Integral-field spectroscopy
Spatially resolved spectra measure stellar motion across an entire galaxy.
Research
Understanding the hidden structure of massive galaxies.
I combine spectroscopy, stellar kinematics, and computational modeling to learn how stars, dark matter, and supermassive black holes evolved together.
Galaxies remember how they grew.
Massive early-type galaxies sit within enormous dark-matter halos and preserve the cumulative effects of mergers, star formation, and orbital change.
Silvana studies fast-rotating members of the MASSIVE Survey. Their angular momentum, shape, and internal motion provide clues to why galaxies that appear similar today may have followed very different routes through cosmic time.
16fast-rotating MASSIVE galaxies in the doctoral sample
K-bandlight used to map stellar mass
Motion reveals mass.
A spectrum contains more than chemical fingerprints: its broadened absorption lines encode the speeds and directions of countless stars.
By fitting these stellar kinematics with Jeans Anisotropic Models and orbit-based methods, Silvana estimates mass-to-light ratios, orbital anisotropy, intrinsic shape, and the balance between visible and dark matter.
From photons to a model
Photometry maps the galaxy’s light. Integral-field spectroscopy measures motion across its face. Computational models then test which mass distributions reproduce those observations.
Measuring a galactic heart.
The gravity of a central black hole reshapes stellar or gas motion in the innermost region of a galaxy.
For NGC 2693, a fully triaxial orbit model produced a black-hole mass of 1.7 ± 0.4 billion times the mass of the Sun. Simpler symmetry assumptions preferred substantially different values, demonstrating why three-dimensional structure matters.
1.7 × 10⁹ M☉measured black-hole mass in NGC 2693
Mapping what does not shine.
Dark matter is detected through gravity: stars move differently when additional, invisible mass is present.
Modeling a galaxy across large radii helps separate the contributions of its stars, central black hole, and dark halo. That decomposition is essential for understanding both present-day structure and formation history.
A careful separation
The same observed motion can sometimes be explained by different combinations of stellar mass and dark matter. Broad spatial coverage and physically informed models help break that degeneracy.
Methods & tools
Observation meets computation.
The work crosses telescopes, spectra, mathematical models, and reproducible scientific software.
Dynamical modeling
JAM and triaxial orbit models connect observed kinematics to mass and shape.
Photometric structure
Multi-Gaussian Expansions translate a galaxy’s light into a model-ready description.
Scientific computing
Python, Linux, HPC pipelines, Bayesian sampling, pPXF, GALFIT, and reproducible workflows.
Selected projects
Questions at galaxy scale.
Fast-rotating MASSIVE galaxies
Dynamical analysis of 16 galaxies using CFHT/WIRCam K-band photometry and Mitchell Spectrograph kinematics to study stellar mass, dark matter, and orbital anisotropy.
The black hole in NGC 2693
A triaxial orbit-based measurement of black-hole mass and intrinsic galaxy shape using Gemini, Hubble, and Mitchell Spectrograph observations.
Galaxies across cosmic time
Projects spanning companions to high-redshift dusty galaxies, Milky Way analogs in the Dark Energy Survey, and astronomical instrumentation.