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201 Publications visible to you, out of a total of 201
Hot Jupiter engulfment by an early red giant in 3D hydrodynamics

Abstract (Expand)

Hot Jupiters are gas giant planets with orbital periods of a few days and are found in 0.1–1% of Sun-like stars. They are expected to be engulfed during their host star’s radial expansion on the red … giant branch, which may account for observed rapidly rotating and chemically enriched giant stars. We performed 3D hydrodynamical simulations of hot Jupiter engulfment by a 1 M⊙, 4 R⊙ early red giant. Our ‘global’ simulations simultaneously resolve the stellar envelope and planetary structure, modelling the hot Jupiter as a polytropic gas sphere. The hot Jupiter spirals in due to ram-pressure drag. A substantial fraction of its mass is continuously ablated in this process, although the mass-loss rate is resolution dependent. We estimate that this could enhance the surface lithium abundance by up to ≈0.1 dex. The hot Jupiter is disrupted by a combination of ram pressure and tidal forces near the base of the convective envelope, with the deepest material penetrating to the radiative zone. The star experiences modest spin-up (∼1 km s−1), and engulfing a more massive companion may be required to produce a rapidly rotating giant. Drag heating near the surface and hydrogen recombination in the small amount of unbound ejecta recorded in the simulation could power an optical transient, although this needs to be confirmed by a calculation that has adequate resolution at the stellar surface.

Authors: Mike Y. M. Lau, Matteo Cantiello, Adam S. Jermyn, Morgan MacLeod, Ilya Mandel, Daniel J. Price

Date Published: 1st Feb 2025

Publication Type: Journal

The Lunar Gravitational-wave Antenna: mission studies and science case

Abstract

Not specified

Authors: Parameswaran Ajith, Pau Amaro Seoane, Manuel Arca Sedda, Riccardo Arcodia, Francesca Badaracco, Biswajit Banerjee, Enis Belgacem, Giovanni Benetti, Stefano Benetti, Alexey Bobrick, Alessandro Bonforte, Elisa Bortolas, Valentina Braito, Marica Branchesi, Adam Burrows, Enrico Cappellaro, Roberto Della Ceca, Chandrachur Chakraborty, Shreevathsa Chalathadka Subrahmanya, Michael W. Coughlin, Stefano Covino, Andrea Derdzinski, Aayushi Doshi, Maurizio Falanga, Stefano Foffa, Alessia Franchini, Alessandro Frigeri, Yoshifumi Futaana, Oliver Gerberding, Kiranjyot Gill, Matteo Di Giovanni, Ines Francesca Giudice, Margherita Giustini, Philipp Gläser, Jan Harms, Joris van Heijningen, Francesco Iacovelli, Bradley J. Kavanagh, Taichi Kawamura, Arun Kenath, Elisabeth-Adelheid Keppler, Chiaki Kobayashi, Goro Komatsu, Valeriya Korol, N. V. Krishnendu, Prayush Kumar, Francesco Longo, Michele Maggiore, Michele Mancarella, Andrea Maselli, Alessandra Mastrobuono-Battisti, Francesco Mazzarini, Andrea Melandri, Daniele Melini, Sabrina Menina, Giovanni Miniutti, Deeshani Mitra, Javier Morán-Fraile, Suvodip Mukherjee, Niccolò Muttoni, Marco Olivieri, Francesca Onori, Maria Alessandra Papa, Ferdinando Patat, Andrea Perali, Tsvi Piran, Silvia Piranomonte, Alberto Roper Pol, Masroor C. Pookkillath, R. Prasad, Vaishak Prasad, Alessandra De Rosa, Sourav Roy Chowdhury, Roberto Serafinelli, Alberto Sesana, Paola Severgnini, Angela Stallone, Jacopo Tissino, Hrvoje Tkalčić, Lina Tomasella, Martina Toscani, David Vartanyan, Cristian Vignali, Lucia Zaccarelli, Morgane Zeoli, Luciano Zuccarello

Date Published: 28th Jan 2025

Publication Type: Journal

Gravitational-wave model for neutron star merger remnants with supervised learning

Abstract (Expand)

We present a time-domain model for the gravitational waves emitted by equal-mass binary neutron star merger remnants for a fixed equation of state. We construct a large set of numerical relativity … simulations for a single equation of state consistent with current constraints, totaling 157 equal-mass binary neutron star merger configurations. The gravitational-wave model is constructed using the supervised learning method of K-nearest neighbor regression. As a first step toward developing a general model with supervised learning methods that accounts for the dependencies on equation of state and the binary masses of the system, we explore the impact of the size of the dataset on the model. We assess the accuracy of the model for a varied dataset size and number density in total binary mass. Specifically, we consider five training sets of simulations uniformly distributed in total binary mass. We evaluate the resulting models in terms of faithfulness using a test set of 30 additional simulations that are not used during training and which are equidistantly spaced in total binary mass. The models achieve faithfulness with maximum values in the range of 0.980 to 0.995. We assess our models simulating signals observed by the three-detector network of Advanced LIGO-Virgo. We find that all models with training sets of size equal to or larger than 40 achieve an unbiased measurement of the main gravitational-wave frequency. We confirm that our results do not depend qualitatively on the choice of the (fixed) equation of state. We conclude that training sets, with a minimum size of 40 simulations, or a number density of approximately 11 simulations per 0.1⁢𝑀⊙ of total binary mass, suffice for the construction of faithful templates for the postmerger signal for a single equation of state and equal-mass binaries, and lead to mean faithfulness values of ℱ ≃0.95. Our model being based on only one fixed equation of state represents only a first step toward a method that is fully applicable for gravitational-wave parameter estimation. However, our findings are encouraging since we show that our supervised learning model built on a set of simulations for a fixed equation of state successfully recovers the main gravitational-wave features of a simulated signal obtained using another equation of state. This may indicate that the extension of this model to an arbitrary equation of state may actually be achieved with a manageable set of simulations.

Authors: Theodoros Soultanis, Kiril Maltsev, Andreas Bauswein, Katerina Chatziioannou, Friedrich K. Röpke, Nikolaos Stergioulas

Date Published: 2025

Publication Type: Journal

Dusty Common Envelope Evolution

Abstract (Expand)

We present the first hydrodynamical simulations of common envelope evolution that include the formation of dust and the effect of radiation pressure on dust grains. We performed smoothed particle … hydrodynamics simulations of the CE evolution for two systems made of a 1.7 M⊙ and 3.7 M⊙ AGB star primary with a 0.6 M⊙ binary companion. The results of our calculations indicate that dust formation has a negligible impact on the gas dynamics essentially because dust forms in the already unbound material. The expansion and cooling of the envelope yield very early and highly efficient production of dust. In our formalism, which does not consider dust destruction, almost 100% of the available carbon that is not locked in CO condensates in dust grains. This massive dust production, thus, strongly depends on the envelope mass and composition, in particular, its C/O ratio, and has a considerable impact on the observational aspect of the object, resulting in a photospheric radius that is approximatively one order of magnitude larger than that of a non-dusty system.

Authors: Lionel Siess, Luis C. Bermúdez-Bustamante, Orsola De Marco, Daniel J. Price, Miguel González-Bolívar, Chunliang Mu, Mike Y. M. Lau, Ryosuke Hirai, Taïssa Danilovich

Date Published: 1st Dec 2024

Publication Type: Journal

Singularity-EOS: Performance Portable Equations of State and Mixed Cell Closures

Abstract (Expand)

We present Singularity-EOS, a new performance-portable library for equations of state and related capabilities. Singularity-EOS provides a large set of analytic equations of state, such as the Gruneisen … equation of state, and tabulated equation of state data under a unified interface. It also provides support capabilities around these equations of state, such as Python wrappers, solvers for finding pressure-temperature equilibrium between multiple equations of state, and a unique modifier framework, allowing the user to transform a base equation of state, for example by shifting or scaling the specific internal energy. All capabilities are performance portable, meaning they compile and run on both CPU and GPU for a wide variety of architectures.

Authors: Jonah M. Miller, Daniel A. Holladay, Jeffrey H. Peterson, Christopher M. Mauney, Richard Berger, Anna Pietarila Graham, Karen C. Tsai, Brandon Barker, Alexander Holas, Ann E. Mattsson, Mariam Gogilashvili, Joshua C. Dolence, Chad D. Meyer, Sriram Swaminarayan, Christoph Junghans

Date Published: 1st Nov 2024

Publication Type: Journal

From spherical stars to disk-like structures: 3D common-envelope evolution of massive binaries beyond inspiral

Abstract

Not specified

Authors: Marco Vetter, Friedrich K. Röpke, Fabian R. N. Schneider, Rüdiger Pakmor, Sebastian T. Ohlmann, Mike Y. M. Lau, Robert Andrassy

Date Published: 1st Nov 2024

Publication Type: Journal

Large-scale ordered magnetic fields generated in mergers of helium white dwarfs

Abstract

Not specified

Authors: Rüdiger Pakmor, Ingrid Pelisoli, Stephen Justham, Abinaya S. Rajamuthukumar, Friedrich K. Röpke, Fabian R. N. Schneider, Selma E. de Mink, Sebastian T. Ohlmann, Philipp Podsiadlowski, Javier Morán-Fraile, Marco Vetter, Robert Andrassy

Date Published: 1st Nov 2024

Publication Type: Journal

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