Explanipedia

Gravitational Waves from Massive Black Hole Mergers in ASTRID: Predictions for LISA Open

Bonny Y. Wang, Yihao Zhou, W. Chen, Nianyi Chen, Tiziana DiMatteo , et al. · 2025

We use the ASTRID cosmological simulation to forecast massive black hole (MBH) mergers detectable by Laser Interferometer Space Antenna (LISA) down to z = 0. ASTRID directly models MBH dynamical friction, allowing a realistic tracking of t…

The Gravitational-wave Background from Massive Black Holes in the ASTRID Simulation Open

Nianyi Chen, Tiziana DiMatteo, Yihao Zhou, Luke Zoltan Kelley, Laura Blecha , et al. · 2025

Recent pulsar timing array (PTA) observations detected nanohertz gravitational waves, likely originating from massive black hole binaries (MBHBs). The detected amplitude is unexpectedly higher than inferred from the electromagnetic measure…

The Astrid Simulation: Evolution of Black Holes and Galaxies to <i>z</i> = 0.5 and Different Evolution Pathways for Galaxy Quenching Open

Yueying Ni, Nianyi Chen, Yihao Zhou, Minjung Park, Yanhui Yang , et al. · 2025

We present new results from the ASTRID simulation from z = 3 to z = 0.5, covering the epoch of cosmic noon. The galaxy stellar mass function, as well as the black hole mass and luminosity functions in ASTRID , exhibit good agreement with r…

Large-scale surveys of the quasar proximity effect Open

Rupert A. C. Croft, Patrick Shaw, Anthony Alexis, Nianyi Chen, Yihao Zhou , et al. · 2025

The UV radiation from high redshift quasars causes a local deficit in the neutral hydrogen absorption (Lyman-alpha forest) in their spectra, known as the proximity effect. Measurements from small samples of tens to hundreds of quasars have…

Central Cluster Galaxies: A Hot Spot for Detectable Gravitational Waves from Black Hole Mergers Open

Yihao Zhou, Tiziana DiMatteo, Nianyi Chen, Luke Zoltan Kelley, Laura Blecha , et al. · 2025

Since pulsar timing arrays (PTAs) announced the evidence for a low-frequency gravitational-wave (GW) background, continuous waves (CWs) have been the next anticipated GW signals. In this work, we model CW sources detectable by PTAs based o…

An AI super-resolution field emulator for cosmological hydrodynamics: the Lyman-α forest Open

Fatemeh Hafezianzadeh, Xiaowen Zhang, Yueying Ni, Rupert A. C. Croft, Tiziana DiMatteo , et al. · 2025

We extend our super-resolution and emulation framework for cosmological dark matter simulations to include hydrodynamics. We present a two-stage deep learning model to emulate high-resolution (HR-HydroSim) baryonic fields from low-resoluti…

The evolution of galaxy morphology from redshift z=6 to 3: Mock JWST observations of galaxies in the ASTRID simulation Open

Patrick A. LaChance, Rupert A. C. Croft, Yueying Ni, Nianyi Chen, Tiziana DiMatteo , et al. · 2025

We present mock JWST observations for more than 250,000 different galaxies from the Astrid simulation with . The mock observations are made using the BPASS stellar SED model, and a simple dust model. They are then viewed through NIR…

AI-assisted super-resolution cosmological simulations IV: An emulator for deterministic realizations Open

Xiaowen Zhang, Patrick Lachance, Ankita Dasgupta, Rupert A. C. Croft, Tiziana Di Matteo , et al. · 2025

Super-resolution (SR) models in cosmological simulations use deep learning (DL) to rapidly enhance low-resolution (LR) runs with statistically correct fine details. These models preserves large-scale structures by conditioning on an LR ver…

Central Cluster Galaxies: A Hotspot for Detectable Gravitational Waves from Black Hole Mergers Open

Yihao Zhou, Tiziana Di Matteo, Nianyi Chen, Luke Zoltan Kelley, Laura Blecha , et al. · 2025

After Pulsar Timing Arrays (PTAs) have announced the evidence for a low-frequency gravitational wave background (GWB), the continuous waves (CWs) are the next anticipated gravitational wave (GW) signals. In this work, we model CW sources d…

The Gravitational Wave Background from Massive Black Holes in the ASTRID Simulation Open

Nianyi Chen, Tiziana Di Matteo, Yihao Zhou, Luke Zoltan Kelley, Laura Blecha , et al. · 2025

Recent pulsar timing array (PTA) observations have detected nanohertz gravitational waves, likely originating from massive black hole binaries (MBHBs). The detected amplitude is unexpectedly higher than inferred from the electromagnetic me…

Forecasting the Detection of Lyman-alpha Forest Weak Lensing from the Dark Energy Spectroscopic Instrument and Other Future Surveys Open

Patrick Shaw, Rupert A. C. Croft, R. B. Metcalf · 2025

The apparent angular positions of quasars are deflected on the sky by the gravitational field sourced by foreground matter. This weak lensing effect is measurable through the distortions it introduces in the lensed quasar spectra. Discrepa…

Forecasting the Detection of Lyman-Alpha Forest Weak Lensing from the Dark Energy Spectroscopic Instrument and Other Future Surveys Open

Patrick Shaw, Rupert A. C. Croft, R. B. Metcalf · 2024

The apparent angular positions of quasars are deflected on the sky by the gravitational field sourced by foreground matter. This weak lensing effect is measurable through the distortions it introduces in the lensed quasar spectra. Discrepa…

z ∼ 2 dual AGN host galaxies are disky: stellar kinematics in the ASTRID Simulation Open

Ekaterine Dadiani, Tiziana Di Matteo, Nianyi Chen, Patrick Lachance, Yu‐Ching Chen , et al. · 2024

We study dual AGN host galaxy morphologies at using the ASTRID simulation, selecting black hole (BH) pairs with small separation (), high mass ( ), and luminosity (). We kinematically decompose (using MORDOR) dual AGN …

The Astrid Simulation: Evolution of black holes and galaxies to z=0.5 and different evolution pathways for galaxy quenching Open

Yueying Ni, Nianyi Chen, Yihao Zhou, Minjung Park, Yanhui Yang , et al. · 2024

We present new results from the ASTRID simulation from $z=3$ to $z=0.5$, covering the epoch of cosmic noon. The galaxy stellar mass function, as well as the black hole mass and luminosity functions in ASTRID, exhibit good agreement with re…

AI-assisted super-resolution cosmological simulations IV: An emulator for deterministic realizations Open

Xiaowen Zhang, Patrick Lachance, Ankita Dasgupta, Rupert A. C. Croft, Tiziana Di Matteo , et al. · 2024

Super-resolution (SR) models in cosmological simulations use deep learning (DL) to rapidly enhance low-resolution (LR) runs with statistically correct fine details. These models preserves large-scale structures by conditioning on an LR ver…

MAGICS I. The First Few Orbits Encode the Fate of Seed Massive Black Hole Pairs Open

Nianyi Chen, Diptajyoti Mukherjee, Tiziana Di Matteo, Yueying Ni, Simeon Bird , et al. · 2024

The elusive massive black hole (MBH) seeds stand to be revealed by the Laser Space Antenna Interferometer through mergers. As an aftermath of galaxy mergers, MBH coalescence is a vastly multi-scale process connected to galaxy formation. We…

The evolution of galaxy morphology from redshift z=6 to 3: Mock JWST observations of galaxies in the ASTRID simulation Open

Patrick A. LaChance, Rupert A. C. Croft, Yueying Ni, Nianyi Chen, Tiziana Di Matteo , et al. · 2024

We present mock JWST observations for more than 250,000 different galaxies from the Astrid simulation with $3 \leq z \leq 6$. The mock observations are made using the BPASS stellar SED model, and a simple dust model. They are then viewed t…

Modeling quasar proximity zones in a realistic cosmological environment with a self-consistent light curve Open

Yihao Zhou, Huanqing Chen, Tiziana Di Matteo, Yueying Ni, Rupert A. C. Croft , et al. · 2024

We study quasar proximity zones in a simulation that includes a self-consistent quasar formation model and realistic intergalactic medium (IGM) environments. The quasar host halo is 1013 M⊙ at z = 6, more massive than typical halos studied…

AI-assisted super-resolution cosmological simulations III: time evolution Open

Xiaowen Zhang, Patrick Lachance, Yueying Ni, Yin Li, Rupert A. C. Croft , et al. · 2023

In this work, we extend our recently developed super-resolution (SR) model for cosmological simulations to produce fully time-consistent evolving representations of the particle phase-space distribution. We employ a style-based constrained…

z~2 dual AGN host galaxies are disky: stellar kinematics in the ASTRID Simulation Open

Ekaterine Dadiani, Tiziana Di Matteo, Nianyi Chen, Patrick Lachance, Yue Shen , et al. · 2023

We study dual AGN host galaxy morphologies at $z=2$ using the ASTRID simulation, selecting black hole (BH) pairs with small separation ($Δr<30\rm{kpc}$), high mass ($M_{\text{BH,12}}>10^7M_\odot$), and luminosity ($L_{\text{bol,12}}>10^{43…

MAGICS I. The First Few Orbits Encode the Fate of Seed Massive Black Hole Pairs Open

Nianyi Chen, Diptajyoti Mukherjee, Tiziana Di Matteo, Yueying Ni, Simeon Bird , et al. · 2023

The elusive massive black hole (MBH) seeds stand to be revealed by the Laser Space Antenna Interferometer through mergers. As an aftermath of galaxy mergers, MBH coalescence is a vastly multi-scale process connected to galaxy formation. We…

The CAMELS Project: Expanding the Galaxy Formation Model Space with New ASTRID and 28-parameter TNG and SIMBA Suites Open

Yueying Ni, Shy Genel, Daniel Anglés‐Alcázar, Francisco Villaescusa-Navarro, Yongseok Jo , et al. · 2023

We present CAMELS-ASTRID, the third suite of hydrodynamical simulations in the Cosmology and Astrophysics with MachinE Learning (CAMELS) project, along with new simulation sets that extend the model parameter space based on the previous fr…

High-redshift supermassive black hole mergers in simulations with dynamical friction modelling Open

Colin DeGraf, Nianyi Chen, Yueying Ni, Tiziana Di Matteo, Simeon Bird , et al. · 2023

In the near future, projects like Laser Interferometer Space Antenna (LISA) and pulsar timing arrays are expected to detect gravitational waves from mergers between supermassive black holes, and it is crucial to precisely model the underly…

Modeling Quasar Proximity Zones in a Realistic Cosmological Environment with a Self-consistent Light Curve Open

Yihao Zhou, Huanqing Chen, Tiziana Di Matteo, Yueying Ni, Rupert A. C. Croft , et al. · 2023

We study quasar proximity zones in a simulation that includes a self-consistent quasar formation model and realistic IGM environments. The quasar host halo is $10^{13}\ M_{\mathrm{\odot}}$ at $z=6$, more massive than typical halos studied …

Flyby Galaxy Encounters with Multiple Black Holes Produce Star-forming Linear Features Open

Nianyi Chen, Patrick A. LaChance, Yueying Ni, Tiziana Di Matteo, Rupert A. C. Croft , et al. · 2023

We look for simulated star-forming linear features such as the one recently discovered by van Dokkum et al. in the cosmological hydrodynamical simulation ASTRID . Among the runaway black holes in ASTRID , none are able to produce clear sta…

Fly-by galaxy encounters with multiple black holes produce star-forming linear wakes Open

Nianyi Chen, Patrick A. LaChance, Yueying Ni, Tiziana Di Matteo, Rupert A. C. Croft , et al. · 2023

We look for simulated star-forming linear wakes such as the one recently discovered by van Dokkum et al. (2023) in the cosmological hydrodynamical simulation ASTRID. Amongst the runaway black holes in ASTRID, none are able to produce clear…

Efficient Reionization in a Large Hydrodynamic Galaxy Formation Simulation Open

J. Davies, Simeon Bird, Simon J. Mutch, Yueying Ni, Yu Feng , et al. · 2023

Accuracy in the topology and statistics of a simulated Epoch of Reionization (EoR) are vital to draw connections between observations and physical processes. While full radiative transfer models produce the most accurate reionization model…

PRIYA: A New Suite of Lyman-alpha Forest Simulations for Cosmology Open

Simeon Bird, Martin Fernandez, Ming-Feng Ho, Mahdi Qezlou, Reza Monadi , et al. · 2023

We present the PRIYA suite of cosmological simulations, based on the code and hydrodynamic model of the ASTRID simulation, and designed for cosmological analyses of the Lyman-$α$ forest. Our simulation suite spans a $9$-dimensional paramet…

AI-assisted super-resolution cosmological simulations III: Time evolution Open

Xiaowen Zhang, Patrick Lachance, Yueying Ni, Yin Li, Rupert A. C. Croft , et al. · 2023

In this work, we extend our recently developed super-resolution (SR) model for cosmological simulations to produce fully time consistent evolving representations of the particle phase-space distribution. We employ a style-based constrained…

The CAMELS project: Expanding the galaxy formation model space with new ASTRID and 28-parameter TNG and SIMBA suites Open

Yueying Ni, Shy Genel, Daniel Anglés‐Alcázar, Francisco Villaescusa-Navarro, Yongseok Jo , et al. · 2023

We present CAMELS-ASTRID, the third suite of hydrodynamical simulations in the Cosmology and Astrophysics with MachinE Learning (CAMELS) project, along with new simulation sets that extend the model parameter space based on the previous fr…

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