Article
Astronomy & Astrophysics
Diptajyoti Mukherjee, Qirong Zhu, Go Ogiya, Carl L. Rodriguez, Hy Trac
Summary: In this study, the impact of collisional relaxation of mass-segregated nuclear star clusters on the dynamics of massive black hole binaries is investigated using high-resolution N-body simulations. The results show that collisional relaxation can accelerate hardening in low mass ratio binaries but has the opposite effect in high mass ratio binaries.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Alessia Gualandris, Fazeel Mahmood Khan, Elisa Bortolas, Matteo Bonetti, Alberto Sesana, Peter Berczik, Kelly Holley-Bockelmann
Summary: Coalescing supermassive black hole binaries (BHBs) are expected to be the loudest sources of gravitational waves (GWs) in the Universe. However, the detection rates for ground or space-based detectors are highly uncertain due to the difficulty in modeling the BHB from merger to inspiral. The eccentricity of the binary is a key factor in determining the GW merger time-scale. Studies show that the initial orbit, dynamical friction phase, and stochastic encounters with stars all contribute to the evolution of the eccentricity. The binding phase of the black holes is characterized by strong perturbations, and the eccentricity changes differently in minor mergers compared to major mergers.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Imran Tariq Nasim, Cristobal Petrovich, Adam Nasim, Fani Dosopoulou, Fabio Antonini
Summary: This paper uses high-resolution N-body simulations to study the merger of two equal-mass galaxies hosting a central SMBH and the formation of SMBH binaries. The research findings suggest that binaries with high eccentricity quickly reverse their sense of rotation due to torque from the triaxial background mass distribution. This has significant implications for the detection of gravitational wave signals emitted by these systems.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Taeho Ryu, Alessandro A. Trani, Nathan W. C. Leigh
Summary: In this study, we investigate the effects of hard SMBHBs on the tidal disruption and direct capture events of stars using a large number of simulations. We find that the probability of full tidal disruption events can be significantly enhanced or suppressed by SMBHBs, depending on the binary parameters. Relativistic effects can further enhance the probability of full tidal disruption events. We also find that the probability of partial disruption events can be higher than that of full tidal disruption events.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Yonadav Barry Ginat, Taras Panamarev, Bence Kocsis, Hagai B. Perets
Summary: This paper presents an analytical model to investigate the phenomenon of resonant dynamical friction and reveals its connection with the singular behavior of the orbit-averaged equations of motion. The study shows that resonant dynamical friction occurs when the argument of the ascending node Omega of the disc stars aligns with that of the perturber Omega(p) with a phase difference of 90 degrees. Additionally, it is found that the rate at which the perturber's inclination decreases is proportional to its mass.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Giacomo Fragione, Rosalba Perna, Abraham Loeb
Summary: This paper discusses how tidal disruption events (TDEs) can offer a unique electromagnetic window into the assembly and merger of binary stellar-mass black holes and intermediate-mass black holes in nuclear star clusters. The predicted rate of TDEs in each galaxy is around 10(-6) to 10(-7) per year. The light curve of TDEs in nuclear star clusters may be interrupted and modulated by the companion black hole in the binary system.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Fazed Mahmood Khan, Kelly Holley-Bockelmann
Summary: Gravitational waves emitted by merging black holes with masses between approximately 10(4) and 10(7) solar masses can be detected by LISA with high signal-to-noise ratios. Studying intermediate-mass black holes (IMBHs) in dwarf galaxies, the research found that IMBHs in these environments form binaries quickly and efficiently merge due to interactions with nuclear star clusters. The study suggests that IMBHs in nucleated dwarf galaxies are promising sources for LISA observations and could be significant for the growth of IMBHs.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Giacomo Fragione, Abraham Loeb
Summary: The study estimated the distribution of recoil kicks imparted to merger remnants in gravitational wave events and determined their retention probability in various astrophysical environments depending on the maximum progenitor spin. The results show that only environments with escape speeds greater than or equal to 100 km/s can efficiently retain the remnants of LIGO/Virgo BBH mergers.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Mark D. Smith, Martin Bureau, Timothy A. Davis, Michele Cappellari, Lijie Liu, Kyoko Onishi, Satoru Iguchi, Eve North, Marc Sarzi
Summary: The study investigates the correlation between SMBH masses and CO line widths using resolved and unresolved methods, finding the tightest correlation with the resolved sample and a total scatter of 0.6 dex, mainly influenced by the intrinsic scatter of 0.5 dex. Additionally, a strong correlation is found between deprojected CO line widths and stellar velocity dispersions averaged within one effective radius.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Gergely Mathe, Akos Szolgyen, Bence Kocsis
Summary: Vector resonant relaxation (VRR) is the fastest gravitational process that shapes the stellar orbits in nuclear star clusters. It leads to the realignment of orbital planes on a time-scale of a few million years, while the eccentricity and semimajor axis of the individual orbits remain conserved. The distribution of orbital inclinations reaches an equilibrium characterized by the total potential energy and total angular momentum. Using a Monte Carlo Markov Chain method, the equilibrium distribution of orbital inclinations in isolated nuclear star clusters with a power-law distribution of orbital parameters is determined. The equilibria show anisotropic mass segregation, with more massive objects being more flattened.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Alessandra Mastrobuono-Battisti, Go Ogiya, Oliver Hahn, Mathias Schultheis
Summary: Galaxy mergers can lead to the formation of supermassive black hole binaries, especially when the black holes are embedded in a nuclear star cluster. This study demonstrates that the structural and dynamical properties of the cluster can be used to identify recently merged galaxies with potential central supermassive black hole binaries. Mergers can affect the shape, density profile, rotation, and velocity structure of the cluster, depending on the mass ratio and initial conditions of the merger. Additionally, mergers may contribute to the formation of the nuclear stellar disc in the galaxy.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
M. Sobolenko, P. Berczik, R. Spurzem
Summary: The hierarchical merging scenario is one mechanism leading to the creation of supermassive black holes, with the ultraluminous infrared galaxy NGC 6240 being one of the strongest SMBHB candidates. Dynamical calculations in dense stellar environments show that initial physical conditions can strongly affect merging time estimations, but within certain parameters, no strong correlation is found between merging time and mass ratios. This research sets an upper limit of around 55 Myr for the merging time of central SMBHBs.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
Yihuan Di, Yuan Li, Feng Yuan, Fangzheng Shi, Mirielle Caradonna
Summary: We conducted high-resolution hydrodynamical simulations using MACER framework to investigate SMBH feeding and feedback in a massive compact galaxy. Compared to a reference galaxy, the compact galaxy shows a higher inflow rate, resulting in stronger SMBH feeding and feedback, and a larger inflow-outflow structure.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Paige Ramsden, Daniel Lanning, Matt Nicholl, Sean L. McGee
Summary: This study investigates the relationship between supermassive black hole (SMBH) mass and host galaxy bulge mass using tidal disruption events (TDEs). The results show a positive correlation between SMBH and bulge mass, providing a way to estimate SMBH masses for large TDE samples without the need for follow-up observations or extrapolations.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Weichangfeng Guo, Daniel Williams, Ik Siong Heng, Hunter Gabbard, Yeong-Bok Bae, Gungwon Kang, Zong-Hong Zhu
Summary: In this study, we investigate the possibility of distinguishing between very short-lived gravitational wave signals from mergers between high-mass black holes and gravitational capture signals produced by a close encounter between two black holes. We compare the posterior probability distributions obtained from analyzing simulated signals from both scenarios under ideal and realistic conditions. Our results show that, while distinguishable under ideal conditions, these sources are indistinguishable under realistic conditions. This finding has important implications for the interpretation of short gravitational wave signals and calls for additional investigation.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Giacomo Fragione, Abraham Loeb, Bence Kocsis, Frederic A. Rasio
Summary: Repeated mergers of stellar-mass black holes in dense star clusters can lead to the formation of intermediate-mass black holes. These events can be detected through gravitational waves, providing an opportunity to study intermediate-mass black holes. Through numerical simulations and statistical analysis, the merger rates under different conditions have been determined, and the number of detections in ground-based and space-based observatories has been computed.
ASTROPHYSICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
Nathaniel W. H. Moore, Gongjie Li, Lee Hassenzahl, Erika R. R. Nesvold, Smadar Naoz, Fred C. C. Adams
Summary: HD 106906 is a planetary system with a wide-orbit companion and a eccentric and flat debris disk, providing important insights into its formation and evolution. Recent observations reveal that the companion has an eccentric and inclined orbit relative to the debris disk. It is found that the presence of the inclined companion causes rapid warping and puffiness of the debris disk, indicating a relatively recent configuration. The possibility of a recent close encounter with a free-floating planet is explored, which can explain the observed structure of the debris disk and the characteristics of the companion.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
Gergely Mathe, Akos Szolgyen, Bence Kocsis
Summary: Vector resonant relaxation (VRR) is the fastest gravitational process that shapes the stellar orbits in nuclear star clusters. It leads to the realignment of orbital planes on a time-scale of a few million years, while the eccentricity and semimajor axis of the individual orbits remain conserved. The distribution of orbital inclinations reaches an equilibrium characterized by the total potential energy and total angular momentum. Using a Monte Carlo Markov Chain method, the equilibrium distribution of orbital inclinations in isolated nuclear star clusters with a power-law distribution of orbital parameters is determined. The equilibria show anisotropic mass segregation, with more massive objects being more flattened.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Tjarda C. N. Boekholt, Connar Rowan, Bence Kocsis
Summary: Close encounters in a disc can result in orbital deflection, but within Jacobi volumes, temporary captures with multiple close encounters can occur. The dynamics of Jacobi captures were studied through three-body simulations, showing a Cantor-like set structure in phase space. The lifetime distribution decreases exponentially and the closest separation follows a power law. Applications include the Moon's Jacobi capture, where tidal captures and giant impacts are possible outcomes, and binary black hole formation in galactic nuclei, where dissipative Jacobi captures form an efficient channel for binary formation.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Gongjie Li, Hareesh Gautham Bhaskar, Bence Kocsis, Douglas N. C. Lin
Summary: This study investigates the impact of secular spin-orbit resonance on the evolution of stellar-mass black hole binaries around a supermassive black hole. It is found that spin-orbit resonance can lead to misalignment between the spins and orbits of the black holes, but the occurrence of such resonances is quite rare in AGN disks.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
Howard Chen, Gongjie Li, Adiv Paradise, Ravi K. Kopparapu
Summary: Climate modeling shows that tidally influenced terrestrial exoplanets, especially those orbiting M-dwarfs, have unique atmospheric dynamics and surface conditions that may increase their chances of hosting habitable environments. However, planetary interactions, such as mean motion resonances in compact planetary systems, can destabilize these exoplanets away from synchronized states. This study uses a three-dimensional N-rigid-body integrator and a general circulation model to simulate the climates of TRAPPIST-1 e and f under different orbital and spin evolution pathways. The results show that planets perturbed by mean motion resonances experience colder and drier conditions compared to their synchronized counterparts, while the differences in perturbed and synchronized planet e are minimal. These findings highlight the vulnerability of planets at the outer edge of habitable zones in compact multiplanet systems to global glaciations.
ASTROPHYSICAL JOURNAL LETTERS
(2023)
Review
Astronomy & Astrophysics
Manuel Arca Sedda, Smadar Naoz, Bence Kocsis
Summary: This review article discusses various mechanisms involved in the formation, evolution, and merger of compact object binaries (COBs) around quiescent supermassive black holes (SMBHs) and active galactic nuclei (AGNs) from a theoretical standpoint. It summarizes the main predictions for current and future gravitational wave (GW) detections and outlines the potential features that can indicate a galactic nuclei origin.
Article
Astronomy & Astrophysics
Thea H. Faridani, Smadar Naoz, Gongjie Li, Nicholas Inzunza
Summary: Short and ultrashort period planets, with periods as short as a few days, are influenced by gravitational perturbation from other planets in their multiplanet systems. This study shows that the evolving J (2) due to magnetic braking can affect the eccentricity and inclination of short-period planets, potentially leading to unstable configurations.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
William Lake, Smadar Naoz, Federico Marinacci, Blakesley Burkhart, Mark Vogelsberger, Claire E. Williams, Yeou S. Chiou, Gen Chiaki, Yurina Nakazato, Naoki Yoshida
Summary: Recent studies suggest that supersonically induced gas objects (SIGOs) formed in the early Universe could be the progenitors of globular clusters (GCs). SIGOs are capable of efficient star formation outside of dark matter halos and are subsequently accreted by these halos on short timescales. This finding suggests that SIGOs are capable of forming star clusters with properties similar to early Universe GCs.
ASTROPHYSICAL JOURNAL LETTERS
(2023)
Article
Astronomy & Astrophysics
Cheyanne Shariat, Smadar Naoz, Bradley M. S. Hansen, Isabel Angelo, Erez Michaely, Alexander P. Stephan
Summary: The Gaia mission has discovered a large number of white dwarfs (WDs) in triple configurations. This study investigates the dynamics of triple-stellar systems and their role in forming binary WD systems and cataclysmic variables. By simulating thousands of systems, the researchers find that the interaction between three bodies and stellar evolution is crucial in these processes. Comparing the results with Gaia observations, they estimate that at least 30% of solar-type stars within 200 parsecs were born in triple systems.
ASTROPHYSICAL JOURNAL LETTERS
(2023)
Article
Astronomy & Astrophysics
Camille R. Butkus, Alexandra O. Warren, Edwin S. Kite, Santiago Torres, Smadar Naoz, Jennifer B. Glass
Summary: Methane is a potential gaseous biosignature on rocky exoplanets, but the possibility of false positive abiotic production pathways needs to be evaluated. We modelled the abiotic methane production from graphite hydrogenation on Mercury and found negligible flux compared to biological methane flux on Earth. Graphite hydrogenation would only yield significant methane fluxes on exoplanets with high temperatures and ion fluxes that would make them inhospitable for life as we know it. Therefore, graphite hydrogenation by stellar wind can be ruled out as a potential false positive methane biosignature source.
Article
Astronomy & Astrophysics
Yonadav Barry Ginat, Taras Panamarev, Bence Kocsis, Hagai B. Perets
Summary: This paper presents an analytical model to investigate the phenomenon of resonant dynamical friction and reveals its connection with the singular behavior of the orbit-averaged equations of motion. The study shows that resonant dynamical friction occurs when the argument of the ascending node Omega of the disc stars aligns with that of the perturber Omega(p) with a phase difference of 90 degrees. Additionally, it is found that the rate at which the perturber's inclination decreases is proportional to its mass.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Connar Rowan, Tjarda Boekholt, Bence Kocsis, Zoltan Haiman
Summary: Motivated by the detections of merging black holes, this study investigates the merger of black hole binary systems in the discs of active galactic nuclei. Three-dimensional hydrodynamic simulations show that binary capture and subsequent hardening by surrounding gas are possible in a range of disc densities. The eccentricity evolution and merger timescale depend on the orbital rotation of the binaries.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
