Tiziana Di Matteo
Professor Carnegie Mellon University
- Pittsburgh PA
Tiziana Di Matteo's research focuses on the study of black holes, encompassing a wide range of topics in high energy astrophysics.
Biography
Areas of Expertise
Media Appearances
ASTRID traces 13.5 billion years of black hole and galaxy evolution
Phys.org online
2026-08-27
"We have this very large simulation and piece of the universe, which captures the growth of black holes from the time at which they were formed all the way to today, as well as the galaxies that form, also from a very early time," said study co-author and ASTRID principal investigator Tiziana Di Matteo, professor of physics and director of CMU's McWilliams Center for Cosmology & Astrophysics.
Hubble Finds Double Quasar in Early Universe
Carnegie Mellon University News online
2023-05-04
“Understanding how black holes form, the first quasars emerge and how they grow along our cosmic histories is one of the greatest theoretical and observational challenges of modern astrophysics,” said Tiziana Di Matteo(opens in new window), professor of physics and director of Carnegie Mellon’s McWilliams Center for Cosmology(opens in new window).
Machine learning accelerates cosmological simulations
EurekAlert! online
2021-05-04
Carnegie Mellon University Physics Professors Tiziana Di Matteo and Rupert Croft, Flatiron Institute Research Fellow Yin Li, Carnegie Mellon Ph.D. candidate Yueying Ni, University of California Riverside Professor of Physics and Astronomy Simeon Bird and University of California Berkeley's Yu Feng surmounted this problem by teaching a machine learning algorithm based on neural networks to upgrade a simulation from low resolution to super resolution.
A taste of James Webb’s potential
Cosmos online
2020-10-17
To determine what Webb is expected to see, the team then used a state-of-the-art computer simulation called BlueTides, developed by a team led by Tiziana Di Matteo from Carnegie Mellon University (CMU) in Pittsburgh, US.
Simulation showing Milky Way-esque galaxy in early universe could prove cold dark matter theory
IBTimes online
2015-08-06
Tiziana Di Matteo, professor of physics at Carnegie Mellon, said: "It's awe inspiring to think that galaxies much like our own existed when the universe was so young. The deepest Hubble Space Telescope observations have thus far only covered small volumes of space and have found very irregular, clumpy galaxies at these early epochs.
Milky Way-like galaxies may have existed in the early universe
Phys.org online
2015-08-05
"It's awe inspiring to think that galaxies much like our own existed when the universe was so young," said Tiziana Di Matteo, professor of physics at Carnegie Mellon. "The deepest Hubble Space Telescope observations have thus only covered small volumes of space and have found very irregular, clumpy galaxies at these early epochs. It is not surprising that in these small volumes some of the small galaxies do not have regular morphologies like large disk galaxies. Similarly, numerical simulations have been limited in size so they have only made predictions for the smaller, clumpier galaxies at these early times."
Media
Industry Expertise
Accomplishments
Carnegie Science Award of Excellence
2008
Royal Astronomical Society Michael Penston Prize
1999
Education
University of Cambridge
Ph.D.
Astrophysics
1998
University College London
B.Sc.
Astrophysics
1995
Affiliations
- American Physical Society : Fellow
- LSST Dark Energy Sciente Collaboration, Cosmological Simulation Task Force : Member
- NSF XSEDE Resource Allocation Committee : Member
- Carnegie Science Center Awards of Excellence Committee : Member
Links
Articles
The ASTRID Simulation at z = 0: From Massive Black Holes to Large-scale Structure
The Astrophysical JournalYihao Zhou, Tiziana Di Matteo, Simeon Bird, Rupert Croft, Yueying Ni, Yanhui Yang, Nianyi Chen, Patrick Lachance, Xiaowen Zhang, Fatemeh Hafezianzadeh
2026-03-01
We present the z = 0 results for the cosmological simulation ASTRID. Hosting 2 × 55003 ≈ 0.33 trillion particles in a box of 370 Mpc per side, ASTRID is one of the largest cosmological hydrodynamic simulations evolved to z = 0. ASTRID features a large population of massive black holes (MBHs), covering a wide mass range 4 × 104 ∼ 2 × 1011 M⊙. The adopted dynamical friction model provides a relatively accurate description of MBH dynamics, making ASTRID a powerful tool to study MBH growth and mergers in a cosmological context. ASTRID successfully captures the coevolution of MBHs and their host galaxies, producing MBH–M⋆ and MBH–σ relations in good agreement with observations. Notably, ASTRID generates scatter in these relations that is more consistent with observations than previous simulations, indicating a more realistic MBH diversity. The galaxy stellar mass function at z = 0 is generally consistent with observational constraints. When dust attenuation is applied, the galaxy luminosity function also agrees well with observations, and the bimodality in galaxy colors is reproduced as well. ASTRID hosts a large population of massive galaxy groups and clusters: seven halos have M200c > 1015 M⊙, and 9709 halos have M200c > 1013 M⊙. We quantify the stellar mass content in these halos, and find that the correlations between the stellar and halo mass match well with observational constraints. Finally, we present the z = 0 power spectra of MBH and galaxies, as well as their bias with respect to the matter power spectrum. We find that MBHs with MBH ≥ 108 M⊙ and galaxies with M⋆ ≥ 1010.5 M⊙ serve as good tracers of large-scale structure.
Heavy Seeds and the First Black Holes: Insights from the BRAHMA Simulations
The Astrophysical JournalAklant K Bhowmick, Laura Blecha, Paul Torrey, Luke Zoltan Kelley, Priyamvada Natarajan, Rachel S Somerville, Rainer Weinberger, Alex M Garcia, Lars Hernquist, Tiziana Di Matteo, Jonathan Kho, Mark Vogelsberger
2026-02-01
From the luminous quasars at z ∼ 6 to the recent z ∼ 9–11 active galactic nuclei (AGN) revealed by JWST, observations of the earliest black hole (BH) populations can provide unique constraints on BH evolution. We use the BRAHMA simulations with constrained initial conditions to investigate BH assembly in extreme overdense regions. The simulations implement heavy ∼104–105 M⊙ seeds forming in dense, metal-poor gas exposed to sufficient Lyman–Werner flux. With gas accretion modeled via the Bondi–Hoyle formalism and BH dynamics with a subgrid dynamical friction scheme, we isolate the impact of seeding, dynamics, accretion, and feedback on BH evolution. With fiducial stellar and AGN feedback inherited from IllustrisTNG, accretion is suppressed at z ≳ 9, leaving mergers as the dominant growth channel. Gas accretion dominates at z ≲ 9, where permissive models (super-Eddington or low radiative efficiency) build ∼109 M⊙ BHs powering quasars by z ∼ 6, while stricter IllustrisTNG-based prescriptions yield much smaller BHs (∼106–108 M⊙). Our seed models strongly affect mergers at z ≳ 9: only the most lenient models (with ∼105 M⊙ seeds) produce enough BH mergers to reach ≳106 M⊙ by z ∼ 10, consistent with current estimates for GN-z11. Our dynamical friction model gives low merger efficiencies. Therefore, even in such extreme regions, we are unable to produce ≳107 M⊙ BHs by z ∼ 9–10, as currently inferred for GHZ9, UHZ1, and CAPERS-LRD-z9. If the BH-to-stellar mass ratios of these sources are indeed so extreme, they would require either very short BH merger timescales or reduced AGN thermal feedback. Weaker stellar feedback boosts both star formation and BH accretion and cannot raise these ratios.
Orbital and radiative properties of wandering intermediate-mass black holes in the ASTRID simulation
Monthly Notices of the Royal Astronomical Society2023
Intermediate-Mass Black Holes (IMBHs) of 103−106M⊙
are commonly found at the centre of dwarf galaxies. Simulations and observations convincingly show that a sizeable population of IMBHs could wander off-centre in galaxies. We use the cosmological simulation ASTRID to study the orbital and radiative properties of wandering IMBHs in massive galaxies at z ∼ 3.
Overmassive central black holes in the cosmological simulations ASTRID and Illustris TNG50
Monthly Notices of the Royal Astronomical Society2023
Recent dynamical measurements indicate the presence of a central supermassive black hole (SMBH) with mass ∼3×106M⊙
in the dwarf galaxy Leo I, placing the system ∼50 times above the standard, local MBH–M⋆ relation. While a few overmassive central SMBHs are reported in nearby isolated galaxies, this is the first one detected in a Milky Way satellite.
Statistics of Galactic-scale Quasar Pairs at Cosmic Noon
The Astrophysical Journal2023
The statistics of galactic-scale quasar pairs can elucidate our understanding of the dynamical evolution of supermassive black hole (SMBH) pairs, the duty cycles of quasar activity in mergers, or even the nature of dark matter, but they have been challenging to measure at cosmic noon, the prime epoch of massive galaxy and SMBH formation. Here we measure a double quasar fraction of ∼6.2 ± 0.5 × 10−4 integrated over ∼0farcs3–3'' separations (projected physical separations of ∼3–30 kpc at z ∼ 2) in luminous (Lbol > 1045.8 erg s−1) unobscured quasars at 1.5 < z < 3.5 using Gaia EDR3-resolved pairs around SDSS DR16 quasars.
Concordance between Observations and Simulations in the Evolution of the Mass Relation between Supermassive Black Holes and Their Host Galaxies
The Astrophysical Journal2022
We carry out a comparative analysis of the relation between the mass of supermassive black holes (BHs) and the stellar mass of their host galaxies at 0.2 < z < 1.7 using well-matched observations and multiple state-of-the-art simulations (e.g., MassiveBlackII, Horizon-AGN, Illustris, TNG, and a semianalytic model). The observed sample consists of 646 uniformly selected Sloan Digital Sky Survey quasars (0.2 < z < 0.8) and 32 broad-line active galactic nuclei (AGNs; 1.2 < z < 1.7) with imaging from Hyper Suprime-Cam (HSC) for the former and Hubble Space Telescope (HST) for the latter.
Unveiling the first seeds of supermassive black holes using cosmological simulations
Bulletin of the American Physical Society2022
Supermassive black holes are now believed to be at the centers of almost every massive galaxy in our Universe. Where and how did they form and grow to their observed masses (a million to tens of billion solar masses)? Unveiling the nature of their first "seeds" is a key science goal for current and future observational facilities such as JWST, LISA and Lynx. Predictions from cosmological hydrodynamic simulations are going to be crucial for using data from upcoming facilities to determine seeding mechanisms.
