demonstrate that this effect will be measurable in the postmerger gravitational wave signal with next-generation observatories at signal-to-noise ratios of 15.

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Nitz, Alexander H., et Tito Dal Canton. « Pre-merger Localization of Compact-binary Mergers with Third-generation Observatories ». Astrophysical Journal Letters 917, n^o 2 (1 août 2021) : L27. http://dx.doi.org/10.3847/2041-8213/ac1a75.

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Bhaskar, Hareesh Gautham, Gongjie Li et Douglas N. C. Lin. « Black Hole Mergers through Evection Resonances ». Astrophysical Journal 934, n^o 2 (1 août 2022) : 141. http://dx.doi.org/10.3847/1538-4357/ac7b26.

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Abstract Mechanisms have been proposed to enhance the merger rate of stellar-mass black hole binaries, such as the Von Zeipel–Lidov–Kozai mechanism (vZLK). However, high inclinations are required in order to greatly excite the eccentricity and to reduce the merger time through vZLK. Here, we propose a novel pathway through which compact binaries could merge due to eccentricity increase in general, including in a near coplanar configuration. Specifically, a compact binary migrating in an active galactic nucleus disk could be captured in an evection resonance, when the precession rate of the binary equals the orbital period around the supermassive black hole. In our study we include precession due to first-order post-Newtonian precession as well as that due to disk around one or both components of the binary. Eccentricity is excited when the binary sweeps through the resonance, which happens only when it migrates on a timescale 10–100 times the libration timescale of the resonance. Libration timescale decreases as the mass of the disk increases. The eccentricity excitation of the binary can reduce the merger timescale by up to a factor of ∼103−5.

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Neijssel, Coenraad J., Alejandro Vigna-Gómez, Simon Stevenson, Jim W. Barrett, Sebastian M. Gaebel, Floor S. Broekgaarden, Selma E. de Mink, Dorottya Szécsi, Serena Vinciguerra et Ilya Mandel. « The effect of the metallicity-specific star formation history on double compact object mergers ». Monthly Notices of the Royal Astronomical Society 490, n^o 3 (16 octobre 2019) : 3740–59. http://dx.doi.org/10.1093/mnras/stz2840.

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ABSTRACT We investigate the impact of uncertainty in the metallicity-specific star formation rate over cosmic time on predictions of the rates and masses of double compact object mergers observable through gravitational waves. We find that this uncertainty can change the predicted detectable merger rate by more than an order of magnitude, comparable to contributions from uncertain physical assumptions regarding binary evolution, such as mass transfer efficiency or supernova kicks. We statistically compare the results produced by the COMPAS population synthesis suite against a catalogue of gravitational-wave detections from the first two Advanced LIGO and Virgo observing runs. We find that the rate and chirp mass of observed binary black hole mergers can be well matched under our default evolutionary model with a star formation metallicity spread of 0.39 dex around a mean metallicity 〈Z〉 that scales with redshift z as 〈Z〉 = 0.035 × 10−0.23z, assuming a star formation rate of $0.01 \times (1+z)^{2.77} / (1+((1+z)/2.9)^{4.7}) \, \rm {M}_\odot$ Mpc−3 yr−1. Intriguingly, this default model predicts that 80 per cent of the approximately one binary black hole merger per day that will be detectable at design sensitivity will have formed through isolated binary evolution with only dynamically stable mass transfer, i.e. without experiencing a common-envelope event.

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Stachie, Cosmin, Tito Dal Canton, Nelson Christensen, Marie-Anne Bizouard, Michael Briggs, Eric Burns, Jordan Camp et Michael Coughlin. « Searches for Modulated γ-Ray Precursors to Compact Binary Mergers in Fermi-GBM Data ». Astrophysical Journal 930, n^o 1 (1 mai 2022) : 45. http://dx.doi.org/10.3847/1538-4357/ac5f53.

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Abstract GW170817 is the only gravitational-wave event for which a confirmed γ-ray counterpart, GRB 170817A, has been detected. Here, we present a method to search for another type of γ-ray signal, a γ-ray burst precursor, associated with a compact binary merger. If emitted shortly before the coalescence, a high-energy electromagnetic (EM) flash travels through a highly dynamical and relativistic environment, created by the two compact objects orbiting each other. Thus, the EM signal arriving at an Earth observer could present a somewhat predictable time-dependent modulation. We describe a targeted search method for light curves exhibiting such a modulation, parameterized by the observer-frame component masses and binary merger time, using Fermi-GBM data. The sensitivity of the method is assessed based on simulated signals added to GBM data. The method is then applied to a selection of potentially interesting compact binary mergers detected during the second (O2) and third (O3) observing runs of Advanced LIGO and Advanced Virgo. We find no significant modulated γ-ray precursor signal associated with any of the considered events.

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Smith, Rory J. E., Colm Talbot, Francisco Hernandez Vivanco et Eric Thrane. « Inferring the population properties of binary black holes from unresolved gravitational waves ». Monthly Notices of the Royal Astronomical Society 496, n^o 3 (10 juin 2020) : 3281–90. http://dx.doi.org/10.1093/mnras/staa1642.

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ABSTRACT The vast majority of compact binary mergers in the Universe produce gravitational waves that are too weak to yield unambiguous detections; they are unresolved. We present a method to infer the population properties of compact binaries – such as their merger rates, mass spectrum, and spin distribution – using both resolved and unresolved gravitational waves. By eliminating entirely the distinction between resolved and unresolved signals, we eliminate bias from selection effects. To demonstrate this method, we carry out a Monte Carlo study using an astrophysically motivated population of binary black holes. We show that some population properties of compact binaries are well constrained by unresolved signals after about one week of observation with Advanced LIGO at design sensitivity.

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Artale, M. Celeste, Michela Mapelli, Yann Bouffanais, Nicola Giacobbo, Mario Pasquato et Mario Spera. « Mass and star formation rate of the host galaxies of compact binary mergers across cosmic time ». Monthly Notices of the Royal Astronomical Society 491, n^o 3 (18 novembre 2019) : 3419–34. http://dx.doi.org/10.1093/mnras/stz3190.

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ABSTRACT We investigate the properties of the host galaxies of compact binary mergers across cosmic time, by means of population-synthesis simulations combined with galaxy catalogues from the eagle suite. We analyse the merger rate per galaxy of binary neutron stars (BNSs), black hole–neutron star binaries (BHNSs), and binary black holes (BBHs) from redshift zero up to six. The binary merger rate per galaxy strongly correlates with the stellar mass of the host galaxy at any redshift considered here. This correlation is significantly steeper for BNSs than for both BHNSs and BBHs. Moreover, we find that the merger rate per galaxy depends also on host galaxy’s star formation rate (SFR) and metallicity. We derive a robust fitting formula that relates the merger rate per galaxy with galaxy’s SFR, stellar mass, and metallicity at different redshifts. The typical masses of the host galaxies increase significantly as redshift decreases, as a consequence of the interplay between delay time distribution of compact binaries and cosmic assembly of galaxies. Finally, we study the evolution of the merger rate density with redshift. At low redshift (z ≤ 0.1) early-type galaxies give a larger contribution to the merger rate density than late-type galaxies. This trend reverts at z ≥ 1.

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Domainko, W., et M. Ruffert. « Long-term remnant evolution of compact binary mergers ». Astronomy & ; Astrophysics 444, n^o 2 (25 novembre 2005) : L33—L36. http://dx.doi.org/10.1051/0004-6361:200500204.

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Tang, Petra N., J. J. Eldridge, Elizabeth R. Stanway et J. C. Bray. « Dependence of gravitational wave transient rates on cosmic star formation and metallicity evolution history ». Monthly Notices of the Royal Astronomical Society : Letters 493, n^o 1 (6 janvier 2020) : L6—L10. http://dx.doi.org/10.1093/mnrasl/slz183.

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ABSTRACT We compare the impacts of uncertainties in both binary population synthesis models and the cosmic star formation history on the predicted rates of gravitational wave (GW) compact binary merger events. These uncertainties cause the predicted rates of GW events to vary by up to an order of magnitude. Varying the volume-averaged star formation rate density history of the Universe causes the weakest change to our predictions, while varying the metallicity evolution has the strongest effect. Double neutron star merger rates are more sensitive to assumed neutron star kick velocity than the cosmic star formation history. Varying certain parameters affects merger rates in different ways depending on the mass of the merging compact objects; thus some of the degeneracy may be broken by looking at all the event rates rather than restricting ourselves to one class of mergers.

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Gottlieb, Ore, Brian D. Metzger, Eliot Quataert, Danat Issa, Tia Martineau, Francois Foucart, Matthew D. Duez, Lawrence E. Kidder, Harald P. Pfeiffer et Mark A. Scheel. « A Unified Picture of Short and Long Gamma-Ray Bursts from Compact Binary Mergers ». Astrophysical Journal Letters 958, n^o 2 (29 novembre 2023) : L33. http://dx.doi.org/10.3847/2041-8213/ad096e.

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Abstract The recent detections of the ∼10 s long γ-ray bursts (GRBs) 211211A and 230307A followed by softer temporally extended emission (EE) and kilonovae point to a new GRB class. Using state-of-the-art first-principles simulations, we introduce a unifying theoretical framework that connects binary neutron star (BNS) and black hole–NS (BH–NS) merger populations with the fundamental physics governing compact binary GRBs (cbGRBs). For binaries with large total masses, M tot ≳ 2.8 M ⊙, the compact remnant created by the merger promptly collapses into a BH surrounded by an accretion disk. The duration of the pre-magnetically arrested disk (MAD) phase sets the duration of the roughly constant power cbGRB and could be influenced by the disk mass, M d . We show that massive disks (M d ≳ 0.1 M ⊙), which form for large binary mass ratios q ≳ 1.2 in BNS or q ≲ 3 in BH–NS mergers, inevitably produce 211211A-like long cbGRBs. Once the disk becomes MAD, the jet power drops with the mass accretion rate as M ̇ ∼ t − 2 , establishing the EE decay. Two scenarios are plausible for short cbGRBs. They can be powered by BHs with less massive disks, which form for other q values. Alternatively, for binaries with M tot ≲ 2.8 M ⊙, mergers should go through a hypermassive NS (HMNS) phase, as inferred for GW170817. Magnetized outflows from such HMNSs, which typically live for ≲1 s, offer an alternative progenitor for short cbGRBs. The first scenario is challenged by the bimodal GRB duration distribution and the fact that the Galactic BNS population peaks at sufficiently low masses that most mergers should go through an HMNS phase.

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Hanauske, Matthias, Jan Steinheimer, Anton Motornenko, Volodymyr Vovchenko, Luke Bovard, Elias R. Most, L. Jens Papenfort, Stefan Schramm et Horst Stöcker. « Neutron Star Mergers : Probing the EoS of Hot, Dense Matter by Gravitational Waves ». Particles 2, n^o 1 (2 janvier 2019) : 44–56. http://dx.doi.org/10.3390/particles2010004.

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Gravitational waves, electromagnetic radiation, and the emission of high energy particles probe the phase structure of the equation of state of dense matter produced at the crossroad of the closely related relativistic collisions of heavy ions and of binary neutron stars mergers. 3 + 1 dimensional special- and general relativistic hydrodynamic simulation studies reveal a unique window of opportunity to observe phase transitions in compressed baryon matter by laboratory based experiments and by astrophysical multimessenger observations. The astrophysical consequences of a hadron-quark phase transition in the interior of a compact star will be focused within this article. Especially with a future detection of the post-merger gravitational wave emission emanated from a binary neutron star merger event, it would be possible to explore the phase structure of quantum chromodynamics. The astrophysical observables of a hadron-quark phase transition in a single compact star system and binary hybrid star merger scenario will be summarized within this article. The FAIR facility at GSI Helmholtzzentrum allows one to study the universe in the laboratory, and several astrophysical signatures of the quark-gluon plasma have been found in relativistic collisions of heavy ions and will be explored in future experiments.

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Lamb, Gavin P., et Shiho Kobayashi. « Low-Γ jets from Compact Binary Mergers as Candidate Electromagnetic Counterparts to Gravitational Wave Sources ». Proceedings of the International Astronomical Union 12, S324 (septembre 2016) : 66–69. http://dx.doi.org/10.1017/s174392131601228x.

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AbstractCompact binary mergers, with neutron stars or neutron star and black-hole components, are thought to produce various electromagnetic counterparts: short gamma-ray bursts (GRBs) from ultra-relativistic jets followed by broadband afterglow; semi-isotropic kilonova from radioactive decay of r-process elements; and late time radio flares; etc. If the jets from such mergers follow a similar power-law distribution of Lorentz factors as other astrophysical jets then the population of merger jets will be dominated by low-Γ values. The prompt gamma-rays associated with short GRBs would be suppressed for a low-Γ jet and the jet energy will be released as X-ray/optical/radio transients when a shock forms in the ambient medium. Using Monte Carlo simulations, we study the properties of such transients as candidate electromagnetic counterparts to gravitational wave sources detectable by LIGO/Virgo. Approximately 78% of merger-jets result in failed GRB with optical peaks 14-22 magnitude and an all-sky rate of 2-3 per year.

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Brown, Stephanie M., Collin D. Capano et Badri Krishnan. « Using Gravitational Waves to Distinguish between Neutron Stars and Black Holes in Compact Binary Mergers ». Astrophysical Journal 941, n^o 1 (1 décembre 2022) : 98. http://dx.doi.org/10.3847/1538-4357/ac98fe.

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Abstract In 2017 August, the first detection of a binary neutron star merger, GW170817, made it possible to study neutron stars in compact binary systems using gravitational waves. Despite being the loudest gravitational-wave event detected to date (in terms of signal-to-noise ratio), it was not possible to unequivocally determine that GW170817 was caused by the merger of two neutron stars instead of two black holes from the gravitational-wave data alone. That distinction was primarily due to the accompanying electromagnetic counterpart. This raises the question: under what circumstances can gravitational-wave data alone, in the absence of an electromagnetic signal, be used to distinguish between different types of mergers? Here, we study whether a neutron star–black hole binary merger can be distinguished from a binary black hole merger using gravitational-wave data alone. We build on earlier results using chiral effective field theory to explore whether the data from LIGO and Virgo, LIGO A+, LIGO Voyager, the Einstein Telescope, or Cosmic Explorer could lead to such a distinction. The results suggest that the present LIGO–Virgo detector network will most likely be unable to distinguish between these systems even with the planned near-term upgrades. However, given an event with favorable parameters, third-generation instruments such as Cosmic Explorer will be capable of making this distinction. This result further strengthens the science case for third-generation detectors.

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Gallegos-Garcia, Monica, Christopher P. L. Berry et Vicky Kalogera. « Evolutionary Origins of Binary Neutron Star Mergers : Effects of Common Envelope Efficiency and Metallicity ». Astrophysical Journal 955, n^o 2 (26 septembre 2023) : 133. http://dx.doi.org/10.3847/1538-4357/ace434.

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Abstract The formation histories of compact binary mergers, especially stellar-mass binary black hole mergers, have recently come under increased scrutiny and revision. We revisit the question of the dominant formation channel and efficiency of forming binary neutron star (BNS) mergers. We use the stellar and binary evolution code MESA and implement a detailed method for common envelope and mass transfer. We perform simulations for donor masses between 7 M ⊙ and 20 M ⊙ with a neutron star (NS) companion of 1.4 M ⊙ and 2.0 M ⊙ at two metallicities, using varying common envelope efficiencies and two different prescriptions to determine if the donor undergoes core collapse or electron capture, given their helium and carbon–oxygen cores. In contrast to the case of binary black hole mergers, for an NS companion of 1.4 M ⊙, all BNS mergers are formed following a common envelope phase. For an NS mass of 2.0 M ⊙, we identify a small subset of mergers following only stable mass transfer if the NS receives a natal kick sampled from a Maxwellian distribution with velocity dispersion σ = 265 km s−1. Regardless of the supernova prescription, we find more BNS mergers at subsolar metallicity compared to solar.

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You, Zhi-Qiang, Gregory Ashton, Xing-Jiang Zhu, Eric Thrane et Zong-Hong Zhu. « Optimized localization for gravitational waves from merging binaries ». Monthly Notices of the Royal Astronomical Society 509, n^o 3 (23 octobre 2021) : 3957–65. http://dx.doi.org/10.1093/mnras/stab2977.

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ABSTRACT The Advanced LIGO and Virgo gravitational-wave observatories have opened a new window with which to study the inspiral and mergers of binary compact objects. These observations are most powerful when coordinated with multimessenger observations. This was underlined by the first observation of a binary neutron star merger GW170817, coincident with a short gamma-ray burst, GRB170817A, and the identification of the host galaxy NGC 4993 from the optical counterpart AT2017gfo. Finding the fast-fading optical counterpart critically depends on the rapid production of a sky map based on LIGO/Virgo data. Currently, a rapid initial sky map is produced, followed by a more accurate, high-latency, ${\gtrsim}{12}\, {\rm h}$ sky map. We study optimization choices of the Bayesian prior and signal model, which can be used alongside other approaches such as reduced order quadrature. We find these yield up to a $60{{\ \rm per\ cent}}$ reduction in the time required to produce the high-latency localization for binary neutron star mergers.

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Niino, Yuu, et Tomonori Totani. « Intracluster Short Gamma-Ray Bursts by Compact Binary Mergers ». Astrophysical Journal 677, n^o 1 (18 mars 2008) : L23—L26. http://dx.doi.org/10.1086/587460.

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Just, O., A. Bauswein, R. Ardevol Pulpillo, S. Goriely et H. T. Janka. « Comprehensive nucleosynthesis analysis for ejecta of compact binary mergers ». Monthly Notices of the Royal Astronomical Society 448, n^o 1 (5 février 2015) : 541–67. http://dx.doi.org/10.1093/mnras/stv009.

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Gallegos-Garcia, Monica, Christopher P. L. Berry, Pablo Marchant et Vicky Kalogera. « Binary Black Hole Formation with Detailed Modeling : Stable Mass Transfer Leads to Lower Merger Rates ». Astrophysical Journal 922, n^o 2 (24 novembre 2021) : 110. http://dx.doi.org/10.3847/1538-4357/ac2610.

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Abstract Rapid binary population synthesis codes are often used to investigate the evolution of compact-object binaries. They typically rely on analytical fits of single-star evolutionary tracks and parameterized models for interactive phases of evolution (e.g., mass transfer on a thermal timescale, determination of dynamical instability, and common envelope) that are crucial to predict the fate of binaries. These processes can be more carefully implemented in stellar structure and evolution codes such as MESA. To assess the impact of such improvements, we compare binary black hole mergers as predicted in models with the rapid binary population synthesis code COSMIC to models ran with MESA simulations through mass transfer and common-envelope treatment. We find that results significantly differ in terms of formation paths, the orbital periods and mass ratios of merging binary black holes, and consequently merger rates. While common-envelope evolution is the dominant formation channel in COSMIC, stable mass transfer dominates in our MESA models. Depending upon the black hole donor mass, and mass-transfer and common-envelope physics, at subsolar metallicity, COSMIC overproduces the number of binary black hole mergers by factors of 2–35 with a significant fraction of them having merger times orders of magnitude shorter than the binary black holes formed when using detailed MESA models. Therefore we find that some binary black hole merger rate predictions from rapid population syntheses of isolated binaries may be overestimated by factors of ∼ 5–500. We conclude that the interpretation of gravitational-wave observations requires the use of detailed treatment of these interactive binary phases.

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Amend, Benjamin, Jonathan Zrake et Dieter H. Hartmann. « R-process Rain from Binary Neutron Star Mergers in the Galactic Halo ». Astrophysical Journal 939, n^o 1 (1 novembre 2022) : 59. http://dx.doi.org/10.3847/1538-4357/ac951b.

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Abstract Compact binary mergers involving at least one neutron star are promising sites for the synthesis of the r-process elements found in stars and planets. However, mergers can take place at significant offsets from their host galaxies, with many occurring several kpc from star-forming regions. It is thus important to understand the physical mechanisms involved in transporting enriched material from merger sites in the galactic halo to the star-forming disk. We investigate these processes, starting from an explosive injection event and its interaction with the halo medium. We show that the total outflow mass in compact binary mergers is too low for the material to travel to the disk in a ballistic fashion. Instead, the enriched ejecta is swept into a shell, which decelerates over ≲10 pc scales and becomes corrugated by the Rayleigh–Taylor instability. The corrugated shell is denser than the ambient medium and breaks into clouds that sink toward the disk. These sinking clouds lose thermal energy through radiative cooling, and are also ablated by shearing instabilities. We present a dynamical heuristic that models these effects to predict the delay times for delivery to the disk. However, we find that turbulent mass ablation is extremely efficient and leads to the total fragmentation of sinking r-process clouds over ≲10 pc scales. We thus predict that enriched material from halo injection events quickly assimilates into the gas medium of the halo and that enriched mass flow to the disk could only be accomplished through turbulent diffusion or large-scale inflowing mass currents.

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Santoliquido, Filippo, Michela Mapelli, Nicola Giacobbo, Yann Bouffanais et M. Celeste Artale. « The cosmic merger rate density of compact objects : impact of star formation, metallicity, initial mass function, and binary evolution ». Monthly Notices of the Royal Astronomical Society 502, n^o 4 (3 février 2021) : 4877–89. http://dx.doi.org/10.1093/mnras/stab280.

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ABSTRACT We evaluate the redshift distribution of binary black hole (BBH), black hole–neutron star binary (BHNS), and binary neutron star (BNS) mergers, exploring the main sources of uncertainty: star formation rate (SFR) density, metallicity evolution, common envelope, mass transfer via Roche lobe overflow, natal kicks, core-collapse supernova model, and initial mass function. Among binary evolution processes, uncertainties on common envelope ejection have a major impact: the local merger rate density of BNSs varies from ∼103 to ∼20 Gpc−3 yr−1 if we change the common envelope efficiency parameter from αCE = 7 to 0.5, while the local merger rates of BBHs and BHNSs vary by a factor of ∼2–3. The BBH merger rate changes by one order of magnitude, when 1σ uncertainties on metallicity evolution are taken into account. In contrast, the BNS merger rate is almost insensitive to metallicity. Hence, BNSs are the ideal test bed to put constraints on uncertain binary evolution processes, such as common envelope and natal kicks. Only models assuming values of αCE ≳ 2 and moderately low natal kicks (depending on the ejected mass and the supernovae mechanism), result in a local BNS merger rate density within the 90 per cent credible interval inferred from the second gravitational-wave transient catalogue.

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Powell, Jade, Simon Stevenson, Ilya Mandel et Peter Tiňo. « Unmodelled clustering methods for gravitational wave populations of compact binary mergers ». Monthly Notices of the Royal Astronomical Society 488, n^o 3 (12 juillet 2019) : 3810–17. http://dx.doi.org/10.1093/mnras/stz1938.

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ABSTRACT The mass and spin distributions of compact binary gravitational-wave sources are currently uncertain due to complicated astrophysics involved in their formation. Multiple sub-populations of compact binaries representing different evolutionary scenarios may be present amongst sources detected by Advanced LIGO and Advanced Virgo. In addition to hierarchical modelling, unmodelled methods can aid in determining the number of sub-populations and their properties. In this paper, we apply Gaussian mixture model clustering to 1000 simulated gravitational-wave compact binary sources from a mixture of five sub-populations. Using both mass and spin as input parameters, we determine how many binary detections are needed to accurately determine the number of sub-populations and their mass and spin distributions. In the most difficult case that we consider, where two sub-populations have identical mass distributions but differ in their spin, which is poorly constrained by gravitational-wave detections, we find that ∼400 detections are needed before we can identify the correct number of sub-populations.

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Fragione, Giacomo, Nathan W. C. Leigh et Rosalba Perna. « Black hole and neutron star mergers in galactic nuclei : the role of triples ». Monthly Notices of the Royal Astronomical Society 488, n^o 2 (1 juillet 2019) : 2825–35. http://dx.doi.org/10.1093/mnras/stz1803.

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ABSTRACT Nuclear star clusters that surround supermassive black holes (SMBHs) in galactic nuclei are thought to contain large numbers of black holes (BHs) and neutron stars (NSs), a fraction of which form binaries and could merge by Kozai–Lidov oscillations (KL). Triple compact objects are likely to be present, given what is known about the multiplicity of massive stars, whose life ends either as an NS or a BH. In this paper, we present a new possible scenario for merging BHs and NSs in galactic nuclei. We study the evolution of a triple black hole (BH) or neutron star (NS) system orbiting an SMBH in a galactic nucleus by means of direct high-precision N-body simulations, including post-Newtonian terms. We find that the four-body dynamical interactions can increase the KL angle window for mergers compared to the binary case and make BH and NS binaries merge on shorter time-scales. We show that the merger fraction can be up to ∼5–8 times higher for triples than for binaries. Therefore, even if the triple fraction is only ∼10–$20\rm{\,per\,cent}$ of the binary fraction, they could contribute to the merger events observed by LIGO/VIRGO in comparable numbers.

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Vynatheya, Pavan, et Adrian S. Hamers. « How Important Is Secular Evolution for Black Hole and Neutron Star Mergers in 2+2 and 3+1 Quadruple-star Systems ? » Astrophysical Journal 926, n^o 2 (1 février 2022) : 195. http://dx.doi.org/10.3847/1538-4357/ac4892.

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Abstract Mergers of black holes (BHs) and neutron stars (NSs) result in the emission of gravitational waves that can be detected by LIGO. In this paper, we look at 2+2 and 3+1 quadruple-star systems, which are common among massive stars, the progenitors of BHs and NSs. We carry out a detailed population synthesis of quadruple systems using the Multiple Stellar Evolution code, which seamlessly takes into consideration stellar evolution, binary and tertiary interactions, N-body dynamics, and secular evolution. We find that, although secular evolution plays a role in compact object (BH and NS) mergers, (70–85)% (depending on the model assumptions) of the mergers are solely due to common envelope evolution. Significant eccentricities in the LIGO band (higher than 0.01) are only obtained with zero supernova (SN) kicks and are directly linked to the role of secular evolution. A similar outlier effect is seen in the χ eff distribution, with negative values obtained only with zero SN kicks. When kicks are taken into account, there are no systems that evolve into a quadruple consisting of four compact objects. For our fiducial model, we estimate the merger rates (in units of Gpc−3 yr−1) in 2+2 quadruples (3+1 quadruples) to be 10.8 ± 0.9 (2.9 ± 0.5), 5.7 ± 0.6 (1.4 ± 0.4), and 0.6 ± 0.2 (0.7 ± 0.3) for BH–BH, BH–NS, and NS–NS mergers, respectively. The BH–BH merger rates represent a significant fraction of the current LIGO rates, whereas the other merger rates fall short of LIGO estimates.

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Riley, Jeff, Ilya Mandel, Pablo Marchant, Ellen Butler, Kaila Nathaniel, Coenraad Neijssel, Spencer Shortt et Alejandro Vigna-Gómez. « Chemically homogeneous evolution : a rapid population synthesis approach ». Monthly Notices of the Royal Astronomical Society 505, n^o 1 (11 mai 2021) : 663–76. http://dx.doi.org/10.1093/mnras/stab1291.

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ABSTRACT We explore chemically homogeneous evolution (CHE) as a formation channel for massive merging binary black holes (BBHs). We develop methods to include CHE in a rapid binary population synthesis code, Compact Object Mergers: Population Astrophysics and Statistics (compas), which combines realistic models of binary evolution with cosmological models of the star formation history of the Universe. For the first time, we simultaneously explore conventional isolated binary star evolution under the same set of assumptions. This approach allows us to constrain population properties and make simultaneous predictions about the gravitational-wave detection rates of BBH mergers for the CHE and conventional formation channels. The overall mass distribution of detectable BBHs is consistent with existing gravitational-wave observations. We find that the CHE channel may yield up to ${\sim} 70{{\ \rm per\ cent}}$ of all gravitational-wave detections of BBH mergers coming from isolated binary evolution.

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Hamers, Adrian S., Hila Glanz et Patrick Neunteufel. « A Statistical View of the Stable and Unstable Roche Lobe Overflow of a Tertiary Star onto the Inner Binary in Triple Systems ». Astrophysical Journal Supplement Series 259, n^o 1 (1 mars 2022) : 25. http://dx.doi.org/10.3847/1538-4365/ac49e7.

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Abstract In compact stellar triple systems, an evolved tertiary star can overflow its Roche lobe around the inner binary. Subsequently, the tertiary star can transfer mass to the inner binary in a stable manner, or Roche lobe overflow (RLOF) can be unstable and lead to common-envelope (CE) evolution. In the latter case, the inner binary enters the extended envelope of the tertiary star and spirals in toward the donor’s core, potentially leading to mergers or ejections. Although studied in detail for individual systems, a comprehensive statistical view on the various outcomes of triple RLOF is lacking. Here, we carry out 105 population synthesis simulations of tight triples, self-consistently taking into account stellar evolution, binary interactions, and gravitational dynamics. Also included are prescriptions for the long-term evolution of stable triple mass transfer, and triple CE evolution. Although simple and ignoring hydrodynamic effects, these prescriptions allow for a qualitative statistical study. We find that triple RLOF occurs in ∼0.06% of all triple systems. Of these 0.06%, ∼64% of cases lead to stable mass transfer, and ∼36% to triple CE evolution. Triple CE is most often (∼76%) followed by one or multiple mergers in short succession, most likely an inner binary merger of two main-sequence stars. Other outcomes of triple CE are a binary+single system (∼23%, most of which do not involve exchange interactions), and a stable triple (∼1%). We also estimate the rate of type Ia supernovae involving white dwarf mergers following triple RLOF, but find only a negligible contribution.

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Artale, M. Celeste, Yann Bouffanais, Michela Mapelli, Nicola Giacobbo, Nadeen B. Sabha, Filippo Santoliquido, Mario Pasquato et Mario Spera. « An astrophysically motivated ranking criterion for low-latency electromagnetic follow-up of gravitational wave events ». Monthly Notices of the Royal Astronomical Society 495, n^o 2 (7 mai 2020) : 1841–52. http://dx.doi.org/10.1093/mnras/staa1252.

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ABSTRACT We investigate the properties of the host galaxies of compact binary mergers across cosmic time. To this end, we combine population synthesis simulations together with galaxy catalogues from the hydrodynamical cosmological simulation eagle to derive the properties of the host galaxies of binary neutron star (BNS), black hole-neutron star (BHNS), and binary black hole (BBH) mergers. Within this framework, we derive the host galaxy probability, i.e. the probability that a galaxy hosts a compact binary coalescence as a function of its stellar mass, star formation rate, Ks magnitude, and B magnitude. This quantity is particularly important for low-latency searches of gravitational wave (GW) sources as it provides a way to rank galaxies lying inside the credible region in the sky of a given GW detection, hence reducing the number of viable host candidates. Furthermore, even if no electromagnetic counterpart is detected, the proposed ranking criterion can still be used to classify the galaxies contained in the error box. Our results show that massive galaxies (or equivalently galaxies with a high luminosity in Ks band) have a higher probability of hosting BNS, BHNS, and BBH mergers. We provide the probabilities in a suitable format to be implemented in future low-latency searches.

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Li, Yan, et Rong-Feng Shen. « Estimates of the Early Electromagnetic Emission from Compact Binary Mergers ». Astrophysical Journal 911, n^o 2 (1 avril 2021) : 87. http://dx.doi.org/10.3847/1538-4357/abe462.

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Lee, William H. « Dynamical Evolution of v-cooled Disks Following Compact Binary Mergers ». International Astronomical Union Colloquium 192 (2005) : 497–501. http://dx.doi.org/10.1017/s0252921100009593.

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SummaryUnderstanding the dynamical evolution of post-merger accretion disks over a long timescale (comparable to their lifetimes) is essential to determine if these can power short GRBs. Here we present preliminary results of such a study, spanning 0.2 seconds, by using a realistic equation of state and taking into consideration the effects of neutrino cooling (the main agent, given the physical conditions in the disks).

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Salafia, O. S., G. Ghisellini et G. Ghirlanda. « Jet-driven and jet-less fireballs from compact binary mergers ». Monthly Notices of the Royal Astronomical Society : Letters 474, n^o 1 (6 décembre 2017) : L7—L11. http://dx.doi.org/10.1093/mnrasl/slx189.

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