DEMOBLACK Publications

Since November 2018

2021

Constraining accretion efficiency in massive binary stars with LIGO-Virgo black holes

The growing sample of LIGO-Virgo black holes (BHs) opens new perspectives for the study of massive binary evolution. Here, we study the impact of mass accretion efficiency on the properties of binary BH (BBH) mergers, by means of population synthesis simulations. We model mass accretion efficiency with the parameter fMT[0.05,1], which represents the fraction of mass lost from the donor which is effectively accreted by the companion. Lower values of fMT result in lower BBH merger rate densities and produce mass spectra skewed towards lower BH masses. Our hierarchical Bayesian analysis, applied to BBH mergers in the first and second observing run of LIGO-Virgo, yields almost zero support for values of fMT0.3. This result holds for all the values of the common-envelope efficiency parameter we considered in this study (αCE=1, 5 and 10). The lower boundaries of the 95% credible intervals are equal to fMT=0.40,0.45 and 0.48 for αCE=1, 5 and 10, respectively. This confirms that future gravitational-wave data can be used to put constraints on several uncertain binary evolution processes.

2020

Hierarchical mergers in young, globular and nuclear star clusters: black hole masses and merger rates

Hierarchical mergers are one of the distinctive signatures of binary black hole (BBH) formation through dynamical evolution. Here, we present a fast Monte Carlo approach to simulate hierarchical mergers in nuclear star clusters (NSCs), globular clusters (GCs) and young star clusters (YSCs). Hierarchical mergers are orders of magnitude more common in NSCs than they are in both GCs and YSCs, because of the different escape velocity. In our fiducial model, the fraction of hierarchical mergers over all mergers is 0.15, 6×103 and 104 in NSCs, GCs and YSCs, respectively. The mass distribution of hierarchical BBHs strongly depends on the properties of first-generation BBHs, such as their progenitor’s metallicity. In our fiducial model, we form black holes (BHs) with masses up to 103 M in NSCs and up to 102 M in both GCs and YSCs. When escape velocities in excess of 100 km s1 are considered, BHs with mass >103 M are allowed to form in NSCs. Hierarchical mergers lead to the formation of BHs in the pair instability mass gap and intermediate-mass BHs (IMBHs), but only in metal-poor environments. In our fiducial model, at metallicity Z0.0002, the fraction of BBH mergers with primary BH in the pair instability mass gap is 7×103, 3×104 and 5×106 in NSCs, GCs and YSCs, respectively. In metal-poor NSCs, the fraction of BBH mergers with primary mass in the IMBH regime is 5×104. The local BBH merger rate in our models ranges from 10 to 60 Gpc3 yr1; hierarchical BBHs in NSCs account for 1020.2 Gpc3 yr1, with a strong upper limit of 10 Gpc3 yr1

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Evolution of fractality and rotation in embedded star clusters

More and more observations indicate that young star clusters could retain imprints of their formation process. In particular, the degree of substructuring and rotation are possibly the direct result of the collapse of the parent molecular cloud from which these systems form. Such properties can, in principle, be washed-out, but they are also expected to have an impact on the relaxation of these systems. We ran and analysed a set of 10 hydrodynamical simulations of the formation of embedded star clusters through the collapse of turbulent massive molecular clouds. We systematically studied the fractality of our star clusters, showing that they are all extremely substructured (fractal dimension D = 1.0-1.8). We also found that fractality is slowly reduced, with time, on small scales, while it persists on large scales on longer time-scales. Signatures of rotation are found in different simulations at every time of the evolution, even for slightly supervirial substructures, proving that the parent molecular gas transfers part of its angular momentum to the new stellar systems.

Binary black hole mergers: formation and populations

We review the main physical processes that lead to the formation of stellar binary black holes (BBHs) and to their merger. BBHs can form from the isolated evolution of massive binary stars. The physics of core-collapse supernovae and the process of common envelope are two of the main sources of uncertainty about this formation channel. Alternatively, two black holes can form a binary by dynamical encounters in a dense star cluster. The dynamical formation channel leaves several imprints on the mass, spin and orbital properties of BBHs.

An astrophysically motivated ranking criterion for low-latency electromagnetic follow-up of gravitational wave events

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.

The cosmic merger rate density evolution of compact binaries formed in young star clusters and in isolated binaries

Santoliquido Filippo, Mapelli, Michela, Bouffanais Yann, Giacobbo Nicola, Di Carlo Ugo N., Rastello Sara, Artale M. Celeste, Ballone Alessandro, The cosmic merger rate density evolution of compact binaries formed in young star clusters and in isolated binaries, 2020, ApJ, 898, 152, https://ui.adsabs.harvard.edu/abs/2020ApJ…898..152S/abstract

Binary black holes in young star clusters: the impact of metallicity

Di Carlo Ugo N., Mapelli Michela, Giacobbo Nicola, Mario Spera, Yann Bouffanais, Sara Rastello, Filippo Santoliquido, Mario Pasquato, Alessandro Ballone, Alessandro A. Trani, Stefano Torniamenti, Francesco Haardt, Binary black holes in young star clusters: the impact of metallicity, 2020, MNRAS, 498, 495,
https://ui.adsabs.harvard.edu/abs/2020MNRAS.498..495D/abstract

 

Fingerprints of binary black hole formation channels encoded in the mass and spin of merger remnants

Arca Sedda Manuel, Mapelli Michela, Spera Mario, Benacquista Matthew, Giacobbo Nicola, Fingerprints of binary black hole formation channels encoded in the mass and spin of merger remnants, 2020, ApJ, submitted, https://ui.adsabs.harvard.edu/abs/2020arXiv200307409A/

Dynamics of black hole – neutron star binaries in young star clusters

Rastello Sara, Mapelli  Michela, Di Carlo Ugo N., Giacobbo Nicola, Santoliquido Filippo, Spera Mario, Ballone Alessandro, Dynamics of black hole – neutron star binaries in young star clusters, 2020, MNRAS, submitted, https://ui.adsabs.harvard.edu/abs/2020arXiv200302277R/ 

 

Impact of the Rotation and Compactness of Progenitors on the Mass of Black Holes

Mapelli Michela, Spera Mario, Montanari Enrico, Limongi Marco, Chieffi Alessandro, Giacobbo Nicola, Bressan Alessandro, Impact of the Rotation and Compactness of Progenitors on the Mass of Black Holes, 2020, ApJ, 888, 76, https://ui.adsabs.harvard.edu/abs/2020ApJ…888…76M/

Mass and star formation rate of the host galaxies of compact binary mergers across cosmic time

Artale M. Celeste, Mapelli Michela, Bouffanais Yann, Giacobbo Nicola, Spera Mario, Pasquato Mario, Mass and star formation rate of the host galaxies of compact binary mergers across cosmic time, 2020, MNRAS, 491, 3419, https://ui.adsabs.harvard.edu/abs/2020MNRAS.491.3419A/

Binary black holes in the pair-instability mass gap

Di Carlo Ugo N., Mapelli Michela, Bouffanais Yann, Giacobbo Nicola, Bressan Alessandro, Spera, Mario, Haardt, Francesco, Binary black holes in the pair-instability mass gap, MNRAS, submitted,

2019

Constraining the fraction of binary black holes formed in isolation and young star clusters with gravitational-wave data

Bouffanais Yann, Mapelli Michela, Gerosa Davide, Di Carlo Ugo N., Giacobbo Nicola, Berti Emanuele, Baibhav Vishal, Constraining the fraction of binary black holes formed in isolation and young star clusters with gravitational-wave data, 2019, ApJ, in press, http://ui.adsabs.harvard.edu/abs/2019arXiv190511054B

Gravitational-wave detection rates for compact binaries formed in isolation: LIGO/Virgo O3 and beyond

Baibhav Vishal, Berti Emanuele, Gerosa Davide, Mapelli Michela, Giacobbo Nicola, Bouffanais Yann, Di Carlo Ugo N., Gravitational-wave detection rates for compact binaries formed in isolation: LIGO/Virgo O3 and beyond, 2019, PhRvD, 100, 4060 ,

https://ui.adsabs.harvard.edu/abs/2019PhRvD.100f4060B/

PAPERS FROM OUR TEAM PUBLISHED BEFORE NOVEMBER 2018 BUT RELEVANT FOR DEMOBLACK SCIENCE

Before 2019

Constraining accretion efficiency in massive binary stars with LIGO-Virgo black holes

Host galaxies of merging compact objects: mass, star formation rate, metallicity, and colours

Artale M. Celeste, Mapelli Michela, Giacobbo Nicola, Sabha Nadeen B., Spera Mario, Santoliquido Filippo, Bressan Alessandro, Host galaxies of merging compact objects: mass, star formation rate, metallicity, and colours, 2019, MNRAS, 487, 1675, http://ui.adsabs.harvard.edu/abs/2019MNRAS.487.1675A

The host galaxies of double compact objects merging in the local Universe

Mapelli Michela, Giacobbo Nicola, Toffano Mattia, Ripamonti Emanuele, Bressan Alessandro, Spera Mario, Branchesi Marica, The host galaxies of double compact objects merging in the local Universe, MNRAS, 2018, MNRAS, 481, 5324, http://ui.adsabs.harvard.edu/abs/2018MNRAS.481.5324M

Merging black hole binaries: the effects of progenitor’s metallicity, mass-loss rate and Eddington factor

Giacobbo Nicola, Mapelli Michela, Spera Mario, Merging black hole binaries: the effects of progenitor’s metallicity, mass-loss rate and Eddington factor, 2018, MNRAS, 474, 2959, http://ui.adsabs.harvard.edu/abs/2018MNRAS.474.2959G

The formation and coalescence sites of the first gravitational wave events

Schneider Raffaella, Graziani Luca, Marassi Stefania, Spera Mario, Mapelli Michela, Alparone Matteo, de Bennassuti Matteo, The formation and coalescence sites of the first gravitational wave events, 2017, MNRAS Letters, 471, L105, http://ui.adsabs.harvard.edu/abs/2017MNRAS.471L.105S

Hierarchical black hole triples in young star clusters: impact of Kozai-Lidov resonance on mergers

Kimpson Thomas O., Spera Mario, Mapelli Michela, Ziosi Brunetto M., Hierarchical black hole triples in young star clusters: impact of Kozai-Lidov resonance on mergers, 2016, MNRAS, 463, 2443, http://ui.adsabs.harvard.edu/abs/2016MNRAS.463.2443K

Dynamics of stellar black holes in young star clusters with different metallicities – II. Black hole-black hole binaries

Ziosi Brunetto M., Mapelli Michela, Branchesi Marica, Tormen Giuseppe, Dynamics of stellar black holes in young star clusters with different metallicities – II. Black hole-black hole binaries, 2014, MNRAS, 441, 3703

http://ui.adsabs.harvard.edu/abs/2014MNRAS.441.3703Z

Dynamics of stellar black holes in young star clusters with different metallicities – I. Implications for X-ray binaries

Mapelli Michela, Zampieri Luca, Ripamonti Emanuele, Bressan Alessandro, Dynamics of stellar black holes in young star clusters with different metallicities – I. Implications for X-ray binaries, 2013, MNRAS, 429, 2298, http://ui.adsabs.harvard.edu/abs/2013MNRAS.429.2298M

Dynamics of massive stellar black holes in young star clusters and the displacement of ultra-luminous X-ray sources

Mapelli Michela, Ripamonti Emanuele, Zampieri Luca, Colpi Monica, Dynamics of massive stellar black holes in young star clusters and the displacement of ultra-luminous X-ray sources, 2011, MNRAS, 416, 1756, http://ui.adsabs.harvard.edu/abs/2011MNRAS.416.1756M