Explore the Data
Simulation Data Explorer
This is an interactive guide to the data products in the Renaissance simulations.
Click the sections below to explore the information found within the Region files and then within each Halo file.
Click the sections below to explore the information found within the Region files and then within each Halo file.
These regions are selected based on large-scale density variations and evolved
to different redshifts, providing a comparison of galaxy formation across environments.
→ Together, they sample overdense, average, and underdense cosmic regions (cosmic variance in structure formation).
→ Together, they sample overdense, average, and underdense cosmic regions (cosmic variance in structure formation).
Rarepeak Region
The Rarepeak region represents a high-density overdense environment
in the early universe where structure formation is accelerated.
Density Environment
→ Strong overdensity relative to the cosmic mean.
→ Leads to earlier gravitational collapse and rapid galaxy formation.
→ Leads to earlier gravitational collapse and rapid galaxy formation.
Evolution Timeline
→ Evolved to z ≈ 15 (earliest snapshot).
→ Captures the onset of galaxy formation in dense environments.
→ Captures the onset of galaxy formation in dense environments.
Halo Population
→ Dense environments produce many early-forming halos.
→ Massive halos form earlier compared to lower-density regions.
→ Massive halos form earlier compared to lower-density regions.
Normal Region
The Normal region represents an average-density environment,
typical of the large-scale structure of the universe.
Density Environment
→ Close to the cosmic mean density.
→ Produces a representative sample of galaxy formation.
→ Produces a representative sample of galaxy formation.
Evolution Timeline
→ Evolved to z ≈ 12.5.
→ Intermediate stage between early collapse and later growth.
→ Intermediate stage between early collapse and later growth.
Halo Population
→ Balanced population of low- and intermediate-mass halos.
→ Serves as a baseline for comparison across environments.
→ Serves as a baseline for comparison across environments.
Void Region
The Void region represents a low-density underdense environment
where structure formation is suppressed.
Density Environment
→ Significant underdensity relative to the cosmic mean.
→ Slower gravitational collapse and delayed galaxy formation.
→ Slower gravitational collapse and delayed galaxy formation.
Evolution Timeline
→ Evolved to z ≈ 8 (latest snapshot).
→ Simulations are evolved further in low-density regions, capturing later stages of galaxy growth.
→ Simulations are evolved further in low-density regions, capturing later stages of galaxy growth.
Halo Population
→ Fewer halos due to lower matter density.
→ Dominated by lower-mass, slowly evolving systems.
→ Dominated by lower-mass, slowly evolving systems.
Datasets → arrays (stars, gas, structure)
Attributes → single halo properties
Attributes → single halo properties
Spectral Data
These datasets describe how galaxies emit light across wavelength.
They are directly comparable to telescope observations (e.g. JWST)
and are used to infer physical properties such as star formation,
stellar age, dust content, and galaxy evolution.
SED_flux
→ 100 galaxies, each with a full spectrum sampled at 2500 wavelengths.
→ Observed brightness as a function of wavelength.
→ Directly comparable to telescope measurements (instrument-dependent).
→ Directly comparable to telescope measurements (instrument-dependent).
SED_flux_density
→ Same structure: 100 galaxies × 2500 wavelength bins.
→ Physical spectral energy distribution (SED).
→ Used for theoretical modeling and luminosity calculations.
→ Used for theoretical modeling and luminosity calculations.
SED_flux_with_noise
→ Same dimensions as SED_flux, with noise added to each wavelength.
→ Simulates real telescope observations.
→ Includes instrument and background noise.
→ Includes instrument and background noise.
SED_flux_density_with_noise
→ Same structure as SED_flux_density, with added noise.
→ Noisy version of the physical SED.
→ Used to test robustness of theoretical comparisons.
→ Used to test robustness of theoretical comparisons.
SED_wav_angstroms
→ 2500 wavelength values defining the spectral grid.
→ Defines the x-axis for spectra (Angstrom-based naming).
→ Shared across all galaxies.
→ Shared across all galaxies.
SED_wav_angstroms_with_noise
→ Same wavelength grid used for noisy spectral data.
→ Paired with noisy SED datasets.
→ Ensures consistent wavelength sampling.
→ Ensures consistent wavelength sampling.
SED_wav_microns
→ Same 2500 wavelength values expressed in microns.
→ Alternative unit representation of the wavelength grid.
→ Often more convenient for infrared astronomy (e.g. JWST).
→ Often more convenient for infrared astronomy (e.g. JWST).
SED_wav_microns_with_noise
→ Same micron-based grid used with noisy spectra.
→ Used alongside noisy SED datasets.
→ Maintains consistency in wavelength sampling.
→ Maintains consistency in wavelength sampling.
UV_continuum_slope
→ One value per galaxy.
→ Measures how UV brightness changes with wavelength.
→ Bluer slopes → younger, less dusty galaxies.
→ Bluer slopes → younger, less dusty galaxies.
UV_continuum_slope_error
→ Two values per galaxy (lower/upper uncertainty bounds).
→ Quantifies uncertainty in UV slope measurements.
→ Important for comparing to observational data.
→ Important for comparing to observational data.
UV_continuum_slope_with_noise
→ One value per galaxy, including observational noise.
→ Simulates measured UV slopes from telescopes.
→ Includes instrument + background noise effects.
→ Includes instrument + background noise effects.
UV_continuum_slope_error_with_noise
→ Uncertainty bounds for noisy UV slope measurements.
→ Reflects realistic observational uncertainties.
→ Used when comparing to survey data.
→ Used when comparing to survey data.
absolute_magnitude_UV
→ One intrinsic brightness value per galaxy.
→ Measures UV luminosity independent of distance.
→ Used in luminosity functions and galaxy evolution studies.
→ Used in luminosity functions and galaxy evolution studies.
absolute_magnitude_UV_with_noise
→ Same as above, with observational noise included.
→ Simulates real observed magnitudes.
→ Important for comparing simulations to telescope surveys.
→ Important for comparing simulations to telescope surveys.
Salpeter_IMF_SFR
→ One star formation rate value per galaxy.
→ Derived from UV emission assuming a Salpeter IMF.
→ Converts observed light into physical star formation activity.
→ Converts observed light into physical star formation activity.
Salpeter_IMF_SFR_with_noise
→ Same structure as above, with observational noise included.
→ Simulates real measured star formation rates.
→ Includes observational uncertainty and noise effects.
→ Includes observational uncertainty and noise effects.
Stellar Data
These datasets describe the individual star particles inside the halo.
Each entry corresponds to a star (or stellar population), including its
position, motion, mass, age, and chemical composition.
pop2_stellar_positions
→ N stars, each with (x, y, z) coordinates.
→ Defines the spatial distribution of stars in the halo.
→ Used to visualize galaxy structure.
→ Used to visualize galaxy structure.
pop2_stellar_velocities
→ N stars, each with velocity components (vx, vy, vz).
→ Describes how stars move within the galaxy.
→ Important for studying dynamics and rotation.
→ Important for studying dynamics and rotation.
pop2_stellar_masses
→ One mass value per star.
→ Determines how much mass is locked in stars.
→ Used to compute total stellar mass.
→ Used to compute total stellar mass.
pop2_stellar_age
→ One age value per star.
→ Tracks when stars formed.
→ Used to study star formation history.
→ Used to study star formation history.
pop2_metallicity_fraction
→ One metallicity value per star.
→ Measures chemical enrichment (elements heavier than helium).
→ Higher values → more evolved stellar populations.
→ Higher values → more evolved stellar populations.
pop2_stellar_angular_momentum
→ N stars, each with angular momentum vector (Lx, Ly, Lz).
→ Describes rotational motion of stars.
→ Used to study galaxy spin and structure.
→ Used to study galaxy spin and structure.
pop3_stellar_masses
→ One mass value per Population III star.
→ Represents first-generation stars (metal-free).
→ Important for early universe studies.
→ Important for early universe studies.
Halo & Gas Structure
These datasets describe the large-scale structure of the halo,
including its total gas content, spatial location, and overall rotation.
Unlike stellar data, these quantities represent the halo as a whole.
gas_mass
→ N gas elements, each with an associated mass.
→ Describes how gas mass is distributed throughout the halo.
→ Used to compute total gas mass and study baryonic structure.
→ Used to compute total gas mass and study baryonic structure.
position
→ Single (x, y, z) coordinate for the halo center.
→ Defines the location of the halo in the simulation volume.
→ Often used as the reference point for centering plots.
→ Often used as the reference point for centering plots.
angular_momentum
→ One vector (Lx, Ly, Lz) describing total halo angular momentum.
→ Measures the overall rotation of the halo.
→ Important for understanding galaxy formation and spin alignment.
→ Important for understanding galaxy formation and spin alignment.
Particle IDs
These datasets provide unique identifiers for particles in the simulation.
They are not physical quantities, but are used to track individual stars
and black holes across time and between datasets.
star_particle_IDs
→ One unique ID per star particle.
→ Used to track individual stars across simulation outputs.
→ Enables matching stars between different snapshots or datasets.
→ Enables matching stars between different snapshots or datasets.
bh_particle_IDs
→ One unique ID per black hole particle.
→ Tracks black holes within the simulation.
→ Useful for studying black hole growth and mergers.
→ Useful for studying black hole growth and mergers.
Global Properties
These attributes describe the halo as a whole, including its identity,
total mass, size, and overall structure. Unlike datasets, these are
single values per halo rather than arrays.
Identification
halo_ID
→ Internal ID of the halo in this snapshot.
unique_halo_ID
→ Unique identifier across the entire simulation.
unique_subhalo_ID
→ Identifier for substructure within the halo (if present).
Mass Properties
total_mass
→ Total mass of the halo (dark matter + gas + stars).
total_DM_mass
→ Total dark matter mass.
total_gas_mass
→ Total baryonic gas mass in the halo.
gas_fraction
→ Fraction of total mass that is gas.
Size & Structure
virial_radius
→ Radius enclosing the gravitationally bound halo.
half_stellar_mass_rad
→ Radius containing half of the stellar mass.
Angular Momentum
specific_stellar_angular_momentum
→ Average angular momentum per unit stellar mass.
Metadata
filename
→ Source simulation file for this halo.
Star Formation
These attributes describe how efficiently the halo forms stars and how
star formation has evolved over recent cosmic time.
Star Formation Rates
pop2_SFR_10Myr
→ Average star formation rate over the last 10 million years.
→ Traces very recent star formation activity.
→ Traces very recent star formation activity.
pop2_SFR_100Myr
→ Star formation rate averaged over 100 million years.
→ Smooths out short-term fluctuations.
→ Smooths out short-term fluctuations.
Specific Star Formation
pop2_sSFR_10Myr
→ Star formation rate per unit stellar mass (10 Myr timescale).
→ Measures how quickly the galaxy is growing relative to its size.
→ Measures how quickly the galaxy is growing relative to its size.
pop2_sSFR_100Myr
→ Same as above, averaged over 100 Myr.
→ Useful for comparing galaxies of different masses.
→ Useful for comparing galaxies of different masses.
Efficiency & Radiation
SFE
→ Star Formation Efficiency.
→ Fraction of gas converted into stars.
→ Fraction of gas converted into stars.
fesc
→ Escape fraction of radiation.
→ Fraction of stellar radiation that escapes the halo.
→ Fraction of stellar radiation that escapes the halo.
fcov
→ Gas covering fraction.
→ Fraction of sightlines blocked by gas within the halo.
→ Fraction of sightlines blocked by gas within the halo.
Gas Composition
These attributes describe the physical state of gas within the halo,
including how much is neutral, ionized, and available for star formation.
Gas Mass Components
total_gas_mass
→ Total gas mass in the halo.
→ Includes all phases of gas (hot, cold, ionized, neutral).
→ Includes all phases of gas (hot, cold, ionized, neutral).
total_cold_gas_mass
→ Mass of cold gas.
→ Cold gas is the primary fuel for star formation.
→ Cold gas is the primary fuel for star formation.
total_HI_mass
→ Mass of neutral hydrogen (HI).
→ Traces dense, star-forming regions.
→ Traces dense, star-forming regions.
total_HII_mass
→ Mass of ionized hydrogen (HII).
→ Indicates regions affected by radiation from stars.
→ Indicates regions affected by radiation from stars.
Evolution
These attributes describe the halo’s evolution over cosmic time,
including its current place in the universe and its merger history.
Cosmological Context
current_redshift
→ Redshift of the halo.
→ Indicates how early in the universe this halo exists (higher = earlier time).
→ Indicates how early in the universe this halo exists (higher = earlier time).
Merger History
last_major_merger
→ When the last major merger occurred.
→ Major mergers strongly influence galaxy structure and star formation.
→ Major mergers strongly influence galaxy structure and star formation.
last_major_merger_halo_mass
→ Mass of the halo involved in the last major merger.
→ Indicates how significant the merger event was.
→ Indicates how significant the merger event was.
Merger Tree Links
unique_desc_halo_ID
→ Identifier of the descendant halo in a later snapshot.
→ Used to track this halo forward in time.
→ Used to track this halo forward in time.
unique_desc_subhalo_ID
→ Identifier for the descendant subhalo.
→ Used for tracking substructure evolution.
→ Used for tracking substructure evolution.
Particle Counts
These attributes describe how many particles of each type exist in the halo,
as well as their total stellar mass. They provide a quick summary of the
galaxy’s composition.
Population II Stars
total_pop2_particles
→ Total number of Population II star particles.
→ Represents the bulk of normal stellar populations.
→ Represents the bulk of normal stellar populations.
total_pop2_stellar_mass
→ Total mass contained in Population II stars.
→ Used to estimate galaxy stellar mass.
→ Used to estimate galaxy stellar mass.
Population III Stars
total_pop3_particles
→ Number of Population III star particles.
→ Represents first-generation (metal-free) stars.
→ Represents first-generation (metal-free) stars.
total_pop3_star_particles
→ Alternate count of Population III star particles.
→ May overlap with total_pop3_particles depending on dataset.
→ May overlap with total_pop3_particles depending on dataset.
total_pop3_mass
→ Total mass in Population III stars.
→ Important for studying early universe star formation.
→ Important for studying early universe star formation.
Black Holes
total_bh_particles
→ Number of black hole particles in the halo.
→ Used to study black hole formation and growth.
→ Used to study black hole formation and growth.